The Surface Of The Rotomolding Mold Can Be Made Of Teflon To Solve The Problem Of Demoulding Difficulties
In the rotational molding process, mold surface treatment is crucial to the demolding effect. Using Teflon (polytetrafluoroethylene, PTFE) coating is indeed a common solution. Here are the key points and precautions:
1. Advantages of Teflon coating
Excellent demolding: PTFE has extremely low surface energy (non-stick), which can significantly reduce the adhesion of molten plastic to the mold.
High temperature resistance: It can withstand the high temperature of the rotational molding process (usually 200-400°C).
Chemical inertness: Resistant to corrosion by most chemicals and prolongs the life of the mold.
2. Application method
Spray Teflon: The coating is formed on the mold surface by thermal spraying or electrostatic spraying, and high temperature curing is required.
Coating treatment: Some manufacturers provide composite coatings (such as nickel-PTFE), combining metal hardness and PTFE demolding properties.
Prefabricated molding lining: For complex molds, custom PTFE liners can be embedded in the mold cavity.
3. Precautions
Coating durability: PTFE coating may gradually fail due to frequent demolding or mechanical wear (such as scratching), and needs to be checked and repaired regularly.
Substrate treatment: Before spraying, the mold surface needs to be pre-treated by sandblasting, cleaning, etc. to ensure coating adhesion.
Cost considerations: PTFE coating will increase the initial cost, but it can reduce the long-term release agent use cost and downtime.
Temperature uniformity: The coating may slightly affect the thermal conductivity of the mold, and the heating process needs to be optimized.
4. Alternative or supplementary solutions
Other release coatings: such as silicone, ceramic coating or hard chrome plating, selected according to material properties.
Release agent assistance: Even if PTFE is used, water-based or solvent-based release agents (such as silicone oils) are still required in some cases.
Mold design optimization: increase the demolding slope, avoid sharp internal angles, and reduce mechanical snaps.
5. Maintenance suggestions
Avoid using metal tools to directly scratch the mold surface.
Clean the mold regularly to prevent carbonization of residual materials from affecting coating performance.
If the coating is partially damaged, timely local repair should be carried out to avoid the problem from expanding.
Conclusion
Teflon coating is an effective way to solve the difficulty of roto-molding demolding, especially suitable for high-precision or large-scale production. However, it is necessary to comprehensively evaluate the cost, maintenance and process adaptability.