How PTFE Compression Molding Works: Key Steps & Benefits

Principle
 

This process shapes PTFE powder into specific forms using pressure and heat.
Core idea: It works because PTFE becomes soft and flows at high temperatures.

How It Works

1. Prepare the Material: PTFE powder is added into a mold. It must be spread evenly so the final product has the same density throughout.

2. Cold Pressing: Pressure (usually 10–30 MPa) is applied to the powder inside the mold. This presses the particles together to form a solid shape (called a “green part”).

3. Sintering: The green part is slowly heated in a furnace. It reaches the melting point of PTFE (327°C), then goes higher (about 360–380°C) and stays there for a while. This melts and fuses the particles into a solid, dense piece.

4. Cooling and Shaping: The part is cooled slowly. During this step, it hardens into its final shape with stable size and strength.

Does PTFE Change During the Process?

• Physical properties: Yes, they change. The powder becomes soft when heated, then hardens again after cooling into a dense solid.

• Chemical properties: No, they stay mostly the same.

 

When to Use Compression Molding

1. For Large or Thick Parts:
   This method avoids internal flaws in big products and keeps the material density even.

2. For Complex or Unusual Shapes:
   Custom molds can be made to form non-standard parts directly, reducing the need for extra machining.

3. For High-Stress Industrial Uses:
   Cold pressing and sintering make the material stronger and more wear-resistant, perfect for high-pressure or heavy-load environments.

4. For High Performance Needs:
   Compression molding helps keep PTFE’s original chemical properties intact.

Where It’s Used

1. Industrial Seals: Large flange gaskets, special-shaped seals

2. Mechanical Parts: Wear-resistant bushings, sliding plates

3. Electronics: High-frequency insulators, insulating parts

4. Medical and Food Use: Non-toxic, compliant tubes and gaskets

 

Advantages and Limitations

• Can make products in any size or shape—sheets, rods, tubes, custom parts

• Mold cost is relatively low

• Custom molds allow flexibility

 

• Low production speed; best for small batches

• Size accuracy depends on the mold

• High energy use due to long high-temperature heating