Rationing of work performed on machines with numerical control. Features of work rationing on CNC machines Auxiliary time on CNC machines
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CENTRAL BUREAU OF REGULATIONS FOR LABOR OF THE USSR STATE COMMITTEE ON LABOR AND SOCIAL ISSUES
GENERAL MACHINE-BUILDING STANDARDS FOR TIME AND CUTTING MODES for standardizing work performed on universal and multi-purpose machines with numerical control
STANDARDS OF TIME
MOSCOW ECONOMY 1990
The standards for time and cutting conditions were approved by the Decree of the State Committee of the USSR on Labor and Social Affairs and the Secretariat of the All-Union Central Council of Trade Unions of February 3, 1988 N9 54 / 3-72 and are recommended for use in machine-building enterprises.
Validity of standards until 1994
With the introduction of this collection, the General Machine Building Standards for the time and cutting conditions for work performed on machine tools with program control (MGNII Labor, 1980) are canceled.
The time standards and cutting modes (4.1 and L) were developed by the Central Bureau of Labor Standards, the Chelyabinsk Polytechnic Institute. Lenin Komsomol, Ryazan and Minsk branches of the institute "Orgstakkinprom" with the participation of regulatory research organizations, engineering enterprises.
The first part contains the standards of auxiliary time for the installation and removal of the part associated with the operation; for control measurements; for the maintenance of the workplace; breaks for rest and personal needs; time standards for setting up equipment; for tool setting outside the machine; a method for calculating service standards, time standards and output during multi-machine maintenance.
The second part contains the standards for cutting conditions and all data on the calculation of the main time and machine-auxiliary time, i.e. to calculate the cycle time of the automatic operation of the machine according to the program.
The standards for time and cutting conditions are designed to calculate the time standards for work performed on the most common types of universal and multi-purpose equipment with numerical control (CNC) used in mechanical engineering in medium and small batch production.
The standards for time and cutting conditions cover the work of machine tool adjusters and CNC manipulators, CNC machine operators, and toolmakers.
The publication is intended for standard setters and technologists, as well as other engineering and technical workers involved in the development of control programs and the calculation of technically justified maintenance standards, time and output for CNC machines.
At the end of the collection, a feedback form is placed, which is filled in by the enterprise, the organization and sent to the address of the CENT. 109028, Moscow, st. Solyanka, d. 3, building 3.
The provision of intersectoral normative and methodological materials on labor is carried out at the request of enterprises and organizations through the local bookselling network. Information about these publications is published in the Annotated Thematic Plans for the Release of Literature by the Ekonomika Publishing House and Bookselling Bulletins.
011(01)-90 ISBN 5-282-00697-9
KB - 32 - 76 - 89
© Central Bureau of Labor Standards of the USSR State Committee for Labor and Social Affairs (CBNT), 1990
The piece time for assembly, adjustment and disassembly of the kit ipprumepm n.i d> * tali operation is determined by the formula
^"Un* = C^shlr1 G ^"|u pr 2 * ^H1U|g)* (1*1 M
where T shlchzh - piece time for assembly, adjustment and disassembly of a set of tools for detail operation, min; n is the number of customizable ingtrums mu per dtalso-operation, pcs.; T t ... T w>fa - piece time for assembly, adjustment and ra:*Sx>rku of various types of tools included in the kit, min.
1.8. Tariffication of work should be carried out according to the Unified Tariff and Qualification Handbook of Works and Professions of Workers (Issue 2, approved by the Decree of the State Committee of the USSR on Labor and Social Issues and the All-Union Central Council of Trade Unions of January 16, 1985 No. 17 / 2-541, taking into account subsequent additions and changes to it The discrepancy between the qualifications of the worker and the established category of work cannot serve as a basis for any changes in the norms of time calculated according to the collection.
1.9. With the improvement of CNC machines and control systems, as well as in those cases, the cost of enterprises has already reached higher)! labor productivity with high-quality performance of work, reducing correction factors can be set to the time standards.
In cases where the local norms of time in force at the enterprises are less than those calculated according to the standards, the current norms should be left unchanged.
1.10. The time standards are put into effect in the manner prescribed by the “Regulations on the organization of labor rationing in the national | (0) economy”, approved by the decree of the USSR State Committee on Labor and Social Issues and the Presidium of the All-Union Central Council of Trade Unions dated June 19, 1986 No. 226 / II-6.
L11. To explain the procedure for using the time standards, examples of the calculation of the preparatory and final time and the piece tool setting time are given below.
Examples of calculating the norms of time, cutting modes and the time of automatic operation of the mill according to the program are given in Part II of the collection in the relevant sections.
1.12. Examples of calculating the norms of the preparatory-final time and piece tool setting time
1.12.1. Examples of calculating the norms of the auxiliary-^ final time
Initial data
1. The name of the operation is turning and turret.
2. Machine - CNC turret lathe.
3. Model of the machine - 1P426DFZ (diameter of the processed bar - 65 mm).
4. Model of the CNC device - "Electronics NTs-ZG, program carrier - memory.
5. The name of the part is the booster piston.
6. Processed material - steel 45, weight - 0.5 kg.
7. The method of installing the part is in a collet chuck.
8. Labor organization conditions: centralized delivery of blanks, tools, devices, documentation to the workplace and their delivery after processing a batch of parts; receiving briefing before starting to process the part. Group processing of parts is carried out (the collet chuck is not installed on the machine spindle).
The part processing program was compiled by a software engineer, entered into the memory of the CNC system by a turner-operator; the program contains 17 processed sizes.
9. Number of tools in setup - 5:
1. Cutter 2120-4007 T15K6 (grooving).
2. Cutter 2102-0009 (through thrust).
3. Special cutter (groove).
4. Cutter 2130-0153 T15K6 (cut-off).
5. Drill 2301-0028 (hole 010).
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Trial Processing 6 Detail accurate (has surfaces with tolerances for diameters over the 11th grade, grooves) for "four tools and four measured Map 29, 8.8 according to the diameter of the surfaces (two outer surfaces: pos. 27, 0 50.3 MO and O 203 MO; one groove b = 6; ind. G; note- single groove-groove 0 30 chan 2, 3 |
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Map 29, 8.8+t
note 1
Total preparatory and final time for a batch of parts
1. The name of the operation is turning and carousel.
4. Model of the CNC-N55-2 device, program carrier - punched tape.
5. Part name - flange. "l.
6. Processed material - ~ SCH20 cast iron, weight -1500 kg.
7. The installation method of the part is in four cams with boxes, each is fixed with six bolts on the faceplate of the machine.
8. Conditions of labor organization: the delivery of tools, fixtures, documentation, blanks to the workplace and their delivery after the processing of a batch of parts is carried out by the operator (adjuster).
The tool on the device for setting outside the machine is not pre-set.
9. Number of tools in setup - 4 (including one grooving cutter, tools 1 and 2 - from the previous setup):
1. Cutter 2102-0031VK8 (through).
2. Cutter 2141-0059 VK8 (boring).
3. Cutter 2140-0048 VK8 (boring).
4. Cutter NZH212-5043 (groove).
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Trial* processing Precision part (has surfaces with tolerances for diameters over the 11th qualifier, a groove) Grooving - one tool, one groove (08ООН9Х07ОО) boring and turning of external and internal surfaces - three tools, three changeable surface diameters - 0 1150h9.0 800H9, Map 30, pos 49, ind. a Map 30, pos. 5, inl. c, all Map 30, note 1 25,5 0,85 - 21,7 263 |
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I t o g o T
Total preparation and closing time per batch of parts
Tn-T u1 + Tn a + T yarv ^ 91.9
Initial data
1. The name of the operation is turning.
Z Machine - CNC lathe.
3. Machine model - 1P756DFZ (the largest diameter of the product installed above the bed is 630 mm).
4. Model of the CNC device - 2S85, program carrier - punched tape, memory.
5. Part name - flange.
6. Processed material - SCH25 cast iron, weight - 90 kg.
7. The method of installing the part is in a three-jaw chuck.
8. Conditions for the organization of labor: delivery * / to the workplace of tools, fixtures, documentation, blanks and their delivery after processing a batch of parts is carried out by the operator (adjuster). Group processing of parts is carried out (a sinful chuck is not installed on the machine spindle).
The part processing program was compiled by a software engineer, entered into the memory of the CNC system by a turner-operator. The program contains 20 processed sizes.
settings):
1. Cutter 2102-0005 (through thrust).
2. Cutter 2141-0604 (boring).
3. Cutter 2141-0611 (boring).
4. Cutter NZh 2126-5043 (groove).
5 Number of tools in setup - 4 (tools 1 and 2 - from the previous
Map, police, index
Time, missions
*1.0
1 Organizational preparation
Map 21. by 1). 2,3,4, incl. P
tions and their delivery after processing a batch of parts; receiving briefing before starting the processing of parts; The assembly of the tool is carried out in a special area for setting up tools of CNC machines.
9. Number of tools in setup - 25 (four tools: 1.12, 24.25 - from the previous setup):
1. End mill 6221-106.005 (planes 800x800).
2. Semi-finishing cutter (hole 0 259.0).
3. Finishing cutter (hole 0259DN9).
4. Semi-finishing cutter (hole 0169.0).
5. Finishing cutter (hole 0169.5H9).
6. Roughing cutter (hole 0 89).
7. Semi-finishing cutter (hole 0 89.5).
8. Finishing cutter (hole 0 90js6).
9. Roughing cutter (hole 0 79).
10. Semi-finishing cutter (hole 0 79.5).
1L Finishing cutter (hole 0 80js6).
12. Disc cutter 2215-0001VK8 (understatement 0 205).
13. Roughing cutter (hole 0 99).
14. Semi-finishing cutter (hole 0 99.5).
15. Finishing cutter (hole 0100js6).
16. Semi-finishing cutter (undercut 0130).
17. Drill 23004-200 (hole Ø 8.6).
18. Tap 26804Yu03 (K1/8" thread).
19. Drill 2301-0046 (hole 014).
20. Drill 2301-0050 (hole 015).
21. Zenker 2320-2373 No. 1VK8 (hole 015.5).
22. Reamer 2363-0050H9 (hole 015.95H9).
23. Reamer 2363-00550H7 (hole 016H7).
24. Drill 2317-0006 (centering).
25. Drill 2301-0061 (chamfers).
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Karga, position, index |
Time, min |
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Organizational preparation Total T P11 |
Map 25, pos. 1,3,4, ind. b |
4,0 + 2,0 + 2,0 8,0 |
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Setting up the machine * fixtures, tools, software devices: | |||
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set the fixture and shine |
Map 25, pos. 13 | ||
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move the table, the headstock is a zone convenient for adjustment |
Map 25, pos. 20 | ||
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set the initial operating modes of the machine (spindle speed) |
Map 25, pos. 21 | ||
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install tool blocks in the magazine and remove 21 tools |
Map 25, pos. 22 | ||
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insert the program medium into the reader and remove |
Map 25, resp 24 | ||
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check the operability of the reader and punched tape |
Map 25, resp 25 | ||
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set the initial X and Y coordinates (adjust the zero position) along the cylindrical surface |
Map 25, resp 29 | ||
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set the tool to the machining length (on the Z-axis for six tools: 1,7,12,16,24 and 25) |
Map 25, resp 30 | ||
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Total Т„ 2 | |||
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And |» O l O L F S II and s |
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In Trial office The detail is accurate (has surfaces with tolerances for lmams * t * ry over the I-th quality, a kanak) for four tools and three measured by dipmshru K; irta 2.4, 8.9 surfaces - e>*2c0hl0,<3 200Е17и канавка b = 10 тч. 6, чпл г Total T p lb Ka p. "2K, b.V + 1 SHSHSH'H.<ииС 1.1 |
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Total preparation time^final time per batch of parts
T "1 + T" 2 + T pr.ar
Example 5 Initial data
1. The name of the operation is vertical milling.
2. Machine - vertical milling with CNC.
3. Model of the machine - 6R13RFZ (with a table length of -1600 mm).
4. Model of the CNC device - NZZ-1M; program carrier - perforated tape.
5. Part name - bar.
6. Processed material - steel 45, weight -10 kg.
7. The method of installing the part is in a reconfigurable universal assembly device (USP).
8. Labor organization conditions: centralized delivery of blanks, tools, devices, documentation to the workplace and their delivery after processing a batch of parts; receiving briefing before starting to process parts.
9. Number of tools in the setup - 6 (tools 1 and 5 - from the previous setup):
1. Drill 2317-003 (centering).
2. Drill 22-2 (hole 0
3. Special end mill (for groove b = 20).
4. Cutter 2234-0007 (for groove b = 8H9).
5. Drill 6-1 (hole 0 6).
6. Countersink 2350-0106 VK6 (understatement 016).
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Trial Processing Slot milling L and AH9 and L slot * 634 Map 33, 192 |
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Total T pro60 _
Total preparation and closing time for a batch of parts
Toz 1 + T and # 2 + Tprobr
1.12.2. Example of calculating piece tool setting time
Initial data
1. The name of the operation is the assembly, adjustment and disassembly of a set of tools necessary for processing parts on a drilling-milling-boring machine.
2. Name of the device - BV-2027, with digital indication.
3. Characteristics of the machine - cone 7:24 No. 50.
4. Labor organization conditions: the delivery of tools and technical documentation to the workplace of a toolmaker is carried out by service production workers, the disassembly of a used tool is carried out by a toolmaker.
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Piece time, mi | |||||
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Applied tool |
Map, position, index |
kya us-groyku and collection * ku |
for disassembly | ||
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Drill 0 83, drill chuck, sleeve |
type of connection - 1 |
2,64 ■ 0,45 - 1,19 | |||
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2 Marks M10, adjustable thread-cutting chuck, holder |
type of connection - 2 |
3,15 * 0,65 = 2,05 | |||
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3 Spade drill 0 32, mandrel, sleeve |
type of connection - 1 | ||||
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4 Cutter mandrel adjustable for Map 38, oblique fastening, cutting, holder type of connection - 3, 0 boring hole - 80 mm | |||||
2. MULTIPLE SERVICE
2.1. To develop and improve the efficiency of multi-machine maintenance of machine tools with numerical control (CNC), the enterprise must create certain organizational and technical conditions that can significantly increase the productivity of operators and adjusters. Work on maintenance of CNC machines provides for the combination of the functions of the operator and the adjuster.
2.2. The most economically feasible form of labor organization in the areas of CNC machines is link (group). With a link (group) form, a certain service area is assigned to a link or a group of workers included in the brigade.
The experience of enterprises shows the advantage of the link form of labor organization in the maintenance of CNC machines, which ensures the best use of working time and equipment.
The best division of labor in servicing jobs of CNC machines is considered to be one in which the multi-machine operator and the adjuster have, along with the separated part of the common functions. General functions include the implementation of operational work, adjustment of machines; the function of setting up the equipment is carried out by the adjuster. This division of labor has economic and social benefits. The possibility of performing the same functions by two workers allows to reduce equipment downtime due to the coincidence in the need to service several machines and improve the use of working time. At the same time, the mastering of the adjustment functions by multi-machine operators increases the content of their work, creates opportunities for the growth of qualifications.
2.3. For the introduction of multi-machine maintenance and the rational use of working time, it is necessary to create a sufficient scope of work for each worker. Equipment, office equipment should be conveniently located, meet the requirements of the brigade form of labor organization. To do this, the design of the organization of jobs for multi-machine operators is carried out in accordance with the schemes presented in section 3.5. Preference should be given to schemes that ensure the full loading of the worker with active work, the shortest length of transitions within the workplace, and good visibility of all machines.
Distinguish between cyclic and non-cyclic maintenance of machines at a multi-machine workplace. In cyclic maintenance, the worker sequentially performs auxiliary work techniques, moving from machine to machine. With non-cyclic maintenance, the worker approaches the machine on which automatic work has ended, regardless of the location of the machines on the site.
2.4. Calculation of service rates
2.4.1. Service rates are set taking into account the normal amount of employment - K yes. When working on CNC machines, taking into account heterogeneous technological operations with a changing range of manufactured parts, K l l - 0.75 ... 0.85. When working on backup machines K A5 = 0.85. D95.
Z42. The calculation of the number of machines serviced by one worker, necessary for servicing the CNC equipment available at the site, and the number of the link is carried out according to the formulas:
a) when working on backup machines
P c \u003d (-bs- + 1) K L1; (21)
b) when working on machines that produce heterogeneous products,
"c \u003d + 1) to, (2-2)
where - the cycle time of the automatic operation of the machine (machine-programmed time for processing the part, the operation of the manipulator or robot, not overlapped by the processing time of the part), min (according to formula 13); 2j - the sum of the processing time
bottling of parts (according to the program and the operation of the manipulator or robot) at the workplace for the period of one cycle, min; T, - time of employment of a worker by performing manual, machine-manual work, active monitoring of the progress of the technological process, etc., min; Jj T a - the sum of the worker's employment time on all serviced machines for the period of one cycle, min; is the normal amount of employment.
The number of the link is calculated by the formula
S - -b "-, (23)
where S is the number of the link required to service the equipment available at the site, people; Pu Ch - the number of CNC machines installed on the site; n s - the number of machines serviced by one worker.
T, - T, y + TYo, + T MM(+ T. + Tn + T^, (2.4)
where T lu - time to install and remove the part manually or with a lift, min; Tio - auxiliary time associated with the operation (not included in the control program), min; T th - time of active monitoring of the progress of the technological process, min; T p - time of transitions of a multi-machine operator from one machine to another (during one cycle), min (given in Table 2.4); T m - auxiliary time for control measurements, min; - time for maintenance of the workplace, min.
2.43. The number of machines at multi-machine workplaces is determined on the basis of a comparative calculation of labor productivity and the cost of processing, especially when installing expensive equipment, such as multi-purpose CNC machines.
The economical number of machines served by a multi-machine can be determined by comparing the costs associated with the operation of a multi-machine and equipment, operating machines and various options for serviced equipment.
When calculating the number of serviced machines corresponding to the lowest total costs of performing operations, the costs of performing operations, the costs of embodied labor required to produce the same volume of products, which include depreciation costs, expenses for current repairs and maintenance, electricity, are taken into account, through from 0
ratio-and employment coefficient K/. 3
1. GENERAL
1.1. The standards for time and cutting conditions are intended for technical regulation of work performed on universal and multi-purpose machines p. numerical control in the conditions of small-scale and medium-scale types of production. One of the main characteristics of the type of production is the coefficient of consolidation of operations (К^), calculated by the formula
where O is the number of different operations; P is the number of jobs that perform various operations.
The coefficient of fixing operations in accordance with GOST 3.1121-84 is taken equal to:
10 < К м £ 20 - для среднесерийного типа производства;
20 < 3 40 - для мелкосерийного типа производства.
The value of the transaction fixing coefficient is taken for a planning period equal to one month.
The collection is based on the medium-scale type of production. For enterprises of a small-scale type of production or for individual sections in a medium-scale type of production, operating in conditions of small-scale production, correction factors for auxiliary time are applied.
1.2. When introducing a brigade (link, group) form of labor organization, the standards can be used to calculate service standards, complex time standards, production and number standards.
13. The use of machine tools with numerical control is one of the main directions of automation of metal cutting, gives a significant economic effect and allows you to free up a large number of versatile equipment, as well as improve product quality and working conditions for machine operators. The greatest economic effect from the introduction of machine tools with numerical control is achieved when processing parts with a complex profile, which is associated with constantly changing cutting parameters (speed, feed direction, etc.).
The use of machine tools with numerical control instead of universal equipment allows:
use multi-machine service and brigade (link, group) form of labor organization;
increase labor productivity by reducing auxiliary and machine processing time on the machine;
exclude marking operations and interoperational control; due to abundant cooling and favorable conditions for the formation of chips, increase the processing speed and eliminate the need for visual tracking of the markup;
automate the methods of auxiliary work (approach and withdrawal of a tool or part, setting a tool to a size, changing a tool), use the optimal tool trajectories;
Expenses * associated with one minute of work of the main multi-machine worker, prn the average percentage of raising the norms, taking into account the accrual of wages, the cost of maintaining auxiliary and maintenance personnel -
Rank of work
w
2.4.4. Employment Rate Calculation
t + t
w - operational time, min.
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Table 2.2 Cost of operating CNC machines for one minute |
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reduce the labor intensity of metalwork refinement due to obtaining high accuracy and less roughness of curved sections of contours and surfaces of parts;
reduce the labor intensity of the assembly of the product, which is due to the stability of the dimensions of the parts (increase in accuracy) and the elimination of fitting operations; reduce the cost of designing and manufacturing tooling.
L4. The collection is developed in two parts. Part I contains the standards for preparatory and final time, time for installing and removing a part, auxiliary time associated with the operation, for servicing the workplace, breaks for rest and personal needs, for control measurements, for tool setting outside the machine; part P contains cutting data standards that allow you to select the tool size, its geometric parameters, the brand of the cutting part of the tool, the required allowance, the number of feed strokes, cutting speeds, and the power required for cutting.
The standards for time and cutting conditions are given both in tabular form and in analytical form, thereby allowing the use of a computer when compiling a program and calculating time standards that correspond to the lowest operating costs and the highest machine productivity while ensuring increased reliability of the tool. The operation of tools in the modes recommended by the standards is possible only if the technological discipline of production is observed (equipment, tools, workpieces, tooling must meet the required standards).
The time standards given in the collection are calculated for the rationing of work when servicing one machine by a worker. When rationing multi-machine work to calculate the norm of time, it is necessary to use the guidelines and time standards for multi-machine work given in cards 17,18,19.
15. When developing standards for time and cutting conditions, the following materials were used as initial data:
primary materials of production observations on the organization of labor, technology, time consumption and cutting modes of engineering enterprises;
industry standards for time and cutting conditions developed by the Orgariminstrument GSPKTB (Moscow), Ryazan, Minsk and Novosibirsk branches of the Orgstankinprom Institute, the Center for the Scientific Organization of Labor of the Min-Tyazhmash (Kramatorsk), etc.;
Determination of time limits for rest and personal needs. Intersectoral guidelines (M.: Research Institute of Labor, 1982);
Development of multi-machine service and expansion of service areas in the industry. Intersectoral guidelines and scientifically based normative materials (M.: Research Institute of Labor, 1983);
General machine-building standards for auxiliary time, for servicing the workplace and preparatory and final time on metal-cutting machines. Small-scale and single production (M.: Research Institute of Labor, 1982);
General machine-building standards for auxiliary time, for servicing the workplace and preparatory and final work for work performed on metal-cutting machines. Medium and large-scale production (M.: Research Institute of Labor, 1984);
passport data of CNC and multi-purpose machine tools; technical literature.
1.6. The norm of time and its components
1.6.1. The norm of time for performing operations on CNC machines when working on one machine (H ^ consists of the norm of preparatory and final time (G in J and the norm of piece time (T ^)
a tta ^ a org a exc \
T D1 = Cr u . + T.-Kj(i +
where T n is the cycle time of automatic operation of the machine according to the program "min;
T.-T. + T., (13)
where T c is the main (technological) time for processing one part, min;
Tn = £ (1.4)
where C - the length of the path traversed by the tool or part in the feed direction when processing the technological section (including infeed and overrun), mm; S* - minute feed in this technological section, mm/min; T m - machine auxiliary time according to the program (for supplying a part or tool from the starting points to the processing zones and retraction; setting the tool to size, changing the tool, changing the magnitude and direction of the feed, the time of technological pauses (stops), etc.), min. ;
m. = Tn + + Tnn, (1.5)
ede T m - time to install and remove the part manually or with a lift, min; T w - auxiliary time associated with the operation (not included in the control program), min; T mai - auxiliary non-overlapping time for measurements, min; K TV - correction factor for the time of performing manual auxiliary work, depending on the batch of workpieces; а^, а^, а ex - time for technical and organizational maintenance of the workplace, for rest and personal needs during single-station service, % of operational time.
1.6.1.1. With a collective form of labor organization, complex norms of labor costs (H wrl, man-hour) are calculated, which can be obtained by applying corrective factors to the sum of operating norms calculated for the conditions of an individual form of labor organization. It is possible to use corrective coefficients to the sum of individual components of the complex norm, reflecting the total value of time spent by categories of these costs.
Complex norm Determined by the formula
n,p,= £n.n-k*, (1.6)
where H (- the norm of time for the manufacture of the i-th part of the brigade set, man-hour; i = 1,2,3, ..., l - the number of parts included in the brigade set;
N.R, \u003d S n * (1.7)
shche H Bpj - the norm of time to perform the j-th operation, man-hour; j = 1, 2,3,..., w - the number of operations required to manufacture the j-th part; - coefficient
teamwork effect (K^< 1).
The brigade work effect coefficient (K^) takes into account the average increase in labor productivity expected in the transition from the individual to the brigade form of labor organization, which should be included in the complex norms.
As a result of the redistribution of functions between members of the brigade, the implementation of mutual assistance or interchangeability, the required time to perform the amount of work assigned to the brigade is reduced, therefore, the corresponding time norm should be reduced. This happens due to the reduction
For more complete and detailed data, see Guidelines for the regulation of workers' labor under collective forms of its organization and stimulation. M.: Economics, 1987.
the values of the individual components of the time norm: auxiliary time, workplace maintenance time, regulated breaks, preparatory "Final time", and also due to the overlap of individual components of the time norm by machine time (in the latter case, the value of each component of the time norm may remain unchanged).
In cross-cutting teams, the labor intensity of manufacturing a team kit can be reduced by eliminating individual elements of the preparatory and final time and the time for servicing the workplace when transferring a shift "on the go".
Team work effect coefficients (К^) are established: at the industry level;
at the enterprise level, if there are no sectoral coefficients or they do not fully reflect the specifics of the brigade organization of labor at a particular enterprise.
are introduced as a Standard for the entire industry for a certain period (at least 1 year).
In order to expand the possibility of using the coefficient of the effect of team work, in addition to the total value of the coefficient, the values of each of its components are calculated.
The effect of teamwork can be obtained through the following components:
expansion of the combination of professions (K ^; expansion of multi-machine service (IQ; mutual assistance and interchangeability of team members (K,); shift transfer "on the go" in through teams (K 4); redistribution of functions between team members (K 3) and so on.
The total value is defined as the product of its components (for a given type of brigade), i.e.
K*-K,-K,-K, ...K, (1.8)
At the level of the enterprise, as a rule, the general values \u200b\u200bof K^ are established, taken during the period for which they are calculated, but not less than a year, if the conditions of production do not change.
If the brigade, in addition to workmen-workers, includes time workers in engineering and technical workers, then the complex time rate (man-hours) cl "then from the sum of the time norms of piecework workers, time workers and engineering and technical workers for the manufacture of one brigade set, adjusted for the teamwork effect factor.
L6.2 Auxiliary time limits for installation and removal of a part. The time standards for installing and removing a part are given by type of fixture, depending on the types of machines and provide for the most common methods of installing, aligning and fastening parts in universal and special clamps and fixtures. As the main factors influencing the time of installation and removal of the part, the mass of the part, the method of installation and fastening of the part, the nature and accuracy of alignment are taken. In addition to these factors, the xapierei of the mounting surface, the number of parts installed at the same time, the number of clamps, etc. were taken into account.
Standard time for installation and removal of the part provides for the following work:
when installing and removing manually
take and install the part, align and secure; turn the machine on and off; unfasten, remove the part and put it in a container; clean the device from chips, wipe the base surfaces with a napkin;
when installing and removing the part with an overhead crane
call the crane; sling the detail; transport the part to the machine; install the part, sling the part, align and secure; turn the machine on and off; unfasten the part; call the crane; sling the detail; remove from the machine, transport it to the storage place; unsling the part, clean the fixture or table surface from chips, wipe the base surfaces with a napkin.
When installing and removing a part with a hoist at a machine (or a group of machines), the same work is performed as when installing and removing a part with an overhead crane, except for calling the crane.
When installed in special fixtures, auxiliary time is defined as the sum of the time: for installing and removing one part; for the installation and removal of each subsequent part more than one in multiple fixtures; to fix the part, taking into account the number of clamps; for cleaning the device from chips, for wiping the base surfaces with a napkin.
At enterprises, in addition to universal and special devices on CNC machines, robots, manipulators and satellite tables are also used to install and remove parts.
Due to the wide variety of types and technical characteristics of robots and manipulators, it is not possible to develop time standards for installing and removing parts with their help; each enterprise needs to draw up maps on the use of robots. Appendix 15 is given as an example. For cases of work on multi-purpose machines using satellite tables, it is necessary to use map 20, which shows the scheme of loading satellites and the time of changing satellites.
In some cases, when the program provides for a special technological pause for re-fastening the part, the standard time should be reduced by an amount overlapped by the automatic operation of the machine. The regulations provide for the installation and removal of parts weighing up to 20 kg manually and over 20 kg using lifting mechanisms.
The time for manual installation of a part weighing more than 20 kg is given in the regulations for use in individual cases when processing in areas where there are no lifting and transport vehicles. It is not allowed to manually install parts weighing more than 15 kg for men under 18 years of age and women.
This takes into account that parts installed manually are at a distance of 2 m from the machine, and installed by a crane - up to 5 m.
1.6.3. The norms of the auxiliary epeuienu associated with the operation. Ancillary time associated with the operation is divided into:
auxiliary time associated with the operation, not included during the cycle of automatic operation of the machine according to the program and providing for the execution of the following work:
turn on and off the tape drive mechanism; set the specified relative position of the part and the tool along the X, Y, 2 coordinates and, if necessary, perform fine-tuning; open and close the cover of the tape drive mechanism, rewind, load the tape into the reader; check the arrival of a part or tool at a given point after processing; move the punched tape to its original position; install the emulsion splash guard and remove;
machine auxiliary time associated with the transition, included in the program and related to the automatic auxiliary work of the machine, which includes: supply of a part or tool from the starting point to the processing zone and withdrawal; setting the tool to the processing size; automatic tool change; turning the feed on and off; idle strokes during the transition from processing one surface to another; technological breaks provided
when abruptly changing the direction of feed, checking dimensions, inspecting the tool and reinstalling or re-clamping the part.
The machine auxiliary time associated with the transition, included in the program for the listed techniques, is determined according to the passport data of the machines or other regulatory documents, is included as constituent elements during the automatic operation of the machine and is not taken into account separately (see appendices 27-30, part II ).
1.6.4. Auxiliary time standards for control measurements. The required dimensions of parts processed on machines with numerical control are provided by the design of the machine or cutting tool and the accuracy of their settings.
In this regard, the time for control measurements (after the completion of work according to the program) should be included in the standard piece time only if it is provided for by the technological process and taking into account the necessary frequency of such measurements in the process of work, and only if it cannot be overridden by the cycle time of the automatic operation of the machine according to the program.
1.6.5. Standards of time for maintenance of the workplace. The time for maintenance of the workplace is given by the types and sizes of equipment, taking into account single-machine and multi-machine maintenance as a percentage of the operational time. Maintenance of the workplace includes the following works:
change of the tool (or block with the tool) due to its blunting; adjustment and readjustment of the machine during operation (change of tool offset value);
sweeping and periodic cleaning of chips during operation (except for sweeping chips from the base surfaces of the installation devices, the time for which is taken into account in the auxiliary time for installing and removing the part).
Organizational maintenance of the workplace includes work to care for the workplace (main and auxiliary equipment, technological and organizational equipment, containers) related to the work shift as a whole: inspection and testing of equipment during work;
layout of the tool at the beginning and its cleaning at the end of the shift (except for multi-purpose machines);
lubrication and cleaning of the machine during the shift;
receiving instructions for the foreman, foreman during the shift;
cleaning the machine and workplace at the end of the shift.
1.66. Standards of time for rest and personal needs. Time for rest and personal needs for the conditions of maintenance by one worker of one machine is not separately allocated and is taken into account in the time for maintenance of the workplace.
For cases of multi-station service, a map of the time of breaks for rest and personal needs is provided, depending on the characteristics of the work and with recommendations on the maintenance of rest.
1.6.7. Standards of preparatory and final time. The standards are designed for setting up CNC machines for processing parts according to embedded control programs and do not include additional programming directly at the workplace (except for machines equipped with operational program control systems).
The norm of time for setting up the machine is represented as the time for receiving preparatory and final work for processing a batch of identical parts, regardless of the batch, and is determined by the formula
T p, \u003d T pz1 + T pz2 + T prlbr, (1.9.
where T pz - the norm of time for setting up and setting up the machine, min; T pz (- the norm of time for organizational preparation, min; T pe 2 - the norm of time for setting up sgaik
fixtures, tools, software devices, min; - time limit for trial processing.
The time for preparatory and final work is set depending on the type and size group of equipment, as well as taking into account the features of the program control system, and is divided into time for organizational training; for setting up the machine, fixtures, tools, software devices; for a trial pass through the program or trial machining of the part.
The scope of work for organizational training is common to all CNC machines, regardless of their group and model. Time for organizational preparation includes:
receipt of an order, drawing, technological documentation, software carrier, cutting, auxiliary and measuring tools, fixtures, blanks before the start and handing them over after the processing of a batch of parts at the workplace or in the tool pantry;
familiarization with the work, drawing, technological documentation, inspection of the workpiece;
master's instruction.
In the brigade form of labor organization, when inter-shift transfer of workpieces is carried out, organizational preparation takes into account only the time for familiarization with the work, drawing, technological documentation, inspection of workpieces and instructing the master.
The composition of the work on setting up the machine, tools and fixtures includes methods of work of a setting nature, depending on the purpose of the machine and its design features:
installation and removal of fasteners;
installation and removal of the block or individual cutting tools;
setting the initial modes of operation of the machine;
installing the program carrier in the reader and removing it; zero position adjustment, etc.
Time for trial processing of parts on lathes (up to 630 mm) and turret groups includes the time spent on processing the part according to the program (cycle time) plus auxiliary time for performing additional techniques related to measuring the part, calculating corrections, and entering correction values into the CNC system , and auxiliary time for machine control and CNC control.
The time for trial processing of parts on lathes (630 mm) % of carousel, milling, boring groups, and general purpose machines includes the time spent on processing parts using the test chip method with a cutting tool, end mills, plus auxiliary time for performing additional techniques related to measuring the part, calculation of correction values, introduction of correction values into the CNC system, and auxiliary time for machine control and CNC control.
1.7. Standards of piece time for dimensional setting of the cutting tool outside the machine
1.7.1. Piece time standards are designed to standardize work on setting up a cutting tool for CNC machines, which is carried out by tool mechanics (tool setting) outside the machine in a specially equipped room using special devices.
The norms of piece time are set depending on:
type of devices used;
the type and size of the tool to be adjusted;
the number of customizable coordinates;
the nature of the setting (according to the actual size or to a given coordinate).
The following devices are used to set up tools at enterprises in the mechanical engineering and metalworking industries:
for machines of the drilling-milling-boring group - optical with digital indication type BV-2027, without digital indication type BV-2015 and contact type devices;
for machines of the turning group - optical with digital indication type BV-2026, without digital indication type BV-2010, BV-2012M and contact type devices.
Taking into account the specifics of the tool setting processes, the time standards are developed separately for the machines of the drilling-milling-boring group and the machines of the turning group.
The most advanced devices with digital indication are taken as the basis, but taking into account the correction factors given in the maps for changed operating conditions, these standards are used when rationing work on devices without digital indication (such as BV-2015, BV-2010, BV-2012M, etc.) and contact devices.
When setting up a tool without devices (using universal measuring instruments), the time standards must be calculated according to the standards for contact-type devices.
The unit time standards for assembling and setting up a cutting tool on imported devices with digital indication must be calculated according to the time standards for domestic-made devices such as BV-2027 n BB-2026 with a coefficient of 0.85; for devices without digital indication - but for devices gopa BV-2015 and BV-2010 with a coefficient of 0.9.
The normative materials of this section cover the most typical connection of a typical / cutting and auxiliary tool for the branches of mechanical engineering and metalworking and are presented in the form of enlarged standards for piece time.
When calculating the norms of time for assembly and adjustment of the cutting tool of the snow profile, take a multiplying factor of 1.2.
In addition to the time for the main work, assembling and setting up the tool, the unit time schedule includes additional time costs such as organizational and technical maintenance of the workplace, preparatory and final time and time for rest and personal needs in the amount of 14% of the operational time.
The expediency of including additional costs in the general time rate is due to the difficulty of separating them from the total time associated with preparing the workplace for tuning, and the time of the assembly itself and tool tuning.
To determine the norms of piece time for disassembling a used tool, in the cards for assembling and setting up a tool, correction factors are given, calculated differentially for each type of work.
Piece time standards for individual assembly methods and tool settings that are not included in the complexes are reflected in cards 50 and 51.
1.7.2. The norm of piece time for assembly, adjustment and disassembly of one tool is determined by the formula
T SLR \u003d T wk + m ^, 0.10)
food T - piece time for assembly, adjustment and disassembly of one tool, min; T shi - piece time for assembling and setting up one tool, min; T shr - piece time for disassembling the tool, min.
V * "b * T" p \u003d T - K '0-11)
where K is the correction factor for piece time, depending on the device used.
T SLR \u003d T w. + = t sh + t sh K = T shi (3 + K).
The most important operation is sirlilno-frosrao-restoring.
The norm of time for performing operations on CNC machines when working on one machine (N VR) consists of the norm of preparatory and final time (T PZ) and the norm of piece time (T W)
where: T CA - the cycle time of the automatic operation of the machine according to the program, min;
T In - auxiliary time to perform the operation, min;
а those, a org, a ex - time for technical and organizational maintenance of the workplace, for rest and personal needs during single-station service, % of operational time;
K t in - correction factor for the time of manual auxiliary work, depending on the batch of workpieces.
The cycle time of automatic operation of the machine according to the program is determined by the formula:
where: T O - the main (technological) time for processing one part, min;
T MB - machine-auxiliary processing time according to the program (for approaching and retracting a part or tool from the starting points to the processing zones; setting the tool to a size, changing tools, changing the magnitude and direction of feed, time of technological pauses, etc.), min .
The main processing time is:
where: L i - the length of the path traversed by the tool or part in the feed direction during processing of the i-th technological section (including infeed and overrun), mm;
S mi - minute feed in this technological section, mm/min.
The auxiliary time for the operation is defined as the sum of the times:
where: T V.U - time to install and remove the part manually or with a lift, min;
T V.OP - auxiliary time associated with the operation (not included in the control program), min;
T V.ISM - auxiliary non-overlapping time for measurements, min;
Machine auxiliary time associated with the transition, included in the program and related to the automatic auxiliary operation of the machine, providing for the supply of a part or tool from the starting point to the processing zone and withdrawal; setting the tool to the processing size; automatic tool change; turning the feed on and off; idle strokes during the transition from processing one surface to another; technological pauses provided for by a sharp change in the direction of feed, checking dimensions, for inspecting the tool and reinstalling or refastening the part, are included as constituent elements during the automatic operation of the machine and are not taken into account separately.
The preparatory and final time standards are designed for setting up CNC machines for processing parts according to the implemented control programs and do not include additional programming directly at the workplace (except for machines equipped with operational program control systems).
The norm of time for setting up the machine is presented as the time for receiving preparatory and final work for processing a batch of identical parts, regardless of the batch, and is determined by the formula:
where: T PZ - the norm of time for setting up and setting up the machine, min;
T PZ 1 - the norm of time for organizational training, min;
T PZ 2 - the norm of time for setting up a machine, fixture, tool, software devices, etc., min;
T PR.OBR - the rate of time for trial processing.
The time for preparatory and final work is set depending on the type and size group of equipment, as well as taking into account the features of the program control system, and is divided into time for organizational training; for setting up the machine, tool fixtures, software devices; for a trial pass through the program or trial machining of the part.
The scope of work for organizational training is common to all CNC machines, regardless of their group and model. Time for organizational preparation includes:
receipt of an order, drawing, technological documentation, software carrier, cutting, auxiliary and measuring tools, fixtures, blanks before the start and handing them over after the processing of a batch of parts at the workplace or in the tool pantry;
familiarization with the work, drawing, technological documentation, inspection of the workpiece;
master's instruction.
The composition of the work on setting up the machine, tools and fixtures includes methods of work of a setting nature, depending on the purpose of the machine and its design features:
installation and removal of fasteners;
installation and removal of the block or individual cutting tools;
setting the initial modes of operation of the machine;
installing the program carrier in the reader and removing it;
zero position adjustment, etc.
The main way to automate the processes of machining parts for small-scale and single-piece production is the use of machine tools with numerical control (CNC). CNC machines are semi-automatic or automatic, all moving parts of which perform working and auxiliary movements automatically according to a predetermined program. The structure of such a program includes technological commands and numerical values of the movements of the working bodies of the machine. The changeover of the CNC machine, including the change of the program, requires little time, so these machines are most suitable for automating small-scale production.
A feature of normalizing the operations of machining parts on CNC machines is that the main time (machine) and the time associated with the transition constitute a single value T a - the time of automatic operation of the machine according to the program compiled by the technologist-programmer, which consists of the main time automatic operation of the machine T o.a and auxiliary time of the machine according to the program T v.a t.e,
T a \u003d T o.a + T c.a;
T v.a \u003d T v.h.a + T oc t
where Li is the length of the path traveled by the tool or part in the feed direction during processing of the 1st technological section (taking into account the plunge and overrun); s m - minute feed in this area; i == 1, 2, ..., n - the number of technological processing sections; T v.h.a - time to perform automatic auxiliary moves (supply of a part or tools from the starting points to the processing zones and retraction, setting the tool to a size, changing the numerical value and direction of feed); T ost - time of technological pauses - stops of feed and rotation of the spindle for checking dimensions, inspection or tool change.
Auxiliary manual work time T in not overlapped by the time of automatic operation of the machine,
T in \u003d t set + t v.op + t counter,
where t mouth - auxiliary time for installation and removal of the part; t v.op - auxiliary time associated with the execution of the operation; t counter - auxiliary non-overlapping time for control measurements of the part.
Auxiliary time for installation and removal of parts weighing up to 3 kg on turning and drilling machines in a self-centering chuck or mandrel. is determined by the formula
t mouth \u003d aQ x
to determine the auxiliary time for insertion and removal of parts in centers or on the center arbor of a lathe
t mouth \u003d aQ x
to determine the auxiliary time for insertion and removal of parts in a self-centering or collet chuck on lathes and drilling machines
t mouth \u003d aD in x l y vy l
to determine the auxiliary time for the installation and removal of parts on the table or square of the drilling and milling machine
t mouth \u003d aQ x N y children + 0.4 (n b -2)
Coefficients and exponents for determining the auxiliary time for installing and removing parts in the vise of a drilling and milling machine
t mouth \u003d aQ x
Auxiliary time machine control. (turning, drilling and milling machines)
t v.op \u003d a + bSH o, Y o, Z o + sK + dl pl + aT a
Auxiliary time for control intentions.
t counter \u003d SkD z change L u
The preparatory-final time is determined
T p-z \u003d a + bn n + cP p + dP pp
After calculating T in, it is adjusted depending on the serial production. Correction factor
k c er \u003d 4.17 [(Ta + TV) n p + T p-z] -0.216,
where n p is the number of workpieces in the batch.
The preparatory-final time is defined as the sum of time: for organizational preparation; installation, preparation and removal of fixtures; setting up the machine and tools; trial run of the program. The main characteristics that determine the preparatory and final time are the type and main parameter of the machine, the number of tools used in the program, the correctors used in the operation, the type of fixture, the number of initial modes of operation of the machine.
The norm of piece time for the operation
T w \u003d (T a + T ser) (1 + (a obs + a ot.l) / 100].
The time for organizational and maintenance of the workplace, rest and personal needs,% of the operational time, is set depending on the main parameters of the machine and the part, the employment of the worker and the intensity of labor. It can be partially overlapped by the time of automatic operation of the machine; piece time in this case should be reduced by 3%.
Automation of the processing and auxiliary work on CNC machines creates the prerequisites for the simultaneous maintenance of several machines by the operator. The performance by the worker-operator of the functions of servicing the workplace on one of the machines usually leads to interruptions in the work of other serviced machines. The time for rest increases due to the higher intensity of labor in the conditions of multi-machine maintenance. The time of operational work in the norm of piece time increases due to the auxiliary time for transitions from machine to machine.
Let's consider what the process of standardization of adjustment work on CNC machines is and why it is needed.
Carrying out the development of complex processes for processing workpieces for CNC machines and programs that control it, the main criterion is the norm of time for the manufacture of parts. Without it, it is impossible to calculate the salary for machine operators, to calculate such an indicator as labor productivity and equipment load factor.
Beginning the process
Typically, workers need to spend extra time on approach and retraction procedures, mode changes, and tool changes. Therefore, as part of the time spent on processing parts, the duration of the adjustment period is also taken into account. The rationing of labor begins with timing in the conditions of the operating machine. With the help of a stopwatch, the time spent is fixed to install one part on the machine, then remove it.
Minutes are spent on site maintenance, the immediate needs of the operator. When working on a turning-and-boring machine (single-column), it takes 14 minutes, and on two-column - 16 minutes.
What is included in the workplace service
The machine maintenance process includes:
- organizational measures - inspection of the machine, its warming up, testing of equipment: running in the hydraulic system and CNC. It takes some time to get instructions and tools from the master along with the task (attire, drawing, software carrier); present the first received sample of the part to the Quality Control Department, lubricate and clean the machine during the shift, clean the place of work after its completion. Fixed time costs for the implementation of a complex of organizational works on turning and rotary equipment, in accordance with the norms, become 12 minutes. When additional maintenance efforts are required, an appropriate amendment is introduced;
- technical measures - replacement of a tool that has become dull; adjustment of machines throughout the shift and adjustment. There are other obligatory works: in the course of the working process, chips must be constantly removed from the cutting or turning zones.
Time spent setting up the machine
The documents that reflect labor standards determine the time for setting up equipment, depending on its design. If the processing is performed on, the standards for installing and removing the cutting tool are taken as the basis for the calculation.
When it is necessary to perform a correction of the positions of the tools that process test parts, the period of processing the part is included in the duration of the preparatory phase.
The standards for setting up and maintaining automatic lathes are an important standard. They are laid in the total time for the production of one part and, accordingly, they form the economic indicators of the worker and production as a whole.
Collections of regulatory documents
Normalizers of plants and factories, where machines with numerical and program control are used, use the standards laid down in the documents in calculating working time:
- Unified tariff-qualification reference book of works;
- All-Russian classifier of occupations for workers;
- Unified qualification directory of positions of managers and specialists;
- Collections of labor standards for the work that is performed to set up the programmable equipment.
IMPORTANT! All this normative literature is basic for managers of all levels and personnel structures.
Without it, it is impossible to determine the time to perform certain amounts of work, the number of specialists that need to be involved, and the time standards used in the development of maps for technological processes.
Setup cards
For a machine of a certain type, a strictly normalized duration of production setup operations is developed and a setup chart is assigned to it. When developing, many factors are taken into account in order to obtain the final picture.
The norm of time allocated to the machine operator provides for:
- the specifics of the procedure for diagnosing the machine park;
- the presence of several options for the adjustment mode;
- compliance with service requirements.
In order to determine the rate of labor intensity (unit of measurement - man-hours or man-minutes) of any work, take into account the time during which one part is processed on a given machine. The rater also operates with the concept of a piece norm of time, which determines the total time in accordance with the types of work.
Accordingly, the total time is divided into main and auxiliary segments, organizational maintenance activities; transitions between machines during multi-machine maintenance; monitoring the work process; pauses due to equipment operation.
The Institute of Labor has the results of standardization for the equipment of milling and drilling and boring groups, lathes and automatic lines are provided with standards.
IMPORTANT! Knowing the standards, managers determine the degree of employment of the worker (his labor intensity is calculated), distribute work zones and set the optimal working pace.
Multi-Station Maintenance - Timing Approaches
In factories with a high degree of automation, multi-machine maintenance of CNC machines is practiced (forms of labor organization - in teams, units and individually). Accordingly, service areas are also fixed.
Multi-machine maintenance provides for the time spent on:
- preheating of equipment at idle, if this is provided for by the operating instructions for turning equipment;
- work according to the machine control program with workplace maintenance;
- installation of blanks, removal of parts and control of their quality;
- fulfillment of personal needs of the operator;
- loss of the planned plan;
- implementation of the preparatory and final stage of work;
The classification of multi-machine labor is carried out according to work; zones, types and systems; functions performed by the multi-machine.
Machine Maintenance Systems and Methods
The enterprises practice a cyclic maintenance system - at workplaces and production lines for machine tools that have an equal or similar length of time for which the part is processed. It is characterized by a constant stream of demands. The non-cyclic is that the operator immediately goes to service the machine, where the automatic mode of operation has ended. It is characterized by occasional demands for service.
Other methods are also possible:
- watchdog - the worker monitors the entire machine park assigned to him, simultaneously determining the need for maintenance. With priority, the order in service is determined by the operator, based on the cost of the machined parts.
- route, it consists in bypassing a group of machines along a predetermined route.
Maintenance of several machines with the same or different duration of workpiece processing operations has its own nuances. However, all of them are subject to rationing during the careful development of the production process.
Conclusion
On CNC machines, to standardize setup work, you need to take into account many nuances when calculating the duration of various operations.
Determining the final processing time of a part on one machine (we are talking about turning or), the norms are also calculated for the entire machine park.
The use of machine tools with numerical control (CNC) is one of the main areas of automation of metal cutting, allows you to free up a large number of universal equipment, as well as improve product quality and working conditions for machine operators. The fundamental difference between these machines and conventional ones is that the processing program is set in mathematical form on a special program carrier.
The norm of time for operations performed on CNC machines when working on one machine consists of the norm of preparatory and final time and the norm of piece time:
The preparatory-final time is determined by the formula
T pz \u003d T pz1 + T pz2 + T pr.obr
The norm of piece time is calculated by the formula
T c. a \u003d T o + T mv,
The main (technological) time is calculated on the basis of cutting conditions, which are determined according to the General Machine Building Standards for time and cutting conditions for standardizing work performed on universal and multi-purpose machines with numerical control. According to these standards, the design and material of the cutting part of the tool is selected depending on the configuration of the workpiece, the stage of processing, the nature of the allowance to be removed, the material being processed, etc. It is preferable to use a tool equipped with hard alloy plates (if there are no technological or other restrictions on their use). Such limitations include, for example, interrupted machining of heat-resistant steels, machining of holes with small diameters, insufficient speed of rotation of the part, etc.
The depth of cut for each stage of processing is chosen in such a way as to ensure the elimination of machining errors and surface defects that appeared in the previous stages of processing, as well as to compensate for errors that occur at the current stage of processing.
The feed for each stage of processing is assigned taking into account the dimensions of the surface to be machined, the specified accuracy and roughness of the material being machined, and the depth of cut selected at the previous stage. The feed selected for the roughing and semi-finishing stages of processing is checked by the strength of the machine mechanism. If it does not meet these conditions, it is reduced to a value allowed by the strength of the machine mechanism. The feed selected for the finishing and finishing stages of processing is checked according to the condition for obtaining the required roughness. The smallest of the innings is finally chosen.
Cutting speed and power are selected according to previously defined tool parameters, depth of cut and feed.
The cutting mode at the roughing and semi-finishing stages is checked by the power and torque of the machine, taking into account its design features. The selected cutting mode must satisfy the following conditions:
N<= N э и 2М <= 2М ст,
| Where | N | - | power required for cutting, kW; |
| N e | - | effective power of the machine, kW; | |
| 2M | - | double cutting torque, Nm; | |
| 2M st | - | double torque on the machine spindle, allowed by the machine according to the strength of the mechanism or the power of the electric motor, Nm. |
Double cutting torque is determined by the formula
If the selected mode does not meet the specified conditions, it is necessary to reduce the set cutting speed according to the value, allowable power or torque of the machine.
Auxiliary time associated with the execution of an operation on CNC machines provides for the implementation of a set of works:
- related to the installation and removal of the part: "take and install the part", "align and fix"; "turn on and off the machine"; "unfasten, remove the part and put it in a container"; "clean the device from chips", "wipe the base surfaces with a napkin";
- associated with the execution of operations that were not included during the cycle of automatic operation of the machine according to the program: "turn on and off the tape drive mechanism"; "set the given relative position of the part and the tool along the X, Y, Z coordinates and, if necessary, make adjustments"; "check the arrival of the tool or part at the point specified after processing"; "advance the punched tape to its original position."
In general, auxiliary time is determined by the formula
T in \u003d T v.y + T v.op + T v.meas,
Auxiliary time for control measurements is included in the piece time only if it is provided for by the technological process, and only when it cannot be blocked by the cycle time of the automatic operation of the machine.
Correction factor (K t in) for lead time manual auxiliary work, depending on the batch of machined parts, is determined from Table. 12.7.
| item number | Operative time (T c.a + T c) min., up to | Type of production | ||||||||
| Small-scale | Medium series | |||||||||
| Number of parts in a batch, pcs. | ||||||||||
| 6 | 10 | 16 | 25 | 40 | 63 | 100 | 160 | 250 | ||
| 1 | 4 | 1,52 | 1,40 | 1,32 | 1,23 | 1,15 | 1,07 | 1,00 | 0,93 | 0,87 |
| 2 | 8 | 1,40 | 1,32 | 1,23 | 1,15 | 1,07 | 1,10 | 0,93 | 0,87 | 0,81 |
| 3 | 30 or more | 1,32 | 1,23 | 1,15 | 1,07 | 1,00 | 0,93 | 0,87 | 0,81 | 0,76 |
| Index | A | b | V | G | d | e | and | h | And | |
Maintenance of the workplace includes the following
