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Acrylic for CNC Machining
Acrylic is an optically clear, lightweight, and UV-stable plastic that exhibits excellent strength and stiffness. These properties make it an ideal glass substitute for many applications. CNC machining in acrylic is widely used in the automotive industry as well as in the test and measurement industry.
About Acrylic for CNC Machining
Acrylic is a thermoplastic, meaning it can be melted and reformed and won’t lose its fundamental material properties. One of the key benefits of acrylic, when compared to other clear plastics, is the fact that it does not discolor with prolonged exposure to sunlight. In addition, it is lighter and more impact resistant than glass. One key weakness, compared to glass, is that acrylic is not suited to high-temperature applications.
Acrylic At a Glance
Acrylic
Acrylic is a tough material that has numerous benefits over glass. For one, acrylic can be easily machined whereas glass cannot. This gives you the option of CNC machining in acrylic when the task requires both complex geometry and high levels of optical clarity in the final part. Acrylic’s clarity makes it ideal for inspection windows, chemical testing hardware, and instrumentation covers.
General Acrylic Properties
| Tensile Strength, Yield (MPa) | Elongation at Break (%) | Hardness (Shore D) | Heat Deflection Temperature (°C) | Melting Point (°C) |
|---|---|---|---|---|
25-85 | 1-85 | 90 | 73-109 | 102-122 |
Finishes
Surface finishes are rarely applied to CNC machined acrylic because most would impede the material’s inherent optical properties. In cases where a finish is needed, opt for one that enhances these properties.
- Bead Blast Polishing: Machined plastics often require additional post-processing to give them smooth, scratch-free surfaces. This is especially important with CNC machined acrylic as tool marks can severely reduce its inherent optical clarity. Polishing acrylic can remove any surface scratches and leave it with a smooth and clear surface.
Cost-saving Design Tips
Acrylic is a readily available material but take care to design within the limits of the available material as described below.
- Design to standard sizes: Acrylic is typically supplied in sheets of varying thicknesses as well as extruded forms such as tubes and solid bars. Designing parts to fall within the dimensions of off-the-shelf sheet and bar stock will keep costs to a minimum. If the required part is too large, consider breaking it into multiple components that can then be glued or fastened together after machining.
