Golden zone, reach and MTM: every movement saved is time gained

Side view: heights (mm)

• Golden zone: optimal average working height 1125 mm ±100
• 800–1500 mm: working area, containers go here too
• Above 1500 (arms above the heart) and below 800 (bending): avoid

Top view: grasp zones

• 1 · Two-handed zone: where the two 280 mm arcs overlap, about 230 mm deep from the edge. This is where assembly happens, right in front of the eyes.
• 2 · One-handed zone: 280 mm radius from two points on the bench edge, 160 mm to the right and left of the operator's centre line. Frequently used parts and tools.
• 3 · Extended one-handed zone: 540 mm radius from the same points. Occasional use; containers stay within 400 mm of the shoulder.
• Absolute limit: forward arm reach of a 5th-percentile woman, 625 mm (DIN 33402). Dimensions in mm, diagram approximately to scale.

Working height: it depends on who is working and what they do

The more precise the work, the closer the part must be to the eyes; the more force and movement needed, the lower it can go.

There are more than 30 cm of height difference between the shortest woman and the tallest man on a shop floor: that's why a height-adjustable workstation serves every shift with the same equipment.

Icons, from left: short woman, average woman, average man, tall man. The four body heights range from the shortest woman (only 5% are shorter) to the tallest man (only 5% are taller). On sit-stand workstations the worktop never goes below 1000 mm, to leave legroom.

Picking from a gravity supermarket

• B · 1025–1225 mm, golden zone: the most frequently picked part numbers, on the chest-height level.
• A · top level, within 1500 mm: light, infrequently picked part numbers; above that you work with your arms above the heart.
• C · bottom level: below 800 mm you bend. Only stock or rarely used containers; heavy ones are better kept close to 800 mm.
• ≤ 400 mm: maximum distance between the shoulder and the front of the container. Inclined roller tracks bring full containers to the operator; empties return via the top level.

Picking from a lift table

• 1 · Layer to pick: always in the 800–1500 mm area, as close as possible to the golden zone. When the layer is finished, the table lowers by one layer.
• 2 · Platform: about 900 mm in this image. A table like the TM 1500 ranges from 230 mm (loading from the floor with a pallet truck) to 1330 mm, with 1100 mm of stroke and a 1700 × 1000 mm platform.
• For pallets you can add tilting towards the operator (lifters and tilters up to 40°), so there's no need to reach over to the far side.

03

MTM: every movement has a time

MTM (Methods-Time Measurement) was developed in 1948 by Maynard, Stegemerten and Schwab. It breaks manual work down into basic motions (reach, grasp, move, position, release) and assigns each one a standard time, measured in TMU: 1 TMU equals 0.036 seconds.

Reach time grows with distance; grasp time with how difficult the grip is. That's why bringing the container closer and making it open reduces cycle time measurably, right from the workstation design stage. In MTM analyses of assembly workstations, correct parts presentation can cut replenishment and picking time by up to 68%. MTM table values belong to the MTM Association: a full analysis requires a certified analyst.