PMMA (Acrylic) Injection Mould

PMMA (Polymethyl Methacrylate), also known as acrylic or plexiglass, is widely used across multiple industries due to its exceptional optical clarity, lightweight nature, and resistance to UV and weathering. Injection-molded PMMA parts are common in the following applications:

1. Eyeglass Lenses

• Exceptional optical clarity

• Lightweight and scratch-resistant

• Best plastic alternative to glass for eyewear

2. Plexiglass Windows

• High transparency and impact resistance

• Used in buildings, aquariums, aircraft windows, etc.

3. Mobile Phone Casings

• Durable, scratch-resistant, and optically clear

• Easily molded into custom shapes

4. Computer and Electronics Casings

• High strength-to-weight ratio

• Offers a premium appearance with functional protection

5. Vehicle Windshields & Light Covers

• Lightweight alternative to glass

• Enhances fuel efficiency while maintaining clarity

6. LED Lenses and Lighting Components

• Used in street lights, home lighting, and car headlights

• Provides excellent light diffusion and focus

Advantages of PMMA Injection Molding

1. Scratch Resistance

• Acrylic products are more scratch-resistant than traditional glass, maintaining surface gloss longer.

2. Superior Light Transmission

• PMMA transmits up to 92% of visible light—higher than glass (91%)—with much lower density (1.185 g/cm³ vs. 2.4 g/cm³).

3. Complex Shape Capabilities

• Capable of producing intricate, high-precision designs

• Ideal for products requiring identical replication in mass production

4. High Production Efficiency

• Faster cycle times than metal molding processes

• Ideal for high-volume manufacturing

5. Color Flexibility

• Easily colored using resin additives during molding

• Enables custom transparent or opaque colored products

6. Suitable for Transparent Precision Components

• Ideal for high-transparency products such as optical lenses, medical containers, and automotive lighting.

Disadvantages of PMMA Injection Molding

While PMMA offers many benefits, it also has some limitations:

1. Lower Impact Strength

• Brittle compared to polycarbonate or metal components

2. Limited Heat Resistance

• Softening point around 80 °C, making it unsuitable for high-temperature environments

3. Lower Mechanical Strength

• Not ideal for load-bearing applications

4. Poor Chemical Resistance

• Susceptible to damage from organic solvents and harsh chemicals

5. High Initial Tooling Costs

• Requires precise, polished molds for transparent parts—less economical for low-volume runs

6. Limited Design Flexibility for Complex Geometry

• Best for simple, uniform shapes; extremely complex parts may require alternative methods

Tips for Producing High-Quality PMMA Injection Molding Parts

Creating clear, defect-free PMMA parts requires attention to material behavior and equipment setup:

1. Optimized Mold Design

• Use Moldflow analysis to determine gate location and flow balance

• Prefer side gates or fan gates to minimize flow marks

2. Special Attention for Thick-Walled Parts

• Thick parts are prone to sinks and bubbles due to shrinkage

• Long cooling times can increase cycle time and cost

Solution:
Use a hot water tank (60–80 °C) to post-treat thick parts. Submerge for 6–12 minutes immediately after demolding to relieve internal stresses and reduce sink marks and voids.

3. Equipment Requirements

• Use drying hoppers to keep material moisture below 0.04%

• Choose injection machines with higher screw L/D ratio for strength-focused applications

• Maintain mold temperature between 60–80 °C

Conclusion

PMMA injection molding offers a unique combination of transparency, lightweight design, and formability, making it ideal for optical and decorative applications. However, success depends on precise mold design, material handling, and post-processing care—especially for high-clarity or thick-walled parts.

Need Help With PMMA Injection Molding?

At SWY MOULD, we specialize in high-transparency PMMA parts. Whether you need clear enclosures, lenses, or precision covers, contact us today (shine@swymould or +86 15757668880) to discuss your requirements and receive expert support on your project.