Core and Cavity for Injection Molding
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PMMA (Acrylic) Injection Molding Service
Crystal-clear PMMA molded parts, ready in as fast as 5 days. Enjoy expert guidance, precise manufacturing, and versatile finish options to bring your vision to life—all at competitive prices.
PMMA in Injection Molding
PMMA (Poly-Methyl Methacrylate), commonly known as acrylic, is a versatile thermoplastic widely used in injection molding for its exceptional optical clarity, impact resistance, and UV stability. This material is favored for applications requiring transparent or translucent parts where aesthetics and durability are critical.
PMMA offers several advantages. Its high transparency, with a light transmission of approximately 92%, makes it an ideal choice for optical applications such as lenses, light covers, and display screens. The material’s ability to maintain clarity over time and its UV resistance ensures longevity in outdoor and high-visibility settings.
Manufacturing PMMA parts via injection molding involves heating the material to its melting point of around 130°C and injecting it into a precision mold under high pressure. This process allows for intricate detailing and consistent quality production of complex geometries. PMMA’s low shrinkage rate, typically between 0.2% and 1%, minimizes dimensional variations in molded parts, ensuring tight tolerances and precise fit.
Design considerations play a crucial role in optimizing PMMA injection molding. Engineers and designers must consider factors like wall thickness uniformity to prevent warping or sink marks, especially in thicker sections. Mold temperature control is critical to achieving uniform part cooling and minimizing internal stresses that could affect optical clarity.
| Price: | $ | Available PMMA at RapidDirect: | PMMA Black, PMMA Transparent, PMMA White. |
|---|---|
| Lead Time: | < 5 days |
| Wall Thickness: | 1mm |
| Tolerances: | ISO2768-C |
| Max Part Size: | 300 mm x 300 mm x 300 mm |
Plastic PMMA Properties
| Properties | Value |
|---|---|
| Technical name | Poly-Methyl Methacrylate |
| Chemical name | (C5H8O2)n |
| Melting Point | 130°C |
| Specific Gravity | 1.18 |
| Shrink rate | 0.2 – 1% |
| Tensile strength | 65 MPa |
| Flexural strength | 90 MPa |
| Visible light Transmission | 92% |
| Standard Injection Mold Temperature | 130°C |
Pros and Cons of PMMA Injection Molding
PMMA plastic offers many benefits that make it suitable for injection molding. However, there are some of its downsides to consider before choosing it for any project.
Pros
- Excellent optical clarity for transparent parts.
- UV resistance makes it suitable for outdoor applications.
- Versatile design options due to moldability.
- Lightweight compared to glass counterparts.
Cons
- Susceptible to scratching and requires careful handling.
- Limited impact resistance compared to some engineering plastics.
- Higher cost compared to some commodity plastics.
- Not suitable for high-temperature applications exceeding its melting point
Applications of PMMA Injection Molded Parts
Injection molded PMMA parts are widely used across various industries, including:
- Automotive: Headlamp lenses, interior trim components.
- Electronics: Display screens, light guides.
- Medical: Laboratory equipment, medical device housings.
- Consumer Goods: Transparent housings, cosmetic packaging.
FAQs
PMMA’s high transparency, excellent UV resistance, and ability to maintain optical clarity make it ideal for injection molding applications requiring clear and aesthetically pleasing parts. Its relatively low shrinkage rate and good dimensional stability contribute to the precise molding of complex geometries.
Designers must prioritize stress concentrations, optimize wall thicknesses to prevent warping and sink marks and ensure uniform cooling for consistent part quality. Attention to gate design and location is crucial to control flow and minimize visible marks on the finished part.
Achieving optimal surface finish and optical clarity in PMMA parts involves meticulous mold polishing and releases to prevent surface defects. Controlling processing parameters such as mold temperature and injection speed helps minimize internal stresses affecting transparency.
Challenges include managing PMMA’s tendency to undergo thermal degradation at high temperatures, which can affect part quality. Controlling mold temperature and injection parameters is critical to preventing surface defects like bubbles or flow marks. Additionally, PMMA’s susceptibility to stress cracking and scratching requires careful handling throughout molding and post-processing operations.
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