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CNC Machining Polypropylene

About Polypropylene (PP)

Polypropylene (PP) is a thermoplastic “addition polymer” derived from a propylene monomer blend. It is used in a wide range of applications, including consumer product packaging, plastic parts for various industries, including the automotive industry, special devices such as living hinges, and textiles.

Polypropylene (PP) Properties

Polypropylene is a polymer composed of linear hydrocarbons. It is semi-rigid and saturated, and it is also referred to as a polyolefin. PP, one of the most versatile polymeric materials, is available as both a fiber and a plastic.

Polypropylene, which appears white and translucent, is an all-purpose thermoplastic that is both durable and lightweight. It is light in weight, has a slick surface, and a low coefficient of friction. It is also extremely heat, electricity, fatigue, chemical, and organic solvent resistant. Stress-cracking is not an issue for PP because it is also corrosion resistant.

Polycarbonate (PC) Material Properties

Polycarbonates are a group of polymers containing carbonate groups in their chemical structures, which gives the material a balance of useful features, such as impact resistance, temperature resistance, optical properties, and rigidity. Then the good machinability and stable dimension make it versatile and good for CNC machining. Some examples of PC CNC parts are gears, rollers, pumps, and internal mechanical parts
Density 1.04 – 1.06 g/cm3
Elastic modulus 1.5 – 3 GPa
Impact strength, Charpy notched 2 – 6 kJ/m2 at 20 °C
Coefficient of thermal expansion 6*10-5 – 1*10-4 1/K at 20 °C
Max, service temperature, short 140°C
Melting point 160 – 168 °C
Specific heat capacity 1520 J/(kg.K) at 20 °C
Thermal conductivity 0.41 W/(m.K) at 20 °C
Flammability UL 94 HB
Dielectric constant 2.8 at 20 °C
Electrical resistivity 1*1013 – 1*1014 Ω.m at 20 °C

Polypropylene Types and How to Choose Them

The two most common types of polypropylene on the market are homopolymers and copolymers.

Polypropylene The most common general-purpose grade is homopolymers. It only contains a semi-crystalline solid propylene monomer. Packaging, textiles, healthcare, pipes, automotive, and electrical applications are among the most common.

Polypropylene The copolymer family is further subdivided into random copolymers and block copolymers, which are created by polymerizing propene and ethane:

1. Polyester Random Copolymer is created by polymerizing ethene and propene together. Ethene units, usually up to 6% by mass, are randomly incorporated into the polypropylene chains. These polymers are flexible and optically clear, making them ideal for applications requiring transparency and products with a high visual appeal.

2. Ethene content is higher in Polypropylene Block Copolymer (between 5 and 15 percent ). It is made up of co-monomer units that are arranged in a regular pattern (or blocks). As a result, the regular pattern makes thermoplastic tougher and less brittle than random co-polymer. These polymers are appropriate for high-strength applications, such as industrial applications.

Benefits of Polypropylene (PP)

Chemical Resistance

Because many chemicals do not react with PP, it is appropriate for plastic pallets and containers that handle such chemicals.

Biological Resistance

PP plastic does not deteriorate or mold due to biological variables like fungi and bacteria.

Water Resistance

This material is highly impermeable, which is essential for total immersion applications such as industrial and medical applications.

Fatigue Resistance

Polypropylene retains its shape after torsion or bending, making it an excellent material for living hinges. This is why shampoo bottles have plastic lids.


Because PP plastic is highly electrically resistant, it is the material of choice in electronic components.

High Melting Point

Because of its high melting point, this material is ideal for kitchen utensils and food appliances.

Low Cost

Polypropylene is a low-cost material that is easily accessible to a wide range of users.

Why is Polypropylene (PP) used so often

Polypropylene is used in both residential and industrial settings. Its distinct properties and adaptability to various fabrication techniques distinguish it as an invaluable material for a wide range of applications. Another valuable property is polypropylene’s ability to function as both a plastic and a fiber (like those promotional tote bags that are given away at events, races, etc).

Why Choose CNCJY Polypropylene (PP)

Polypropylene’s unique ability to be manufactured in a variety of ways and for a variety of applications meant that it quickly began to challenge many of the old alternative materials, particularly in the packaging, fiber, and injection molding industries. Its expansion has been sustained over the years, and it is now a major player in the global plastics industry. CNCJY has used polypropylene in a variety of applications across multiple industries. The ability to CNC machine polypropylene to include a living hinge for prototype living hinge development is perhaps the most intriguing example.

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