What Should You Know About Plastics CNC Machining (2024)

The new-found interest in plastic as a substitute for metals is a result of the machinability of plastics. With the help of CNC machining, plastics can be cut across easily, and accurately as needed. 

This article discussed the emergence of plastic machining, its importance, and the simple-yet-complex process. Additionally, we will expose you to the benefits of plastics CNC machining compared to usual 3D prototyping.

What is Plastics CNC Machining

Plastics CNC machining entails numerous processes, and the use of machines to yield different plastic molds or designs. These processes can differ for different plastic types or be altered to produce custom plastic designs.

Definition of Plastics CNC Machining 

Plastic CNC machining is a process that involves feeding huge formless blocks of plastics into a machine (which is often robot or computer-controlled) to create unique plastic designs, parts, or components. 

This machine is so versatile that it can work on almost all kinds of plastics ranging from acrylic, polycarbonate, nylon, and PTFE. 

How Does it Work

The working mechanism of plastic machining is straightforward. It involves creating a CAD drawing of the product and setting up the machine to run the design. 

Then, you simply select an appropriate plastic machining method and supply the CNC machine with formless plastic materials. The machine then produces the product according to the CAD drawing description.

Hence, the plastic machining process begins with a block of plastic brick. This solid plastic brick is reformed into a functional product when it is placed inside the machine. The CNC machine does this by passing it through one of the three CNC procedures (which is turning, milling, and drilling.)

Benefits of Using Plastics CNC Machining Technology

The use of plastic CNC machining technology is highly beneficial for making plastic goods. It provides a quicker way to refine plastic products. Below are the advantages of CNC machining.

Quick Speed 

Plastics CNC machining has a faster tooling lead time than injection molding. What this means is that the time it will take to produce one tool from start to finish with CNC machining is shorter than the time it will take to produce that same tool with injection molding. 

If your aim is to produce a few numbers of parts, CNC machining will be a faster way to get it done.

Tight Tolerance

Plastics CNC machining is unarguably the best method for making plastic products with tight tolerance. Its complex processes allow for the creation of plastic products, such as machine compartments and aerospace body parts, that are highly accurate and precise in size.

Cost-Effective for Small Batches

Making numerous tiny plastic parts can cost a lot, take lots of time, and also waste tons of plastic materials if done with. Companies looking for a cost-effective way to produce miniature plastic parts can use plastic machining as it can help cut costs and prevent wastage.

Industrial Applications of Machinable Plastics

Plastics can be machined to suit different industries’ needs of plastic. The CNC-machined plastic parts are used to produce consumer electronics, aerospace parts, medical appliances, and automotive components.

Consumer Electronics

Plastics are important raw materials in industries that manufacture electrical and electronic appliances for obvious reasons. One, they are excellent insulators. Two, they are easy to mold into whatever design. Some of the electronic appliances and gadgets we use at home are produced with CNC plastic machining.

Machinable plastics are in great demand because of their use in the consumer goods market, particularly in consumer electronics. They are the perfect materials for complex designs. Machinable plastics are often used in the production of computers, televisions, cell phones, and many other household gadgets. 

Aerospace Parts

Aerospace industries are constantly evolving in their choice of material. They keep looking for ways to go lighter and they achieve this by using light, durable, and strong materials. Plastic is one of the major materials used in bulk in the aerospace industry.

The aerospace industry requires a high level of precision when constructing any component of the aircraft. This is why machinable plastic is of great benefit to the aerospace industry. 

Also, the flexibility and ease of molding the machinable plastic will allow engineers in this industry to explore innovative ways of getting things done. Some examples of machinable aerospace components include engine mounts, airplane sit mounts, landing gear components, gaskets, and a lot more.

Medical Industry

A lot of equipment used in the medical industry is made from plastics. Laboratory equipment, implants, prosthetics, and even surgical equipment and much more are made with plastics that are easy to machine. 

These plastics are properly selected and have high tensile strength, and durability, and should be safe for human contact. Machinable plastics allow easy production and customization of medical equipment.

Automotive Components

Fast cars, saloons, SUVs RVs motorbikes, and all other automobiles depend to a large extent on machinable plastics. Plastics are used because of their lightweight, strength, durability, and versatility. 

Machinable plastics are used in the automotive industry to produce automotive exterior and interior parts that promote the aesthetics of the automobile. Some of the parts include bumpers, grilles, and interior trim. They can also be used to make unique custom parts, replacement parts, dashboard panels, and gas gauges.

Situations You Need to Choose Plastics CNC Machining

Plastic machining is not always the most suitable production process for every plastic product. So when can it be used? Which conditions certify the application of plastic CNC machining? All these questions will be answered below.

When Your Products Are in Testing Stage

At the testing stage, the product is designed and a small number is produced to see if it is properly made, or if it can serve the intended purpose perfectly. 

It’s mentioned earlier that plastic CNC machining is faster when produced in small batches. This is why this process should be chosen during the testing stage. Adjustments can be easily made to products until the testers are satisfied with the quality of the product manufactured.

When Plastic Prototype Requires Superior Surface Finish

Perhaps, your desired design has a complex or superior surface finish that cannot be produced accurately by other prototyping or modeling processes. In that situation, plastic machining is the way to go. As long as you input the right design code, you are assured of receiving the right design products.

Plastic machining can be helpful to make a superior finish because it helps produce an accurate result if done properly. However, it allows the use of bead blasting for a smoother finish. Bead blasting is the use of compressed air on the surface of the machined plastic to correct any defects or scratches that might be caused during the production process.

When Plastic Prototype Requires Tight Tolerance

In this case, where tight tolerance is needed, you should be thinking of producing all the products with plastic CNC machining. This will allow you to be very accurate and precise in manufacturing the product, whereas some other design methods might not be able to keep up with the accuracy that is needed.

When Your Products Require Special Materials

CNC machining has a way of helping to achieve products that seem impossible. It gives a versatile approach to special material requirements, especially those that are not easily fabricated with other means. CNC is suitable for processing many plastic polymers.

When You Need a Cost-Saving Plan

One way to save production costs and maximize profit is by using CNC machining for the production of plastic products.

The setup cost of a CNC machine for a medium-sized project is low compared to injection molding. If the production will be done in small batches, it will be more economical to use the CNC machine in the production. 

Considerations of Choosing Plastics for CNC Machining

The following factors should be considered before deciding to choose plastic for plastic machining: strength of the plastic material, thermal properties, chemical reactivity, and physical appearance.

Hardness & Strength

Plastic machining is a rigorous process so it is good to make sure that the plastic block selected is strong enough to handle the rigorous process. Also, the strength of the material should be compared with the strength requirement of the machined part to be produced.

Thermal Property

The CNC machining process generates some heat that can affect the plastic if care is not taken. This is why it is good to first ensure that the melting temperature of the plastic chosen should be more than the temperature generated during the machining process. 

Also, all the thermal properties such as thermal conductivity, thermal expansion, and heat resistance of the plastic should be carefully considered because the selected plastic material determines the thermal property of the plastic component that will be produced. 

Chemical Reactivity

Some polymers react with other elements when exposed to certain conditions like moisture, UV light, coolant, and some additives. All these should be taken into consideration. If you don’t want this for your product, select the less reactive material.

Physical Appearance and Transparency

How you want your plastic to look depends to a large extent on the materials you choose. Some polymers can only give your product a solid or translucent finish, some can give you a transparent product, some will have a rough finish, and some can give you a smooth finish.

Whatever physical appearance you intend to give your machined plastic part depends on your choice of plastic.

Top 10 Machinable Plastic Materials

We’ve compiled a list of 10 machinable plastics to help you narrow down your search for the right plastic polymer for your next product.

Polytetrafluoroethylene (PTFE)

Looking at the properties of PTFE, one would think this plastic cannot be machined. PTFE is a softer material when compared with other machinable materials. Its tendency to deform when it undergoes stress has caused some speculations that this plastic material might not be suitable for machining.

However, PTFE is very machinable, it has a low friction property, a high thermal conductivity, is resistant to chemicals, and has a high-temperature stability. These properties allow PTFE compounds to be easily machined into PTFE tubes, rods, films and sheets by CNC milling or turning machines.

Polyether Ether Ketone (PEEK)

There is no doubt about the machinability of PEEK. PEEK is an excellent machinable plastic. It has a low coefficient of thermal friction which increases its stability during the machining process. There will be ‘little to no’ dimensional change under a stable machining condition.

Acrylonitrile Butadiene Styrene (ABS)

ABS is another relatively soft material that can be machined. Although it can experience some level of flexing and deformation during machining, it is machinable. 

To machine ABS material without any hassle, the CNC machine should be set up in a way that vibration will be minimized. In addition, a proper cooling system should be in place to prevent deformation from the heat generated from machining. 

Nylon

Nylon is suitable for CNC machining under a controlled system of machining, nylon is a great machining material. It is a silk-like thermoplastic that can be easily heated, cut, or compressed into different parts. Nylons have a low absorption rate and thus cannot absorb moisture from the environment during the CNC machining process.

It is suitable for manufacturing wear-resistant products, gaskets, and washers.

POM/Delrin

Polyoxymethylene (POM) is used to make mechanical and automotive parts that would traditionally be made of metal. It is extremely rigid, long-lasting, and strong, possessing features similar to metals. It is highly acidic and should not come in contact with nitric acid and hydrochloric acid. 

Polyoxymethylene (POM) is used in making ball bearings, fasteners, knife handles, and automotive gears.

PMMA (Acrylic)

Acrylic has a high tensile strength and thermal stability. It is an excellent machinable material used in various applications. They are mostly used for products that are transparent or that need light to pass through them. It can be used to produce road signages, lighting fixtures, and optical components. 

Although PMMA is machinable, they are sensitive to heat. This is why a good cooling system should be in place during CNC machining.

Polypropylene (PP)

PP has good impact resistance, chemical resistance, and low density. This property makes it quite easy to machine PPs. PP has a wide application in many industries that rely on plastics. They are used in the automotive industries, aerospace industries, and for the manufacturing of a lot of consumer goods. 

PP has a lower melting point compared with other thermoplastics. The heating speed can be controlled by using a lower cutting speed and providing a cooling system during CNC machining.

Polycarbonate (PC)

Polycarbonate is a thermoplastic that is heat-resistant by nature, yet durable and efficient. Components produced with PC usually have a smooth finish. Although sometimes marks from machining might be left to the material. 

To prevent scratches and marks during CNC machining, some conditions have to be met. This includes using the right feed rate, using the appropriate temperature, and using sharp cutting tools. 

High-density Polyethylene Plastics (HDPE)

HDPE is a flexible, easy-to-process plastic that’s resistant to stress cracking, chemicals, and corrosives even at low temperatures. However, this material has poor UV resistance and is commonly used in the production of plugs, seals, and electrical insulators.

HDPE is used for CNC machining because of all the above properties. They can be easily processed into complex components. HDPE has enough structural stability that allows it to withstand all the rigorous processes of all the CNC machining methods without damage in the process.

Ultra-high Molecular Weight Polyethylene (UHMW)

UHMW is a strong, adaptable, and incredibly machinable plastic with great resistance to abrasion and wear. However, UHMW shouldn’t be utilized in temperatures beyond 80 to 100°C and isn’t recommended for high-load applications due to its high creep susceptibility. 

It is used to produce truck bed liners, components of food processing machines, wear strips, and maritime dock fender pads.

Although UHMW is not suitable for high-temperature CNC machining, it can be machined at a relatively low temperature with the CNC turning method.

Choose Suitable CNC Machining Methods 

CNC material machining has made amazing strides in recent years and we will give you a thorough guide to choosing the three best CNC machining techniques. Below are some popular CNC machining techniques:

CNC Turning

CNC turning consists of a fixed tool to remove extra material from a revolving workpiece that is attached to a lathe. CNC turning is most suitable when a lot of parts or pieces are needed. 

Spheres and cones are the two most used cylindrical shapes in CNC turning. Some turning centers contain both a main spindle and a sub-spindle for even faster operation.

For multiple spindle turning centers, the workpiece is controlled by the main spindle. This is before it is transferred to the sub-spindle to finish the task on the opposite side of the machine. CNC turning is used in producing complex short-run manufacturing parts and precision components and parts.

CNC Milling

The CNC milling process also makes use of mill machines or mills, which are CNC-enabled milling equipment that can be oriented either horizontally or vertically. In this method, materials are chopped and shaped using spinning tools with several points, allowing for thousands of RPMs per minute for rotational speed. 

Three-axis motions are possible in basic mills, while more complex models can accommodate more axes. There are several types of milling machines. They are; hand, plain, universal, and universal mills. 

Processing plastics using CNC milling starts with designing the product with CAD software. After the design is properly done, appropriate sharp cutting tools will then be installed on the CNC milling machine for easy cutting of the material. Also, a big block of the chosen plastic material will be mounted on the machine.

CNC Drilling

If you compare drilling to other plastic machining methods you will see that it is a rather cheap and simple operation. It creates cylindrical holes in the workpiece by using its rotating drill bits. 

The design of the drill bit enables the waste metal, or chips, to detach from the workpiece easily. These drill bits come in different varieties and they all have different tasks they can perform.

Some of the different types of drill bits are spotting drills, peck drills, and screw machine drills. They can create a variety of holes because they can hold numerous drill bits. Without a tool turret to change drill bits as needed, the application might be restricted and drilling can become difficult. 

Begin State-of-the-Art Plastics CNC Machining with LSH

Are you looking to bring your product to life, LSH is ready to do justice to that with our exceptional CNC machining. Our state-of-the-art plastic CNC machining services can give you just what you need without stress. LSH is ready to take over the product production process for your business.

LSH: Top 3 PTFE Plastics Experts in China

At LSH, we boast of being among the top 3 PTFE plastics experts in China. Our list of services includes PEEK Bottles, PTFE caps, and other specialty plastic items (including seals, bellows, and other components.) 

We use unique technologies like LSH’s Premium PTFE Compression Molding, Automatic Production, CNC Lathe Machining, and CNC Machining. We also offer Stamping and Fast Turnaround Machining to our clients.

Provide High-Precision Plastics Machining With No MOQ

Our high-speed, precise auto machine produces machined plastic parts. Our products feature a maximum diameter of 25 mm so that they work well for milling tiny, precise pieces. 

We make plastic tools with close-tolerance precision. This is done by our experienced engineers who use cutting-edge CAD/CAM software to make unique plastic prototypes.

Our high precision plastics machining products include bellows, ball valve seats, O-rings, insulators, guide rings, labwares, seals, and bushings.

Conclusion

Plastic CNC machining has great benefits for different industries. Complex designs can be brought to life with CNC machining as long as the right machinable plastic is used. Although CNC offers a faster way of producing prototypes, you would still have to consider some factors before choosing CNC machining.

If you are still not sure if you need CNC machining done for your product, or you are confused about the material to choose. LSH will always be available to enlighten you. LSH offers one of the best CNC machining services for all industries. Whatever you need, we can produce. Contact us today to get a quote.