CNC Plastic Selection Guide

CNC Machining, custom plastic parts

Choosing the right CNC plastic material for your intended use is the first step in CNC machined part design. The decision-making process doesn’t finish once you’ve decided that your part should be constructed of plastic and machined utilizing CNC technology. There are many different types of CNC plastic that can be machined, and they all have different qualities. Generally speaking, CNC-machined plastic parts are easily available and excellent for prototyping.
We hope this guidance will help you match the right material for CNC plastic components with your project needs. We will concentrate on a few plastic materials made available by the Sungplastic platform and present details on their characteristics, benefits, and common uses.

Visit the “Materials” area of our website to learn more about Sungplastic’s entire range of capabilities for a more extensive variety of CNC plastic suitable for CNC machining.

Our main objective is to give a general overview of the material characteristics, advantages, disadvantages, and typical uses of the following CNC plastic:
Nylon, Acrylic, Delrin, HDPE, Polycarbonate, Nylon, ABS, and Delrin

P.S. We suggest reading our article on this subject first if you are positive that your item should be constructed of plastic but are unsure of whether CNC machining or 3D printing is the preferable option.

CNC plastic machining

ABS Plastic CNC Machining

ABS, a widely used general-purpose CNC plastic, boasts a versatile range of qualities. It offers high impact resistance, toughness, and electrical insulating properties, all at an affordable price point. Moreover, ABS is highly amendable to post-processing, readily accepting painting, gluing, and welding. When subjected to ABS machining, the resultant surface finish tends to be matte, though it can achieve a somewhat glossy appearance depending on the machining method employed. ABS CNC machining entails cutting or engraving using CNC milling machinery.

Processes for ABS CNC Machining

1. CNC Milling
2. CNC Lathe

Benefits of ABS CNC Machining

ABS proves to be an excellent choice for a variety of applications, including general-purpose prototyping, pre-molding prototypes, parts that require impact resistance and toughness, or when cost-effectiveness is a primary consideration.

Drawbacks of ABS CNC Machining

While ABS offers several advantages, it has some limitations. Notably, it lacks strong resistance to abrasion and chemicals and is susceptible to melting when exposed to acetone. ABS is not exceptionally robust in terms of mechanical strength. Additionally, due to stringent environmental regulations on the West Coast of the U.S., the production of large ABS pieces is mainly concentrated in the Midwest and on the East Coast. Consequently, stock exceeding two inches in thickness often requires up to a week for shipping, resulting in extended production times for sizable ABS components.

Common Applications of ABS

ABS finds widespread utility in various applications, including the creation of pre-injection molding prototypes, electronic enclosures, household appliances, and the iconic Lego bricks, among others.

Nylon CNC Machining

At Sungplastic, we offer two varieties of nylon for CNC machining: Nylon 6/6 and glass-filled nylon. Nylon 6/6 is a robust and durable CNC plastic suitable for a wide range of applications. It boasts substantial chemical and heat resistance, combined with the rigidity required to maintain shape and withstand deformation under various load conditions. Glass-filled nylon is also a popular choice, offering excellent properties for CNC machining.

Processes for Nylon CNC Machining

1. CNC Milling
2. CNC Lathe

Benefits of Nylon CNC Machining

Nylon exhibits high strength and rigidity across a broad temperature spectrum, excellent electrical insulation properties, and strong resistance to chemicals and wear. Nylon 6/6 proves to be an economical choice when robust and durable parts are essential.
Glass-filled nylon is prized for its rigidity, strength, hardness, toughness, and dimensional stability.

Drawbacks of Nylon CNC Machining

Nylon 6/6 tends to absorb moisture, causing swelling and a potential reduction in dimensional accuracy. Additionally, it may warp when subjected to significant asymmetric material removal during machining due to inherent internal stresses within the material.

Common Applications of Nylon

Nylon finds extensive use in various applications, including medical devices, circuit board mounting hardware, electrical insulation, automobile engine compartment components, and aerospace parts. It often serves as a cost-effective alternative to metals in these applications.

Acrylic CNC Machining

Acrylic, also known by its trade names Plexiglass or Lucite, is composed of PMMA (Poly Methyl MethAcrylate) plastic. It is characterized by its toughness, decent impact strength, and scratch resistance. Acrylic can be readily bonded using acrylic cement.

Processes for Acrylic CNC Machining

1. CNC Milling
2. CNC Lathe

Benefits of Acrylic CNC Machining

Acrylic finds its niche in applications requiring optical transparency or translucence. It serves as a cost-effective alternative to polycarbonate, especially when exceptional durability is not paramount. Its scratch-resistant properties make it ideal for environments with minor abrasion.

Drawbacks of Acrylic CNC Machining

Acrylic is inherently brittle, with a propensity to crack or shatter rather than exhibiting ductile stretching like some materials. Attention should be paid to the thickness of walls in acrylic components, as thinner walls are more prone to brittleness.

Machined surfaces on acrylic pieces lose their transparency and adopt a frosted, translucent appearance. Consequently, it is advisable to consider whether an acrylic part should maintain its original stock thickness to preserve transparency. If transparency is crucial on a machined surface, it can be achieved through additional post-processing steps, such as polishing.

Common Applications of Acrylic

Acrylic, in its machined state, offers transparency and is frequently used as a lightweight substitute for glass or in the fabrication of light pipes. Other common applications encompass automobile light components, light tubes, tanks, panels, and components for optical engineering.

Delrin/POM CNC Machining

Delrin, a trademarked name for a type of semi-crystalline thermoplastic acetal resin, is also known as POM (Polyoxymethylene). It is esteemed for its slippery, low-friction surface, exceptional dimensional stability, and high stiffness.
Various classifications exist for this acetal resin, including:
Low friction

Sungplastic’s material selection for plastic CNC-machined components extends to Delrin with glass fibers and Delrin AF. Delrin infused with glass fibers is favored for its superior stiffness, dimensional stability, and high creep resistance. On the other hand, Delrin AF, another variant, offers an increased coefficient of friction, providing self-lubrication, alongside excellent wear resistance, toughness, and strength.

Processes for Delrin/POM CNC Machining

1. CNC Milling
2. CNC Lathe

Benefits of Delrin/POM CNC Machining

Delrin/POM serves as an excellent choice for applications prone to friction, necessitating tight tolerances, or requiring a high-stiffness material. It has a long-standing reputation in commercial markets owing to its reliability, durability, and remarkable resistance to impact, chemicals, moisture, and fatigue. Delrin/POM is also well-suited for CNC machining due to its ease of processability.

Thanks to its high stiffness and rigidity, Delrin excels in CNC plastic machining for parts demanding dimensional accuracy and precise tolerances.

Drawbacks of Delrin/POM CNC Machining

Despite its many merits, Delrin’s slippery, wear-resistant surface makes it challenging to bond with adhesives. The material also harbors internal stresses, making it susceptible to warping in areas with thin sections or substantial asymmetric material removal. Moreover, subjecting Delrin/POM to excessive heat beyond its maximum capability can result in hazardous off-gassing.

Common Applications of Delrin/POM

Delrin is commonly utilized in gears, bearings, bushings, fasteners, jigs, fixtures for assembly, as well as components in the automotive, construction, and electronics industries, owing to its exceptional properties and reliability.

HDPE CNC Machining

HDPE, an abbreviation for high-density polyethylene, is characterized by its natural opacity resulting from a crystalline structure, presenting a waxy finish. It is also available in a commercially produced black-dyed variant.

Processes for HDPE CNC Machining

1. CNC Milling
2. CNC Lathe

Benefits of HDPE CNC Machining

Despite its name, HDPE is Sungplastic’s least dense plastic offering. It boasts excellent chemical resistance, electrical insulation properties, and a slippery surface. With a low coefficient of friction and robust low-temperature impact resistance, HDPE proves to be a cost-effective and durable choice for CNC-machined plastic components.

Drawbacks of HDPE CNC Machining

HDPE’s primary drawback lies in its relatively poor strength, particularly when subjected to tension and flexing. This susceptibility makes it prone to stress cracking.

Common Applications of HDPE

HDPE finds common use in fluid applications such as fuel tanks, plastic bottles, and fluid flow pipes. Its chemical resistance and slipperiness make it an ideal choice for crafting plugs and seals. Additionally, it is well-suited for weight-sensitive or electrically sensitive applications.

Polycarbonate CNC Machining

Polycarbonate, often referred to as PC, ranks as the most resilient CNC plastic material offered by Sungplastic. PC is a transparent thermoplastic renowned for its durability and is one of the most frequently CNC machined plastics globally. It also enjoys a prominent position as one of the most widely recycled plastics worldwide. In its natural state, it possesses a transparent, milky-blue appearance, although it can be commercially obtained in a black variant. Both the black and milky-blue variations inherently exhibit a glossy finish.

Sungplastic offers machine-grade polycarbonate, specifically tailored to provide the transparency and high impact strength required for structural applications.

Processes for Polycarbonate CNC Machining

1. CNC Milling
2. CNC Lathe

Benefits of Polycarbonate CNC Machining

Polycarbonate boasts an exceptional combination of attributes, including very high impact resistance, stiffness, and functionality across a broad temperature range. It retains optical semi-transparency, although it can be dyed black for applications requiring opacity. Polycarbonate excels in applications demanding exceptionally robust or strong plastics and those where optical transparency is desired. Consequently, it stands as one of the most utilized and recycled plastics globally.

Polycarbonate is often chosen over glass due to its remarkable 250X greater impact resistance and over acrylic due to its superior resilience.

Drawbacks of Polycarbonate CNC Machining

Pure polycarbonate tends to lack wear resistance and is susceptible to scratches. To enhance wear resistance or optical clarity, anti-scratch coatings and vapor polishing can be applied as post-processing steps when necessary. Additionally, polycarbonate is typically unavailable in thicknesses exceeding two inches, limiting the size of parts that can be fashioned from this material.

Common Applications of Polycarbonate

Polycarbonate’s durability and transparency render it indispensable in the production of optical disks, safety glasses, light pipes, CDs, DVDs, mobile phone components, and even bulletproof glass.

Custom CNC Machined Plastic Products at Sungplastic

This CNC plastic guide should have helped you determine which CNC plastic is ideal for your specific applications. Visit the website of Sungplastic to learn more about various CNC plastic materials and CNC machining services in general.

Other CNC plastic we provide: PP, PS, PE, PVC, PEEK, PU, EPDM, TRE, TPU, TPR and modified CNC plastic. Please consult us for more information.

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