Plastic CNC Machining: How It Works, Benefits, And Types

Plastic CNC machining
Plastic CNC machining

Plastic is, no doubt, vital in today’s manufacturing industry. It is no surprise that plastic CNC machining is one of the most commonly used processes in the manufacturing sector. And while a variety of methods can be used to machine plastics, computer numerical control (CNC) machining is often seen as the best option for achieving precise results.

If you’re new to plastic CNC machining or just looking for a refresher, this quick guide is for you. We’ll cover the basics of CNC machining plastics, including the different types of plastics that can be machined, the benefits of using CNC over other methods, and even the CNC machining service.

What is Plastic CNC Machining?

Plastic CNC machining uses computer-controlled tools to remove some material from a plastic block in a subtractive machining process. This contrasts with additive manufacturing methods like 3D printing, which build a product from scratch.

CNC machining plastic helps create parts with tight tolerances and smooth finishes. You can also use it to create small and large plastic parts suitable for various applications. Some of the standard products that are made using CNC machined plastic include:

  • Electronic components such as circuit boards and housings
  •  Medical devices such as implants and prosthetics
  •  Plastic gears and other components for machinery
  •  Automotive parts, and much more!

Plastic for CNC Machining

Not all plastic can be a machine. Some, like resin, are too soft, while others may not be able to withstand heat. The plastic for CNC machining must be able to stand up to several factors, including:

  • The speed of the cutting tool
  •  The temperature generated by the cutting process
  •  The type of cutter being used

In light of that, some plastics are better suited to CNC machining than others. Some of the popular types of machinable plastic that are used with CNC machines, together with their properties, are listed below:

Acrylonitrile Butadiene Styrene (ABS): With a good balance of strength and machining ease, ABS is one of the most commonly used plastics in CNC machining. ABS is also heat resistant. CNC machining ABS is a cost-effective process that you can use for a wide range of applications, including prototypes.

Polycarbonate (PC): PC is a strong and durable plastic often used to make electronic components and lenses. It is also resistant to heat and chemicals, making it an ideal plastic material for various industrial uses.

Nylon (PA): Nylon combines strength and heat resistance to make it a good plastic for CNC machining. It’s also low-cost and can be used for a wide range of applications, including prototypes and production runs.

Acrylic (PMMA): This CNC plastic material is a clear plastic often used in making signs, displays, and other products where transparency is required. It’s also strong and easy to machine, among other properties.

High-Density Polyethylene (HDPE): HDPE is a strong and durable plastic often used to make pipes and other products that need to withstand high temperatures and pressures. It’s also resistant to chemicals and easy to machine.

Setting up for plastic machining process
Setting up for plastic machining process

Plastic Machining Process

The first step in the plastic CNC machining process is to create a computer-aided design (CAD) model of the desired part. This model will be used to generate the toolpaths that will guide the cutting tools during the machining process.

After the toolpaths have been generated, they are loaded into a CNC machine. The machine then uses these instructions to guide the cutting tools as they remove material from the plastic block.

The amount of material that is removed during each pass can be controlled, meaning that very precise tolerances can be achieved.

Once the machining process is complete, the finished part is then ready for use. The finished parts can then be used as-is or undergo further finishing processes, such as painting, plating, or anodizing.

Advantages of Plastic CNC Machining

There are many advantages to using CNC machining for plastic parts, including:

  • Machining ease: Plastics are pretty easy to machine and don’t require special tooling like some metals.
  • Material availability: You can get plastic in just about any color, hardness, or size you need.
  • Low cost: Plastic CNC machining is generally a very cost-effective way to produce parts.
  • Fast production: CNC machines can churn out plastic parts very quickly, given the ease to machine the material.
  • Chemical resistance: Plastics are generally resistant to chemicals, making them ideal for certain environments.
  • Low weight: Plastic parts tend to be lighter than metal parts, which is good for applications where weight is a concern.

There are also some disadvantages to using CNC plastic machining to create components or products:

  • Limited material selection: Not all plastics can be machined using CNC technology.
  • Low thermal conductivity: Most plastics have poor thermal conductivity, and may warp during the machining process due to the heat generated by the cutting tools.
CNC plastic milling
CNC plastic milling

Plastic CNC Machining Types

Plastic CNC machining involves a number of different operations. Depending on the desired finish and the type of plastic being used, different machining techniques will be employed. Some of the most common types of CNC plastic machining include:

Plastic CNC Turning

Plastic CNC turning is a process that involves rotating the workpiece on a lathe as cutting tools remove material. This process is well suited for creating cylindrical parts with very tight tolerances. The specifications of the finished product can be controlled by adjusting the speed of the lathe, the depth of cut, and the feed rate.

Plastic CNC Milling

Plastic CNC milling is similar to traditional milling, but it uses a computer-controlled cutting tool instead of a manual one. The cutting tool is mounted on a spindle and moves in multiple directions as it removes material from the workpiece. The best plastic for CNC milling must be able to withstand the resulting heat.

Plastic CNC Drilling

This type of plastic machining is exactly what it sounds like – holes are drilled into the workpiece using a CNC-controlled drill bit. This process is often used to create pilot holes for larger ones or to create threaded holes for screws and bolts. It is often used in the aerospace and medical industries where precision is essential.

Plastic CNC Routing

A plastic CNC router is a machine that uses rotary cutting bits to remove material from a workpiece. This plastic machining process is similar to machining with a milling machine, but it is often used for larger parts. CNC routers are well suited for creating signs, moldings, and three-dimensional (3D) sculptures.


Plastic CNC machining, despite being a major with its benefits and drawbacks, is a field that’s rapidly growing. As technology continues to develop, the capabilities of plastic CNC machines will continue to increase. This means that more and more parts can be created with ever-increasing precision and accuracy.

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