In an assembly cycle, much of the time is not assembly at all: it is reaching, turning, looking for the part. These are short movements repeated hundreds of times per shift. Here are the 10 checks to make in front of a workstation, with the dimensions to verify with a tape measure.
1–3 · The right height
- Is the work between 800 and 1500 mm? Above it you work with your arms above the heart, below it you bend over.
- Is assembly in the golden zone? The optimal average working height is 1125 mm ±100.
- Does the height match the person and the task? For average assembly work it ranges from 1000 mm (short woman) to 1250 mm (tall man); precision work goes up to 1350 mm, heavy work drops to 900. Between the shortest woman and the tallest man in a department there are over 30 cm of height: an adjustable workstation serves every shift.
4–6 · Within reach
- Is assembly done in the two-hand zone? It is where the two 280 mm arcs overlap, about 230 mm deep from the edge of the bench: the part is right in front of the eyes.
- Are the most used parts in the one-hand zone? Radius 280 mm from two points on the edge, 160 mm to the right and left of the operator's centreline.
- No container more than 400 mm from the shoulder? The extended zone (R 540 mm) is only for occasional use; the absolute limit is the outstretched arm of the 5th-percentile woman, 625 mm.
7–8 · Posture
- Does the trunk stay within 20° of inclination and the neck within 25°? If the operator looks down for the whole cycle, the part is too low or too far away.
- No trunk rotation with loads of 1 kg or more? The container goes in front, not to the side or behind.
9–10 · Grasping and replenishment
- Can the part be picked without searching for it? Open-fronted containers tilted towards the operator make picking easy: it is the easy grasp of MTM.
- Do full containers arrive by themselves and empties go back without walking? With gravity roller tracks the container slides towards the operator; the most frequently picked items go on the level at chest height.
What half a second is worth
MTM assigns a standard time to every basic movement: reach grows with distance, grasp with how difficult the grip is. If the new layout saves half a second per cycle, with 1,000 cycles per shift, 2 shifts and 220 working days that is 220,000 seconds: about 61 hours a year on a single workstation. The starting value must be measured on your own cycle.
Want to check a workstation with us? Write to us: we start from the real dimensions and your cycle.