The Assembly Cell Redesign Under a Fixed Capital Deadline
A manufacturer is rebuilding a final assembly cell in 14 weeks. The current cell has a 1.4 m reach to the rear parts bin, and 22 operators work a 10-hour shift with a 30-minute unpaid lunch. Reported shoulder complaints are rising. Engineering has released drawings with the bin at the same 1.4 m depth because moving it would require rerouting a conveyor at a cost of $85,000 and a 3-week schedule slip. The ergonomics review was scheduled for week 12. The project manager asks you to sign off on the drawings so fabrication can start.
1. Evaluate the timing of the ergonomics review and the request to sign off. What is the professional response?
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The review is scheduled at week 12 of a 14-week build, which means it cannot influence the design. An ergonomics review that arrives after fabrication drawings are released is a documentation exercise, not a control. Signing off would attach professional endorsement to a design with a known, quantified exposure and no plan to address it.
The correct response is to decline sign-off as requested and immediately escalate the reach issue as a design change, not a post-occupancy finding. The 1.4 m reach to a rear bin forces trunk flexion and shoulder elevation on every cycle for 22 operators over a 10-hour shift; that is a high-frequency, high-duration exposure, and the rising complaints are consistent with it.
Offer to work the tradeoff now: evaluate alternatives that do not require the conveyor move, such as rotating the bin to a front-load position, adding a gravity-flow front presentation, or splitting the part set. Present the $85,000 and 3 weeks against the cost of continued exposure across 22 operators. If leadership accepts the exposure, document the decision and the residual risk with the decision-maker named.
2. The project manager says the 10-hour shift is an HR issue, not an ergonomics issue. How do you respond, and what do you recommend about shift length?
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Shift length is an exposure-duration variable and therefore squarely an ergonomics issue. The same task performed for 10 hours rather than 8 produces more cumulative loading and less recovery between shifts, and fatigue degrades posture and attention late in the shift when injury risk is highest. HR owns the schedule; ergonomics owns the exposure consequence of that schedule and must state it.
Recommend that the design be evaluated against the actual shift, not an 8-hour assumption. If the 10-hour shift stays, the design must be more conservative on reach and repetition, not less. A 30-minute unpaid lunch on a 10-hour shift also compresses recovery; flag it as a factor to review with HR rather than silently accepting it.
Frame the recommendation as a joint decision with a named owner for each element: engineering owns reach, HR owns schedule and breaks, and you own the exposure assessment and the record. That prevents the issue from falling between functions, which is how it reached week 12 unresolved.