Injection
mold surface treatment
What methods of injection mold parts
surface treatment? In the working process of the injection mold parts on the
surface of the working condition is bad, so it's easy to damage, therefore,
need for some parts surface to surface treatment, for local enhancement.
The effect of surface treatment (1) parts
In mould processing, surface treatment can
make the parts for the following properties: increasing surface hardness,
increase the compressive strength, abrasion resistance, improve the corrosion
resistance and improve the sliding, etc.
(2) parts surface treatment methods
Surface treatment method are many, but for
the mold parts, main methods of surface treatment are the following.
1) carburizing. Carburizing is to the steel
surface infiltration carbon atoms. It is to put the parts into can release the
active carbon atom medium, heat insulation, make activated carbon atoms permeability
and the surface of the steel. Its purpose is to improve the surface of the
carbon content, the subsequent heat treatment, the surface hardness increased,
while the core remains resilient. Therefore, carburizing steel must be 0.15% ~
0.25% (mass fraction), the carbon content of mild steel. Methods include solid
carburizing, carburizing liquid carburizing and gas carburizing, is widely used
gas carburizing.
2) nitriding (also called nitride).
Nitriding is to the steel surface infiltration nitrogen atoms. Its purpose is
to improve the parts table surface hardness, wear resistance, corrosion
resistance and fatigue strength. At present, the most widely used method of
nitriding is gas nitriding. It is to put the parts into the airtight furnace,
the ventilation with NH3, heating to 500 ~ 600 ℃, the ammonia
decomposition of reactive nitrogen atoms, the nitrogen atom is easy to be
absorbed by the workpiece surface and spreading inside, forming a nitride
layer, nitriding layer is 0.1 ~ 0.6 mm. Nitriding layer has high hardness and
excellent dimensional stability, and can noticeably improve wear resistance and
fatigue strength, corrosion resistance has greatly improved. In the mold
processing, almost all steel nitriding processing. But it's a longer production
cycle, high cost.
3) hard chromium plating. Hard chrome
plating is will adopt the method of plating chromium plating on surface of
parts, thereby gaining the surface of the hard and wear resistant, it to
contain the abrasive plastic molding parts, hard chromium plating layer is very
effective. In addition, the hard chromium layer can not only reduce the wear
and tear, and can significantly improve the corrosion resistance of parts. Can
also be used when repair the wear surface hard chromium plating method
processing.
4) hard nickel plating. Hard nickel plating
is to use chemical method will nickel plating layer on surface of parts. In the
process, deposition of nickel layer does not use imposed by the electron flow,
so you don't happen like electroplating on the edge, especially along the edge
to form different thickness of electroplating film formation (edge) of the
phenomenon. This method of nickel plating in the hole, opening and the place
such as contour surface defects will not appear. The nickel plating layer often
about 40 microns thick, it can form has good corrosion and wear resistance of
the surface.
5) coated hard layer. In order to make the
part surface with a high wear resistance and corrosion resistance, there is a
new technology is in the surface coated with titanium nitride and similar
material for grass-roots approach, it is easy to operate, and the effect is
very good.
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