Types of Materials Suitable for CNC Machining of Plastics

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CNC machining of plastics can handle a very wide range of materials, covering almost all common industrial-grade solid engineering plastic sheets, rods, or tubes.
This is a core advantage of CNC machining compared to 3D printing: it can directly use the same engineering plastics as the final mass-produced parts, thereby obtaining the most authentic and reliable material performance test results.

Below are the common types of plastic materials suitable for CNC machining, along with their characteristics and typical applications:

I. General-Purpose Plastics

These materials are the most common, easy to process, and cost-effective.

  1. ABS (Acrylonitrile Butadiene Styrene)
    • Characteristics: Good strength and toughness, well-balanced mechanical properties, easy secondary processing (e.g., bonding, spraying, electroplating).
    • Machinability: Excellent machinability; chips are flexible and string-like.
    • Common Applications: Electronic product housings, automotive parts, consumer goods, conceptual models.
  2. PMMA (Polymethyl Methacrylate / Acrylic)
    • Characteristics: High transparency, high surface hardness, good weather resistance, can be polished to a crystal-clear finish.
    • Machinability: Easy to cut but relatively brittle and prone to cracking. Requires appropriate tool selection and parameters to prevent chipping. Transparency can be restored after machining via flame polishing or abrasive polishing.
    • Common Applications: Optical lenses, display racks, windows, transparent covers, indicator lamps.
  3. PC (Polycarbonate)
    • Characteristics: High strength, high impact resistance (better than ABS), excellent heat resistance (up to ~120°C), and transparency.
    • Machinability: Moderately tough; prone to stress whitening during machining. Requires sharp tools and appropriate feed rates.
    • Common Applications: Bullet-proof shields, safety glasses, automotive lamp covers, high-strength housings, baby bottles (food-grade).

II. Engineering Plastics

These materials offer superior mechanical properties, heat resistance, and chemical stability.

  1. Nylon (PA, Polyamide)
    • Characteristics: Excellent toughness, wear resistance, and self-lubrication. Available in various grades such as PA6, PA66, and MC901 (glass-filled).
    • Machinability: Hygroscopic; material should be dried before machining. Chips tend to stick to tools; good chip removal and cooling are essential.
    • Common Applications: Gears, bearings, pulleys, wear-resistant components.
  2. POM (Polyoxymethylene / Acetal)
    • Characteristics: High strength, stiffness, excellent dimensional stability, and low friction coefficient. Ideal for manufacturing precision parts.
    • Machinability: Very easy to machine; achieves excellent surface finish and dimensional accuracy. Note its thermal expansion coefficient.
    • Common Applications: Precision gears, bearings, cams, valves, tool handles.
  3. PP (Polypropylene)
    • Characteristics: Low density (can float on water), good chemical corrosion resistance (especially to acids and alkalis), and high toughness.
    • Machinability: Relatively soft and tough; prone to burrs during machining. Requires very sharp tools.
    • Common Applications: Chemical containers, laboratory equipment, binders, automotive components.
  4. PE (Polyethylene)
    • Characteristics: Good chemical stability, corrosion resistance, and electrical insulation. Includes HDPE (High-Density) and UHMWPE (Ultra-High Molecular Weight) variants.
    • Machinability: Soft and tough; prone to deformation and burrs during machining. Cooling and chip removal are critical.
    • Common Applications: Cutting boards, wear-resistant parts, chemical tanks, insulating components.

III. High-Performance Engineering Plastics

These materials are expensive but offer exceptional properties for extreme environments.

  1. PEEK (Polyether Ether Ketone)
    • Characteristics: Top-tier performance! Extremely high heat resistance (long-term use over 250°C), very high mechanical strength, excellent chemical resistance, and flame retardancy.
    • Machinability: Difficult to machine; requires professional tools and strict parameter control. High cost.
    • Common Applications: Aerospace components, medical implants, semiconductor manufacturing equipment parts.
  2. PTFE (Polytetrafluoroethylene / Teflon)
    • Characteristics: Extremely low friction coefficient, excellent chemical resistance (almost inert to all chemicals), high temperature resistance, and good electrical insulation.
    • Machinability: Very soft and tough; highly prone to deformation during machining. Demanding requirements for tools and clamping.
    • Common Applications: Seals, bearings, insulating parts, anti-corrosion components.

IV. Composite Materials

  1. Phenolic Sheets / Bakelite
    • Characteristics: High strength, rigidity, good electrical insulation, and heat resistance. Common examples include G10/FR4 (glass fiber epoxy composites).
    • Machinability: Highly abrasive to tools; generates dust during machining. Requires proper protection. Carbide or diamond-coated tools are recommended.
    • Common Applications: Circuit boards (PCBs), insulating spacers, gears.