How to Select The Right Plastic For Your CNC Machined Parts

plastic cnc machining

One of the most important steps in designing a part is to decide what material it should be made of. If you decide to use plastic, you know there are many plastic machining options today. Each one has its own set of properties. CNC-machined plastic components are easy to use and make great prototypes. But which one should you choose? Do you understand each of them?

This guide will help you match your project requirements with the right material for CNC plastic part manufacturing. With good knowledge of the material will also help you communicate better with the machining manufacturer.

I will give you an overview of material properties, including the pro and cons of each. The following plastics will be covered in this post:

  • ABS
  • Nylon
  • Acrylic
  • HDPE
  • Polycarbonate

ABS Plastic CNC Machining

ABS is a versatile general-purpose plastic that is widely used. ABS is a versatile plastic that can withstand high impacts, is tough, and has low electrical resistance. It can also be painted, glued, or welded together. ABS CNC machining is cutting or engraving with a CNC milling machine.


ABS is a great choice for general prototyping, pre molding prototypes, and parts that will be subject to impact and require toughness or when low costs are desired.


ABS is not chemical-resistant or abrasion-resistant and can melt in acetone. ABS is not a strong plastic. Due to stricter environmental regulations on the West Coast, large amounts of ABS can only be made in the Midwest or East Coast. Large ABS parts can take up to a week to ship if stock is more than 2 inches thick.

Common Applications

ABS is commonly used for preinjection molding prototypes to make electronic enclosures, household appliances, and iconic Lego bricks.

Nylon CNC Machining

We have Nylon 6/6 and glass-filled nylon. Nylon 6/6 plastic is strong and can be used for many purposes. It also has the rigidity required to maintain its shape under load conditions. It is also very popular to use glass-filled nylon for CNC machining.


Nylon is strong and rigid and can maintain over a wide temperature range. It also has good electrical insulation and chemical and wears resistance. Nylon is an excellent choice for strong and durable parts but at a lower price.

The glass-filled nylon is strong, rigid, tough, and dimensionally stable.


Nylon absorbs moisture and can swell, which causes it to lose some of its dimensional accuracies. Due to the internal stresses in the material, it can also warp when there is too much asymmetric material removal during machine machining.

Common Applications

Nylon is often used in medical devices, circuit board mounting hardware, and electrical insulation. It can also be found in automobile engine compartment components and aerospace components. It is often used in these applications as an economically viable alternative to metals.


Acrylic is also known as Plexiglass and Lucie. It has a chemical composition called PMMA (Poly Methyl Methacrylate). Acrylic cement can be used to bond it. It has good scratch resistance and impact strength.


It can be used in any application that requires optical transparency or translucence. Its scratch resistance makes it ideal for areas that are prone to abrasion.


Acrylic is a hard plastic that can crack and shatter rather than stretch like a pliable material. Acrylic components are fragile because they have thinner walls.

All machined surfaces made from acrylic will lose transparency and turn translucent. It is a good idea for acrylic parts to be kept at the stock thickness in order to maintain transparency. It is possible to polish the surface if transparency is required on a machined surface.

Common Applications

Acrylic is machined and transparent. It is often used as a lightweight replacement for glass or to make light pipes. Other common uses include light tubes, light tubes, light tubes, and panels, as well as components for optical engineering.

HDPE CNC Machining

HDPE is high-density polyethylene. HDPE is an opaque crystalline material. It can be finished with a waxy or black dye, but it is also available commercially.


HDPE, despite its name, is one of the lightest plastic. It also has great chemical resistance and electrical insulation. It has a low coefficient for friction and is resistant to low-temperature impact. It is an affordable and durable option for CNC-machined plastic parts.


HDPE’s biggest disadvantage is its weak strength in tension and flexing. It is also susceptible to stress cracking.

Common Applications

HDPE is used frequently in fluid applications such as fuel tanks, plastic bottles, fluid flow pipes, and other fluids. HDPE is a great choice for plugging and sealing because of its chemical resistance and slipperiness. It also works well in electrically sensitive or weight-sensitive applications.

Polycarbonate CNC Machining

The most durable plastic is polycarbonate (or PC). PC is a transparent thermoplastic. It is also one of the most widely CNC machined plastics and the most frequently recycled plastics worldwide. Although it has a transparent, milky-blue appearance, it is also available commercially in a dark hue. Both the black- and milky blue tints are naturally glossy.


Polycarbonate is very tough and rigid and can withstand high temperatures. It remains functional for a long time. It can also be dyed black to achieve opaqueness. Polycarbonate is the best choice for applications where a tough, strong, or transparent plastic is required or desired. Polycarbonate is one of the most widely used and frequently recycled plastics.

Polycarbonate is used more often than acrylic due to its 250X greater impact resistance and higher resilience.


Polycarbonate is susceptible to scratches and has poor wear resistance. As an optional step after processing, anti-scratch coatings or vapor polishing may be applied to increase wear resistance and optical clarity. It is not available in pieces larger than 2 inches thick. This limits the number of parts made from polycarbonate.

Common Applications

Polycarbonate’s transparency and durability make it ideal for optical disks and safety glasses.

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Want.Net Technical Team

Want.Net Technical Team

The Want.Net Technical Team has diverse members with extensive education and training in CNC machining. They prioritize precision, efficiency, and innovation to provide high-quality manufacturing solutions globally.

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