Did you know that plastic is the most commonly used material in the world? In fact, it’s so prevalent that it’s estimated that we produce over 300 million tons of it every year. And while a lot of that plastic ends up in landfills and oceans, a lot of it is also machined into all sorts of products.
Do you know that new car smell? The one that wafts through the air when you first open the door of your brand-new ride? It’s not just a coincidence – that intoxicating scent is thanks to the plastic inside the car. Almost all new products have at least some plastic in them, and for a good reason.
In this article, we’ll look at CNC plastic machining, some of the products that can be made with it, and how you can get your custom plastic machined parts. Keep reading!
Overview of Plastic Machining
Plastic machining is a specialized skill that requires knowledge, experience, and precision to produce the desired result. The machines used for plastic CNC machining are the same as those used when working with metal; however, plastic presents a unique set of challenges due to its amorphous nature.
As the material is heated and cooled during machining, it can expand haphazardly, leading to creeping, melting, chipping, and pitting issues.
To succeed in CNC plastic machining, these factors must be considered when selecting the proper tools and material and ensuring adequate stabilizing procedures have been implemented along the machining processes.
Different Types of CNC Plastic Machining
There are several types of CNC plastic machining. Each type has its own set of advantages and disadvantages. These types include:
Threading/Tapping
Plastic threading or tapping creates fine threads in plastic materials that are too soft to hold threads well.
A generous machining allowance is typically considered when threading plastic because it is more notch-sensitive than metal and will often tear when making fine-pitch threads.
By properly threading plastic components, it allows for the use of fasteners like screws, bolts, and rivets to secure them in place. The plastic threading or tapping process provides secure assemblies while ensuring that plastic components blend easily into almost any application.
Drilling
Plastic drilling is a CNC plastic machining type that creates parts and components by removing material by rotating drill bits. However, without precise control, the CNC machining process used to make plastic materials will generate too much friction and heat, potentially damaging the product.
By adjusting factors like cutting speeds, cutting tool designs, feed rates, and coolants when drilling plastics, you can reduce the amount of heat generated and preserve the material.
With the right drilling settings, a drilling machine can rapidly create accurate plastic parts of excellent quality.
Milling
CNC milling is a subtractive CNC plastic machining process in which material is removed from the surface of a part with specially designed cutting tools, such as endmills, ball mills, and face mills. It is often used to create complex parts and components from materials like plastic that are difficult to machine.
To use this technique effectively, the CNC milling machine must have a precise spindle and feed system to allow quick and accurate machining.
Additionally, the cutting tools must be correctly selected based on the hardness of the plastic being milled to ensure that it is strong enough to avoid breakage.
Turning
This CNC plastic machining creates CNC-machined parts and components with intricate turning. It involves using a CNC-controlled lathe or CNC turning machine to cut into materials at high speeds to create precise shapes.
Turning is often employed when making bearings, valves, pistons, and fuel injectors.
This technique requires great skill and accuracy as the turning machine must move in two directions—axially and radially—to cut into the material.
The parts are then formed to the desired shape before being finished with surface treatments such as anodizing or electroplating.
To properly carry out turning machining processes, the turning machine must be set up first.
This includes selecting the right cutting tools, setting the spindle speeds and feeds, and determining the optimal cutting parameters. It also requires close monitoring of the workpiece during CNC machining to ensure that it is cut accurately and with minimal deformities.
Sawing
Sawing in CNC plastic machining is making precise cuts in plastic parts. This is often done with an automated saw, such as a CNC router or laser cutter. Sawing is used to cut pieces into different shapes and sizes. It can also be used to create intricate patterns and designs.
To use this method, a toolpath is programmed into the sawing machine, and the plastic part is placed on a jig or holding fixture.
The saw then moves along the programmed path to perform the cuts. Sawing is an ideal method for cutting intricate parts that require precise edges and curves.
The sawing process can be done using various blades, such as circular blades, diamond-tipped blades, or band saws. The type of blade chosen will depend on the cut material and the desired finish.
For example, a diamond-tipped blade may achieve a smooth finish on plastics that are difficult to cut with other blades.
Grinding
Plastic grinding includes the use of specialized CNC grinding machines to shape and finish a wide variety of plastic parts. Plastic can be machined with precision, accuracy, and repeatability when the right machine is used.
The most common type of CNC grinding for plastics includes cylindrical grinding, surface grinding, centerless grinding, and profile grinding. The CNC grinding machines must be equipped with the right abrasives, tools, and grinding wheels to achieve the desired finish.
How to Get a Perfect Finish on Plastic Machined Parts?
The Plastics Industry Association has defined four categories to describe the appearance quality of finishes, which are:
- Glossy
- Semi-glossy
- Matte
- Textured
Getting a fine finish can be more difficult with some plastics, depending on their hardness and other characteristics. Proper preparation and attention to detail are crucial to achieving a perfect finish.
To get the best results, you should do the following:
- Choose the right plastic. Some plastics are easier to machine than others. Doing your research beforehand can help you select the right plastic for the job.
- Use the right cutting tools. Make sure that the cutting tools you’re using are suitable for the type of plastic you’re machining.
- Use the correct feed and speed. Setting the correct feed and speed is essential for achieving a fine finish on plastic machined parts.
- Check the coolant flow. Using the correct coolant, and ensuring there is enough of it, can help reduce friction and increase cutting speeds.
- Pay attention to detail. Make sure that all edges are smooth and free of burrs, chips, or blemishes.
When to Give Priority to Plastic CNC Machining
Plastic CNC machining offers precise control over complex parts and products. As such, it can be used for a variety of occasions including prototyping, low-volume production runs, and the production of intricate shapes.
When it comes to prototyping, this CNC machining process can help you quickly, and accurately create components that mimic the end product. Low-volume production runs are ideal as plastic CNC machining can handle small batch sizes while still delivering accuracy.
And finally, due to its precise nature, it is the best option for creating intricate components that are difficult or impossible to machine with traditional methods. All in all, when precision and accuracy matter most, it’s best to give priority to plastic CNC machining.
Industrial Applications of Plastic Machined Parts
CNC Plastic machining parts are widely used in a variety of industrial applications. Some of the most common applications include:
Medical devices
With advancements in medical technology, the application of plastic machining parts for the creation of personalized medical devices such as dental surgical guides and cardiac implants is now quick and easy. Thanks to automation, this integrated manufacturing process delivers high precision and accuracy.
This means that laboratories no longer need to order large batches of parts from suppliers – instead they can easily custom-make devices to specific application requirements and individual patient preferences with the help of 3D printing, laser cutting, and CNC machining technologies.
Automotive components
The automotive industry uses plastic machining parts to create components such as headlights, taillights, air conditioning ducts, and even fuel injection systems.
The benefits of using plastic machining parts in the automotive sector are clear – they offer superior strength and flexibility, as well as resistance to environmental factors such as temperature and corrosion.
On top of that, plastic machining parts are also lighter than their metal counterparts, meaning they can help reduce the overall weight of vehicles.
Aerospace components
CNC machined parts are also used in the aerospace industry to create components such as engine covers, instrument panels, and aircraft fuselages.
These machined plastic parts are typically lightweight, durable, and resistant to extreme temperatures – all of which are key considerations for aerospace components.
The accuracy and precision offered by plastic machining can also help reduce the risk of failure in aerospace components.
Food grade products
Finally, machined plastic parts are used to create food-grade products such as utensils, containers, and bottles.
The main benefit of using this technology is that it allows manufacturers to produce parts with intricate designs, while still meeting the highest food safety standards.
The non-porous nature of plastic parts also makes them highly hygienic, ensuring that food products remain safe and uncontaminated.
Benefits & Drawbacks of Plastic Machining
Benefits
- Plastic machining parts offer superior strength and flexibility, as well as excellent resistance to environmental factors such as temperature and corrosion. This makes them ideal for components that need to be used in extreme conditions or require a high level of durability.
- Plastic machining parts are also much lighter than their metal counterparts, offering a great way to reduce the overall weight of components.
- As plastic machining parts can be produced with intricate designs, they are perfect for applications that require complex shapes and patterns. This is especially useful in industries such as medical and automotive, where customization is key.
- Finally, plastic machining is a highly precise process that can help reduce the risk of failure in components.
Drawbacks
- Plastics are more difficult to machine than metals due to their lower strength and higher thermal expansion and are prone to deformation.
- Plastic machining often produces a lot of dust and debris which can be hazardous to workers’ health.
Key Considerations for Plastic Machining
When machining with plastics, it is important to consider several key considerations to ensure a successful outcome.
Molding Process
First and foremost, the injection molding machining processes must be considered; this technique for forming plastic parts involves forcing molten material into a die cavity. Doing so requires precise design, component geometry, and machine ability to achieve the desired results.
Type of Plastic Grade
Additionally, consideration must be given as to what type of plastic grade should be used; some grades are designed for high-precision applications while others are more durable and suitable for hard use.
The Finish on a Machined Part
Furthermore, the finish on a machined part is critical; it should be polished or textured depending on the end user, and a standard of smoothness must be maintained in order to keep any stress-inducing surface imperfections to a minimum.
High-Quality Equipment
Finally, it is wise to choose only machines with excellent capabilities when machining plastics; by using advanced equipment that can adjust torque, speed, and cutting pressure according to the specific requirements of your project you will likely acquire top-notch results.
