Types of Plastics for CNC Machining Materials ( 20 Types Introduced)

Updated: Jan. 10, 2024

Plastics are widely used in CNC machining from excellent prototypes to engineering models and end-use components. Most plastics are affordable and cheaper than metals. Some plastics are general-use materials, like ABS, they are quite machinable and suitable for testing designs at a low cost. Some plastics, like PEEK, are always used to replace metals.

 

Generally, plastics are extremely durable, high fatigue resistance, and shock absorbent. Due to its lightweight, plastics is more suitable for CNC machined parts with simple geometries. ISO 2768MK tolerance is always conducted.

 

In this article, we will provide 20 types of commonly used CNC machining plastic materials, with their properties, advantages, disadvantages, applications, processing methods, and surface finish treatment explained. Since this article introduces all the common plastics used in CNC machining, the length is relatively long. Readers can quickly jump to the materials you are interested in by clicking on the left navigation bar.

1. ABS Plastic CNC Machining

Overview

Acrylonitrile butadiene styrene, ABS for short, is a widely used thermoplastic material with general use. ABS is commonly used because of its relatively low cost, high impact strength, good toughness, and electrical resistance. ABS is easy for CNC machining, including cutting, milling, turning, and engraving. CNC-machined ABS parts always have a matte finish.

 

CNC machining ABS is a cost-effective way for custom parts without expensive mold investment, especially for prototypes, jigs and fixtures, and low-volume production. 

 

General ABS Specification

ABS Mechanical Properties 
Ultimate tensile strength27.6 – 55.2 MPa
Yield strength18.5 – 51 MPa
Young’s modulus1.1 – 2.9 GPa
Elongation at break10 – 50 %
Hardness5.6 – 15.3 HV
ABS Thermal Properties 
Maximum service temperature61.9 – 76.9 °C
Thermal expansion coefficent84.6 – 234 10^-6/ºC
Thermal conductivity0.188 – 0.335 W/(m⋅°C)

 

Advantages

High impact resistance

Good machinability

Excellent durability

Great aesthetic appearance

Low cost

 

With the above properties, CNC-machined ABS parts are excellent for general-purpose prototypes, and molding prototyping parts.

 

Disadvantage

ABS lacks robust resistance to abrasion and chemicals and will dissolve when exposed to acetone. It is not extremely strong.

 

Poor dimensional stability

CNC-machined ABS plastic parts may have poor dimensional stability when exposed to changing temperature and humidity. High dimensional precision can not be assured.

 

Relatively low strength

Compared to some other engineering plastics, for example, PEEK, ABS has relatively low strength. ABS is not suitable for high mechanical strength components.

 

Limited heat resistance

The max service temperature of general ABS is 80℃. When exposed to high temperatures, ABS may deform and the mechanical properties will decrease.

 

Sensitivity to certain chemicals

ABS plastic is sensitive to certain chemicals and will melt in acetone. It does not have good abrasion and chemical resistance.

 

Common Applications

ABS is commonly used in pre-injection molding prototypes, the fabrication of electronic enclosures, casings, household appliances, and iconic Lego bricks.

 

ABS CNC Machining Processes

CNC milling

CNC turning

 

ABS CNC Machining Post-Processing

Typical machined ABS colors are beige/natural, black, white and blue. As machined CNC ABS parts can reach Ra 3.2 with a somewhat matte finish. Post processing like sandblasting, spray painting, and plating are available for cnc ABS parts.

abs cnc machining

2. Acrylic/PMMA Plastic CNC Machining

Overview

The chemical name of Acrylic is PMMA, Poly Methyl Methacrylate. Two famous acrylic brands are Plexiglass and Luctie.

 

Acrylic is a thermoplastic material, that can be melted, reformed, and easily glued using acrylic cement. It has good toughness, decent impact strength, and high scratch resistance. Acrylic does not discolor when exposed to sunlight for a long time.

 

General PMMA Specification

Acrylic Mechanical Properties 
Ultimate tensile strength55 – 83 MPa
Yield strength64 -80 MPa
Young’s modulus2.76 – 3.3 GPa
Elongation at break3 – 6.4 %
Hardness64 – 105 HRM
Acrylic Thermal Properties 
Maximum service temperature70 – 80 °C
Thermal expansion coefficent50 – 90 10^-6/ºC
Thermal conductivity0.19 – 0.2 W/(m⋅°C)

 

Advantages 

Excellent transparency

Strong weather resistance: Good weather resistance and resistance to yellowing or aging.

Lightweight and Sturdy: A substitute choice for glass.

Ease of machining

Good chemical stability

 

Considering the above properties, acrylic is very suitable for applications requiring transparency or translucence. It is a less durable but cheap alternative to PC material.

 

Disadvantage

Higher Cost

The cost of acrylic is more expensive than other plastics. For projects with a limited budget, the cost will be a consideration.

 

Brittle and Crack

Acrylic is brittle and tends to crack during CNC machining. For acrylic components with thinner wall thickness, it is easier to crack or shatter.

 

Relatively low scratch resistance

 

Temperature sensitivity

Like ABS, acrylic may deform at high temperatures over 80℃.

 

Not solvent resistant

Acrylic is sensitive to certain solvents, so careful consideration is required when using it in specific environments.

 

Common Applications

Acrylic is a good substitute for glass because acrylic can be easily machined. That is why acrylic is also called acrylic glass. CNC machining in acrylic can achieve complex geometry and optical clarity in the final parts. As machined acrylic is ideal for light pipes, light tubes, automobile light components, tanks, panels, optical engineering components, inspection windows, chemical testing hardware, and instrumentation covers.

 

Acrylic CNC Machining Processes

CNC Mill

CNC Lathe

 

Acrylic CNC Machining Post-Processing

Acrylic is transparent or semi-transparent in the unfinished state with many colors available. After CNC machining, clear acrylic will have a frosted translucent appearance with visible tool marks.

 

To get high transparency CNC machined acrylic parts, sandblasting, polishing, and polishing are needed. Read the blog Acrylic Polishing: The Complete Guide to learn more.

 

Sandblasting is also available for acrylic parts to cover the tool marks and get a consistent matte frosted appearance.

acrylic cnc machining part

3. PC Plastic CNC Machining

Overview

PC, or polycarbonate is a transparent amorphous thermoplastic engineering plastic. As one of the most commonly used CNC machined plastics, PC has good clarity, shatter resistance, and lighter weight. PC has higher temperature resistance than acrylic.

 

Raw clear PC has a natural milky blue transparent appearance. PC is also available in other colors.

 

General PC Specification

PC Mechanical Properties 
Ultimate tensile strength60 – 72.4 MPa
Yield strength59- 70 MPa
Young’s modulus2 – 2.44 GPa
Elongation at break50 – 120 %
Hardness17.7 – 21.7 HV
PC Thermal Properties 
Maximum service temperature101 – 144 °C
Thermal expansion coefficent120 – 137 10^-6/ºC
Thermal conductivity0.189 – 0.218 W/(m⋅°C)

 

Advantages

High impact resistance

High transparency

Lightweight

High-temperature resistance

Ease of machining

 

Compared to other engineering plastics CNC machined PC parts have good impact resistance while at the same time offering optical clarity, UV resistance, and higher-than-normal temperature resistance.

 

Disadvantage

High cost: PC is more expensive than most of the common plastics including PMMA(for general use).

 

Yellowing Over Time: With prolonged exposure to UV radiation, PC may become yellowing.

 

Scratch Sensitivity: Polycarbonate can be prone to scratches.

 

Chemical Sensitivity: PC may be sensitive to certain chemicals, and exposure to incompatible substances could lead to degradation.

 

Limited Chemical Resistance

While resistant to many chemicals, polycarbonate has limitations in resisting certain aggressive chemicals.

 

Common Applications

Polycarbonate is best suited for applications in which both high strength and optical transparency are required. Typical applications include optical disks, safety glasses, light pipes, power distribution covers and housings, connectors, battery boxes, CDs, DVDs, mobile phones, and even bulletproof glass.

 

PC CNC Machining Processes

CNC Mill

CNC Lathe

 

PC CNC Machining Post-Processing

Like acrylic, PC is also likely to crack and get scratches during CNC machining.

 

Vapor polishing

As machined PC parts often have tool marks on the surface and look frosted. To get optical clear PC components, polishing is the first step to remove the tool marks. Then vapor polishing will evens out the surface finish, and achieve a high transparent appearance.

 

Scratch resistant coating

CNC PC parts are prone to get scratch easily. We can apply some coating on its surface, improve the scratch resistance and keep the clarity at the same time.

PC cnc machining

4. Delrin/POM Plastic CNC Machining

Overview

Polyoxymethylene, POM for short, is a semi-crystalline thermoplastic acetal resin. POM has many good properties including excellent dimensional stability, high stiffness, low friction surface.

 

Delrin is the trademark name for POM produced by DuPong company. Polyoxymethylene is the scientific name, POM is the abbreviation of polyoxymethylene, acetal is the generic name. These four names all refer to Polyoxymethylene as an engineering plastic. Other famous brands of POM include Tecaform, Sustarin.

 

There are different types of POM, standard POM, toughened POM, low friction POM, glass-filled POM(Reinforced POM), UV stabilized POM.

 

At ECOREPRAP, we provide Delrin, Delrin with glass fibers and Delrin AF for CNC machining. Glass-filled Delrin provides excellent stiffness, excellent dimensional stability and high creep resistance. Delrin AF have an increased friction coefficient, which provide a self-lubrication, excellent wear resistance and good toughness and strength.

 

General POM Specification

Acetal Copolymer (POM-C) Mechanical Properties 
Ultimate tensile strength60 – 70 MPa
Yield strength60 – 67 MPa
Young’s modulus2.5 – 2.7 GPa
Elongation at break30 – 32 %
Hardness88 HRM
Acetal Copolymer (POM-C)  Thermal Properties 
Maximum service temperature82 – 90 °C
Thermal expansion coefficent90 – 97 10^-6/ºC
Thermal conductivity0.31 – 0.39 W/(m⋅°C)

 

Advantages

High mechanical strength

Low friction and wear resistance

Chemical resistance

Dimensional stability

Low moisture absorption

Good machinability by CNC

 

Due to its reliability and durability, Delrin/POM are commercially used for decades. Delrin is an ideal choice for CNC machining precision parts which both need tight tolerance and high stiffness.

 

Disadvantage

Sensitive to UV Exposure: It can lead to degradation and reduced performance.

 

Not Suitable for High-Temperature Applications

 

Difficult to Bond or Adhere: The surface of Delrin is slippery and hard to glue. There are internal stresses inside Delrin, and Delrin is likely to wrap during CNC machining, especially in the parts with thin areas or have a lot of materials to be removed.  

May Generate Formaldehyde under Certain Conditions

Cost: POM is more expensive than ABS.

 

Common Applications

CNC machining Delrin/POM is perfect for high-precision mechanical components that need both strength and tight tolerance, like bearings, gears, fasteners, bushings, jigs, fixtures, snap fits, chemical pumps, automotive parts, construction parts, and consumer electronics.

 

Delrin/POM CNC Machining Processes

CNC Mill

CNC Lathe

 

Important notes:

Stress relief is a critical consideration for POM CNC machining, to minimize the part distortion and dimensional instability.

 

POM CNC Machining Post Processing

As machined Ra 3.2 is the most commonly used for POM CNC parts. To cover the toll marks on the POM surface, sandblasting can be performed. However, the black POM surface will look grey after sandblasting.

POM CNC Machining

5. PE Plastic CNC Machining

Overview

Polyethylene, PE by short, is one common thermoplastic with good climate resistance, good impact stamina and a high strength-to-weight ratio. HDPE, high-density polyethylene has high tensile strength. UHMWPE, ultra-high molecular weight polyethylene has good wear resistance, impact resistance and chemical stability.

 

Both HDPE and UHMWPE are widely used in CNC machining.

 

General PE Specification

Mechanical PropertiesHDPEUHMWPE
Ultimate tensile strength22.1 – 31 MPa38.6 – 48.3 MPa
Yield strength26.2 – 31 MPa21.4 – 27.6 MPa
Young’s modulus1.07 – 1.09 GPa0.894 – 0.963 GPa
Elongation at break500 – 700 %200 – 500 %
Hardness7.9 – 9.9 HV3.4 – 8.3 HV
Thermal PropertiesHDPEUHMWPE
Maximum service temperature113 – 129 °C80 – 110 °C
Thermal expansion coefficent106 -198 10^-6/ºC234 – 360 10^-6/ºC
Thermal conductivity0.461 – 0.502 W/(m⋅°C)0.19 – 0.197 W/(m⋅°C)

 

Advantages

The advantages of HDPE include chemical resistance, lightweight, good impact resistance, low moisture absorption, and low cost.

 

UHMWPE has excellent wear resistance, low friction coefficient,  good chemical resistance, high impact strength, and self-lubrication.

 

Disadvantage

HDPE is sensitive to temperature, and not UV resistance.  

 

UHMWPE is difficult to be bonded and has limited heat resistance. The cost of UHMWPE is higher than HDPE.

 

Common Applications

HDPE CNC parts are commonly used for packaging and piping, for example, fluid flow pipes, plugs and seals.

 

UHMWPE CNC parts are generally used for marine and automotive industries, such as,conveyor lines, gears, bearings, pistons, valves, wear plates, seals, food processing devices, and shutoffs.  UHMW-PE is prone to creep and not suitable for parts under continuous stress.

 

PE CNC Machining Processes

CNC mill

CNC lathe

 

PE CNC Machining Post-Processing

As machined and sandblasting are common for HDPE and UHMWPE surface finishes.

 

PE CNC Machining

6. Nylon Plastic CNC Machining

Overview

Nylon is a thermoplastic material that has good toughness, good hardness, high chemical resistance, and good abrasion resistance. Nylon is one type of polyamide and is used as an engineering plastic.

 

There are different grades of Nylon, Nylon 6, flame retardant Nylon 6, Nylon 6 with 30% Glass Filled, and Nylon 6/6 with 30% Glass Filled.

 

General Nylon Specification

Nylon 6 Mechanical Properties 
Ultimate tensile strength64.7 – 79.1 MPa
Yield strength51.2 – 63.8 MPa
Young’s modulus1.58 – 1.97 GPa
Elongation at break200-300 %
Hardness16.4-18.1 HV
Nylon 6 Thermal Properties 
Maximum service temperature90 – 130 °C
Thermal expansion coefficent88.2 – 91.8 10^-6/ºC
Thermal conductivity0.294 – 0.306 W/(m⋅°C)

 

Advantages

High strength and durability

Excellent wear resistance

Chemical resistance

Low friction coefficient

Lightweight

Versatility in machining

Electrical insulation properties

 

With the above properties mentioned, CNC Nylon parts are suitable for environments that require a combination of strength, durability, and versatility.

 

Disadvantage

Moisture Absorption: Nylon tends to absorb moisture from the surroundings.

 

Dimensional Stability: Due to moisture absorption, the dimensions of CNC Nylon parts may change over time.

 

UV Sensitivity: Nylon is sensitive to UV, and prolonged exposure can result in degradation and color fading.

 

Not Suitable for High-Temperature Applications

 

Common Applications

As an economical alternative to metals, Nylon is widely used in electrical components like circuit board mounting hardware, electrical insulation, automobile engine compartment components, medical devices, aerospace components, and transportation parts.

 

Nylon CNC Machining Processes

CNC mill

CNC lathe

 

Nylon CNC Machining Post-Processing

CNC-machined Nylon parts often are as machined because sanding on the Nylon surface makes the parts look worse. Sandblasting can be performed to cover the tool marks, achieving a lower surface roughness. Nylon is prone to absorb liquid so dyeing is available for Nylon to get different colors.

Nylon Bar
blue nylon cnc part

7. PEEK Plastic CNC Machining

Overview

PEEK, polyether ether ketone, is a thermoplastic engineering material. With excellent mechanical properties, PEEK is chemical resistant even at high temperatures. It is resistant to moisture, steam, water, seawater, wear, and chemicals.

 

PEEK is a great lightweight substitute for most soft metals in high-stress and high-temperature applications.

 

Glass-filled PEEK provides better rigidity, strength, and toughness than PEEK. Due to the addition of glass fibers, the glass-filled PEEK can maintain dimensional stability even in harsh chemical and thermal environments. Thus, it is a high-performance plastic for aircraft, automotive, medical, chemical, semiconductor, and microwave industries.

 

General PEEK Specification

PEEK Mechanical Properties 
Ultimate tensile strength70.3 – 103 MPa
Yield strength87 – 95 MPa
Young’s modulus3.76 – 3.95 GPa
Elongation at break30 – 150 %
Hardness26.1 – 28.5 HV
PEEK Thermal Properties 
Maximum service temperature239 – 260 °C
Thermal expansion coefficent50 – 60 10^-6/ºC
Thermal conductivity0.24 – 0.26 W/(m⋅°C)

 

Advantages

High-temperature resistance

High strength and stiffness

Low friction coefficient

Electrical insulation properties

Biocompatibility

Radiation resistance

Chemical Resistance

 

Disadvantage

High Cost: PEEK is the most expensive plastics. The cost is must consideration for application.

 

Processing Challenges: PEEK CNC machining can be challenging, and specialized equipment and expertise are often required, which makes higher machining costs.

 

Limited Color Options: PEEK is typically available in opaque grey or beige.

 

Common Applications

CNC machine PEEK parts are widely used for bushings, bearings, seals and backup rings, pump and valve components, medical instrumentation, and food processing machinery components.

 

PEEK CNC Machining Processes

CNC mill

CNC lathe

 

PEEK CNC Machining Post Processing

PEEL parts are often as machined. Sandblasting may be used to remove the tool marks.

PEEK CNC machining

8. Teflon/PTFE Plastic CNC Machining

Overview

Polytetrafluoroethylene (PTFE)  is a high-performance engineering plastic with low friction and good chemical resistance. Compared with other engineering plastics, the high melting point and high chemical resistance are the main factors for its wide application.

 

Teflon is the DuPont trade name for its PTFE material. In common usage, we often use the term “Teflon” to refer to PTFE. Teflon has the highest temperature resistance among all common engineering plastics. Due to fluoropolymer existence, Teflon is exceptionally corrosion resistant.

 

Due to low strength and relative softness, CNC machining in PTFE/Teflon is relatively easy. But high precision is difficult.

 

General Teflon/PTFE Specification

Teflon/PTFE Mechanical Properties 
Ultimate tensile strength25 – 31 MPa
Yield strength14 – 41.4 MPa
Young’s modulus0.39 – 2.25 GPa
Elongation at break300 – 450 %
Hardness50 – 65 Shore D
Teflon/PTFE Thermal Properties 
Maximum service temperature250 – 270 °C
Thermal expansion coefficent7 – 20 10^-6/ºC
Thermal conductivity0.23 – 0.5 W/(m⋅°C)

 

Advantages

Low friction coefficient

Chemical resistance

Nonstick properties

Wide temperature range

Electrical insulation

Inert nature

 

Disadvantage

Difficult to bond

Limited wear resistance

Not suitable for high load applications

High cost

 

Common Applications

The high melting point, low friction coefficient, and chemically inert properties distinguish PTFE/Teflon from most engineering plastics. PTFE/Teflon coating is well-known in nonstick cookware. CNC-machined Teflon parts are widely used in bearings, chemical engineering, general machinery construction, electrical applications and the food industry.

 

PTFE CNC Machining Processes

CNC mill

CNC lathe

 

PTFE CNC Machining Post Processing

Teflon material is available in opaque white and black. It has a slippery surface texture and is nonstick. For CNC machined Teflon parts, it is always as machined. Sandblasting can make the Teflon parts a smoother and uniform surface smoothness finish by removing irregularities.

 

9. PET Plastic CNC Machining

Overview

With excellent strength and stiffness, PET/PETP, polyethylenetarapthalate, is one commonly used engineering thermoplastic. There is quite a machinability to tight tolerance.

 

General PET Specification

PET/PETP Mechanical Properties 
Ultimate tensile strength50 – 90 MPa
Yield strength47 – 90 MPa
Young’s modulus2 – 3 GPa
Elongation at break20 – 300 %
Hardness80 – 96 HRM
PET/PETP Mechanical Properties 
Maximum service temperature60 – 115 °C
Thermal expansion coefficent40 – 60 10^-6/ºC
Thermal conductivity0.15 – 0.28 W/(m⋅°C)

 

Advantages

Good mechanical strength

Reasonable resistance to many chemicals

Good resistance to weathering

Good electrical insulation   

A recyclable plastic relatively

Low moisture absorption

 

Disadvantage

Temperature sensitivity  

Sensitive to scratches and abrasion

Transparency changes exposed to light, moisture, or certain chemicals  

Limited pliability

Higher raw material cost

 

Common Applications

CNC-machined PET/PETP is a functional plastic product suitable for various applications, including food product packaging, drink containers, fibers, movies, industrial parts, and fibers. Among the factors for its prevalent usage is its exceptional efficiency and reasonably inexpensive.

 

PET CNC Machining Processes

CNC mill

CNC lathe

 

PET CNC Machining Post-Processing

For CNC machined PET/PETP parts, always keep them as machined. No more post processing is needed.

PET CNC Machining

10. PP Plastic CNC Machining

Overview

Polypropylene, PP for short, is a semi-crystalline thermoplastic. There are two forms of PP, homopolymer and copolymer. Homopolymer PP is the most generic grade. There are different degrees of ethylene mixed for copolymer PP.

 

PP is BPA-free plastic. With exceptional fatigue resistance and toughness, PP is also a lightweight plastic and resistant to many solvents and chemicals.

 

Because PET tends to gall and meld during CNC machining, it may be more challenging than other plastics.

 

General PP Specification

Mechanical PropertiesPPPP HomopolymerPP+GF(30%)
Ultimate tensile strength23 – 33 MPa 68 – 85 MPa
Yield strength30 – 32 MPa19 – 30 MPa6.5 – 7 GPa
Young’s modulus0.9 – 1.6 GPa0.7 – 1.2 GPa2.1 – 3.4 %
Elongation at break8 – 12 %min. 50 %110 HRC
Hardness65 – 102 HRR  
Mechanical PropertiesPPPP HomopolymerPP+GF(30%)
Maximum service temperature80 – 130 °C80 °C100 °C
Thermal expansion coefficent6 – 17 10^-6/ºC 25 – 70 10^-6/ºC
Thermal conductivity0.22 – 0.27 W/(m⋅°C) 0.27 – 0.3 W/(m⋅°C)

 

Advantages

Excellent chemical resistance

Lightweight material

A cost-effective material

Good electrical insulation  

Low moisture absorption

High impact strength

A recyclable material

 

Disadvantage

Limited temperature resistance

Not UV stable  

Poor adhesion properties

 

Common Applications

PP’s excellent resistance to most solvents and chemicals and fatigue strength make CNC machined PP components especially suitable for flexible parts and parts that are exposed to corrosive environments, such us laboratory equipment, containers, interior automotive components like bumpers, electrical housings and connectors, and industrial components, such as tanks, pipes, and fittings.

 

PP CNC Machining Processes

CNC mill

CNC lathe

 

PP CNC Machining Post Processing

In the market, the default PP is semi-clear white. Opaque white is also available on request. As machined is the default surface finish. Usually, there is no need for further post-processing.

 

11. PPS Plastic CNC Machining

Overview

Polyphenylene sulfide, PPS for short, is a semi-crystalline engineering thermoplastic with excellent high-temperature resistance. PPS is a high-performance engineering plastic in harsh chemical environments due to its extremely stable molecular structure.

 

General PPS Specification

PPS Mechanical Properties 
Ultimate tensile strength70 – 100 MPa
Yield strength50 to 80 MPa
Young’s modulus2 to 3 GPa
Elongation at break1% to 3%
Hardness70 to 90 Shore D
PPS Mechanical Properties 
Maximum service temperature200 to 240 °C
Thermal expansion coefficent30 to 60 10^-6/ºC
Thermal conductivity0.25 to 0.35 W/(m⋅°C)

 

Advantages

Excellent high-temperature resistance

Good dimensional stability

Good electrical insulation

Excellent chemical resistance

Low moisture absorption

High strength and stiffness

Low coefficient of friction

 

Disadvantage

Higher cost

 

Common Applications

With excellent resistance to heat, acids, alkalines, mildew, bleaches, aging, sunlight, and abrasion, CNC PPS parts are widely used in high-temperature and harsh chemical applications, for example, automotive components like engine parts, fuel system components, and electrical connectors, electrical and electronic applications like connectors, insulators, and housing for electronic devices, industrial components such as pumps, valves, and seals, aerospace components, medical devices and oil and gas applications.

 

PPS CNC Machining Processes

CNC mill

CNC lathe

 

PPS CNC Machining Post Processing

PPS raw material will take an opaque, off-white finish. After CNC machining, it has a smooth, matte appearance. No further post-processing is needed usually.

 

12. PVC Plastic CNC Machining

Overview

Polyvinyl Chloride, PVC for short, is the world’s third most used plastic with all-around excellent chemical resistance, good weather resistance, good electrical insulation, and nice mechanical properties like good toughness. Due to PVC’s hardness and rigidity, CNC machining in PVC material is easy.

 

There are two forms of PVC, plasticized and unplasticized. Unplasticized PVC is applied in rigid parts like fittings and pipes. For CNC machining PVC material, is unplasticized PVC. Plasticized PVC is more flexible, typical applications include cables and tubes.

 

If exposed to sunlight or other UV sources, transparent PVC parts will discolor over time, though the mechanical properties remain unchanged.

 

General PVC Specification

PVC Mechanical Properties 
Ultimate tensile strength45 to 60 MPa
Yield strengthabout 40  MPa
Young’s modulus2.4 to 3.1 GPa
Elongation at break40% to 100%
Hardness80 to 95 Shore D
PVC Mechanical Properties 
Maximum service temperature60 to 70 °C
Thermal expansion coefficent50 to 60 10^-6/ºC
Thermal conductivity0.15 to 0.25 W/(m⋅°C)

 

Advantages

Good resistance to chemicals, acids, and alkalis

Effective electrical insulator

Good durability and toughness

Good resistance to weathering and uv exposure

Easy to machine using cnc processes

Cheap raw material price

 

Disadvantage

Limited temperature resistance

Not suitable for high load applications

Poor fire resistance

 

Common Applications

Due to PVC’s excellent to chemical resistance, UV resistance, and moisture resistance, CNC machined PVC components are suitable for construction and building parts like pipes, fittings, window profiles, and door frames, electrical components, automotive components like interior trim and gaskets, signage, display boards, and exhibition materials, plumbing systems like pipes and fittings.

 

PVC CNC Machining Processes

CNC mill

CNC lathe

 

PVC CNC Machining Post-Processing

PVC is very suitable for CNC machining and CNC machined PVC parts always have a smooth, shiny surface finish. There is no need for further post-processing if there is no special requirement.

 

Most engineering plastics can not be painted. But PVC can be painted easily for aesthetic purposes and also to increase its outdoor lifespan. The painting shall not contain solvents that attack polyvinyl chloride. Otherwise, it will decrease the PVC’s mechanical properties.  

13. PU Plastic CNC Machining

Overview

Polyurethane, or PU, is a versatile polymer with excellent elasticity. PU is available with different hardness, while Shore A and Shore D scales are commonly used. Shore A PU is softer and more flexible, while Shore D PU is harder and more rigid. For CNC machining PU, Shore D is preferred as the hardness is more suitable for machining.

 

PU Mechanical Properties 
Ultimate tensile strength20 to 60 MPa
Yield strength10 to 50 MPa
Young’s modulus0.5 to 3.5 GPa
Elongation at break100% to 1000%
HardnessShore A 20 to Shore D 80
PU Mechanical Properties 
Maximum service temperatureUp to 150°C
Thermal expansion coefficent50 to 200 x 10^-6 /°C
Thermal conductivity0.01 to 0.03 W/(m·K)

Advantages

Versatile excellent wear resistance   

Good resistance to oils and chemicals  

Excellent damping and vibration isolation properties  

 

Disadvantage

Limitations in extreme temperature conditions

Hydrolysis susceptibility

 

Common Applications

CNC machined PU parts find applications in various industries, including machine components like bushings, gears, and housings, and automotive components like suspension bushings, bumpers, seals and gaskets, rollers, and wheels.

 

PU CNC Machining Processes

CNC mill

CNC lathe

 

PU CNC Machining Post-Processing

There is no need for post-processing for CNC-machined PU parts. Keep them as machined.

pu cnc machining

14. PPSU Plastic CNC Machining

Overview

As a lightweight plastic, PPSU (polyphenylsulfone) can withstand high temperatures up to 180 ℃ and have excellent dimensional stability. As a high-performance plastic, PPSU maintains toughness over a broad temperature range and good chemical resistance. It is remarkably resistant to gamma and X-rays radiation. 

 

General PPSU Specification

PPSU Mechanical Properties 
Ultimate tensile strength70 MPa
Yield strength 
Young’s modulus2.3 GPa
Elongation at break60 – 120 %
Hardness 
PPSU Mechanical Properties 
Maximum service temperature180 °C
Thermal expansion coefficent30.6 10^-6/ºC
Thermal conductivity 

 

Advantages

Excellent heat resistance    

Dimensional stability

Good chemical resistance

Good electrical insulation

Radiation resistance to gamma and x-rays

Flame retardant

Steam sterilization

Biocompatibility(Some grade)

 

Disadvantage

Higher cost

 

Common Applications

PPSU’s heat resistance, flame retardance, and dimensional stability make it suitable for many applications, including the aerospace industry like aircraft interiors, electrical components, chemical processing equipment. Biocompatible grade PPSU can be used for medical components.

 

PPSU CNC Machining Processes

CNC mill

CNC turning

 

PPSU CNC Machining Post Processing

As machined is the default for PPSU CNC-machined part

15. HIPS Plastic CNC Machining

Overview

High-impact polystyrene, HIPS for short, is one durable light weight thermoplastic. HIPS is suitable for application which need consider weight as well as toughness and impact resistance.

Advantages

Cost-effective

Ease of machining

Lightweight.

Good impact resistance

Thermal insulation

Disadvantage

Limited heat resistance

Chemical sensitivity

Not suitable for outdoor applications

Limited mechanical strength

Common Applications

Due to its lightweight nature, ease of machining, and cost-effectiveness, CNC-machined HIPS parts are suitable for prototyping, packaging components, and educational models.

HIPS CNC Machining Processes

CNC mill

CNC lathe

HIPS CNC Machining Post Processing

CNC machined HIPS parts usually does not need any further post processing.

16. Bakelite Plastic CNC Machining

Overview

Bakelite, also known as phenolic resin, is a thermoplastic material. The most notable feature for bakelite is excellent electrical insulation. Bakelite also have impressive heat resistance and chemical resistance.

 

In electrical engineering, it was popular for making insulators, switches, and connectors because of its excellent insulating properties. The automotive sector benefited from Bakelite in components like distributor caps and brake systems. Consumer goods, especially radios and telephones, often used Bakelite. Its heat resistance and durability made it suitable for industrial components like gears and handles.

 

Although it’s less common now due to modern plastics, Bakelite holds historical significance for its role in the early development of synthetic polymers.

Advantages

Electrical insulation

Good thermal insulation

Good chemical resistance

Good machinability

Dimensional stability

Cost-effective

Disadvantage

Relatively brittle

Soften or degrade at high temperatures

Not UV resistant

Limited mechanical strength

Common Applications

Bakelite CNC-machined parts can be used in electrical applications, including insulators, connectors, and switch gear components and industrial equipment.

Bakelite CNC Machining Processes

CNC mill

CNC lathe

Bakelite CNC Machining Post-Processing

There is no need for further post-processing for bakelite CNC-machined parts.

CNC Machining Materials Bakelite

17. FR4 Plastic CNC Machining

Overview

FR4 is a flame-retardant glass epoxy laminate. It consists of woven fiberglass cloth impregnated with an epoxy resin. The “FR4” designation often refers to a specific grade of glass epoxy laminate known for its flame-retardant properties.

 

FR4 is commonly used as a substrate material for printed circuit boards (PCBs) due to its excellent electrical insulation properties, mechanical strength, and flame resistance.

 

General FR4 Specification

FR4 Mechanical Properties 
Ultimate tensile strength240 – 310 MPa
Yield strength 
Young’s modulus12 – 27 GPa
Elongation at break0.008 – 0.01 %
Hardness100 – 110 HRM
FR4 Mechanical Properties 
Maximum service temperature122 – 145 °C
Thermal expansion coefficent9.9 – 11.9 10^-6/ºC
Thermal conductivity0.29 – 0.34 W/(m⋅°C)

 

Advantages

Excellent electrical insulation

Good mechanical strength and dimensional stability

Flame Resistance

Easy to machine using CNC processes

 

Disadvantage

Relatively brittle

Tool wear

 

Common Applications

Due to its electrical insulation properties, FR4 CNC machined parts are extensively used as the substrate material for PCBs in the electronics industry, electrical components, including insulators, connectors, and switchgear, and automotive electronics.

 

FR4 CNC Machining Processes

CNC mill

CNC lathe

 

FR4 CNC Machining Post Processing

There is no further need for post processing treatment for FR4 cnc machining parts.

nc machining FR4

18. G-10 Plastic CNC Machining

Overview

G10 is a high-pressure fiberglass laminate. Similar to FR4, it is composed of woven fiberglass impregnated with an epoxy resin. The “G10” designation typically indicates a specific grade of glass epoxy laminate.

 

G10 is often used in applications where high mechanical strength and dimensional stability are crucial. It is commonly employed in various industrial and mechanical components.

 

General G-10 Specification

Garolite G-10 Mechanical Properties 
Ultimate tensile strength260 – 310 MPa
Yield strength 
Young’s modulus12 – 14 GPa
Elongation at break 
Hardness100 – 110 HRM
Garolite G-10 Mechanical Properties 
Maximum service temperature122 – 140 °C
Thermal expansion coefficent9.9 – 11.9 10^-6/ºC
Thermal conductivity0.288 W/(m⋅°C)

 

Advantages

High mechanical strength and dimensional stability

Electrical Insulation

Good resistance to various chemicals

Low moisture absorption

Relatively easy to machine using CNC processes

 

Disadvantage

Relatively brittle

Tool wear

 

Common Applications

G-10 CNC-machined parts find applications in various industries, including mechanical components, such as gears, bearings, and structural supports, electronics industry for insulating components and electrical connectors, and knife handles.

 

G-10 CNC Machining Processes

CNC mill

CNC lathe

 

G-10 CNC Machining Post Processing

There is no further need for post processing treatment for G-10 cnc machining parts.

19. Carbon Fiber Plastic CNC Machining

Overview

Carbon fiber plastic is known for its strength and durability with a lightweight. Carbon fiber is available in tubes and sheets.

 

Advantages

High strength-to-weight ratio

Excellent stiffness

Corrosion resistance

Low thermal expansion

High fatigue resistance

Aesthetic appeal

Electromagnetic transparency

 

Disadvantage

Expensive cost

Brittleness in certain directions

Abrasive nature

Difficult to recycle

 

Common Applications

Due to its exceptional strength-to-weight ratio and other properties, CNC machined carbon fiber parts are widely used in different industries, including aerospace for components like aircraft structures, interior panels, and UAV components, automotive industry for lightweight body panels, interior components, and structural elements, sports equipment such as bicycle frames, golf clubs, and racing gear, orthopedic implants and diagnostic equipment, and consumer electronics like laptops and smartphones.

 

Carbon Fiber CNC Machining Processes

CNC mill

CNC lathe

 

Carbon Fiber CNC Machining Post-Processing

There is no further post-processing for CNC machining carbon fiber parts.

20. PEI Plastic CNC Machining

Overview

Polyetherimide , or PEI, is a high-performance engineering thermoplastic. The remarkable properties of PEI include high strength and stiffness, exceptional electrical insulating properties, high temperature and chemical resilience,  biocompatibility, and great machinability via CNC machining.

 

ULTEM is a PEI trade name owned by SABIC, which are often used in CNC machining.

 

ULTEM 1000 is a translucent amber-colored plastic. Including its excellent durability, strength, stiffness, and heat resistance, ULTEM 1000 is a better choice over Nylon or Derlin because of its highest dielectric properties. CNC-machined ULTEM 1000 parts are suitable for industrial equipment, medical devices, and electronics.

 

ULTEM 2300 is 30% glass fiber reinforced. As a high-performance thermoplastic, ULTEM 2300 provides super strength, stiffness, excellent chemical resistance, and flame resistance. It is suitable for electrical and electronic applications, high-strength and heat applications and reusable medical equipment.

General PEI Specification

Mechanical PropertiesPEI Ultem 1000PEI Ultem 2300 30% Glass Filled
Ultimate tensile strength125 MPa135 MPa
Yield strength125 MPa135 MPa
Young’s modulus3.1 – 3.3 GPa5.3 GPa
Elongation at break12 – 35 %4%
Hardness  
Mechanical Properties  
Maximum service temperature170 °C170 °C
Thermal expansion coefficent50 10^-6/ºC30 10^-6/ºC
Thermal conductivity0.21 – 0.24 W/(m⋅°C)0.23 W/(m⋅°C)

 

Advantages

Excellent heat resistance

Good dimensional stability

Resistant to a wide range of chemicals

Excellent electrical insulating

High tensile and flexural strength

Good resistance to high-energy radiation  

Flame retardant biocompatible(some grade)

Disadvantage

Higher cost

Brittle at low temperatures

Common Applications

ULTEM is excellent when used as an electrical insulator. CNC machining ULTEM parts are suitable for components of the medical, aerospace, and automotive industries.

PEI CNC Machining Processes

CNC mill

CNC lathe

PEI CNC Machining Post-Processing

ULTEM is in a naturally translucent amber color. After CNC machining, the surface will become slightly frosted. As machined is always preferred, no further surface treatment is needed.

Summary

20 types of common CNC machining plastics are introduced in this article. Each has its advantages and disadvantages. Whether to use metal or plastic for your CNC machining projects? How to select the right type? We will give you more information in the other blogs.

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