Hiflon 71 is white irregular shaped very fine cut particles PTFE powder and having an average particle size of 50 microns. It is a homopolymer of pure TFE polymerized under strictly controlled conditions. Hiflon 71 is allows easy processing using low moulding pressure and makes it possible to obtain high mechanical and electrical properties. Due to finer particle size, it allows better cohesion of the PTFE particles during moulding and sintering. Hiflon 71 offers the characteristics of type –II PTFE in accordance with the ASTM D- 4894 specifications.
The important applications of Hiflon 71 are:
- Compression moulding of delicate parts and are required to have high mechanical, electrical properties and free from porosity.
- Compression moulding of cylinders/billets for machining of components for high mechanical, high electrical voltage applications and skiving of thin tapes for electrical applications.
The Hiflon 71 grade properties are given table.
Before processing the powder is to be conditioned above 19 deg C and below 23 deg C to avoid lumps formed during transportation. First mould is filled with powder evenly. Filled mould is placed between hydraulic press platens and compressed slowly to degasse the entrapped air in between PTFE powder particles. Finally powder is compacted with final recommended pressure. It is called perform. Then the perform is sintered in sintering oven with different cycles (both controlled heating and cooling is called cycle) based on the component size.
The sintering cycles (guideline purpose) is given below: