Why and when to do a pull test

There are two popular ways to tell if a thermofoil component is manufactured well. The first is the appearance and the second is the adhesion on the edges. 

Appearance examples:
- Telegraphing of the mdf through the film
- visible wrinkles, shadowing, defects
- overstretched corners or whitened corners

Adhesion:
- clear bite of the film to the edge of the component. You can tell by a pull test
- adhesion down in raised panel profiles, no bridging

For the sake of this post, I'd like to discuss why and when to do a pull test. Firstly when the heat is activated well the film will stick well to the sides of the components.  Examples are below:

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Good times to do a fiber pull test are:
- When lowering temps significantly
- When changing film thicknesses more than .1mm
- When adding working with a new vendor
- When adding a protective film

In conclusion, pull tests are great way for manufacturers to spot check their components to better ensure good adhesion on the sides of the components and can be an integral part of QC.