What causes fault code PKG-SHRINK1 (Shrink Tunnel — Temperature Fault / Uneven Shrink)?

Tunnel temperature set incorrectly for the film type — PVC, polyolefin, and PE all have different shrink temperatures. Heater element burned out — one zone not heating, causing cold spot in the tunnel. Air circulation fan failed — hot air not circulating evenly around the product. Conveyor speed through tunnel too fast — product not in the heat zone long enough. Film wrapping not uniform — too much or too little film on one side before entering tunnel

How do I fix fault code PKG-SHRINK1?

Check tunnel temperature at multiple points — use a thermocouple probe at the inlet, middle, and outlet. Verify heater elements are all functioning — measure resistance on each element. Check circulation fans — all should be running at full speed during operation. Adjust conveyor speed through the tunnel — slower speed = more heat exposure = tighter shrink. Verify film type matches the tunnel temperature setting — PVC: 275-325F, polyolefin: 300-375F. Check for air leaks at tunnel inlet and outlet — curtains or air curtains should minimize heat escape

Shrink Tunnel — Temperature Fault / Uneven Shrink

PKG-SHRINK1

Shrink tunnel producing uneven, incomplete, or excessive shrink on products. Film is not conforming uniformly to the product contour.

medium packaging

packaging shrink tunnel temperature heater film pvc

Probable Causes (ranked)

Tunnel temperature set incorrectly for the film type — PVC, polyolefin, and PE all have different shrink temperatures
Heater element burned out — one zone not heating, causing cold spot in the tunnel
Air circulation fan failed — hot air not circulating evenly around the product
Conveyor speed through tunnel too fast — product not in the heat zone long enough
Film wrapping not uniform — too much or too little film on one side before entering tunnel

Fix Steps

1 Check tunnel temperature at multiple points — use a thermocouple probe at the inlet, middle, and outlet
2 Verify heater elements are all functioning — measure resistance on each element
3 Check circulation fans — all should be running at full speed during operation
4 Adjust conveyor speed through the tunnel — slower speed = more heat exposure = tighter shrink
5 Verify film type matches the tunnel temperature setting — PVC: 275-325F, polyolefin: 300-375F
6 Check for air leaks at tunnel inlet and outlet — curtains or air curtains should minimize heat escape

Field Trick

If one side of the product shrinks tight and the other side is loose, the problem is the upstream wrapper, not the tunnel. The loose side has too much film, so even though it shrinks, there's excess material that bunches up. Fix the wrapper so film distribution is even, then the tunnel produces uniform shrink.

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