PP (Polypropylene)
Frequently asked questions
Can PP (Polypropylene) be laser cut?
No: PP (Polypropylene) is not suitable for laser cutting. Adequate extraction/ventilation is required.
Can PP (Polypropylene) be CNC machined?
Yes: PP (Polypropylene) can be CNC machined.
Is PP (Polypropylene) food safe?
Yes, PP (Polypropylene) is food safe even in its raw state.
Physical properties
| Density | 900.0–910.0 kg/m³ |
|---|---|
| Tensile strength | 35.0 MPa |
| Melting point | 160.0–165.0 °C |
| Glass transition (Tg) | -10.0 °C |
| Thermal expansion | 150.0 µm/m·K |
| Moisture absorption | Negligible |
Laser processing
Melting PP releases aliphatic hydrocarbons and propylene oligomers. Not acutely toxic but irritating to the respiratory tract. Forced ventilation recommended.
CO₂: Unsuitable for cutting: PP melts without vaporising, producing irregular edges and runs of molten material. Engraving is possible but results are superficial and poorly defined.
Diode: Not recommended. The high thermal expansion coefficient causes deformation and localised melting without clean ablation.
Fiber: Not applicable for sheets or panels. Marking possible on flat surfaces with high-power fibre laser, variable results.
CNC / milling processing
CNC machinable but requires attention to heat management. Very low Tg (-10°C): even the heat generated by the bit is sufficient to melt and re-weld chips. Use sharp single-flute bits, fast feed rates and compressed air cooling.
Plotter and thermoforming
Post-processing
Sanding: Difficult to sand: the material is waxy and tends to smear rather than abrade. Abrasive paper clogs rapidly. Prefer mechanical or thermal finishing.
Primer: mandatory. PP has poor adhesion to paints and adhesives due to its non-polar surface. Requires specific primer for polyolefins or plasma/flame pre-treatment before painting or gluing.
Gluing: Extremely difficult to bond with common adhesives. Use special polyolefin adhesives (e.g. Lord Fusor) or ultrasonic/heat welding. The surface must be pre-treated.
Over time: Good chemical resistance to oils, greases and solvents. Moderate UV resistance: yellows and embrittles with prolonged exposure without stabilising additives. UV-stabilised grades available.
Common defects
- Chip melting and re-welding to the cutter during CNC machining
- Poor adhesion to paints and adhesives without surface pre-treatment
- Thermal deformation during laser cutting (melts rather than vaporises)
Safety
Generally safe material to handle. Approved for food contact (in the absence of problematic additives). During hot processing, ventilate the area.
Availability and formats
Commercial formats: sheets 1–20mm, tubes, round and square bars, granules, non-woven fabric
Related materials
Sources
- ISO 1873 — Polypropylene (PP) moulding and extrusion materials
- Datasheet tecnici Sabic PP homopolymer
Information on compatibility, processing parameters and safety is purely indicative. MakerSpecs accepts no liability for damage to persons or property arising from the use of this data. Always check the safety rules and the manufacturer's official manuals before carrying out any processing.