Plastic machining is one of the most common industrial processes due to the high usage of this material. However, modern-day plastic CNC machining isn’t what it used to be. Plastics nowadays can be built strong enough to stop a bullet’s impact. This calls for a very rugged machining method.
CNC machining plastics has become a great solution for these requirements. Plastics have a lot of variety, with differences in physical properties and chemical structure. All of these varieties are easy to machine with CNC machining.
This article will explore the applications of CNC machining of plastic materials. It will go into the details of different kinds of CNC machined plastic parts and their physical properties. You can decide which plastic materials best suit your job requirements based on the information provided here.
What is Plastic CNC Machining?
Plastic CNC Machining is a CNC machining process that uses Computer Numerical Control (CNC) technology to automate machining of plastic materials. This is achieved through computer programming guiding the machine tools.
While CNC machining technology supports a variety of materials, such as metals, alloys, glass, wood, and ceramics, this specific term refers to its application in plastic machining.
Can Plastics Be CNC Machined?
Yes, CNC machining plastics is possible. In fact, CNC machining is the best way to make plastic components. This is because of the high accuracy and speed of this process. The quality of plastic CNC machining is way ahead of other alternatives like injection molding or 3D printing.
What Are the Common CNC Machining Plastics?
Any plastic can undergo CNC machining. Some common plastics that use this process are:
Nylon (PA)
Nylon has good chemical resistance and heat resistance. Therefore, nylon usage is commonly found in applications such as insulations and sheaths. Nylon spacers are used in circuit breakers for the electronics sector. Commonly used processes on nylon are CNC mills and lathes. There are many different grades of nylon. Nylon 6/6 is a common type used in plastic CNC machining.
Advantages
Disadvantages
Uses
Polyethylene (PE)
Polyethylene is also known by its common name Polythene. It is the most commonly used and produced plastic type. The high popularity of polythene has led to the emergence of several different types. Two of the commonly found polythenes for plastic CNC machining are LDPE and HDPE.
Low-Density Polyethylene (LDPE)
LDPE has low tensile strength, high ductility, and low density. Common applications of LDPE are for making trays and foils in the packaging industries. It has very low moisture absorption.
High-Density Polyethylene (HDPE)
HDPE has better physical properties than LDPE. The main attractive points of HDPE are its high density and tensile strength. Plastic bottles and pipes are made of HDPE material.
Advantages of POlyethylene
Disadvantages of Polyethylene
Uses
Polyethylene Terephthalate (PET)
Polyethylene Terephthalate (PET) is in the subclass of polyester plastic materials. It is the major constituent of packaging in the food and beverage industries. It is a hygienic, water-resistant, and lightweight material. It is also one of the easy-to-machine plastics used in plastic CNC machining projects.
Advantages of PET
Disadvantages of PET
Non-biodegradable
Uses of PET
Polyvinyl Chloride (PVC)
PVC is one of the most popular plastics used for its high strength. It is a very durable material with high tensile strength, lightweight nature, and chemical resistance. There are many different forms of PVC available for different applications.
Advantages of PVC
Disadvantages of PVC
Uses
Chlorinated polyvinyl chloride (CPVC)
Chlorinated Polyvinyl Chloride is derived from PVC itself. CPVC is obtained after successive chlorination of PVC resin. CPVC has improved properties than PVC plastics. The purpose of CPVC is to eliminate the vulnerability of PVC to temperatures during the plastic CNC machining process.
Advantages of CPVC
Disadvantages of CPVC
Uses
Polycarbonate (PC)
Polycarbonate is a type of thermoplastic polymer. More than one billion kg of Polycarbonate is manufactured annually. This is because of the high-grade physical properties and widespread PC applications.
Advantages of PC
Disadvantages of PC
Uses
Polypropylene (PP)
Polypropylene is also known by its common name Polypropene. It belongs to the thermoplastic polymer category. Its properties are a slight improvement to polythene.
Advantages of PP
Disadvantages of PP
Uses of PP
Polyphenylsulfone (PPSU)
Polyphenylsulfone is an aromatic ring polymer. It is an easy-to-machine plastic. It is also moldable with injection molding. It is a high-performance thermoplastic.
Advantages of PPSU
Disadvantages of PPSU
High fouling tendency
Uses
Polysulfone (PSU)
Polysulfone is another high performance thermoplastic like PPSU. PSU parts can be used in a wide range of temperatures. Common range is -100°C to 200°C. The temperature range makes them one of the highest service temperatures of plastic.
Advantages of PSU
Disadvantages of PSU
Uses
Polyphenylene sulfide (PPS)
PPS is known by a lot of different names due to various brands manufacturing it. Some common brand names are Durafide, Petcoal, Ecotran, and Fortron. It is a high temperature thermoplastic polymer.
Advantages of PPS
Disadvantages of PPS
Uses
Polyetherimide (PEI) – Ultem
PEI is an amorphous thermoplastic. Its color spectrum can vary from amber to transparent. It provides a cheaper alternative to PEEK thermoplastic with similar properties.
Advantages of PEI
Disadvantages of PEI
Lower impact resistance
Uses
3D Printer beds
Ultra High Molecular Weight Polyethylene (UHMW)
Ultra-high molecular weight polyethylene is a subtype of Polyethene thermoplastic. It also goes by High Modulus Polyethylene (HMPE). It has a good load-handling capability due to long-chain polymers.
Advantages
Disadvantages
Uses
Polyoxymethylene (POM or Acetal)
Acetal is one of the most used plastics in CNC machining. It also goes by its other name Delrin. It is a very easy to machine plastic.
Let’s explore some of the Delrin machining characteristics.
Advantages
Disadvantages
Poor resistance to acids
Difficult to bond
Uses
Polystyrene (PS or Styrofoam)
Polystyrene is a solid of foamed polymer. The foamed variety has been patented and the trademarked name goes by Styrofoam. Styrofoam is actually an Extruded Polystyrene (XPS). DuPont owns the trademark of styrofoam and manufactures it globally. 98% of styrofoam is air, leading to its foamy nature.
Advantages
Lightweight
Buoyant
Disadvantages
Environmentally harmful
Uses
Acrylonitrile Butadiene Styrene (ABS)
ABS is another popular CNC machining plastic. It is a thermoplastic polymer. It has impressive physical properties which lead to a lot of applications find different industries.
Advantages
Disadvantages
Uses
Carbon Fiber (CF)
Carbon fiber is basically Carbon Fiber Reinforced Polymers (CFRP). It has thin strands of carbon fiber added to a base plastic for improved properties. It is classified as a composite material.
Advantages
Disadvantages
Uses
Polytetrafluoroethylene (PTFE or Teflon)
Teflon is a brand name of polytetrafluoroethylene. It is patented by Chemours. Interestingly, Teflon was also discovered by DuPont, which already holds the trademark for Styrofoam. Chemours was branched from DuPont and is the global manufacturer of Teflon.
Let’s get into more details of using Teflon for CNC machining.
Advantages
Disadvantages
Uses
Poly(methyl methacrylate) (PMMA) or Acrylics
PMMA goes by a lot of different names, such as Acrylic and Acrylic Glass. Many other brand names exist, like Lucite, Plexiglass, Perclax, Perspex, etc. Its high transparency is why Acrylic finds many applications in machining, replacing the traditional glass.
Advantages
Disadvantages
Uses
Polysiloxane (Silicone)
Polysiloxane is a colorless, rubber-like substance also called Silicone. It is used for many plastic CNC machining applications in electronics, household, electrical, automobile, and aviation manufacturing industries.
Advantages
Disadvantages
Uses
Poly Paraphenylene Terephthalamide (Kevlar)
Poly Paraphenylene Terephthalamide usually goes by its common names kevlar and twaron. It is one of the most popular aromatic polyamides globally. It is a synthetic fiber developed by DuPont. Its physical properties are comparable to or even better than metals and alloys.
Advantages
Disadvantages
Uses
Acetal copolymer (Celcon)
Celcon is a high-performance acetal polymer that works in a wide range of temperatures. It is resistant to most adverse conditions and has a long service life. There are many subtypes of Celcon, like UV-resistant, wear-resistant, glass-reinforced, bleach-resistant, impact resistant. etc.
Advantages
Disadvantages
A certain level of toxicity
Uses
Polyphenylene oxide (PPO)
PPO is a high-temperature thermoplastic. It is a hard-to-manufacture material. Therefore, it is generally used in its blended form. It is also known as Polyphenylene Ether (PPE). It has quite good performance characteristics. It is mixed with Polystyrene to improve its physical chacteristics.
Advantages
Disadvantages
Uses
Kapton
Kapton is a special type of polyamide film. DuPont invented it. It has one of the best temperature handling amng all plastics. It can sustain temperatures between -269°C to 400°C.
Advantages
Disadvantages
Uses
Polyethersulfone (PES)
PES plastic is available in blocks, sheets, and rods. It is also sometimes referred as PESU. These plastics have great physical properties and temperature handling. The color of PES is reddish brown with good transparency.
Advantages
Disadvantages
Uses
Polyvinylidene fluoride (PVDF)
PVDF is a chemically inert thermoplastic. It is a special kind of plastic used in very niche applications. The main use case for this plastic is when a highly non-reactive material is required. PVDF can resist any chemical. It can be obtained in many different forms, like pipes, sheets, powder, tubes, plates, and films.
Advantages
Disadvantages
Uses
Thermoplastic elastomers (TPE)
TPE is also sometimes termed as Thermoplastic Rubber. It is a mix of different polymers, often plastic and rubber. TPE is different from conventional elastomers, which is thermosetting in nature. However, the thermoplastic properties of TPE allow the application of many different manufacturing methods.
Advantages
Disadvantages
Uses
Thermoplastic polyurethane (TPU)
TPU is a wide class of Polyurethane (PU). It can exhibit a range of different properties. It is easy to machine with CNC, extrusion, and injection molding. It can also be shaped with calendering. Due to the wide range of manufacturing processes, TPU scrap can be recycled over and over.
Advantages
Disadvantages
Uses
Polyetheretherketone (PEEK)
PEEK is a very popular CNC machining thermoplastic. It is colorless in pure form. Its melting point is 343 °C, which makes it good for high-temperature applications. Operating temperatures of many PEEK subtypes easily go up to 250 °C.
Advantages
Disadvantages
Uses
What CNC Machining Process is Most Suitable for Plastics?
All CNC processes work well for plastic CNC machining. CNC mills and lathes are some of the most common machines used for these materials. Other processes like CNC drills and waterjet cutters also provide good results for plastic machining.
Applications of Plastic CNC Machining
There are many use cases for using CNC machining for working on plastic materials. Some of these applications are:
Plastics are used for making a lot of different parts in the automobile sector. Interior parts such as linings, handles, and dashboards are plastic. Even exterior components like bumpers use plastics. Other miscellaneous plastic components are engine covers. electronics housing, etc.
Oil and Gas Industries
The chemical resistance of plastics has many applications in the oil and gas industry. Plastics make seals and containers for oil extraction and storage. Electrical connectors in heavy mining machinery are also made of plastic.
Food Processing
Plastic is used extensively in the food processing industry as a primary and secondary packaging material. Food-grade plastic containers are machined with CNC to provide a safe storage option. CNC-made plastic trays provide an impact-resistant transportation option for food items.
Agriculture Industries
Plastics are widely used in the agriculture sector for a variety of equipment. They are applied for making irrigation and drainage solutions. Plastics are applied for making sillage and nets. Agricultural components like greenhouses, planters, and tools also increasingly use plastics.
Aerospace
Several plastics have a high impact and corrosion resistance. This makes them ideal for making parts that face extreme pressure, like valves and pumps. Plastics like thermosetting polyimide also make structural components for the aerospace sector.
CNC-machined plastics are used for making implants and many other devices. Electronics enclosures of medical devices like pacemakers, vitals monitoring, and others are made with high-grade plastics. Many plastics have a wear-resistant surface and resistance to stress cracking. This is why they are beneficial for making implants.
Electrical and Electronics Appliances
Cases of appliances like TV, laptops, and smartphones are made with CNC-machined plastics. These CNC machines are accurate and provide the consistent results required in this sector.
How to Choose the Right Plastic For Your CNC Project?
There are many different plastics to choose from for whatever you manufacture. The choice of plastic should be done by evaluating the various parameters that influence the decision. Some of these factors are:
Hardness and Strength: Hardness and strength are the primary consideration when choosing plastics. The plastic should be strong enough to bear the weight and impacts of the particular applications for the part.
Chemical Resistance: Chemical resistance is important when plastic undergoes harsh conditions.
Moisture Resistance: Moisture resistance is a parameter for plastics that will face high humidity. Outdoor applications also require moisture-resistant plastics.
Appearance: The appearance of plastic is important when aesthetically appealing parts are required. This is vital for use cases like toys. Sometimes, a transparent thermoplastic is used when visibility is required.
Heat Resistance: The heat resistance of plastics is important for outdoor applications, thermal applications, and even electrical insulators.
Budget: Plastics have a wide budget range. Materials like polythene and nylon can be very cheap. At the same time, high-strength plastic composites can be expensive.
Where to Find a Good Provider For Plastic CNC Machining?
Getting a CNC machine can be a very costly investment. This is why there is a new trend where manufacturers choose to outsource the CNC machining of plastic materials.
Proto MFG is the market leader for plastic CNC machining services and parts. Proto MFG’s CNC machined plastics are high-quality parts that work better as intended.Proto MFG uses the most advanced CNC machinery to fulfill any complex requirements that you might have. The manufacturing time is quite low, and you get your parts as soon as you require them. Contact Proto MFG to get a quote for your project.
Endnotes
CNC plastic machining is the go-to process for plastic materials when quality and precision are important. Injection molding fails tremendously in terms of consistency and precision. Additionally, additive manufacturing techniques work only for plastics that can be molded by heat. If you want to use plastic material for your next project,Proto MFG CNC plastic machining services can be the perfect fit.
Frequently Asked Questions (FAQs)
1.What is the strongest plastic for CNC machining?
Polyamideimide is the strongest plastic for CNC. It has a tensile strength of over 21,000 psi. Even with this extremely high strength, it is easy to machine with a CNC.
