Key Difference Between Acrylic Machining And Polycarbonate Machining

Acrylic and polycarbonate machining offer the flexibility to create custom parts and products with unique properties. Understanding the characteristics of each plastic material and employing appropriate machining techniques are essential for achieving high-quality and precise results. Here are some guides to help you find the right material between polycarbonate and acrylic.

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Overview of Acrylic Sheet And Polycarbonate Sheet

Acrylic and polycarbonate sheets are durable and versatile materials with unique properties. Acrylic sheet is known for its clarity and ease of machining, while polycarbonate sheet excels in impact resistance and flexibility. Here we won’t talk more about it. You can find the difference of acrylic sheets and polycarbonate sheets in our previous blog. In this blog, we will focus on the difference of machining of acrylic sheet and polycarbonate sheet. While you choose the two materials, it depends on specific application requirements and desired characteristics.

Key Fabrication And Finishing Methods

Acrylic and polycarbonate offer distinct advantages in fabrication and finishing.

From cutting to drilling, acrylic’s precision and clarity complement polycarbonate’s durability and impact resistance.

When it comes to finishing, acrylic shines with its polished edge, while polycarbonate stands strong with its resilience to sanding.

Both materials embrace painting and UV coating for customization and protection.

In the realm of fabrication and finishing, acrylic and polycarbonate showcase their unique properties, inviting creativity and innovation in plastic applications.
Here we provide a very comprehensive comparison between acrylic and polycarbonate across key fabrication and finishing methods. Let me dive into each section with some additional insights:

Acrylic CNC Cutting Vs. Polycarbonate CNC Cutting

Material Properties:

Optical Clarity: Both materials are known for their excellent optical clarity, with acrylic having a visible light transmittance of up to 92% . Polycarbonate also offers high transparency but slightly lower than acrylic at around 90%, and it can block UV radiation .
Toughness and Durability: Polycarbonate is highly resistant to impact, making it more durable compared to acrylic, which can chip or crack during the machining process .
Cost: Acrylic is generally less expensive than polycarbonate, making it a more cost-effective option for many applications.

Machining Parameters:

Cutting Speed and Feed Rate: acrylic recommended cutting speed ranges from 3,000 to 6,000 SFM while polycarbonate requires a slower cutting speed range of 1,000 to 4,000 SFM with similar feed rates.
Additionally, setting appropriate speed and feed rates is vital to prevent overheating and melting.
Tool Selection: Sharp tools with aggressive rake angles are essential for both materials to limit friction and prevent melting. The use of diamond cutters can improve surface finish but at a higher cost. Carbide and PCD cutters are ideal for both acrylic and polycarbonate. It is essential to use sharp tools for CNC acrylic to prevent heat buildup during machining, as this material has a lower melting point.

Acrylic Laser Cutting Vs. Polycarbonate Laser Cutting

Acrylic laser cutting usually produces precise and high-quality cuts with minimal kerf width and excellent edge finish.

Acrylic is transparent to CO2 laser wavelengths, making it well-suited for cutting with CO2 lasers. The material’s clarity allows for intricate details and fine cutting lines.

CO2 lasers offer high precision and can produce intricate designs with smooth, polished edges.

Polycarbonate laser cutting can also achieve clean cuts with proper settings but may require additional finishing to remove any melted edges or burrs. The material’s toughness may result in a slightly different edge finish compared to acrylic.

Is it safe to laser-cut polycarbonate?

Laser cutting polycarbonate can be safe if done correctly, but polycarbonate is a thermoplastic material that can release potentially harmful fumes when heated.

It’s essential to use a well-ventilated area and appropriate safety equipment, such as a fume extractor, to minimize exposure to any smoke or gases produced during the cutting process.

Additionally, the laser settings must be properly adjusted to avoid damaging the material. Too high a power setting can cause excessive melting or burning, while too low a setting may not cut through the material effectively.

Challenges Of Laser Cutting Polycarbonate

Heat Sensitivity: Polycarbonate is sensitive to heat, and excessive heat generated during laser cutting can cause the material to melt, burn, or develop rough edges.
Thermal Stress: Laser cutting generates heat that can create thermal stress in polycarbonate, leading to warping or distortion of the material.
Difficulty Achieving Clean Edge: Achieving clean and smooth edges in polycarbonate laser cutting can be challenging due to the material’s toughness and tendency to melt.
Material Thickness: Thicker polycarbonate sheets may pose challenges in laser cutting, as deeper cuts require higher power levels. Adjusting the cutting parameters and optimizing the cutting speed for different thicknesses is essential to ensure consistent and quality cuts across varying material thicknesses.
Residue and Fumes: Laser cutting of polycarbonate can produce fumes and residue that may be harmful if not properly ventilated.
Complex Geometries: Cutting intricate designs and complex geometries in polycarbonate using a laser can be challenging due to the material’s thermal properties and tendency to melt or deform.
Effects Of Additives And Coatings: Polycarbonate sheets with additives and coatings come with more challenges. When the material is heated these additives and coatings produce additional toxic gases and bi-products.

The Best Way To Cut Polycarbonate

The most effective methods for cutting polycarbonate vary based on factors like thickness and precision requirements. Here are some of the best options:

CNC Knife Cutter
CNC Router
Table Saw
Jigsaw
Score and Snap Method
Waterjet Cutting

These methods have been found to be effective, offering high precision and fewer difficulties.

Screen Printing On Acrylic Vs. Polycarbonate

Acrylic Sheet Printing:

Clarity and Transparency: Acrylic is known for its optical clarity and transparency, which can enhance the visual appeal of screen-printed designs. The smooth surface of acrylic allows for sharp and vibrant prints, making it ideal for applications where color accuracy and visibility are important.
Scratch Resistance: Acrylic sheets are relatively scratch-resistant, which helps maintain the integrity of screen-printed designs over time.
Finishing Options: After screen printing, acrylic sheets can be further finished with processes like polishing, coating, or engraving to achieve specific effects or enhance the visual appeal of the printed designs.

Polycarbonate Sheet Printing:

Material Flexibility: Polycarbonate sheets offer higher impact resistance and flexibility compared to acrylic. The material’s flexibility may require additional considerations in terms of ink adhesion and curing to ensure long-lasting printed designs.
UV Resistance: Polycarbonate is known for its UV resistance, making it suitable for outdoor applications where printed designs may be exposed to sunlight. UV-resistant inks may be preferred for screen printing on polycarbonate sheets to maintain the colorfastness of the prints.
Toughness: The toughness of polycarbonate can make it more challenging to achieve fine details or intricate designs in screen printing.
Post-Printing Considerations: Polycarbonate sheets require additional curing time or heat treatment after screen printing to ensure proper ink adhesion and durability.

Digital Printing On Acrylic Vs. Polycarbonate

While surface and ink adhesion are similar when digital printing on acrylic and polycarbonate sheets, the key difference lies in the requirement for UV stability, especially when using UV lighting for drying the printed surface.

Polycarbonate sheets with UV coating provide added protection and durability for digital prints, ensuring long-lasting and vibrant designs in outdoor settings.

Before digital printing on acrylic sheets, it is essential to verify the UV stability of the material to maintain the quality and longevity of the printed designs.

Drilling Acrylic Vs. Polycarbonate

Acrylic sheets are more brittle and prone to cracking and chipping during drilling, while polycarbonate sheets are tougher and less likely to crack or chip.

It is advised to use moderate drilling speed and light pressure to prevent cracking, starting with a small pilot hole and gradually increasing the drill size.

Cooling the drilling area with water or compressed air is essential to avoid melting and deformation. Properly securing the acrylic sheet minimizes vibration and movement.

Polycarbonate also requires cooling during drilling to prevent heat build-up, but it is less prone to melting compared to acrylic.

Acrylic Thermoforming Vs. Polycarbonate Thermoforming

Thermoforming is a production method in which plastic sheets are heated to become flexible, then shaped using a mold, and finally trimmed to produce functional items.

Thermoforming mainly has 2 different processes: Vacuum Forming and Pressure Forming.

Vacuum forming heats a sheet to a pliable state and then pressed against a 3D mold by vacuuming out the air between the sheet and the mold.

On the other hand, pressure forming also involves heating a plastic sheet until it becomes flexible, but in addition to vacuuming out the air between the sheet and the mold, and mold as well as applying air pressure to the outside of the sheet to help shape it.

Vacuum forming has clearly sharper details and needs for undercuts. It also has tighter tolerances and molded-in textures. Pressure forming is good for complex shapes.

Thermoforming Of Polycarbonate

Freedom to develop complex shapes and forms
Cost/performance characteristics superior to traditional methods
Low-cost tooling
Ability to produce large parts
Reduced lead times

Thermoforming Of Acrylic

Protect from impact, elements, ultraviolet radiation and corrosion to all types of OEM equipment.
Customizable shapes and designs through aluminum tooling
Flexible ordering options
Short lead times

The Differences Between The Thermoforming Processes Of Polycarbonate And Acrylic

Softening Temperature:
– Polycarbonate softens above 147 °C (297 °F) and flows above 155 °C (311 °F).
– Acrylic softens at higher temperatures but does not melt until it reaches 160 °C (320 °F).
Outgassing Characteristics:
– Polycarbonate has a high outgassing rate and moisture absorption, which can cause issues during forming if not dried properly.
– Acrylic also has a high outgassing rate and moisture affinity but requires prolonged pre-drying at lower temperatures to prevent bubble formation.

Applications Of Thermoforming Two Materials

– Common applications for thermoformed polycarbonate include boat windows, shatterproof glass, and electronic displays.
– Thermoformed acrylic is used for signs, retail displays, skylights, and aquarium tanks.

Acrylic Bending Vs. Polycarbonate Bending

Polycarbonate sheets can be bent or deformed both hot and cold. Polycarbonate is very strong, so it doesn’t break easily if you bend the material cold. Of course, this also depends on the thickness and dimensions of the panel.

Tips For Bending Polycarbonate With A Convection Oven:

Never heat the polycarbonate sheet on a rack, but on a flat, heat-resistant tray.

Place the tray with the sheet on it in the oven during preheating and allow it to heat up gradually.

When the set temperature has been reached (180 ° C to 210 ° C), leave the sheet for four to five minutes. Thinner sheet thicknesses of up to 5mm will be ready to bend more quickly.

Fix the polycarbonate in the desired shape until it cools. The sheet will now remain in the desired bend without springing back.

Tips For Bending Acrylic:

1. Use a Heat Source: Acrylic sheets can be bent using heat. A heat gun, strip heater, or oven can be used to heat the acrylic along the bend line. It is essential to heat the acrylic evenly to avoid warping or uneven bending.

2. Temperature Control: Monitor the temperature of the acrylic sheet during heating. The ideal temperature for bending acrylic is typically around 300 to 350 degrees Fahrenheit (150 to 180 degrees Celsius). Avoid overheating, as it can lead to bubbling or discoloration.

3. Forming Jig or Mold: To achieve a precise bend angle, use a forming jig or mold to guide the bending process. The acrylic sheet should be positioned over the mold while it is still pliable from the heating process.

4. Bend Slowly and Evenly: Apply pressure gradually and evenly along the bend line to achieve a smooth and uniform bend. Avoid applying excessive force, as it can cause the acrylic to crack or deform.

5. Cooling Process: After bending the acrylic sheet to the desired angle, allow it to cool and set in position before removing it from the forming jig. Cooling the acrylic gradually helps stabilize the bend and prevent it from springing back.

Acrylic Polishing Vs. Polycarbonate Polishing

Acrylic Polishing

Purpose: Acrylic polishing aims to restore clarity, remove scratches, and achieve a high shine.
Methods:
– Rough Polish: Start with a rough polish using coarse grit sandpaper or a polishing agent like Zvizzer Heavy Cut .
– Fine Luster Polish: Follow with a fine luster polish to smooth out any remaining imperfections .
– Hand Polishing: Use hand polishing techniques to achieve a crystal-clear edge .
– Polishing Pastes: Products such as VuPlex are recommended for their effectiveness in removing scratches and enhancing transparency.
Techniques:
– Cloth Wheel Polishing: This method involves using a cloth wheel to apply polishing compounds evenly across the surface .
– Acrylic Diamond Polishing Machine: These machines provide clear edges, transparency, and a clean finish .

Polycarbonate Polishing

Purpose: Polycarbonate polishing is used to improve clarity, remove scratches, and restore the material’s shine.
Methods:
– Machine Polishing: For deep scratches, machine polishing is the best option. Start with standard sandpaper or sanding wool, then use a coarse grain such as Zvizzer Heavy Cut .
– Vapor Polishing: This method uses special chemical vapor to flow over the surface and enhance the finish .
– Hand Polishing: Lightly buff the sheet with loose abrasive on a buffing machine, avoiding holding the workpiece in one place to prevent damage .

Key Differences

– Clarity and Shine: Both materials can be polished to restore clarity and achieve a high shine, but acrylic is generally easier to polish to a high level of transparency .
– Scratch Removal: Acrylic polishing often involves multiple steps (rough, fine, hand) to fully restore its appearance, while polycarbonate may require more aggressive methods like machine polishing for deep scratches .
– Flexibility: Polycarbonate is more flexible than acrylic and can be bent cold, which might affect the polishing process differently .

The key difference between acrylic machining and polycarbonate machining lies in the material properties of each thermoplastic. Acrylic, known for its optical clarity and brittleness, requires careful machining to avoid chipping and cracking. On the other hand, polycarbonate, prized for its toughness and impact resistance, is more forgiving during machining but may require specialized cutting tools for optimal results.
Understanding the differences is essential for successful machining applications and ensuring high-quality finished products.

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