Insulation foam distribution and void analysis in refrigerator doors and cabinets

Need

The foam expands in a closed volume between skin and liner and cannot be seen from outside; a void leaves no trace on the surface. The reaction heat reaches the surface as a difference of a few degrees and for a limited time, so the scan must fall within that window while the door is on the line.

Solution approach

A photo-sensor stops the door at the station; the injection head fills foam via the fill hole, then the thermal camera scans it from above. It faces the plastic liner: high emissivity, no bare-metal reflections. Filled regions appear warm from reaction heat, unfilled ones stay cool. The cool region is contoured along an isotherm; its area and temperature difference are compared with limits.

Process steps

1. 01

   Infeed

   The door arrives at the foaming station on the roller line and the photo-sensor stops the line.

2. 02

   Foam fill

   The injection head lowers and foam fills the gap between skin and liner.

3. 03

   Thermal scan

   The thermal camera builds the temperature map of the door surface.

4. 04

   Void analysis

   Cool regions are searched; their contour and area are computed.

5. 05

   Decide

   Void area and temperature difference are compared with the limits.