Acrylic, also known as plexiglass or polymethyl methacrylate (PMMA), It is commonly used in various applications due to its versatility, transparency, and durability, transparent plastics suitable for manufacturing parts via CNC machining. Acrylic is known for its glass-like appearance but is lighter and less prone to breakage than actual glass.
Polycarbonate is a type of thermoplastic polymer widely used in various industries due to its remarkable strength, impact resistance, and optical clarity.Among the five major engineering plastics, polycarbonate has the best overall performance.
While acrylic and polycarbonate are similar in many respects, there are some important differences between these two common materials that can make one better suited for a particular application over the other, or impact the machining process and thus lead time and cost. In this article, we’ll go over what you need to know about machining acrylic and polycarbonate so that you can select the best manufacturing option for your project and create designs that work with the material you choose.
Machining Acrylic And Polycarbonate: What You Need To Know
1.Machining Acrylic Notes
Machining acrylic involves using various tools and techniques to cut, shape, and finish acrylic sheets or blocks.Here are some common methods used for machining acrylic:
- Cutting: Acrylic can be cut using several tools such as a table saw, circular saw, jigsaw, or laser cutter. When using saws, it’s important to use a fine-toothed blade designed for cutting plastics to minimize chipping and ensure a clean cut. Laser cutting provides precise and intricate cuts with minimal material waste.
- Drilling: Acrylic can be drilled using standard drill bits, preferably those designed for plastics or metals. It’s essential to use low drill speeds and apply gentle pressure to prevent cracking or melting of the acrylic. It’s also recommended to back the acrylic with a sacrificial piece of wood to prevent chip-out on the exit side.
- Routing and Milling: Acrylic can be shaped and profiled using a router or milling machine with appropriate cutting bits. Carbide or diamond-tipped router bits work well for acrylic machining. It’s important to use proper speeds, feeds, and depth of cut to prevent overheating or melting of the material.
- Sanding and Polishing: Acrylic can be sanded and polished to achieve a smooth and glossy finish. Start with a coarser grit sandpaper (around 220 or 320) and gradually work your way up to finer grits (400, 600, 800, or higher) for a smoother finish. To achieve a polished look, use a polishing compound or a plastic polishing kit specifically designed for acrylic.
- Heat Bending: Acrylic can be easily heat-bent to create curved or angled shapes. This involves heating the acrylic until it becomes pliable and then carefully bending it into the desired shape using jigs or molds. Proper temperature control is crucial to avoid overheating or scorching the material.
- When machining acrylic, it’s important to take safety precautions such as wearing eye protection, a dust mask, and appropriate personal protective equipment. Acrylic can produce sharp edges and fine plastic dust particles, so proper ventilation and dust collection systems are recommended.
Additionally, it’s a good practice to test any machining techniques on a scrap piece of acrylic before working on the final piece to ensure desired results.
2.Machining Polycarbonate Notes
Machining polycarbonate, a durable and transparent thermoplastic, requires specific techniques to achieve accurate cuts and smooth finishes. Here are some common methods used for machining polycarbonate:
- Cutting: Polycarbonate can be cut using tools such as a table saw, circular saw, jigsaw, or laser cutter. To minimize chipping and achieve clean cuts, it’s important to use a fine-toothed blade specifically designed for cutting plastics. Laser cutting is also a precise method for cutting polycarbonate.
- Drilling: Polycarbonate can be drilled using standard drill bits designed for plastics or metals. It’s crucial to use a slow drill speed and moderate pressure to prevent melting or cracking of the material. Backing the polycarbonate with a sacrificial piece of wood or using a clamp can help prevent chip-out on the exit side.
- Routing and Milling: Polycarbonate can be shaped and profiled using a router or milling machine with appropriate cutting bits. Carbide or diamond-tipped router bits designed for plastics work well for machining polycarbonate. Similar to drilling, using proper speeds, feeds, and depth of cut is important to avoid overheating or melting.
- Sanding and Polishing: Polycarbonate can be sanded and polished to achieve a smooth finish. Start with a coarser grit sandpaper (around 220 or 320) and gradually move to finer grits (400, 600, 800, or higher) for a smoother surface. Polishing compounds specifically made for plastics can be used to achieve a polished look.
- Heat Bending: Polycarbonate can be heat-bent to create curved or angled shapes. It requires careful heating of the material until it becomes pliable and then bending it into the desired shape using jigs or molds. Proper temperature control is crucial to avoid overheating or warping.
Similar to machining acrylic, safety precautions should be taken when machining polycarbonate. Wear appropriate protective equipment such as safety glasses, a dust mask, and gloves. Adequate ventilation and dust collection systems are recommended to minimize exposure to fine plastic particles. Testing machining techniques on scrap polycarbonate before working on the final piece is advisable.
It’s worth noting that polycarbonate has a lower melting point compared to acrylic, so special care should be taken to prevent overheating and melting during machining operations.
Applications For Acrylic And Polycarbonate
Acrylic and polycarbonate are versatile materials with various applications across different industries. Here are some common applications for acrylic and polycarbonate:
1.Applications For Acrylic
- Signage and Displays: Acrylic is widely used for creating signs, point-of-sale displays, and exhibition stands due to its transparency, durability, and ease of fabrication. It can be easily laser cut, engraved, or thermoformed into various shapes.
- Windows and Skylights: Acrylic sheets are used as a lightweight alternative to glass for windows, skylights, and domes. Acrylic offers high optical clarity, UV resistance, and impact resistance, making it suitable for both interior and exterior applications.
- Automotive: Acrylic is used in automotive applications such as headlight lenses, interior trim, instrument panels, and rear windows. Its lightweight nature and high impact resistance make it an ideal choice for automotive components.
- Retail Displays and Fixtures: Acrylic is commonly used in retail environments for product displays, shelving, cosmetic stands, and point-of-purchase displays. Its clarity and ability to be molded into different shapes make it suitable for showcasing products.
- Aquariums and Fish Tanks: Acrylic is often used to construct aquariums and fish tanks due to its excellent transparency, impact resistance, and ability to be molded into curved shapes without seams. It provides a clear view of aquatic life and is less prone to breakage compared to glass.
1.Applications For Polycarbonate
- Safety Glazing: Polycarbonate is widely used in safety glazing applications such as protective shields, security windows, machine guards, and riot shields. It offers exceptional impact resistance, making it highly suitable for environments requiring high levels of protection.
- Greenhouses: Polycarbonate sheets are commonly used in greenhouse construction due to their excellent light transmission properties and durability. They provide insulation, UV protection, and impact resistance while allowing sunlight to pass through for plant growth.
- Electrical and Electronic Components: Polycarbonate is used for manufacturing electrical enclosures, circuit boards, connectors, and other electronic components. Its electrical insulation properties, flame resistance, and dimensional stability make it a preferred material for these applications.
- Bulletproof Windows and Safety Equipment: Polycarbonate’s exceptional impact resistance and toughness make it suitable for bulletproof windows, riot gear, face shields, and safety helmets. It can withstand high-energy impacts while providing optical clarity.
- Sports Equipment: Polycarbonate is used in the production of sports equipment such as helmets, face shields, goggles, and protective gear. Its lightweight nature, impact resistance, and optical clarity are beneficial in ensuring athlete safety.
These are just a few examples of the wide range of applications for acrylic and polycarbonate. Both materials offer unique properties that make them valuable in various industries where transparency, impact resistance, and durability are required.
The Pros And Cons of Acrylic Machining Parts
Using acrylic for parts offers several advantages and disadvantages. Let’s explore the pros and cons of using acrylic:
1.The Pros of Using Acrylic
- Transparency: Acrylic has excellent optical clarity, allowing for high transparency similar to glass. This makes it suitable for applications where visibility is important, such as display cases or windows.
- Lightweight: Acrylic is a lightweight material, weighing about half as much as glass of the same thickness. This makes it easier to handle and reduces the weight load in applications where weight is a concern.
- Impact Resistance: Acrylic is more impact-resistant than glass, making it less likely to shatter or break. It can withstand accidental impacts, making it suitable for applications where safety is a priority.
- Versatility: Acrylic is highly versatile and can be easily molded, cut, drilled, or shaped into various forms. It can be thermoformed or laser cut to create complex shapes, making it suitable for custom designs.
- Weather Resistance: Acrylic has good weather resistance and can withstand exposure to UV radiation without significant yellowing or degradation. It is often used in outdoor applications such as signage or architectural elements.
2.The Cons of Using Acrylic
- Scratches: Acrylic is more prone to scratching compared to glass. Care must be taken during handling, cleaning, and maintenance to avoid scratches that can affect its appearance.
- Chemical Sensitivity: Acrylic is sensitive to certain chemicals, such as solvents or cleaners containing alcohol. These substances can cause the material to crack, craze, or cloud, so it’s important to use compatible cleaning agents.
- Lower Heat Resistance: Acrylic has a lower heat resistance compared to materials like glass or polycarbonate. It begins to soften and deform at relatively low temperatures, making it unsuitable for high-temperature applications.
- Limited Impact Strength: While acrylic is impact-resistant, it is not as strong as materials like polycarbonate. It may crack or chip under severe impact, so it may not be suitable for applications requiring extremely high impact resistance.
- Flammability: Acrylic is flammable and can melt or burn when exposed to high heat or flames. Special care should be taken to avoid exposing acrylic parts to open flames or high-temperature environments.
It’s important to consider these pros and cons of using acrylic to determine if it is the right material for your specific application. Factors such as visibility requirements, impact resistance, weight considerations, and environmental conditions should be taken into account when selecting a material for your parts.Your product’s intended use will also determine whether acrylic is the best option for your project. For example, acrylic’s extreme biocompatibility makes it a good option for bone implants, dentures, or other skin-contact applications; similarly, its resistance to weather, UV radiation, and scratching make it a good fit for parts which will be used outdoors. On the other hand, acrylic might not be the best choice for food containers that will be exposed to high temperature environments, such as dishwashers or microwaves, since acrylic parts will only maintain their dimensions up to 149°F (65°C), at which point they begin to soften.
The Pros And Cons of Polycarbonate Machining Parts
Using polycarbonate for parts offers several advantages and disadvantages. Let’s explore the pros and cons of using polycarbonate:
1.The Pros of Using Polycarbonate
- Impact Resistance: Polycarbonate is extremely impact-resistant, making it highly durable and able to withstand strong impacts without breaking or shattering. It is about 200 times stronger than glass of the same thickness, making it suitable for applications requiring high impact resistance.
- Transparency: Polycarbonate has good optical clarity, similar to acrylic. It offers excellent light transmission, making it suitable for applications where visibility is important, such as windows, safety glasses, or protective shields.
- Lightweight: Polycarbonate is a lightweight material, approximately half the weight of glass. This makes it easier to handle and reduces the overall weight of parts or products where weight is a concern.
- UV Resistance: Polycarbonate has inherent UV resistance properties, which allows it to withstand prolonged exposure to sunlight without significant degradation or yellowing. This makes it suitable for outdoor applications that require long-term UV protection.
- Temperature Resistance: Polycarbonate has a high heat resistance and can withstand temperatures up to around 250 degrees Celsius (482 degrees Fahrenheit). It retains its properties in high-temperature environments, making it suitable for applications that involve heat or thermal stress.
2.The Cons of Using Polycarbonate
- Scratch Sensitivity: Polycarbonate is more susceptible to scratching compared to materials like glass. While it is coated with scratch-resistant coatings, it can still be prone to fine scratches. Proper care must be taken during handling and maintenance to avoid scratches that can affect its appearance.
- Lower Chemical Resistance: Polycarbonate is sensitive to some chemicals and solvents, which can cause it to craze, crack, or degrade. Certain cleaning agents or chemicals should be avoided to prevent damage to polycarbonate parts.
- Higher Cost: Polycarbonate tends to be more expensive than materials like acrylic or glass. The higher cost can be a limiting factor when considering it for large-scale or cost-sensitive projects.
- Flammability: Polycarbonate is flammable and can melt or burn when exposed to high heat or flames. Flame-retardant grades are available, but special precautions should be taken to prevent exposure to open flames or high-temperature environments.
- Yellowing Over Time: While polycarbonate has good UV resistance, it can still experience some yellowing or discoloration over time when exposed to prolonged UV radiation. This may affect its appearance and transparency in long-term outdoor applications.
Considering these pros and cons of using polycarbonate will help you determine if it is the right material for your specific application. Factors such as impact resistance, transparency requirements, temperature resistance, cost considerations, and potential chemical exposure should be taken into account when selecting a material for your parts.
The Surface Treatment Options For Acrylic And Polycarbonate
Both acrylic and polycarbonate offer various finishing options to enhance their appearance and functionality. Here are some common finishing options for acrylic and polycarbonate:
1.Finishing Options for Acrylic
- Polishing: Acrylic can be polished to achieve a smooth and glossy surface. This can be done using polishing compounds specifically designed for plastics. Polishing removes any scratches or imperfections, resulting in a clear and polished finish.
- Flame Polishing: Flame polishing is a technique where the surface of acrylic is heated using a controlled flame. The heat causes the surface to melt and smooth out, resulting in a glossy finish. This method is often used for small areas or edges of acrylic parts.
- Sanding: Acrylic can be sanded to remove imperfections or create a matte finish. Starting with a coarser grit sandpaper and gradually moving to finer grits can achieve the desired smoothness. Wet sanding with water can help prevent heat buildup and melting.
- Painting: Acrylic can be painted using acrylic or plastic-specific paints. This allows for customization and the addition of color to the acrylic surface. Proper surface preparation, such as cleaning and priming, is necessary for optimal paint adhesion.
- UV Coating: Applying a UV protective coating to acrylic helps prevent yellowing or degradation caused by prolonged exposure to UV radiation. UV coatings provide additional protection and help maintain the transparency and appearance of the acrylic.
2.Finishing Options for Polycarbonate
- Polishing: Similar to acrylic, polycarbonate can be polished to achieve a smooth and glossy surface. Polishing compounds and techniques designed for plastics can be used to remove scratches and imperfections.
- Flame Polishing: Flame polishing can also be used for polycarbonate, similar to acrylic. Care must be taken to control the heat and avoid overheating, as excessive heat can cause melting or deformation of the polycarbonate surface.
- Sanding: Polycarbonate can be sanded to remove imperfections or create a matte finish. As with acrylic, starting with a coarser grit sandpaper and gradually progressing to finer grits helps achieve a smooth surface.
- Hard Coating: Applying a hard coating to polycarbonate improves its scratch resistance and durability. Hard coatings can enhance the surface hardness and provide additional protection against scratches, chemicals, and UV radiation.
- Anti-Static Coating: Polycarbonate parts can be coated with an anti-static coating to reduce dust attraction and improve cleanliness. Anti-static coatings help prevent the accumulation of dust particles on the surface.
When selecting a finishing option, it’s essential to consider the specific requirements of your application and the desired appearance or functionality. Additionally, it’s advisable to test the chosen finishing option on a small area or scrap piece to ensure compatibility and desired results before applying it to the final part.With sufficient care during the cutting process, machined surfaces of acrylic and polycarbonate parts will typically be translucent, but can become nearly opaque if the material melts. Should melting occur, it may be possible to address surface opacity with post-processing options such as vapor polishing. However, it’s worth noting that as-machined finishes for acrylic and polycarbonate parts will not be optically clear, although it may be possible to achieve optical clarity if diamond tooling is used, but this must be specifically requested during the quoting process, as it will significantly add to cost.
Machining Parameter Comparison Chart Table For acrylic and polycarbonate
Here’s a comparison chart table outlining some common machining parameters for acrylic and polycarbonate:
| Machining Parameters | Acrylic | Polycarbonate |
|---|---|---|
| Cutting Speed | 3,000-6,000 SFM (Surface Feet per Minute) | 1,000-4,000 SFM |
| Feed Rate | 0.003-0.006 inches per tooth | 0.002-0.004 inches per tooth |
| Depth of Cut | 0.005-0.010 inches | 0.005-0.015 inches |
| Tool Material | Carbide or High-Speed Steel | Carbide or High-Speed Steel |
| Coolant | Coolant is not required, but compressed air can be used for chip removal | Coolant is not required, but compressed air can be used for chip removal |
| Tool Geometry | Sharp cutting edges with high rake angles | Sharp cutting edges with high rake angles |
| Machine RPM | 10,000-20,000 RPM | 8,000-15,000 RPM |
| Clamping/Workholding | Use clamps or vacuum tables to secure the material | Use clamps or vacuum tables to secure the material |
These parameters are general guidelines and may vary depending on the specific machine, tooling, and the desired results. It’s important to refer to the manufacturer’s recommendations and perform test cuts on scrap material to optimize the parameters for your specific setup. Additionally, always follow proper safety practices and use appropriate protective equipment when machining acrylic or polycarbonate.
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Are you looking for a acrylic and polycarbonate CNC machine shop that guarantees precision, efficiency, and quality? Numerous CNC machining plastic materials may be compatible with your part’s design and intended application, and choosing the right one can be a complicated process. Fortunately, a manufacturing partner like Be-Cu Prototype can reduce that complexity and address the challenges certain materials present. At Be-Cu Prototype, we combine cutting-edge technology with expertise to deliver unparalleled CNC machining services. Contact us today to bring your manufacturing vision to life.