plastic required lesser clamping force than for machining metal.
As engineering plastics are not as rigid as metal. It is always
advise to support the work adequately during the machining process
in order to prevent deflection or deformation. For example, thin
wall tubes require the use of internal plug or support in order
to allow accurate machining with respect to roundness and it tolerances.
steels (HSS) are usually used for cutting engineering plastic. High
speed steels works well on glass filled fiber reinforced material.
Diamond coating tooling is sometime used to provide optimum tooling
not typically necessary for thermoplastic machining operation, gentle
compressed air blow are usually use to clean the machining areas
and keep the cutting area cool to improves surface finish and maintain
are required, water-soluble coolants general do very well. However,
the part after machining should be thoroughly cleaned with isopropyl
alcohol and rinsed with water to reduce the risk of stress cracking.
Due to the poor
thermal conductivity of plastics, provision has to be made for good
heat dissipation. Heat is best dissipated via the chips.
Machining by lathe. ( Turning )
large rake angle and large side clearance are required for turning
of engineering plastics. For particularly high quality surface finishes,
the tip of the cutting tool is to be shaped as a broad-nosed profile.
A "V" shape cutting edge is required for parting off plastic
to prevent remaining stump.
Some time, it is better to work with tools that are ground to a
knifelike cutting geometry on thin-walled and particularly flexible
For plane surfaces,
face milling is more economical than peripheral milling. For peripheral
milling and profiling, conventional end mill is not suitable. Single
lip cutting tool or double edges slot drill are normally used. The
cutting tools should not have more than two cutting edges. Higher
spindle speed is recommenced.
removal rates and surface finish are obtained with single-point
3. Drilling and boring
can be used for drilling of engineering plastic. In general, the
drill have an angle of twist of 12-16° and very smooth helical
flutes for good chip removal. Larger holes should be rough-drilled
or produced by internal turning if possible.
Drill must be proper sharpened, otherwise, the developing compressive
strain can build up and cause the material to split.