Measure the production duty, not only the installed rating
The installed electrical rating is needed for site services, but it does not by itself describe energy per accepted pack. Actual use depends on warm-up, tunnel insulation and openings, conveyor operation, loading pattern, stop time, airflow, ambient conditions and the number of accepted bundles produced. Compare options using a defined production schedule and measured site data where available.
A tunnel should apply sufficient heat, airflow and dwell for the selected film and pack. Increasing temperature to compensate for poor airflow, wide gaps or incorrect film can raise heat exposure without producing a balanced result. Establish an approved operating window from representative trials, then control loading and start-up so operators are not continually chasing the finish.
| Variable | Effect on the process | Evidence to collect |
|---|---|---|
| Warm-up and readiness | Starting before the heated zone and airflow have stabilised can create rejects and repeat passes. | Defined ready condition, start-up time and first-off approval. |
| Pack loading and spacing | Large gaps waste available tunnel capacity; overcrowding can disturb airflow and pack recovery. | Pack spacing, bundle size, achieved accepted output and line-stop pattern. |
| Airflow balance | Blocked or poorly directed air can overheat one face while leaving another loose. | Defect position, clean-air-path checks and comparison across tunnel width. |
| Dwell and conveyor speed | Time in the effective heated zone changes film recovery and product exposure. | Approved speed or recipe and result on the smallest and largest packs. |
| Openings and heat loss | Oversized openings, damaged curtains or excessive cold-air entry increase heat loss and may disturb the pack. | Opening setup, curtain condition, ambient effects and maintenance record. |
| Stops and idle time | Keeping a tunnel hot during long non-production periods uses energy, while frequent shutdown may create repeated warm-up loss and rejects. | Actual shift pattern and an approved run, idle and shutdown procedure. |
| Cooling | Inadequate cooling can cause rework or bundle failure after energy has already been used. | Cooling distance, fan condition and pack stability at the handling point. |
Use accepted packs as the denominator
When comparing operating conditions, record energy over a representative period and divide it by accepted production, not total cycles. Include warm-up and normal stops if they are part of the real shift. Record product, film, tunnel settings, pack spacing, accepted count and reject count so the result can be understood later. Any electrical measurement should be completed by competent personnel using suitable equipment.
Maintenance supports efficiency and consistency
Keep airflow paths, fans, conveyor components, insulation, openings and temperature-control equipment in the condition required by the manufacturer's instructions. A gradual change in pack finish can be an early sign of contamination, obstruction or wear. Do not compensate indefinitely with higher heat; investigate why the approved condition no longer produces the accepted pack.