3 Common Polystyrene Sheet Problems

by Kurt Bartosch, Engineering Manager

Every foam plant experiences quality problems with their extruded foam sheet at some point.  While it can be difficult to pinpoint the exact cause of your sheet problems, we have compiled a short list of some common issues. While by no means is this an exhaustive list, it should help get you started down the right path to finding and correcting extrusion process issues. The 3 most commonly encountered issues when extruding polystyrene foam include:  




Example of Orientation Testing

Bad Orientation/Unbalanced Sheet

Bad orientation is when you experience excessive shrink or growth in one or both directions. Both issues can cause problems in thermoforming.  This can be observed in two directions traverse direction and machine direction, when this issue is present your sheet will not expand uniformly affecting the product when it is used in your thermoformer. 





Brittle Sheet

Brittle sheet may cause difficulty in thermoforming due to rolls being fragile and breaking before they can be fed into the thermoformer.  Trays made from brittle sheet are a source of customer complaints which include trays cracking during automated wrapping or trays breaking during handling.  




Corrugated Sheet

This occurs when the rate of foaming is too fast, causing varying sheet thickness across the web resulting in poor tray quality and wasted raw materials. Many things can contribute to this issue starting with line speed , ingredients , die settings and other factors.




Each situation is different and will require some investigation and process review.  Experience can shorten the time to optimize your process. Commodore can help evaluate your machinery and process and get your sheet issues under control. Contact us today.