The Comprehensive Guide to CNC Plastic

CNC Plastic is an innovative technique used for generating complex plastic components. There are many benefits associated with it including compatibility, accuracy, and speed.q: The article discusses machinable plastic worlds. What are these materials? Why are they difficult to machine? Where are these plastics applied? How is a precise operation done in this procedure?

Table of Contents

What is CNC plastic?

CNC plastic machining is a technique whereby plastic cutting tools are guided by computer numerical control technology. The process, also known as CNC, involves accurate movements of tools and workpieces and predetermined computer instructions that make different plastics including parts and products. Because it can produce very precise, intricate models it is widely used in producing small-scale components.

The types of machinable CNC plastics Material

ABS (Acrylonitrile Butadiene Styrene Copolymer):

ABS is a hard, robust thermoplastic commonly employed to manufacture hard parts such as those with good shock absorption properties. It is processable and widely used in manufacturing automotive parts and consumer electronics.

Polycarbonate (PC):

PC is one of the toughest transparent thermoplastics with high-impact strength and resilience. Bulletproof glass, eyeglass lenses, and device housing are examples of things it is utilized for.

Polypropylene (PP):

PP is a lightweight chemical resistant plastic. Many people use it for laboratories’ containers, and medical device components among others.

Polyethylene (PE):

There are two types of polymers, namely, PE and PP. It is categorized into two types: The types of polyethylene include High-Density Polyethylene (HDPE) and Low-Density Polyethylene (LDPE.). As explained before, HDPE is a hard and strong material that is preferred in the manufacture of durable pipes and containers. On the other


Its high strength makes nylon an exemplary thermoplastic polyamide that is resistant to abrasion and chemicals. In the production process of gearboxes, bearings, and other similar mechanical parts, it is often employed.

POM (Polyoxymethylene):

POM is a very rigid heat-resistant thermoplastic that resists wear and keeps its size after processing. It has diverse applications in the production of high-precision components including gears, shafts, and running surfaces.

PTFE (Polytetrafluoroethylene):

With the popular name of Teflon, PTFE is a heat and chemical resistance polymer. Amongst others, it is often employed in making valves, seals, as well as non-adhesion surfaces.

Polyetheretherketone (PEEK):

PEEK is an advanced thermoplastic well-known for its superb thermal stability and mechanical robustness. It is applied in a wide variety of areas such as production for aerospace purposes, manufacturing medical devices, and making high-load mechanical elements as well as heat-resistant parts in motor cars.

Polyoxymethylene (Acetal):

In most cases, this material is termed Delrin; it is a strong and rigid engineering plastic. It is commonly used in producing precision parts like sliders, gears, and key elements.

Acrylic (PMMA):

plexiglass CNC machining

As explained, acrylic is famous for its optics, transparency, and weather-resistant nature. Widespread application: In making displays, billboards, windows, lampshades, etc. Acrylic is easy to work with and color, hence suitable for creating lightweight decoration and artwork.

The related properties of plastic in CNC machining

As explained, acrylic is famous for its optics, transparency, and weather-resistant nature. Widespread application: In making displays, billboards, windows, lampshades, etc. Acrylic CNC machining is easy to work with and it has many colors for selection, hence suitable for creating lightweight decoration and artwork.

MaterialMechanical StrengthHeat ResistanceMachining DifficultyMelting Point(°C)
Polycarbonate (PC)HighHighModerate225-250
Polypropylene (PP)MediumMediumEasy160-170
Polyethylene (PE)Low to MediumLowEasy120-130 (LDPE), 130-137 (HDPE)
POM (Polyoxymethylene)HighMediumModerate175-180
Polyetheretherketone (PEEK)Very HighVery HighDifficult343
Polyoxymethylene (Acetal)HighMediumModerate175-180
Acrylic (PMMA)MediumMediumEasy160-16

What is the CNC plastic machining process?

CNC Milling Plastic:

CNC milling is a common plastic machining method. this process uses rotary cutters to remove excess material from the workpiece. Proper choice of tooling and cutting speeds during machining will be essential to avoid plastic material from warping or tool damage. CNC plastic trimming is a key step to ensure highly intricate shapes can be molded, highlighting its importance in plastic part manufacturing.

CNC Turning Plastic:

, CNC turning constitutes fastening a turning workpiece on a spindle and then revolving it against a cutting tool while moving in opposing directions. When turning, you must have a strong grasp of the part held. CNC turning is commonly used in the manufacture of rotationally symmetric parts such as screw thread and shafts.

CNC Drilling Plastic:

CNC plastic videos

CNC drilling is used to create holes or bores in plastic workpieces. Choosing the right drill bits and speeds is critical to ensure hole quality and precision. Additionally, secure workpiece fixation is necessary to prevent deviations or damage during drilling.

CNC Engraving Plastic:

CNC engraving is a method used to create fine patterns or text on the surface of plastic. Selecting appropriate tools and engraving depths is essential to ensure engraving quality. This method is commonly used for producing signs, ornaments, and engraved artwork.

CNC Cutting Plastic:

CNC cutting involves cutting plastic workpieces into desired shapes. Cutting methods include straight-line cutting, plasma cutting, and waterjet cutting, among others. The choice of cutting method depends on the material type and part requirements. CNC cutting is suitable for various plastic materials and thicknesses.

CNC Grinding Plastic Parts:

CNC grinding is a method used for high-precision finishing of plastic parts. It is often employed for the final machining stages. Proper selection of grinding wheels and control of grinding speeds and pressures are essential to achieve the desired surface quality.

How to choose CNC bits for plastic?

CNC bits for plastic

Material Type:

Properties vary for different kinds of plastics, hence the choice of a bit will depend on if you are dealing with acrylic, polycarbonate, PVC, or any other kind of plastic. Specifically, some soft plastics need altered bit geometry to avoid melting and chipping.

Bit Material:

The sharp and durable nature of solid carbide bits is the reason they are normally used on plastics. The other, which is a better option, is high-speed steel (HSS) bits that, however, might not last long enough.

CNC edge bits:

Plastics are usually drilled using single or double-edged bits. This reduces the heat built-up and permits for better chip removal using single flute bits. Plastic tends to melt more easily when there are more flutes leading to increased contact friction in the area of interaction.

Bit Shape and Size:

Plastics are normally drilled with spiral bits. Up-cut spiral is beneficial for better chip extraction and down-cut spirals provide a smooth finishing on the top surface. The “bit” should relate to how many details there are in your project, and how large of a scale.

What are the advantages of CNC machining for plastic?

Complex Geometric Capabilities:

One of the most remarkable features of CNC machining is its ability to create shapes that are difficult or even impossible to achieve with traditional methods. This attribute is especially crucial in the manufacturing of intricate medical devices and precision instruments, where the complexity of the parts can be critical to their functionality. The versatility of CNC machines in handling these complex geometries makes them indispensable in advanced manufacturing sectors.

Precision and Accuracy:

CNC machines stand out for their extraordinary precision, often reaching up to 0.001 inches (0.025 mm). This level of accuracy is essential for designs that require exact measurements and detailed intricacies. The ability to consistently produce such precise components is a significant advantage, particularly in industries where small deviations can have substantial impacts, such as in aerospace and automotive manufacturing.

Efficiency and Speed:

The efficiency of CNC machining is a major advantage over manual processes. Tasks that could take hours to complete manually can be done in a fraction of the time with CNC machining. This time efficiency translates into faster production cycles, enabling manufacturers to meet tight deadlines and increase their output, which is crucial in high-demand industries.

Consistency and Reproducibility:

CNC machining offers almost 100% consistency in production. This uniformity is essential for large-scale manufacturing, where every part needs to be identical. Such consistency ensures high-quality standards and reduces the risk of defects, which is particularly important in industries where safety and reliability are paramount, such as in automotive and aerospace applications.

Design Flexibility:

CNC machining offers the ability to make rapid design changes. Unlike traditional manufacturing methods, where making changes can be time-consuming and costly, CNC programming adjustments can be made quickly and easily. This flexibility is invaluable in prototyping and custom manufacturing, where designs often evolve rapidly based on testing and feedback.

Superior Surface Finish:

CNC machines can achieve a surface roughness as low as 0.4 microns. This high-quality finish reduces or even eliminates the need for additional surface treatments or post-processing, saving time and resources. Such a superior finish is particularly beneficial in consumer-facing products where aesthetics are important, as well as in components where surface smoothness affects performance.

What are the challenges of plastic CNC machining?

Material Characteristics Challenge:

Due to their high elasticity and thermal expansion coefficient, plastics tend to deform during machining. This deformation can lead to inaccuracies in dimensions, especially noticeable in fine detailing.

Compared to metals, plastics are less tough, increasing the difficulty of control during machining. Solutions include using specially designed fixtures to secure the material, minimizing movement and vibration during machining, and selecting CNC machines and tools suitable for plastic characteristics.

Accuracy Issues:

Maintaining precision in machining plastics is challenging due to their plasticity. Even minor temperature changes can cause the material to expand or shrink, affecting the final product’s dimensions and shape.

To address this, precise temperature control before and after machining can ensure stability in the machining environment. Additionally, using high-precision CNC machines and appropriate tools can reduce errors caused by material properties.

Tool Wear Challenge:

Although plastics are softer than metals, certain types of plastics can rapidly wear down tools during machining. This not only increases costs but also affects machining precision.

To reduce tool wear, tools specifically designed for machining plastics, which generally have better wear resistance and cutting performance, can be used. Regular checking and replacement of tools to ensure sharpness and precision are also essential maintenance measures.

Surface Finishing Difficulty:

Maintaining surface smoothness and aesthetics is another major challenge in plastic CNC machining. The machining process can easily produce burrs or scratches, affecting the product’s visual quality.

To improve this, appropriate surface finishing, such as meticulous sanding, polishing, or applying special chemical treatments, can be performed post-machining. These post-processing steps can significantly enhance the product’s surface quality and overall appearance.

What are the applications of CNC machined plastic parts?

CNC machining plastic aerospace parts

CNC machining of plastic aerospace parts plays a crucial role in aircraft manufacturing. For instance, precision-engineered plastic components such as cabin walls, seat assemblies, engine cowls, and flight surfaces are required. These parts must be lightweight, heat-resistant, and corrosion-resistant to ensure aircraft performance and safety.

CNC machining plastic auto parts

CNC plastic parts find significant applications in the automotive industry. For example, interior components like dashboards and door panels are often CNC machined to ensure high-quality surface finishes and proper fit. Additionally, plastic components in engine parts and chassis assemblies also require CNC machining to enhance fuel efficiency and vehicle performance.

CNC machining medical plastics

The medical field is also a key application area for CNC plastic machining. The manufacturing of medical equipment and instruments demands highly precise plastic parts, such as surgical tools, medical syringes, and patient monitoring devices. The precision and quality of these parts are critical for patient health and safety.

Plastic prototype

CNC machining plays a vital role in producing plastic rapid prototypes. Whether for early validation of product design or prototype creation before market launch, CNC machining can rapidly produce highly accurate plastic prototypes, helping businesses save time and costs while ensuring product quality.

How to select a surface finish for CNC plastic component

CNC plastic parts printing

Some of the common surface finishes in CNC plastic parts are painting, anodizing, electroplating, sandblasting, polishing, and laser engraving. Every finish has its distinct look and characteristics.

There are various vital considerations when selecting an appropriate surface finish. The second factor is how it will be used. Choosing a hard-wearing finish for this component is essential if it will be operating in harsh conditions such as exposure to extreme heat and/or chemical contamination. For instance, electroplating will add another layer of anti-corrosive protection.

Next, consider aesthetic requirements. Painting and polishing could also go as appropriate if the appearance of the part is vital. With painting, there are various colors available and with polishing, the parts develop a fine, high-gloss finish.

Finally, there is the cost of manufacture and time for production. Some finishes like anodizing and electroplating may take a long time or cost more than others. For projects that have stringent timelines and financial constraints choose those finishes which are economical and low in processing rates.

Finally, one must look into how compatible a particular material is when it comes to use with others. All finishes do not fit all plastics. For example, some specific treatments might not be suitable for high-temperature plastics or plastic with a special composition. It is important to ensure that the selected finish goes along well with a particular type of plastic.

The suitable CNC plastic machining feeds and speeds rate

For different types of plastic materials, the suitable CNC plastic machining feeds and speeds, including CNC plastic rpm, vary depending on the material’s hardness, melting point, and cutting characteristics. Below are the recommended CNC machining feeds and speed parameters for different plastic materials:

Polycarbonate (PC):

Feed rate: 1500-3000 mm/min

Spindle speed: 8000-10000 RPM

Polypropylene (PP):

Feed rate: 2000-4000 mm/min

Spindle speed: 6000-8000 RPM

Polyethylene (PE) and Nylon:

Feed rate: 1000-2500 mm/min

Spindle speed: 6000-8000 RPM

Polyoxymethylene (POM):

Feed rate: 1500-3000 mm/min

Spindle speed: 8000-10000 RPM

Polytetrafluoroethylene (PTFE):

Feed rate: 1000-2000 mm/min

Spindle speed: 6000-8000 RPM

Polyetheretherketone (PEEK):

Feed rate: 800-1500 mm/min

Spindle speed: 10000-12000 RPM

Polyoxymethylene (Acetal):

Feed rate: 1500-3000 mm/min

Spindle speed: 8000-10000 RPM

Acrylic (PMMA):

Feed rate: 1000-2500 mm/min

Spindle speed: 6000-8000 RPM

These are just for reference; real CNC plastic machining parameters depend on the particular machine, tooling conditions for a particular workpiece under consideration as well for a particular complex machining. When setting up machining parameters it is advisable to carry out some tests and adjustments for optimal result in machining performance and surface quality.

The steps of custom CNC plastic parts

Step 1: Define Requirements

Engage in thorough communication with the customer to understand their needs. This includes detailed information on the part’s dimensions, shape, material, usage, and quantity.

Step 2: Design and Modeling

Based on the customer’s requirements, perform 3D modeling and design. Create precise models of the parts using CAD software to ensure they meet functional and quality standards.

Step 3: Material Selection

Choose suitable plastic materials according to the part’s purpose and customer specifications. Consider factors like wear resistance, chemical resistance, and temperature requirements.

Step 4: CNC Machining

Load the designed 3D model into CNC machine tools for cutting, engraving, and drilling processes. Ensure accuracy and surface quality during machining.

Step 5: Quality Control

Conduct strict quality control and inspection of the machined parts to ensure they conform to specifications and standards.

Step 6: Surface Treatment

Apply surface treatments such as polishing, painting, or plating to enhance appearance and performance.

Step 7: Assembly and Testing

If necessary, assemble the custom parts into the overall product and perform functional testing to ensure proper operation.

The tips for precision plastic machining

Typical surface finishes used on CNC plastics comprise painting, anodization, electroplating, sandblasting, polishing, and laser engraving. Every finish is different and has its own look and characteristics.

Several important considerations exist in selecting proper surface finishes. First, the purpose for which the part was designed will be highlighted. Choosing a strong and reliable finish is particularly important if the component will have to work in extreme conditions such as high temperatures, or direct contact with chemicals. However, it also offers extra corrosion like electroplating.

Next, consider aesthetic requirements. For example, if looks are important for the part then painting or polishing would probably be desirable On one hand, painting is another option that comes with countless shades of color while polish presents a polished and shiny finished outlook for the metal part.

The third consideration is cost as well as time of manufacture. The other finishes may prove expensive in comparison to the common ones like anodizing and electroplating which take a bit of time. For projects under tight budgeting and time constraints, economical and quickly processable finishes would be appropriate.

Finally, the suitability of the material needs to be taken into account. However, not all finishes can be applied to every type of plastic. As an example, some regents may be unsuitable for high-temperature plastics with unique chemical composition. It is necessary to ensure that the selected finish is compatible with a particular plastic variety.+


Plastic CNC machining has become vital to precision production in the aerospace, auto, and medical sectors. Careful selection of appropriate materials and modern equipment can overcome the difficulties to yield remarkable outcomes as well as sustained development.

Seek out the best in professional CNC machining plastic parts in this part. You can always depend on us as a reliable producer when it comes to medical device parts and industrial applications. Free sample requests, price lists, and contact top suppliers here. The professionals in CNC machining plastic elevate your project.


What is rigid plastic?

Rigid plastic, also known as stiff plastic, refers to a category of plastics that have high tensile strength and stiffness. Common examples include Polyethylene Terephthalate (PET) and Polyvinyl Chloride (PVC). These materials maintain their shape and structure even under significant loads.

What is the hardest plastic CNC machining?

The hardest plastic for CNC machining is typically Acetal (POM), with a high hardness rating of around 80-90 Rockwell M scale. Its excellent machining properties and resistance to wear make it suitable for precision engineering applications.

What is the soft plastic for CNC machining?

Soft plastic for CNC machining includes materials like Polyethylene (PE) and Polyurethane (PU). These plastics are pliable and have low hardness values, making them ideal for applications where flexibility and impact resistance are essential.

What is the durable plastic CNC machining

Durable plastic for CNC machining often includes materials like Nylon (PA) and Acrylonitrile Butadiene Styrene (ABS). These plastics offer excellent strength, toughness, and resistance to various environmental factors, making them suitable for long-lasting applications.

what is the lightweight plastic for CNC machining?

Lightweight plastic options for CNC machining comprise materials like Polycarbonate (PC) and Polypropylene (PP). These plastics are known for their low density and high strength-to-weight ratio, making them suitable for lightweight structural components and products.


On-demand CNC Machining prototyping and parts with Custom Finishes and low volume manufacturing.

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