TABLE OF CONTENTS Characteristics of HDPE, which make it acceptable for blow moulding are:
High impact strength
Low temperature toughness
Excellent resistance to chemicals
Good electrical insulating properties
Poor ultraviolet resistance
Drying required:
No
Melt temperature range: 188 - 232 C
A recommended temperature profile is given in Table 2.5.
| Feed | 187-193 C | 370-390 F |
| Transition | 193-204 C | 380-400 F |
| Metering | 193-204 C | 380-400 F |
| Head | 193-221 C | 380-430 F |
Regrind Ratio: Up to 100% can be used for two generations without it affecting the physical properties.
Pellet type: Virgin has a spherical shape.
Die Swell: 2 or 3:1 depending on die design and push out rates.
Blow up rate: 3:1 safely, 4:1 is possible depending on a part design.
Hang Strength: Very good when at proper processing temperatures.
Shrinkage: 0.38-1.02 mm/mm or 1.5-4.0%
Material Identification: Material in natural state is milky white. Burns easily with the smell of candle wax. Has a melting point of 130-135 C. It can be cut easily with a knife or scratched with a fingernail.
Residence Time: In the absence of air, it remains stable for up to four hours.
Temperature consideration: Try to hold melt temperature at the lower end of the range. Temperatures that fall below this range can result in non-melt and/or have a rough finish. Temperatures above this range may result in high...
