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Today we are going to look at the manufacturing processes of acrylic polymer or optical prototyping. It is one of the most widespread plastics all over the world and a prominent competitor to glass and polycarbonate. Due to the fact that acrylic parts are used in a lot of industry areas, it seems a good idea to look into its manufacturing processes, specifically CNC acrylic machining since that is the process that is present in almost any kind of acrylic production.
In this article, we will discuss all you need to know about acrylic CNC cutting, its applications, and the relevant tips you need.
Many manufacturers can trust CNC machining when it comes to cutting acrylic because of the precision it offers. This CNC (computer numerical control) machining is an automated process that uses specialized tools to cut and shape different materials into usable parts and products.
In addition to precision, acrylic machining with CNC tools also offers other benefits, which include:
There are some complex 3D geometries you can only achieve with CNC machining because of its multi-axis machining parts. Designers can use CAD/CAM software to simulate these complex geometries to ensure precision and accuracy before machining.
CNC machining allows for high adaptability in acrylic fabrication. Whether producing prototypes, custom designs, or low-volume parts, the process can accommodate various project requirements with minimal setup changes. Additionally, manufacturers can quickly switch between different part designs, reducing lead times and improving efficiency.
Unlike other cutting methods, CNC machining produces a superior surface finish. The automated process reduces the chipping/cracking of the acrylic which in turn, results in a high-quality surface fit for further processing.
if you’re looking to produce small acrylic components within a reasonable time, you can trust CNC machining to help you get the job done. Unlike manual methods, this automated process ensures greater efficiency and productivity in the manufacturing process.
Acrylic, popularly known as PMMA (Polymethyl Methacrylate), is a common material for plastic CNC machining. It is lightweight and has an aesthetically pleasing look and sheen that makes it a preferred choice in many industries.
Beyond this aesthetics, there are several other material properties it possesses that are relevant to CNC machining and they include:
UV Resistance: PMMA typically resists UV rays and light degradation, making it excellent for outdoor use without the fear of discoloration and wear.
Durability: Acrylic has a tensile strength of up to 10,000 PSI and is suitable for medium-impact and moderate-stress applications.
Transparency: They are ideal for use in signages and other areas where visual clarity is important because they have a light transmission of up to 92%.
Easy Joining: you can join acrylic parts together with a simple solvent-based glue and form a solid bond immediately.
Chemical Resistance: Although it can be damaged by some strong solvents, PMMA is largely resistant to acids, alkaline, and many other chemicals.
Typically, acrylic blanks are manufactured using two methods: extrusion and casting. The first method is used to manufacture sheets, while the other is used to manufacture sheets and any other kind of form. Acrylic thickness from using both methods usually varies from 1.5 to 25 mm.
Such a variety of thicknesses makes acrylic a good choice for cutting out flat emblems and signs. Let’s see which kind of blanks have better properties for CNC acrylic cutting.
Extrusion consists of melting large volumes of acrylic pellets in a special tank and extruding the resulting liquid through a specifically formed whole – an extrusion nozzle. Casting acrylic is similar to casting any other material. The pellets are melted and poured into a casting form, which is later cooled down and extracted.
Extruded and Cast blanks behave differently under a cutting tool. Extruded acrylic has more leftover tensions so it is more susceptible to cracks and overall more brittle. That’s why machining it is a disaster. In addition, extruding makes its properties anisotropic, so you are basically machining different materials along the X and Y axes.
If you want to use acrylic CNC machining for your manufacturing process, pick only cast blanks. Extruded ones are not worth the effort.
When it comes to acrylic machining, there are different operations. This is to ensure that produce CNC acrylic parts that would fit the desired use.
This CNC machining operation is similar to cutting, however, it uses multi-dimensional rotating cutting tools to ensure a smooth finish. These tools rotate and cut off parts of the material till they form a desired three-dimensional workpiece.
When it comes to manufacturing intricate parts and designs for specific industries that require tight tolerances, this machining process is the way to go. Some of those industries include aerospace, medical, automotive, etc.
Many of the cylindrical and rod-like acrylic tools you see today have gone through this process. With the use of a lathe, the machine rotates the material and holds it in place while it feeds a cutting tool into its middle.
The most common uses of the resulting products include consumer electronics, lighting fixtures, architectural elements, etc. As long as you need a PMMA part of a high-quality, smooth finish, you can get such results through CNC turning acrylic.
With CNC drilling, you can create holes in the PMMA material while maintaining its quality. The specialized drills create clean holes of different sizes with accurate dimensions that can fit into desired spaces.
The trick to getting the perfect hole size is to adjust the speed and feed rate of the drill at all times. This method is common for creating CNC acrylic parts that will fit into other devices or be assembled into a final product.
Engraving is a variation of the acrylic machining process. The engraving of acrylic is done in the same way as milling but with a different cutting tool. It is a very widespread method since a lot of acrylic parts serve for advertisement or aesthetic purposes. Modern CNC systems have enabled the engraving of the most complex designs on a plastic sheet. The resulting groove can then be filled with some paint in order to make the design more visible.
Once you’ve fixed acrylic into place, it’s time to cut to the chase, so to speak. The majority of acrylic blanks are milled. The actual machining of acrylic on a CNC router is in many ways similar to machining polycarbonate. First of all, use a similar RPM: 15,000-18,000 RPM. Then, use a stable and considerably aggressive feed rate. That is required to prevent the tool from staying in the same place too much and generating heat with the friction that comes from the cutting. If the feed rate is too small, the chips will start welding back onto the part and you will ruin the valuable surface finish and precision.
Special cutting tools are a must. You need to buy special acrylic cutting bits because they have flutes that ensure optimal chip removal and consequently, precision. In addition, when drilling acrylic, the drill tip angle must be much smaller than that of a standard drill. Instead of 120 degrees, it should be 60. That is also modified for better chip removal. Oh, and don’t worry if you haven’t achieved a perfect optical clear surface after machining, It’s impossible. In order to get a completely transparent part, you’ll have to employ some more effort with finishing operations.
In any kind of CNC acrylic cutting process, keeping the temperature to a minimum is a must. That is why a lot of acrylic sheets are cooled down before machining. It makes for better chip removal and a lower starting temperature. Apart from that, you can use some standard coolants, however, if they have oils, make sure those don’t react with PMMA.
Having achieved the desired precision and form of the acrylic parts, it is always necessary to grind and polish the parts. That is usually done by consecutively applying polishing tools with a smaller grit and a linen towel with polishing paste at last. Apart from that, there are some chemical polishing methods that involve pouring special gas to melt the outer layer of acrylic. Last but not least is the exotic diamond tool single-tip milling process, when a tiny amount of plastic is cut from the surface by a very sharp and durable single-tip mill.
After the CNC acrylic machining process, some parts undergo further touches and finishing to improve their appearance and functionality. The ideal finish for each part is largely dependent on its use and design.
Some of the common finishes for CNC acrylic parts include:
This finish is perfect for removing imperfections and smoothing the surface of acrylic parts. It is ideal for achieving a specific texture and refining the surface of the acrylic material without necessarily removing excess material.
With this process, you can create your desired finish. There are different grit levels of sandpaper you can use to achieve diverse degrees of smoothness; from coarse scratches to fine polishes, it’s all up to you.
To achieve this finish, you would have to dip the acrylic part in a specialized chemical solution that would dissolve and smooth out the surface. It is a perfect alternative to heated polishing methods and it also enhances the final gloss and clarity.
This finish is most effective for delicate parts where mechanical polishing would prove difficult. Chemical polishing minimizes stress concentration, creates a uniform surface, and improves the overall appearance of the acrylic.
As the name implies, this finish involves applying a layer of protective coating or painting to the surface of the acrylic part. This finish helps improve UV resistance and also hardens the surface of the finished product.
The coating can also improve the scratch resistance, chemical resistance, and anti-static resistance of the final acrylic piece. Additionally, a clear coat can add more gloss and improve the lifespan of the painted surface.
To achieve this finish, you have to shoot fine beads onto the material surface at a high velocity. The beads do not cause any damage to the surface, rather, they create a consistent finish that covers up blemishes and marks.
Bead blasting adequately hides minor surface defects and creates a good base for subsequent painting. It creates a matte finish; adding extra texture to the surface area, thereby reducing glare and improving grip.
With the advent of technology like plastic CNC machining, we can now apply acrylic and other poly-based materials in our daily activities. You can spot CNC machined acrylic parts in:
Thanks to CNC machining of acrylic, interior trim pieces like control knobs and dashboard parts are all products of CNC machining. To ensure a high-quality finish, manufacturers also produce custom lighting assemblies like headlight casings through this process.
Many of the transparent closures for medical equipment are products of Acrylic CNC machining. They provide a sterile, protective barrier that allows clinicians to enjoy visibility as they work.
Beyond illumination, CNC machining acrylic helps with the manufacturing of complex, custom light fixtures and reflectors that improve ambiance. These acrylic parts can easily integrate with other components and wiring, ensuring a clean look. Many interior designers rely on CNC machining fir bespoke lighting fixtures and decorative pendants.
Thanks to acrylic CNC machining there are now several high-resolution signages with intricate designs and logos. Brands can now create impactful visual displays that captivate their audience with acrylic. This process has also birthed interactive product demos and custom displays to enhance marketing and increase customer engagement.
| Acrylic Machining | 3D Printing | Injection Molding |
| Medium cost; depends on production volume | Low cost for products and medium/high cost for production | High setup cost, low production cost |
| Can only use acrylic material | Wide range of materials including plastic, metals, etc | Can only use thermoplastics |
| Has an excellent glossy finish | The finish varies depending on the post-production process | Has a consistent and smooth finish |
| Perfect for displays, signages, lenses, tubes, light fixtures, etc | Perfect for prototypes, custom parts, and low-volume production | Perfect for mass production, consumer goods, automotive parts, etc |
| Easy to modify the design | Easy to modify the design | Difficult and expensive to modify the design |
| Requires minimal tools and simple fixtures | No need for tools; manufacturing is done digitally | Requires expensive tools |
Dawopu as a professional prototype manufacturer takes pride in creating clear acrylic optical components in the plastic machining industry with 3-axis, 4-axis, or even 5-axis CNC machines. To advance the development of ultra-precision manufacturing, we have adopted the latest diamond machining technology. This technique called SPDM or SPDT can match the ability of 5-axis micro-milling to produce a range of lens and light guide types of excellent optical quality in an array or freeform pattern.
In the future, We will continue to improve our CNC machining services and upgrade machining equipment and cutting tools in order to maintain the highest quality machined clear plastic parts in the industry. To do this, we aim to provide the best service for customers who need to machine all kinds of optical components in any complicated shape as required.
Contact:Mr Liu
Mobile:15869109368
Tel:86-571-89967020
E-mail:info@dawopu.com
Address:No151 ,ZiDingXiang Rd, Hangzhou. Zhejiang Province, China