The ultimate guide to CNC machining acrylic parts
Acrylic is a standard transparent plastic used in CNC machining. As opposed to polycarbonate and glass, acrylic materials have many advantages, making them a popular choice for various applications.
Acrylic production methods include acrylic CNC machining, a precise and versatile process that allows for the creation of complex and detailed parts and designs. Acrylic components, such as acrylic sheets and acrylic machining, have widespread use in various industries.
What is Acrylic?
Acrylic, also known as PPMA or Plexiglas, is a type of plastic material commonly used in various applications due to its transparency, strength, and versatility. It is often used as a replacement for glass and is known for its ability to withstand shock and other types of damage.
Acrylic is a great material for CNC machining, as it can be easily shaped and molded into various forms. It can be machined using a CNC system to achieve precise cuts and smooth finishes, making it a good starting point for those working with plastic materials. In addition to being used in CNC machining, acrylic can be joined together using double-sided tape or other methods, such as solvent bonding or welding.
Despite its strength and durability, acrylic is a relatively soft material and can be easily scratched or marred if not handled properly. It is important to handle acrylic carefully and use appropriate techniques, such as clamping the material tight and using a linen towel to wipe away any excess debris to ensure that it is machined properly.
Properties of Acrylic
CNC acrylic has many properties that make it a popular choice for a wide range of applications. It is transparent, brilliant, clear, and has a high light transmittance, making it similar to glass in many ways. The manufacturing industry relies on acrylic due to its durability and low potential for damage. Let’s take a closer look at the various properties of acrylic.
Surface Hardness
Acrylic is a lightweight, strong, and durable thermoplastic with a density of 1.17 to 1.20 grams/cm³ It has excellent scratch resistance compared to other transparent polymers and is also consistent in its dimensions. However, acrylic is not very good at absorbing liquids.
UV Resistance
Acrylic is resistant to UV rays, making it suitable for outdoor use. It can withstand long periods of time in direct sunlight without degrading or discoloring.
Transmittance
The refractive index of acrylic is 1.49, allowing it to transmit up to 92% of the light that strikes it. This level of transparency is higher than that of glass and most other polymers. As a result, acrylic plastic can be both unique and highly transparent.
Resistance to Chemicals
Acrylic is resistant to most chemicals found in aqueous solutions in the lab and most household cleaning chemicals, such as alkalis, detergents, and diluted inorganic acids.
The benefits of using CNC machining to make acrylic
CNC machining is highly effective for cutting and shaping acrylic and other plastic materials. Using a CNC system allows for precise control over the cutting process, resulting in a smooth finish and high accuracy.
One of the significant benefits of using CNC machining to cut acrylic is the ability to achieve a razor-sharp edge. This is especially important when working with acrylic, as it is a versatile material that can be used in various applications, including as a replacement for glass. Diamond cutters and other cutting tools with cutting-edge rake angles can be used to cut acrylic effectively, resulting in a precise and clean cut.
In addition to achieving a clean cut, CNC machining can also form acrylic into various shapes and sizes. This is done by inputting the desired parameters into the CNC system and guiding the cutting tool to shape the acrylic according to the specified design.
To properly machine acrylic, it is important to use a vacuum table to clamp the material tight and prevent excess vibration during the cutting process. The correct feed rate and clearance angles should also ensure a smooth finish and effective chip removal. In addition, a polishing paste and UV light can help achieve an excellent surface finish on the product.
CNC machining is a great starting point for working with acrylic and other plastic materials. It is a low-cost and highly effective method for cutting and shaping these materials. It is the only way to achieve an excellent surface finish on acrylic and other plastics. Acrylic is an ideal material for various applications and is highly resistant to shock and other types of damage, and CNC machining is the best way to work with it.
Choose extrusion acrylic material to make CNC machining
Acrylic fabricators can benefit from using extrusion acrylic material in their CNC machining process because it enhances the fabrication of their materials. Typically, this step occurs before the bonding or lamination phases.
Extrusion acrylic is widely used in manufacturing, particularly for fabricating pipes, tubes, and sheets. There are two types of acrylic extrusion: profile extrusion and sheet extrusion. Both methods can be used to achieve the desired outcome.
Considerations for CNC machining acrylic parts
Temperature
When the surface temperature of an acrylic material approaches its melting point, acrylic melting occurs. To avoid the meltdown of your acrylic, consider the following:
- Raise the bit size in use.
Larger cutter sizes appear to perform better at clearing away plastic chips when cutting acrylic. They can create clean cuts before the friction causes the material to melt. Any acrylic can be worked with, beginning with a 0.25-inch bit. Or you might just go with the biggest option if it meets the specs. - Cut at a steady rate.
The fluctuating rate usually causes the workpiece to melt at random intervals. Raising the IPM ensures that the cutter is not in touch for any longer than is required, preventing this issue. Move rapidly but steadily so that you don’t lose your bearings. - Keep the acrylic cool.
You can prevent acrylic from rebonding after cutting by placing it in the freezer for a few minutes, and it will reduce the initial temperature. To further lower the temperature, spray the plastic and the blade with a cool mister.
- Use a higher feed rate.
Once again, increasing the feed rate will allow you to work at a greater RPM while still making quick work of the plastic. Maintaining a steady temperature for acrylic components is also beneficial.
Take care of the surface.
Using the following guidelines, your acrylic CNC cutting project will look great.
- Secure your material
Clamps, wise, or whatever else is necessary, keep the acrylic polymer sheet firmly planted on the workbench. Due to its brittle nature, machining acrylic requires extra care to prevent workpiece vibration. When used excessively, the cutting quality and, more specifically, the surface finish may severely degrade. - Use the right bits and ramps.
The correct drill bit is essential when milling acrylic, and carbide is highly recommended. In addition, several factories use an O-flute cutter made of solid carbide that is 1/4 inch in diameter and is optimized for use with acrylic. Looking for alternatives that are designed for acrylic cutting is also an option.
Sharpen the pieces, as dull ones won’t be able to produce smooth enough edges. Dull tools easily damage acrylic, and if your cutters aren’t up to snuff, you’ll likely see several flaws in the finished products. Use a ramp in addition to your bit, as this is another helpful piece of advice. It dramatically lessens the likelihood that a drill bit would crack the acrylic. To achieve the best possible result, use a smooth slope of 1 to 3 inches in height.
- Use the correct revolutions per minute (RPM)
Feed rates must be correlated with speed rates, and the settings will vary greatly depending on the type of acrylic you use. A higher feed rate is typically needed when increasing the RPM of a mill to prevent the material from melting due to the increased friction impact. - Set the pass depth at the correct inch
The depth at which you cut is also crucial, and it should be around half a bit’s diameter for most materials. However, a pass depth of 0.0625 inches may be necessary for some materials like acrylic to achieve the best results. Again, it could take multiple tries to get it right. - Cut direction is important.
It’s not easy to advocate for chopping anticlockwise. On the contrary, it is commonly accepted that going in a clockwise manner yields the best results. It’s important to remember to select them with the cutter’s rotational orientation in mind. - Don’t forget the ramp feature.
Using a ramp is highly recommended when dealing with CNC acrylic. The ramp ensures that the bit enters your material at precisely the right angle and won’t fall in a straight line. You will achieve your goals if you choose a smooth ramp between 1 and 3 inches in height.
Conclusion
CNC machining acrylic parts is a precise and complex process that requires the right tools and techniques to achieve the desired results. Acrylic, also known as extruded acrylic, is a versatile plastic material prized for its optical clarity and resistance to stress cracking. Following the guidelines, manufacturers can successfully produce complex shapes and achieve great surface finish using a CNC router and specialized cutting tools. Overall, CNC machining acrylic parts is a cost-effective way to make precise and complex shapes with high precision and minimal waste.
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