| Machining
is often necessary in manufacturing processes at plastic
injection molding companies and Aline Components is
no exception. We offer machining as a value added feature
in addition to our core competency in custom plastic
injection molding. Typically our injection-molded plastic
parts or components do not require any machining operations
apart from removal of sprues and flash. If plastic machining
is necessary, we provide this service at a nominal fee.
Before plastic machining begins, we
consider…
- Heat conductivity
- Thermal expansion coefficient
- Internal stresses
When machining plastics, it is important
to consider that the heat conductivity of these materials
is only one hundredth to one thousandth of that of metals.
Plastics tend to lose heat more slowly than metals and
in order to avoid local melting and gumming, we machine
plastics with a high cutting speed, a low feed rate,
and sharp, well polished tools.
Plastics typically have a high thermal
expansion coefficient, up to 10 times greater that that
of metals. At Aline Components, we take this into consideration
prior to machining and measure the dimensions of machined
plastic parts or components after they have cooled.
During machining, internal stresses can develop in the
plastic part or component. In critical cases, we may
consider annealing to prevent environmental stress cracking.
Aline's Precision
Plastic Machining Process
Aline Components knows what fixtures, tool materials,
angles, speeds, and feed rates to employ in precision
plastic machining to obtain optimum results. We use
standard high-speed steel tools or carbide tools, which
are generally used for machining metals; as well as
tools specially designed for plastics. Each tool type
has its own set of unique benefits, however, tools designed
for plastics allow higher production rates and better
chip removal capabilities. Carbide tipped tools and
diamond tools offer a longer tool life and are ideally
suited for filled polymers. To minimize frictional heating
our cutting tools have a generous back clearance.
Although we may utilize metal machining
tools, we tend to avoid using cutting oils and cooling
liquids found in the metal industry as they may not
be chemically compatible with plastics and also must
be removed afterwards. In our precision plastic machining
processes, we use a forced air stream for cooling. When
more intensive cooling is needed, a water spray mist
or a water-soluble cooling liquid is used. To prevent
clogging, we utilize adequate chip clearance. Additionally,
to restrict deflection away from the cutting tool, our
equipment is designed to properly support the material
during machining operations. |
