Why is PTFE difficult to machine?

PTFE is difficult to mold and secondary process. PTFE material has a large shrinkage rate and a very high melt viscosity, so it cannot be used in secondary processing processes such as injection molding and calendering, which are commonly used for plastics. PTFE rod ram extruder meets the needs for processing. So why is PTFE difficult to process?

1. Poor mechanical properties and load-bearing capacity. The mechanical strength of PTFE is only 14 to 25 MPa, with no resilience, but the fracture elongation is large. The coefficient of linear expansion is large. In -50 ~ 250 ℃, the PTFE linear expansion coefficient of 1.13 × 10-4 ~ 2.16 × 10-5 / ℃, is 13 times the steel. Therefore, it is easy to deform, crack, and other phenomena with other materials.

2. Poor thermal conductivity. Thermal conductivity of only 0.24kcal/(m-h-℃), easy to cause thermal expansion, thermal fatigue, and thermal deformation.

3. Poor creep resistance, easy to cold flow. PTFE in the long-term role of load, creep is larger, and prone to cold flow phenomenon. Poor abrasion resistance, PTFE material hardness is low, and abrasion is large. When the load (P) and sliding speed (V) exceed certain conditions, its frictional wear becomes large. The PV value is therefore somewhat limited in the application and the production costs are high. The above defects of PTFE limit its application, to improve its comprehensive performance. Research on PTFE at home and abroad has focused on finding suitable methods to modify it, thus improving its performance to a certain extent and expanding its range of applications.

4. It also has excellent resistance to high and low temperatures, which makes it very widely used in applications such as the manufacture of non-stick pans for anti-adhesive purposes. The surface of the PTFE molecule is entirely wrapped by fluorine atoms and therefore has a non-stick character, which makes it difficult to bond by conventional methods. The anti-adhesive process consists of two main types: mounting PTFE parts or sheets on the substrate and heat-shrinking PTFE coatings or lacquered cloth laminated with glass onto the substrate.


Post time: Dec-09-2022