Design Capabilities: Secondary Operations
Plastics' mineral-reinforced nylon 6 material (Ultramid® 8260),
which is designed to accept plating, results in excellent plating
adhesion and appearance. Plating can be used to enhance conductivity,
shielding and/or aesthetics. An electrolytic pre-plating process
of copper or nickel prepares the surface for final electroplating
of copper, nickel and chrome in that sequence. Other plating materials
can also be used where desired. Good design practice for an effective
end product includes:
1. Avoiding deep cavities or sharp corners.
2. Application of abundant radii to avoid plating buildup.
Deep pockets can be expected to be void of plating. Special surface
preparation may be needed in some cases. The total thickness of
plating is in the range of .001 in. to .005 in.
Most plastics accept paint systems well, especially the amorphous
resins. With special preparation of the surface for better adhesion
(cleaning is essential), even the more difficult plastics, such
as PE, PP and Acetal that have more slippery surfaces and chemical
resistance, can be painted.
Plastics materials will accept paint systems well. Nylon or
PET are excellent resins for paint applications, especially
where high-temperature curing is required. Their ability to
tolerate high temperatures for long periods of time without
softening is a key advantage.
All known printing methods are effective when using BASF Engineering
Plastics materials. Occasional surface preparation may be needed
for improved adhesion quality. A well-cleaned surface is the
most important preparation for quality adhesions.
Engineering resins are readily machinable using conventional
metal-cutting equipment. Cutting techniques for plastics are
different than those for metals and special preparations should
be taken. When cutting, you should remember to:
Provide for cooling
during the cutting process (especially for un-reinforced materials).
sharp tool with relief after the cut, especially for reinforced
support at the cutting area.
Apply low cutter
Use cutting points with a radius.
A designer can choose from a variety of surface treatments and
plastic colors. Both can be molded into the plastic part and
require no further finishing operations. The injection molding
process will accurately duplicate the mold surface. Part function
and/or aesthetics usually dictate the surface requirements.
A smooth, uniform surface is often preferred for plating and
painting, and high gloss is popular on many consumer applications.
However, matte or textured surfaces are also attractive, are
less slippery, provide contrast, hide sink marks, and disguise
wear and abuse.
mold finish has often been arbitrary or neglected completely.
A practical guide to surface finish selection is the SPI Mold
Finish Guide, which is available from the Society of the Plastics
Industry. The finish should be specified by SPE/SPI number where
Uniform matte and textured mold surfaces are usually less costly
than a high polish and can be obtained by vapor blast or glass
blast, while machining or chemical etching can produce a variety
of patterns and textures. A wide selection of textures are available
from companies that specialize in mold engraving.