Can We Use a PVC Machine for CPVC Production?

The CPVC process using extrusion and injection is very similar to the PVC process.

Additionally, you can typically use PVC equipment and tools in the CPVC manufacturing process. However, proper temperature settings, screws and molding tools are necessary.

What Is the Main Difference Between CPVC and PVC Processing?

The main difference between PVC and CPVC processing lies in thermal stability and viscosity.

If you don’t apply moderate temperatures and heat to CPVC, it won’t melt, and its physical properties won’t perform well. Hydrochloric acid decomposes when exposed to high temperatures. For reference, we’ve illustrated the crystalline melting points for PVC and CPVC below.

This is not guaranteed - for reference purposes only.

Can We Use a PVC Machine for CPVC Production?

Key Points

PVC and CPVC materials have different thermal stabilities:

  • CPVC materials must reduce the residence time of the molding tools as much as possible.
  • Resin temperature settings are important to ensure the material’s melting and gelation.

Viscosity (Fluidity)

Generally, CPVC’s viscosity is higher than that of PVC. You can simply read PVC’s viscosity as K-Value = Polymerization. For CPVC, you calculate viscosity (K-Value) by PVC polymerization degrees and chlorination degrees.

Key Points

  • Motor load, back pressure
    If back pressure is high and increasing production speed is difficult, the material will remain inside the die longer and burn.
  • Screw/mold shape
    The structure of the screw and die tools is an important factor. You must match the tools with CPVC production.
  • Attention to shear heating
    The screw undergoes shear heating. As a result, moderate heat is necessary to keep the plastic at the correct temperature.

Processing Differences Between CPVC vs. PVC

Extrusion Differences Between CPVC vs. PVC

PVC CPVC
Machine Screw mortar:High torque
Screw:Parallel φ60-170
      Conical φ50-85
Screw mortar:High torque
Screw:Parallel φ60-135
      Conical φ50-70
Condition Screw Rotation Lower than PVC
Barrel Temp. 300 – 340℉ 340 – 410℉/span>
Mold Type Stainless steel chrome plate Stainless steel chrome plate
Less volume (residence part)
Mold angle

*We cannot guarantee these reference values.

Injection Differences Between CPVC vs. PVC

PVC CPVC
Machine Screw mortar: High torque
Barrel cooling: Blower
Screw mortar: High torque
Barrel cooling: Blower
Barrel zone: 4-5 zone
Nozzle: Short nozzle、φ:Larger than PVC
Condition Screw Rotation 9-14 m/sec 8-13 m/sec
(lower than PVC)
Barrel Temp. 320 – 365℉ 320 – 392℉
Holding Pressure 100 – 170 MPa 100 – 170 MPa
Mold Type Stainless steel chrome plate
Runner: Thick
Hot runner: No need
Gate: Direct gate
Wall thickness > gate diameter
Stainless steel chrome plate
Runner: Thick
Hot runner: No need
Gate: Direct gate
Larger than PVC

*We cannot guarantee these reference values.

Single Extruder (Profile) Differences Between CPVC vs. PVC

PVC CPVC
Machine Single screw machine
Screw: Dulmate, Fullfight
Single screw machine
Screw: Recommend Fullfight (Dulmate)
L/D = 22 – 25
Compression ratio: 2.5 – 3.2
Condition Screw Rotation 15~ rpm (65 mm single) 15–25 rpm (65 mm single)
Barrel Temp. 284 – 338℉ 300 – 370℉
Mold Type Stainless steel chrome plate Stainless steel chrome plate

*We cannot guarantee these reference values.