long draw surface finish

[shoobaka1]

What type of surface finish works well for PSU release.
High polish ? Vapor Hone ? Would an electroless nickel PTFE coating help ?

The application is an injection molded part with a 12" x .400" core.

 

[patprimmer]

Polysulphone is a particularly hard plastic, so no undercuts should be left on the surface of the mould.

That means no vapour hone unless you have a good draft angle.

It is most important that the polish be in line of draw, as even microscopic undercuts can cause the part to jamb onto the mould.

It is not the tackiness that causes the sticking, but the material conforming to the surface of the mould, then not deflecting nor yielding as the mould is opened, so it is not the surface energy that is important, it is the physical shape, down to microscopic level, hence draw polishing. Nickle plating, whether by electrical or elecroless methods will not help. PTFE coating just might, but it will not be durable. Some ceramic coatings might help, but are not proven.

Dusting or spraying the surface with a mould release can help. These might be zinc stearate powder or silicone oil spray or similar proprietary products. They might introduce surface blemishes on the moulding if over used

Regards
pat pprimmer@acay.com.au
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[shoobaka1]

Would a chrome coating impart a surface characteristic that would be a benefit for release ? (Applied after draw polish )