Acrylic CNC Machining: Everything You
Need to Know

Polymethyl methacrylate (PMMA) or Acrylic is a thermoplastic polymer. This transparent plastic material is recognized for its strong mix of properties, including exceptional optical clarity, surface hardness, weatherability, and dimensional stability, making it a great alternative to glass for several reasons. It is:

• 50% Lighter Than Glass
• Generally More Affordable
• Has Higher Impact Resistance

These appeals make acrylic a popular choice in many sectors for both prototyping and production purposes, often manufactured via CNC machining.

Why use CNC machining to cut acrylic?

CNC (Computer Numerical Control) machining is a automated manufacturing process that uses precise cutting tools to shape raw materials into finished parts or products. It is popular method for cutting acrylic due to several advantages it offers:

1. Material Compatibility

Acrylic is a thermoplastic that becomes malleable on exposure to heat. This quality makes it well-suited for CNC machining as it can be easily fabricated and shaped using this process.

2. Builds High Precision Parts

CNC machines are capable of extremely precise cuts with tolerances measured in thousandths of an inch. This level of accuracy is crucial when working with materials like acrylic, which require clean edges and precise dimensions.

3. Increases Rate of Production

CNC machining is one of the most efficient ways of fabricating acrylic material, particularly for small batch acrylic parts. It allows for faster production compared to manual method.

4. Minimized Waste

Thanks to its precise manufacturing methods, CNC can cut acrylic with just the right amount of force to avoid irreversible damage, quickly and effectively producing acrylic components with accurate shapes and sizes. This increases accuracy and minimizes wastes.

5. Results in High Repeatability

The automated CNC process ensures consistency across multiple parts or batches, producing stable replication accuracy in each PMMA workpiece.

6. Saves on Manufacturing Cost

CNC machining can lead to cost savings in manufacturing due to reduced material waste, increased efficiency, and lower labor costs compared to manual machining methods.

Applications of CNC acrylic parts

There are many applications of CNC acrylic parts across various industries. The major applications of CNC acrylic parts include:

• Automotive industry: automotive manufacturers produce many interior and exterior automotive parts using acrylic CNC machining. They include headlights, indicators, brake lights, sirens and gear bearings.
• Medical sector: CNC acrylic is often used to make syringes, clear enclosures, and incubators in the medical sector. In dental care, PMMA it is commonly used for temporary crowns.
• Consumer goods: CNC machined acrylic components show various applications in consumer goods from smartphones and laptops to signages.
• Architecture and construction: Due to acrylic’s high impact and UV light resistance, it has several applications in the construction industry. This includes canopies, panels, and façade designs.

Considerations for CNC machining acrylic

To ensure precision and minimal damage in the final acrylic part, consider these five tips when using CNC cutting machines for cutting acrylic:

• Ensure Acrylic Billet is Secure — Properly securing your acrylic workpiece to the machine is essential. Failure to do so could result in low-quality products, as excess vibration may cause the PMMA material to shift or become misaligned during the machining process.
• Choose the Right Cutter — When CNC machining acrylic, it’s essential to select cutters with razor-sharp and strong edges. This will help prevent acrylic from melting, which negatively affects appearance and functionality. Avoid using cutters previously employed with metal, as they will likely have cuts or jagged edges. Opting for smooth, sharp cutter edges ensures cleaner cuts and enhanced overall quality.
• Monitor Cutting Depth and Direction — When using a CNC machine to cut acrylic, the direction of the tool is as important as the cutting depth. Make sure you know which way your CNC cutter is rotating or spinning — to the left vs. the right, or counterclockwise vs. clockwise — in order to ensure accuracy in your design features.
• Set the Correct Feed Rate — It’s important to set the correct feed rate when using a CNC machine. While using a faster feed rate will prevent acrylic from melting, increased cutting pressure can potentially cause the acrylic workpiece to break. The type of acrylic material you choose, as well as part geometry, will determine what feed rate is best for your project.
• Check the Number of RPM — The feed rate and the Revolutions per minute (RPM) work hand in hand. When using a fast RPM, increasing the feed rate can help prevent material melt, as it ensures that the cutting tool moves through the material quickly enough to dissipate heat effectively.

Custom CNC acrylic parts with HLH Rapid

At HLH Rapid, we have years of experience cutting and shaping acrylic products using the latest CNC machining technology. To get a free quote and start your next custom CNC acrylic project, submit your CAD designs and project details to our site contact form, and our team will get back to you within 24 hours.