What MTM and predetermined time systems are
Predetermined time systems estimate the time of a manual task by adding tabulated values for each basic motion, without a stopwatch. MTM (Methods-Time Measurement) is the best known: you break the work into reach, grasp, move, position and release, and add the times in TMU (time measurement units).
MTM was developed by Maynard, Stegemerten and Schwab and published in 1948. The table values already correspond to a skilled operator at a normal pace, so there is no pace rating step as in a time study.
Visual map of MTM
The map shows the TMU unit, the basic motions and the 381 TMU assembly example.
The TMU unit and the basic motions
The TMU is a fraction of an hour, chosen to avoid decimals in the tables:
1 TMU = 0.00001 h = 0.036 s | 1 s = 27.8 TMU | 100,000 TMU = 1 h
In MTM-1, the basic motions are:
- Reach (R): moving the hand to a point. Time depends on distance and type of reach.
- Grasp (G): taking hold of the object. Depends on size, shape and whether other objects are nearby.
- Move (M): carrying the object elsewhere, by distance and weight.
- Position (P): fitting the object, by clearance, symmetry and ease of handling.
- Release (RL): opening the hand and letting go.
- Turn (T), apply pressure (AP) and disengage (D): motions with resistance or torque.
- Eye, body and leg motions: eye focus, bending, walking, sitting.
Each combination of class and distance has a value in the official table. The values in the example below are illustrative; for a real study, use the licensed tables from your country's MTM association.
Example: assembling a housing with 4 screws and a label
Fictional example with illustrative TMU values for a manual assembly station:
| Element | Repetitions | TMU each | TMU total |
|---|---|---|---|
| Reach for and grasp the housing | 1 | 16 | 16 |
| Move and position in the fixture | 1 | 30 | 30 |
| Pick up and position the screw | 4 | 38 | 152 |
| Pick up the screwdriver | 1 | 14 | 14 |
| Drive the screw | 4 | 22 | 88 |
| Put the screwdriver back | 1 | 10 | 10 |
| Pick up and apply the label | 1 | 45 | 45 |
| Move the assembly to the box and release | 1 | 26 | 26 |
| Total | 381 |
Checked sum: 16 + 30 + 152 + 14 + 88 + 10 + 45 + 26 = 381 TMU. Conversion:
381 TMU × 0.036 s = 13.7 s (normal time)
MTM does not include personal needs, fatigue or unavoidable delays. With a 15% allowance (an example figure; each company sets its own):
standard time = 13.716 s × 1.15 = 15.8 s
In 27,000 s available per shift (7.5 h), the station makes 27,000 ÷ 15.77 = 1,711 parts. With demand of 1,500 parts per day, takt time is 27,000 ÷ 1,500 = 18 s. The 15.8 s standard time fits, at a loading of 15.77 ÷ 18 = 87.6%.
MTM variants
- MTM-1: the basic system, with the most detail. Suited to short, repetitive cycles and to building data for other levels.
- MTM-2: groups motions into larger blocks, with faster analysis and lower precision.
- MTM-UAS: universal analyzing system for medium and large series, common in the European automotive sector.
- MTM-MEK: aimed at one-off production and small series.
The more grouped the level, the faster the analysis and the lower the detail. Pick the level by series size and cycle length.
MTM or stopwatch?
| Criterion | MTM | Stopwatch study |
|---|---|---|
| Needs the process running | No, works for a station still in design | Yes |
| Pace rating | No, the time is already normal | Yes, subjective |
| Analysis effort | High: requires MTM training | Medium |
| Compares methods before implementation | Yes | No |
| Covers machine and process time | No, manual work only | Yes, the full cycle |
The two complement each other: MTM sets the manual time of a new method; time study validates it on the shop floor.
How to apply it, step by step
- Define the method: sequence, part and tool positions, left and right hand.
- Break it into basic motions, hand by hand.
- Pick the class, distance and weight of each motion in the table.
- Add the TMU, removing motions that happen at the same time as another hand's (the longer one governs).
- Convert to seconds and add the allowance.
- Compare with takt, adjust the layout and method, and redo the calculation. Use the result in the standard work combination sheet and in line balancing.
Because MTM looks at each motion, it points to ergonomic gains: long reaches, trunk turns and difficult positioning. For posture analysis see RULA and REBA, and for the overview see ergonomics in production.
Common mistakes and limits
- Using values from memory or from unlicensed tables and treating them as official.
- Forgetting the allowance: MTM time is normal time, not standard time.
- Adding the motions of both hands when part of them are simultaneous.
- Analyzing a method that is not the one practiced and expecting the operator to reach the result without training. See standard work.
- Applying MTM to machine, mental or decision work; the system covers manual motions.
- Ignoring part variation and material quality, which raise the real time.
Frequently asked questions
What does MTM stand for?
Methods-Time Measurement, a predetermined time system that estimates manual time from basic motions.
How much is 1 TMU?
0.00001 hour, or 0.036 second. So 1 second equals 27.8 TMU.
Do I need a stopwatch to use MTM?
No. The time comes from the tables, so you can estimate a station's time before it exists.
Does MTM include allowances?
No. The values correspond to normal pace; add allowances for personal needs, fatigue and delays.
What is the difference between MTM-1 and MTM-2?
MTM-1 analyzes individual basic motions and is more detailed. MTM-2 groups motions and is faster, with less precision.
Who can use the official tables?
Trained practitioners licensed by their country's MTM association. This article uses illustrative values only to teach the calculation.
Sources
- MAYNARD, H. B.; STEGEMERTEN, G. J.; SCHWAB, J. L. Methods-Time Measurement. McGraw-Hill, 1948.
- NIEBEL, B. W.; FREIVALDS, A. Methods, Standards, and Work Design. McGraw-Hill.
- BARNES, R. M. Motion and Time Study: Design and Measurement of Work. Wiley.
- ZANDIN, K. B. MOST Work Measurement Systems. CRC Press.
Keep studying: trusted sources and links
- ABEPRO: Associação Brasileira de Engenharia de Produção (in Portuguese)
- Ministério do Trabalho e Emprego: Normas Regulamentadoras (NRs) (in Portuguese)
- Wikipedia: Time and motion study
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About the author
Lean Manufacturing & Behavioral Management Specialist
Over 20 years in the automotive and metalworking industries (GM and Dana), Lean Manufacturing practitioner since 2006. SENAI instructor and mentor in Brazil’s Brasil Mais Produtivo program, delivering consulting, training and audits for 50+ companies, combining quality, productivity and people development.
