TABLE OF CONTENTS This chapter will illustrate recommended drying and processing settings for the most common plastics. This will include recommended settings for temperature profiles, injection pressure and speeds, holding pressures, back pressures and cooling times. It will also discuss the injection moulding process parameters and their effect on the process. However, before some materials can be moulded, they must first be dried. This chapter therefore begins with a guide to drying materials prior to moulding. A summary is shown in Table 8.1. Incorrect drying can lead to moulding faults, which will be further discussed in Chapter 9
| Product | Maximum dryingm temperature ( C) | Maximum allowable moisture content (granulate)(%) | Drying time(h) |
|---|---|---|---|
| PA | 100 | < 0.15 | 4 |
| PBT | 120 | < 0.02 | 4 |
| PBT + PC/ASA | 120 | < 0.02 | 4 |
| POM | 120 | < 0.15 | 4 |
| PES | 200 | < 0.05 | 4 |
| PSU | 160 | < 0.05 | 4 |
| PAEK | 200 | < 0.05 | 4 |
| LCP | 80 | < 0.02 | 3 |
| SB | 80 | < 0.2 | 3 |
| ABS | 90 | < 0.2 | 3 |
| PP + Talc | 120 | < 0.03 | 3 |
| ASA/PC | 110 | < 0.1 | 3 |
| ASA = acrylonitrile-styrene-acrylate |
Many plastics are hygroscopic (absorb water) and must be dried before moulding to remove this residual moisture. There are a number of different types of material dryer available on the market. Often they come equipped with the ability to delivery the material straight to the hopper to prevent further moisture build up. Attention should be paid to the...
