Case Studies: Polymers
Machining of Polymers: Variables Affecting Surface Finish
Material Variables
- Glass Transition Temperature (Tg)
- Melt Temperature (Tm)
- Viscosity
- Molecular Weight
Machining Variables
- Cutting Speed (relaxation rate)
- Cutting Edge Radius
- Tool Angles (Rake/Clearance)
- Feedrate
- Tool surface tribological properties
Representative Temperature Sweep for Thermoplastic Polymers
Rationale Behind Temperature Control (Tg < Room Temperature)
Rationale Behind Temperature Control (Tg > Room Temperature)
PEEK Machining Demonstration
Objective(s):
- To investigate the impact of various cryo gas temperatures on burr formation.
- To compare surface characteristics of hydroxyapatite filled PEEK when machined dry and cryogenically.
Materials:
- Unfilled PEEK, hydroxyapatite filled PEEK.
Machining conditions:
- Tooling and machining standards per publicized guidelines (constant for dry and cryo machined samples).
- Cooling:
– Compressed air
– Various cryogenic cooling conditions:
+ Liquid nitrogen, Cryo gas at -250°F, -150°F, -100°F and -50°F.
+ Cryo brushing at -250°F.
Analytical information:
- Light microscopy, SEM, EDS analysis.
Note: Cryo gas temperature measured at End-of-Line (EOL) box prior to nozzle.
Dry Machining vs. Cryo-machining Results
Dry machining + Cryo machining Cryo machining + Cryo compressed air (-250°F cryo gas) brushing (-250°F cryo gas)
Comparison of Surface Profiles (Dry Cutting Vs. ICEFLY)
