MATERIAL PREPARATION

We begin with some initial material preparation before processing the plastics resin.

3.2.1 Inspecting Material

Check material carefully for consistency and for foreign materials such as dirt, paper, other plastics, etc.

SPECIAL NOTE:
In all cases, it is extremely important to properly identify and mark plastics containers to ensure correct usage.

3.2.2 Removing Moisture

In some cases, dryers are used to reduce the moisture content of the plastics resin to ensure proper processing. Moisture has an adverse effect on plastics, and if the resin is processed without removing it, cosmetic defects such as splay (bubbles) may occur. Moisture can also cause a reduction of physical characteristics of the moulded part, such as strength and impact resistance.




To remove the moisture in a plastics, a desiccant type dryer is used. A desiccant dryer works by passing hot air through a desiccant bed that will trap the moisture that is in the air.

To ensure that a plastics material has been properly dried, a dew meter is used to check the dew point of the circulating air. Resin manufacturers supply the recommended drying time, temperature, and dew point for each type of resin.