Week six of a long build. The fabrication bay has finished the base frame and gone quiet. The machine shop waits on castings the foundry promised a fortnight ago. Two fitters are re-stacking racks in stores. Week fourteen: the castings came late, assembly runs nights, the panel shop wires on Sundays, and the PLC programmer cannot start until mechanical completion. Dispatch is ten days away.
The hub page for machine and equipment makers lists this swing among its recurring patterns. Most owners feel it. Few can see it in numbers, because the plan follows the machine rather than the people building it.
How the swing shows itself
- Overtime spikes in the weeks before dispatch, then falls to nothing.
- Idle hands get make-work: painting railings, sorting offcuts, re-labelling bins.
- The panel shop and the programmer are always last and always late, since they start only when mechanical work ends.
- Skilled fitters leave in lean months for steadier shops, then are missed in the rush.
- Leave is refused before dispatch and pushed into a quiet month, when it helps nobody.
- Several builds peak together, because start dates were set by order dates rather than by load.
What the swing costs
Idle weeks cost wages with no output. Peak weeks cost premium hours and mistakes from tired hands. Rework climbs in the final push, when fitters close up gearboxes without the checks they would make in a normal week. Late dispatch strains the customer's patience and can lose the next order.
The people cost arrives more slowly. Fitters who lurch between idle afternoons and double shifts stop trusting the plan. The best of them go where the work is steadier.
Why the plan hides it
- Schedules track machines, not skills. One Gantt bar for assembly hides that it needs four fitters and a wireman. That wireman may be booked on two other machines.
- Bought-out items set the pace. Castings, gearboxes, servo drives and bearings arrive when vendors deliver, and the shop waits.
- Work runs in sequence by habit. Wiring begins after mechanical completion, though much of a panel could be built and tested earlier on a bench.
- Start dates follow order dates. Builds launch the week an order lands, so they bunch.
- Headcount is set by the last rush. Each crunch prompts hiring, and each lull prompts regret.
Checks before redrawing the plan
- Pull overtime hours by week and by skill group for the past year, with dispatch dates marked on the same sheet.
- Ask supervisors to log idle and make-work hours for one month.
- For each live build, list the hours each skill group needs, week by week. Rough figures will do.
- Find the bought-out items that most often arrive late, and the teams that stand waiting on them.
The fix, in order
- 1
Group people by skill, not department
Fabricators and welders, machinists, mechanical fitters, panel wiremen, programmers, test and trial staff, field engineers. Count who is free in each group, net of leave and training.
- 2
Estimate hours per build by group
Use past builds of similar machines. Spread each group's hours across the weeks it works on the build.
- 3
Draw a weekly loading sheet
Stack every live build by skill group, week by week, against hours available. Peaks and troughs jump out at once.
- 4
Set start dates by load as well as by order
When a new order is accepted, place it on the sheet and choose a start that avoids a clash in the scarcest group.
- 5
Pull work forward where you can
Build and test panels on a bench before the frame is ready. Pre-assemble sub-assemblies while castings are awaited.
- 6
Cross-train neighbouring groups
Welders who can help with fitting, fitters who can do simple wiring, machinists who can run a test bench. Pick pairs from the clashes the sheet keeps showing.
- 7
Use lean weeks on purpose
Plan training, jig and fixture upkeep and stock builds of common sub-assemblies into the troughs the sheet predicts.
Rows: a line for each skill group, for example fabrication, machining, fitting, panel wiring, programming, testing and field.
Columns: weeks, for the next three to six months.
Each cell: hours needed by all live builds, beside hours available after leave and training.
Shade cells above available hours red, and cells well below them blue.
Notes: the bought-out items each cell depends on, with promised dates.
Owner: the planning engineer updates it weekly, and the works manager reviews it.Making the sheet a weekly habit
The sheet earns its keep only if someone updates it each week and sales sees it before promising a date. Put it on the agenda of the weekly production meeting. Tie it to hiring: a peak in one group that recurs month after month argues for headcount. A one-off peak argues for overtime or a later start. Workforce planning sets this up across a whole order book.
Special purpose builders and conveyor makers both live with long, lumpy builds; see the planning pages for special purpose machines and conveyors. To size the team for a year rather than a week, read planning headcount against the order book.
