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A double feed costs more than a sheet of paper. For an offset press, the larger cost is often the minutes between the first misfeed and the first good sheet after restart. This worksheet helps a production manager measure that cost and decide whether a static-control change pays for itself.
Illustrative total: $93.60 per shift, before any separately documented rework. Include stock only if the press-hour rate excludes it.
Which stops belong in the static log?
A sheet clinging to a second sheet at pickup, dust attracted to a charged substrate and a pile that will not separate are clues. A worn suction cup, poor feeder air setup or curled stock can produce similar symptoms. Ask the operator to mark the event as suspected until a repeatable observation or approved surface-charge measurement supports it.
Build the cost from a press ticket
- Record the event. Note job, stock and coating, press speed, feeder or delivery location, room RH and temperature, and the time from stop to the first acceptable sheet.
- Count net waste. Record stock discarded, sheets recovered and any separately invoiced rerun. Keep routine makeready on its normal cost code.
- Choose the hourly rate. Use the rate agreed by the production manager and finance team. Count labor separately only when the press rate excludes it.
- Normalize production. Calculate confirmed stops and minutes lost per 10,000 good sheets. Compare the same substrate, job family and operating speed.
What would an improvement be worth?
At 200 comparable shifts, the example totals $18,720 per year. If a controlled trial cuts verified static-related losses in half, the modeled gross benefit is $9,360 annually. Deduct utilities, consumables, service and any ongoing QA work before comparing the result with installed cost. Recovered press time creates revenue only if the plant can sell or use it.
Test one change at a time
Start by checking feeder settings and conditioning stock as specified by the paper supplier. Compare charge at the same location, with the same instrument and geometry. Document grounding and ionizing equipment under the plant’s approved procedures. If winter humidity is implicated, log RH near the feeder, at the pile and in stock storage. Let wrapped stock reach the specified temperature before opening it.
During a trial, record good-sheet count, double feeds, feeder interventions, delivered stock moisture where measured, and local conditions. Compare matched runs before and after changing an RH band or static-control device. A single good shift on different stock does not isolate the cause.
