Acrylic CNC Machining: A Complete Guide to Cutting, Engraving, and Finishing
Acrylic, also known as PMMA (polymethyl methacrylate), is a versatile, lightweight plastic prized for its optical clarity, durability, and ease of machining. From eye-catching signage and elaborate displays to critical components in medical devices and prototypes, acrylic CNC machining is the go-to method for cutting, engraving, and shaping this material with unmatched precision. In this guide, we explore everything from choosing the best CNC machine for acrylic to optimizing your machining process and post-processing for flawless results.
Why Use CNC Machining for Acrylic?
CNC machining is ideal for working with acrylic because it allows manufacturers to achieve highly precise tolerances (typically ±0.1 mm) and smooth edges without inducing cracks or chips. Here are the main advantages:
- Precision and Accuracy:
CNC machines enable intricate designs and detailed cuts, ensuring that every piece meets design specifications. - Smooth Edges:
With proper tooling and optimized parameters, a CNC machine can cut acrylic without the chipping or cracking that may occur with manual methods. - Versatility:
CNC machining can cut, drill, engrave, and bevel acrylic in a single setup. This flexibility is particularly beneficial when producing complex 3D contours or combining different finishing operations. - Speed:
For thicker acrylic sheets (≥10 mm), CNC machining can be faster than laser cutting while maintaining precision. - Repeatability:
Automated processes ensure that each part is produced with consistent quality, essential for high-volume production.
Types of CNC Machines for Acrylic
There are two main types of CNC machines used for processing acrylic, each with its own set of advantages:
1. CNC Router Machines
CNC router machines are especially effective for cutting thicker acrylic (up to 50 mm), creating 3D contours, and handling high-volume production. Key features include:
- Spindle Speed:
Typically 18,000–24,000 RPM to avoid heat buildup and melting. - Cooling System:
Use of air blasts or mist cooling helps dissipate heat and protect the material. - Tooling:
Single-flute O-flute bits (like Onsrud 63-700) are optimal for clean cuts and smooth edges.
| Machine Model | Price Range | Workspace |
|---|---|---|
| ShopBot PRSalpha | $15,000–$25,000 | 48″ x 96″ |
| Axiom Precision Elite | $8,000–$12,000 | 24″ x 36″ |
| Great Light CNC Router | Custom Quote | Up to 60″ x 120″ |
2. CNC Laser Cutting Machines
Laser cutting machines are best suited for thin acrylic (≤10 mm) and for applications requiring detailed engraving and a polished edge finish.
- Laser Power:
CO₂ lasers typically range from 40–100W, with optimal results at a wavelength of 10.6 µm. - Speed and Precision:
Laser systems offer high-speed cutting and can engrave at fine resolutions.
| Machine Model | Price Range | Laser Power |
|---|---|---|
| Glowforge Pro | $6,000–$8,000 | 45W |
| Epilog Fusion Pro | $25,000–$50,000 | 120W |
| Trotec Speedy 360 | $20,000–$40,000 | 80W |
How to Cut Acrylic with a CNC Machine – Best Practices
Tool Selection
- End Mills:
Use single-flute O-flute bits to minimize heat buildup and ensure clean cuts. These tools help reduce chip formation and prevent melting of the acrylic. - Laser Settings:
For laser cutting, optimal settings for 3 mm acrylic might be a speed of 12–15 mm/s at around 80% power. Adjust settings based on thickness and desired edge quality.
Optimal Machining Parameters
| Acrylic Thickness | Spindle Speed (RPM) | Feed Rate (mm/min) | Depth of Cut (mm) |
|---|---|---|---|
| 3 mm | 18,000 | 3,000 | 2 |
| 10 mm | 16,000 | 2,400 | 3 |
| 20 mm | 14,000 | 1,800 | 4 |
Preventing Common Issues
- Melting:
Use lower RPM and higher feed rates. Employ cooling systems (air or mist) to dissipate heat. - Chipping:
Secure acrylic sheets with vacuum tables or clamps to prevent vibration and movement. - Fogging:
Apply masking film on the acrylic surface prior to machining to protect against laser-induced fogging.
Post-Processing Acrylic Parts
Once machining is complete, proper post-processing is crucial to achieve a professional finish:
- Deburring:
Use flame polishing or hand files to remove sharp edges. - Polishing:
Dip parts in a solvent such as ethanol or use a muslin wheel buffing process to achieve optical clarity. - Engraving:
For logos or text, laser etching at 600 DPI resolution delivers detailed and precise engravings.
CNC Laser vs. Router for Acrylic – Pros and Cons
| Factor | CNC Router | CNC Laser |
|---|---|---|
| Edge Quality | May show slight tool marks; requires polishing | Produces polished, flame-like edges |
| Thickness Limit | Effective up to 50 mm with multiple passes | Best for acrylic up to 10–15 mm |
| Speed | Slower for thin sheets; ideal for 3D contours | Faster for intricate engraving and thin cuts |
| Cost | Higher upfront cost ($8K–$25K range) | Varies widely; $6K–$50K depending on laser power |
Top 5 CNC Machines for Acrylic
- Axiom Precision Elite – Best for small workshops; offers compact workspace and precision cutting.
- ShopBot PRSalpha – Ideal for large-format signage with a spacious 48″ x 96″ work area.
- Epilog Fusion Pro – A top laser cutting machine for detailed engraving and precise cuts.
- Great Light CNC Router – Customizable for industrial-scale production with workspaces up to 60″ x 120″.
- Trotec Speedy 360 – High-speed laser system for mixed material projects.
Acrylic CNC Machine Price Guide
| Machine Type | Entry-Level Price | Mid-Range Price | Industrial Price |
|---|---|---|---|
| CNC Router | $8,000–$12,000 | $15,000–$25,000 | $30,000+ |
| CO₂ Laser Cutter | $6,000–$10,000 | $20,000–$40,000 | $50,000+ |
| Fiber Laser | N/A | $30,000–$60,000 | $80,000+ |
Note: Prices exclude software, tooling, and installation fees.
Why Partner with Great Light CNC Machining?
Great Light CNC Machining offers advanced 5-axis CNC routers and laser cutting services that are also ideal for cutting acrylic. Our expertise extends beyond metal machining to include high-precision acrylic processing, ensuring that your designs are realized with impeccable accuracy and finish.
Advantages for Acrylic Machining
- High-Precision Prototypes:
Whether for medical devices, optical components, or signage, our CNC machines achieve consistent tolerances and clean edges. - Advanced Cooling Systems:
Our systems incorporate air and mist cooling to prevent acrylic warping and melting. - Polishing and Finishing:
We offer flame or solvent polishing to achieve optical clarity, enhancing both appearance and functionality. - Global Shipping:
With efficient logistics, we deliver your parts from our facilities directly to your doorstep.
How to Order
- Upload Your CAD File:
Submit your design in STP or STL format via our secure online portal. - Select Material:
Choose from our extensive range of acrylics, from standard to high-impact variants. - Choose Finish:
Specify your desired surface finish, whether it’s as-machined, anodized, or polished. - Get a Quote:
Receive an instant quote based on your design’s specifications, material choice, and production volume. - Track Production:
Enjoy real-time updates on your part’s progress from machining to shipping.
FAQs About Acrylic CNC Machining
Can a CNC Machine Cut Acrylic Without Melting?
Yes, using low RPM (10,000–18,000 RPM), high feed rates, and the appropriate O-flute bits, a CNC machine can cut acrylic without causing it to melt.
What’s the Best CNC Bit for Cutting Acrylic?
Single-flute spiral O-flute bits, such as the Onsrud 63-700, are ideal for cutting acrylic as they minimize heat buildup and produce smooth edges.
How Thick Can Acrylic Be Cut With a CNC Router?
CNC routers can effectively cut acrylic sheets up to 50 mm thick with multiple passes; however, 10–20 mm is optimal for maintaining speed and quality.
Conclusion
Acrylic CNC machining unlocks endless possibilities for designers and engineers by combining high precision with efficient production processes. Whether you opt for a CNC router to handle thick sheets or a laser cutter for intricate engravings, the key to success lies in optimizing tool selection, machining parameters, and post-processing techniques. For mission-critical projects and high-quality outputs, partnering with experts like Great Light ensures you receive superior parts, on time and within budget.
Start Your Acrylic Project Today:
✅ Upload your design for a free quote.
✅ Access expert DFM feedback and finishing options.
✅ Experience the benefits of precision 5-axis CNC machining for acrylic and multi-material projects.
