Have you ever struggled to make accurate and clean acrylic parts? Traditional methods often result in uneven edges, cracks, or cloudy finishes, causing frustration and wasted resources. Acrylic CNC machining solves these problems, providing precise, clear, and durable parts quickly and efficiently. This method ensures your designs come out exactly as intended, saving you time and money.
If you’re new to CNC machining, this guide explains clearly how machined acrylic parts are created. You’ll quickly learn the basics and advantages, so keep reading to discover more.
What Is CNC Acrylic Machining?
CNC acrylic machining is a subtractive process. Using high-speed rotating tools, a CNC machine removes material from a solid acrylic sheet. The machine follows a digital design file to accurately cut, drill, or mill the acrylic.
This method creates smooth edges, clean holes, and complex shapes. It works well for both prototypes and finished products. Acrylic is strong, lightweight, and has excellent optical clarity, making it a popular choice.
Why Acrylic (PMMA) Is Popular for Machining?
Acrylic, or PMMA, is widely used because it is clear, strong, and easy to machine. It works well for both prototypes and final products.
Géométries complexes
CNC machining can create sharp angles, detailed cuts, and tight tolerances in acrylic. The material holds its shape well and doesn’t deform easily during cutting.
Flexibilité
Acrylic comes in different grades and thicknesses. It works for many products, from simple covers to detailed lens housings. You can mill, drill, or engrave it with precision.
Fine Surface Finish
With the right speed and tool, CNC can produce smooth, glossy edges on acrylic. Polissage or flame treatment makes the finish even better for visual parts.
Increased Rate of Production
CNC machining allows repeatable results with fast cycle times. This helps reduce lead times and supports short-run or high-volume orders without extra tooling costs.
Types of Acrylic Materials
There are several kinds of acrylic materials, each with its strengths. Choosing the right type affects how the part looks, feels, and performs.
Cast Acrylic
Cast acrylic is more transparent and stronger. It machines cleanly and resists cracking, making it ideal for parts that need a polished look or tight tolerances.
Extruded Acrylic
Extruded acrylic is cheaper and easier to form. It has more thickness variation and is softer than cast acrylic. It works well for parts that don’t need high precision.
Optical-Grade Acrylic
This type is used for lenses, light guides, and display covers. It offers high-light transmission and minimal distortion. To maintain its clarity, it needs careful handling during machining.
Impact-Modified Acrylic
This acrylic has added toughness, making it less likely to crack under stress. It’s suitable for parts exposed to vibration or repeated handling, like housings or safety covers.
Properties of Acrylic Relevant to CNC Machining
Acrylic has specific traits that make it suitable for CNC work. Knowing these helps you choose the correct settings and tools during machining.
UV Resistance
Acrylic resists yellowing and breaking down in sunlight, making it a good choice for outdoor signs, covers, and lighting parts.
Strength and Rigidity
Acrylic is strong and holds its shape well. It doesn’t flex much, which helps maintain precision during cutting or drilling.
Transparency
Acrylic offers high-light transmission. Clear grades look like glass but weigh less. With proper machining and polishing, the edges can stay clear and smooth.
Thermal Behavior
Acrylic softens when heated. Too much heat during machining can cause melting or warping. Sharp tools and controlled speeds help prevent heat buildup.
Résistance chimique
Acrylic is resistant to many cleaners and mild chemicals. However, some solvents may cause cracks or cloudiness, so material selection matters.
Surface Finish Characteristics
Acrylic is well-suited to polishing and flame finishing. After CNC machining, smooth, glossy edges, and surfaces can be achieved with minimal extra work.
Acrylic CNC Machining Processes
Different CNC machining processes are used to shape acrylic parts. Each process has unique features and works best for specific tasks.
Fraisage
Fraisage involves a spinning cutting tool that removes acrylic material. It can create flat surfaces, complex shapes, slots, and pockets. CNC milling is precise and effective, allowing accurate control of depth and shape.
Tournant
Tournant shapes round acrylic parts by spinning the material while a fixed cutting tool removes layers. This process is best for cylindrical components like rods, tubes, or rings. It produces smooth surfaces quickly and accurately.
Forage
Drilling creates clean, precise holes in acrylic parts. Perçage CNC ensures the holes are positioned exactly as planned. It avoids cracking or chipping, giving consistently good results, even with small diameter holes.
Gravure
Gravure uses CNC tools to etch precise text or patterns onto acrylic surfaces. This process provides accurate, clear markings that are easy to read. It’s often used for logos, labels, or decorative details on acrylic products.
Coupe
Découpe CNC uses tools like router bits or lasers to slice acrylic sheets into accurate shapes. Router bits produce clean, polished edges, while lasers create precise cuts quickly. Both methods ensure smooth, consistent results ideal for final parts or prototypes.
Design Considerations for Acrylic CNC Machining
Good design makes machining easier and helps avoid problems like cracking, poor fit, or weak parts. These basic rules help ensure your acrylic parts come out right.
Wall Thickness and Support
Thin walls can crack during cutting or under stress. Keep walls thick enough to stay strong—usually no thinner than 1.5 mm. Add ribs or support structures if needed. This helps prevent warping or breakage during use.
Corner Radii and Sharp Edges
Acrylic doesn’t like sharp internal corners. Always add a radius that matches the tool size. This reduces stress and allows the tool to move smoothly. Avoid sharp edges where possible to lower the risk of cracks.
Hole Sizes and Tolerances
Acrylic can chip if the holes are too small or tight tolerances are applied without care. Use slightly larger holes when possible. Design for standard drill sizes and leave room for final reaming if precision is needed.
Threading and Inserts
Cutting threads directly into acrylic isn’t ideal. The material can strip or crack. For better durability, use threaded metal inserts. Depending on the part’s design, heat-set or press-fit inserts are both good options,
Tooling and Cutting Parameters
When machining acrylic, choosing the right tools and settings is key to getting clean, accurate parts. Acrylic is sensitive to heat and pressure, so even small changes can affect the result.
Outils de coupe
The best tools for acrylic are sharp, single-flute end mills or plastic O-flute cutters. These tools clear chips quickly and create less heat, which helps prevent melting and keeps edges smooth. Double-flute tools can also work if you need a finer surface, but they need slower feed speeds to stay cool.
Dull tools should always be avoided. They build heat, damage the edges, and may crack the material. It’s best to use carbide tools because they stay sharp longer and hold their shape well.
Optimal Speeds and Feeds
Acrylic cuts best with high spindle speeds and slow feed rates. Most setups run between 12,000 and 24,000 RPM, depending on the tool size. Lower feed rates help control chip size and reduce heat.
You might get melting or rough edges if the feed is too fast. Also, keep the depth of each cut shallow. Deep cuts can cause the material to crack or melt, especially on thinner parts.
Coolant Usage and Air Blasting
Avoid using liquid coolants on acrylic. Coolants can get into the plastic and lead to cracks or surface damage later on. Instead, use compressed air.
Air helps cool the tool and clears chips from the cutting path. A steady airflow is a good way to keep the plastic clear and avoid tool burn for long jobs or large parts.
Chip Removal and Heat Management
If chips stay in the cut, they get re-cut and create heat. This can damage the surface and make the part cloudy. Tools with polished flutes and machines with vacuum or air systems work best to remove chips.
Try to keep the tool moving steadily. If the cutter stays in one spot too long, it can overheat the material. Smooth toolpaths with fewer sharp turns help avoid stress and heat buildup.
Techniques de finition de surface
Acrylic parts often need a smooth and clean look, especially for display or customer-facing uses. These finishing methods help improve appearance and function.
Polishing (Flame, Vapor, Mechanical)
Polishing makes the acrylic surface transparent and glossy.
- Flame polishing uses a flame to melt and smooth edges quickly.
- Vapor polishing uses chemical vapors to soften the surface, often for optical parts.
- Polissage mécanique uses buffing wheels and pastes for a high-gloss finish.
Choose based on the needed clarity and part shape.
Deburring Methods
Machining can leave small burrs or rough edges. Use soft brushes, hand scraping, or light sanding to remove them. This step improves safety and gives the part a clean, finished look.
Painting and Coating Compatibility
Acrylic can be painted or coated if the surface is prepped properly. Use coatings made of plastics. Avoid paints with solvents that can cause cracks. Spray painting works well with smooth finishes, while masking allows clean edges.
Screen Printing and UV Printing
Screen printing is outstanding for solid colors and large batches. Impression UV prints full-color images and cures them instantly with UV light. Both options stick well to acrylic and are often used for signs, panels, and branded covers.
Common Applications of CNC Acrylic Parts
CNC acrylic parts are used in many fields because they’re clear, strong, and easy to shape. They can be found in both functional and decorative products.
Display and Signage
Acrylic is clear, smooth, and easy to cut into custom shapes. It’s ideal for display stands, nameplates, store signs, and point-of-sale materials. CNC machining ensures sharp edges and clean finishes for professional looks.
Dispositifs médicaux
Acrylic is non-toxic and resists chemicals, making it suitable for medical trays, guards, or equipment covers. It also allows clear visibility of instruments or contents, which is helpful in labs or hospitals.
Lighting Components
Because acrylic transmits light well, it works great for light diffusers, lenses, and LED panels. CNC machining helps create precise shapes and clear finishes without blocking or distorting light.
Automotive and Aerospace Prototypes
Acrylic is often used for transparent parts in the early design stages. Engineers use it for headlight covers, dashboard panels, or airflow models. It’s fast to machine and shows fine details clearly.
Consumer Electronics Housings
Acrylic can be shaped into protective covers or phone, tablet, or control panel cases. It looks good, holds its shape, and gives a high-end feel. CNC machining ensures all cutouts and features are placed accurately.
CNC vs. Laser Cutting for Acrylic
CNC and laser cutting can shape acrylic, but each has strengths. Choosing the right one depends on the part’s design, finish, and production needs.
Accuracy and Edge Finish
Découpe au laser offers very high precision and ultra-smooth, glossy edges. It’s perfect for detailed patterns or parts that need a polished look straight from the machine.
CNC cutting is also accurate but may leave tool marks or rougher edges that need polishing.
Thickness Capabilities
CNC machines can handle thick acrylic sheets with ease. They can also make deep cuts and pockets.
Laser cutting works best for thinner sheets, usually under 25 mm. Cutting thick acrylic with a laser can cause melting or uneven edges.
Production Volume Suitability
Laser cutting is excellent for large batches of flat parts. It works fast and doesn’t need tool changes.
CNC machining is better for complex 3D parts or smaller runs with varying designs. It’s more flexible for changes and custom features.
Efficacité en termes de coûts et de délais
Laser cutting is faster for simple shapes and uses less labor. It’s often cheaper for flat parts with slight variation.
CNC machining takes longer but adds more features, like pockets or drilled holes. It’s better when parts need more than just a 2D cut.
Acrylic CNC Machining: Challenges and Troubleshooting
Machining acrylic can lead to a few problems if not handled carefully. Knowing how to solve these issues helps avoid scrap and keeps quality high.
Cracking and Crazing
Cracks or small surface lines (crazing) often come from stress or poor handling.
To avoid this:
- Use sharp tools with the correct feed rates.
- Avoid tight corners without radii.
- Keep acrylic clean and dry before machining.
- Annealing the parts after machining can also relieve internal stress and reduce cracking.
Melting and Burr Formation
Acrylic melts at a low temperature. Heat builds up if the tool moves too slowly or the speed is too high. This can cause melted edges or burrs.
To fix this:
- Use high feed rates with moderate spindle speeds.
- Choose tools designed for plastics.
- Add air blast or coolant to reduce heat.
Chipping and Poor Surface Finish
The acrylic may chip or look cloudy if the cutting tool is dull or the settings are off.
Prevent this by:
- Using sharp, single-flute cutters.
- Setting the correct spindle speed and feed rate.
- Avoiding aggressive plunges or sharp direction changes.
Warping and Stress Relief
Large, flat acrylic parts can warp after machining due to internal stress or uneven removal.
To reduce warping:
- Clamp parts evenly.
- Use light, even cutting passes.
- Let the part rest or anneal it after machining to release stress.
Conclusion
CNC machining is a reliable way to create clear, accurate, and detailed acrylic parts. Acrylic is strong, lightweight, and visually clear, which makes it ideal for many industries. With the proper setup, CNC-machined acrylic parts can look clean and perform well in any application.
Looking for precision-machined acrylic parts? Contact Shengen today for fast quotes, expert advice, and high-quality results tailored to your project needs.
Hey, je suis Kevin Lee
Au cours des dix dernières années, j'ai été immergé dans diverses formes de fabrication de tôles, partageant ici des idées intéressantes tirées de mes expériences dans divers ateliers.
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Kevin Lee
J'ai plus de dix ans d'expérience professionnelle dans la fabrication de tôles, avec une spécialisation dans la découpe au laser, le pliage, le soudage et les techniques de traitement de surface. En tant que directeur technique chez Shengen, je m'engage à résoudre des problèmes de fabrication complexes et à favoriser l'innovation et la qualité dans chaque projet.
