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Views: 0 Author: Site Editor Publish Time: 2025-08-01 Origin: Site
Table of Contents
| 1.Introduction |
| 2.Acrylic Material Properties |
| 3. Injection Molding Process Parameters |
| 4. Key Considerations in Acrylic Injection Mold Design |
| 5. Advantages and Disadvantages of Acrylic |
| 6. Applications of Acrylic Material |
| 7. Conclusion |
Acrylic, also known as polymethyl methacrylate (PMMA), is a thermoplastic polymer renowned for its excellent optical clarity and outstanding processability. With high transparency, strong weather resistance, and aesthetic surface quality, acrylic is widely used in automotive, optical, home appliance, and electronics industries. In the field of Acrylic Injection Molding, the material not only offers enhanced design flexibility but also poses higher demands on mold design and process control.
Acrylic features high rigidity and excellent dimensional stability at room temperature. It has good tensile and flexural strength, making it suitable for injection molded parts requiring structural integrity. However, due to its relatively low impact strength and inherent brittleness, mold designs should avoid sharp corners and stress concentrators to minimize cracking risks. Proper cavity pressure control and optimized cooling speed during the acrylic molding process can help reduce internal stress and improve mechanical performance.
Acrylic has a heat deflection temperature ranging from 95℃to 115℃, making it suitable for moderate-temperature applications. Its glass transition temperature (Tg) is around 105℃, allowing it to tolerate short-term heat loads without deformation. During injection molding pmma, the recommended melt temperature is between 200℃and 250℃, and mold temperature should be controlled between 40℃and 80℃. Note that acrylic has low thermal conductivity, so cooling is relatively slow. A well-designed cooling system is crucial to shorten the molding cycle.
Acrylic is one of the most transparent thermoplastics, with a light transmittance rate up to 92%, even surpassing standard glass. Its exceptional optical performance makes it ideal for lamp covers, optical lenses, display panels, and light guides. Surface polishing can achieve a mirror-like finish, but the mold must be polished to an extremely high standard. To maintain high transparency during the acrylic plastic injection process, material drying, temperature control, and injection speed must be strictly managed to prevent silver streaks, bubbles, and other visual defects.
Acrylic shows strong resistance to most polar chemicals (e.g., diluted acids, alkalis, and alcohols) but is sensitive to certain non-polar solvents such as acetone and benzene, which can cause stress cracking or swelling. In product design, avoid direct contact with incompatible solvents. During molding and post-processing, use clean-release agents and avoid oil-based chemicals. Long-term exposure of acrylic parts to organic solvents during storage or assembly should also be avoided.
Features | Parameters |
Molecular Formula | (C5O2H8)n |
Density | 1.15 – 1.19 g/cm³ |
Melting Point | 150℃ |
Light Transmittance | 92% |
Tensile Strength | 50-77MPa |
Glass Transition Temperature | 105℃ |
Acrylic offers excellent optical performance and high rigidity, but it is also highly sensitive to molding conditions. Even slight deviations can lead to surface defects, high internal stress, or reduced transparency. Therefore, precise control of acrylic injection molding parameters is crucial for ensuring product quality.
Acrylic is extremely moisture-sensitive. Excess moisture in the resin can lead to defects such as silver streaks, bubbles, and reduced clarity during heating. Proper drying before processing is essential.
● Drying Temperature: 80℃to 90℃
● Drying Time: 2 to 4 hours (adjust based on pellet size and humidity)
For high optical quality parts, a desiccant dryer is recommended to maintain consistent drying, especially for injection molding pmma products.
Although acrylic has a broad processing temperature window, excessive temperatures can cause degradation, odor, or discoloration, while insufficient temperatures may lead to poor flow or rough surfaces.
● Melt Temperature: 200℃to 250℃
● Optimal Range: 220℃to 240℃
The barrel heating zones should be set with a gradual temperature increase to avoid localized overheating. Residence time in the barrel should be minimized to reduce thermal degradation — a key consideration in pmma injection molding temperature control.
Mold temperature greatly influences surface gloss, shrinkage, and internal stress in acrylic parts.
● Recommended Mold Temperature: 50℃to 80℃
● For high-transparency optical parts, maintain mold temperature above 70℃
If mold temperature is too low, surface fogging and weld lines may occur. Higher mold temperatures promote better polymer chain flow, improving surface finish and dimensional precision in acrylic molding process applications.
Acrylic has high viscosity and moderate flowability, requiring sufficient injection pressure and appropriate injection speed to achieve complete mold filling while minimizing air entrapment.
● Injection Pressure: 80 to 120 MPa
● Injection Speed: Medium to high; avoid overly fast injection to prevent burn marks and silver streaks
A well-designed venting system at the gate and runner is essential to release trapped air and avoid bubbles or voids during acrylic injection molding.
Holding pressure ensures the part is compact and dimensionally stable by compensating for material shrinkage.
● Holding Pressure: Slightly lower than injection pressure, with stable transition
● Holding Time: Typically 5 to 15 seconds depending on part thickness and geometry Cooling time directly affects demolding efficiency and final shrinkage. Acrylic cools slowly due to low thermal conductivity, requiring extended cooling within the mold.
● Cooling Time: Usually 20 to 40 seconds; longer for thick-walled parts
During pmma injection molding, optimizing cooling channel layout improves efficiency and shortens the cycle time.
In the Acrylic Injection Molding process, mold design plays a critical role in determining the final product's transparency, dimensional stability, and surface quality. Given acrylic's high rigidity, low toughness, moisture sensitivity, and low thermal conductivity, mold development must be approached with precision in structure, material selection, and manufacturing process. The following are key technical elements to consider during acrylic mold design:
Acrylic components are often used in aesthetic or optical applications, requiring excellent surface finish. Therefore, mold steel must offer high polishability, corrosion resistance, and dimensional stability. Common choices include:
● S136 Stainless Steel:Excellent corrosion resistance and superior polishing ability, ideal for high-transparency products
● 420 Steel:High hardness and good machinability, suitable for molds requiring frequent maintenance
● NAK80 Pre-hardened Mirror Steel: No need for heat treatment, good polishability, suitable for medium-precision transparent parts
Recommended steel hardness: HRC 45–50 to balance wear resistance and polishability — essential for high-end injection molding pmma molds.
Acrylic parts often require mirror-grade surface finishes (above #12000). Poor polishing can lead to hazing, flow lines, or optical distortion. Use non-contaminating polishing materials such as diamond paste and micro-abrasives to avoid residue.
Avoid stress concentrators in the mold design, such as sharp corners, deep ribs, and abrupt wall thickness changes. Design sufficient draft angles (≥1°) in all demolding areas to prevent scratches, whitening, or cracking during part ejection. For products with high optical or assembly precision, reserve micro-tolerance allowance for post-polishing adjustment.
Gate design in acrylic plastic injection molds is vital to minimizing surface defects, stress concentrations, and flow marks. Recommended gate types include:
● Pin Gate:Suitable for small, precise transparent parts; leaves minimal gate marks
● Submarine Gate: Hidden on non-visible areas, enables automatic separation, ideal for mid-sized parts
● Film Gate: Best for large flat parts; ensures even flow distribution and reduces warpage
Avoid placing gates on optical or high-appearance surfaces. For large parts, consider multi-gate or ring-gate configurations to ensure uniform filling and pressure balance — a best practice in injection molding pmma workflows.
In Acrylic Injection Molding, proper venting and temperature control are essential for achieving high product quality, particularly in optical or transparent applications. Due to acrylic’s relatively high melt viscosity and moderate flowability, the injection process is prone to gas entrapment, which can result in defects such as bubbles, burn marks, or short shots. To mitigate these issues, vents must be carefully designed. The recommended vent depth is between 0.01 mm and 0.02 mm, with a width of 1.5 mm to 2 mm. This allows trapped gases to escape quickly without risking material leakage. For complex or closed cavities, micro-vacuum venting systems may be incorporated to further enhance mold filling efficiency and surface integrity.
Temperature control is equally critical, as it directly influences the optical clarity, gloss, and internal stress distribution of acrylic parts. If the mold temperature is too low, common defects such as haze, weld lines, or dull surfaces can occur. On the other hand, excessively high mold temperatures may lead to shrinkage, deformation, or difficulty in demolding. For standard applications, a mold temperature range of 60°C to 80°C is typically sufficient. However, for optical-grade components, the mold temperature can be increased to around 85°C to enhance surface quality and transparency.
The cooling system within the mold should be evenly distributed and symmetrically arranged, ensuring that all critical areas are adequately covered. It is best practice to use high-efficiency cooling channels combined with precise temperature control devices such as mold temperature controllers. This not only stabilizes the pmma injection molding temperature but also contributes to shorter cycle times and reduced internal stress, especially in high-volume production settings.A robust venting and thermal control design is a key enabler for producing consistent, defect-free acrylic parts, particularly when tight tolerances and high surface standards are required.
Acrylic, commonly referred to as “organic glass” or “plexiglass,” is a versatile thermoplastic known for its balanced performance and exceptional transparency. Due to its excellent optical clarity and processability, acrylic is widely used in Acrylic Injection Molding, especially for applications that demand high surface aesthetics and light transmittance. Below is a brief analysis of the major pros and cons of acrylic from the perspective of injection molding engineers and procurement teams.
Acrylic offers extremely high optical clarity, with a light transmittance rate of up to 92%, outperforming glass and other plastics. This makes it the preferred material for optical components, lamp covers, and light guides. Acrylic parts molded via acrylic plastic injection have high surface gloss and can be polished to a mirror-like finish, making them suitable for display-grade applications.
Acrylic exhibits strong rigidity and stable dimensions at room temperature. It does not deform easily, allowing for high-precision molding of structural parts such as instrument panels, display housings, and protective covers in injection molding pmma applications.
Compared to materials like PC and PS, acrylic has better resistance to sunlight and ultraviolet radiation. It does not yellow or degrade easily when used outdoors, making it ideal for automotive lighting, solar panels, outdoor signage, and other exterior-use products.
Acrylic is compatible with various manufacturing methods such as injection molding, extrusion, thermoforming, and bonding. Its surface can also be treated with coating, screen printing, and metallization. These capabilities offer excellent flexibility for functional and decorative applications. In Acrylic Injection Molding, its ease of molding enhances design freedom and part customization.
Despite its rigidity, acrylic is relatively brittle compared to materials like PC or ABS. It has poor impact resistance and is prone to cracking or breakage. Mold and product designs must avoid sharp edges and stress points. Structural reinforcements or co-injection techniques may be used to improve toughness in critical parts.
Acrylic requires precise control of processing parameters such as moisture content, melt temperature, mold temperature, and injection speed. Improper settings can easily lead to defects like bubbles, silver streaks, and high internal stress, which affect both the transparency and mechanical properties of the final product. This makes pmma injection molding temperature control particularly important in quality assurance.
Although its surface hardness is higher than many plastics, acrylic can still be scratched easily during transportation, assembly, or daily use. For exposed surfaces, protective coatings or films may be necessary to maintain aesthetics.
Acrylic is sensitive to certain organic solvents, such as acetone, toluene, and gasoline. Contact with these chemicals can cause stress cracking or swelling. In product design and user instructions, it is important to warn against prolonged exposure to incompatible substances.
Thanks to its exceptional optical clarity, weather resistance, and stable processability, acrylic has found wide application across various industries. Through Acrylic Injection Molding, complex structures and high-gloss surfaces can be achieved in a single molding cycle, fulfilling both aesthetic and functional requirements. This makes acrylic particularly suitable for mid- to high-end transparent and visual parts. The following are typical application areas of acrylic molded components:
In the automotive sector, acrylic is widely used for front and rear lamp covers, tail lights, and turn signal lenses that demand high light transmission. Compared to traditional glass, acrylic offers lighter weight and greater impact resistance. Using injection molding pmma methods, complex curved surfaces can be precisely reproduced, enhancing both safety and appearance. Acrylic is also used in dashboard protection panels and ambient light diffusers due to its UV resistance and long-term weatherability. For automotive lighting applications, molds often require mirror-grade polishing and precision venting systems to ensure optical performance.
Acrylic is an ideal material for manufacturing optical components such as reading magnifiers, camera lens covers, LED light guides, and diffuser sheets in LCD displays. Its 92% light transmittance and excellent optical uniformity make it a superior alternative to glass in many acrylic molding process applications. To maintain optical quality during production, molds must be made from high-grade steel and polished to mirror finish. At the same time, strict control of material drying, mold temperature, and injection parameters is essential for eliminating visual defects.
In household and consumer products, acrylic’s high gloss, clarity, and weather resistance make it ideal for items like soap boxes, tumblers, decorative lamp covers, photo frame panels, and upscale sanitary products (e.g., faucet faceplates, bathtub trim). The Acrylic Injection Molding process allows for the creation of intricate curves and smooth surfaces, enhancing design freedom. Its excellent post-processing compatibility also enables secondary treatments like spraying, electroplating, and screen printing, increasing the product’s perceived value.
In the electronics industry, acrylic is often used for LED lamp housings, transparent casings for digital displays, speaker covers, and dust shields. Its dimensional stability and precision moldability support detailed and functional component design. Acrylic’s transparency allows users to clearly observe internal components or light effects. For these applications, mold design must balance structure, appearance, and mold durability. Incorporating high-quality steel and hot runner systems can significantly enhance efficiency and product consistency — best practices in injection molding pmma scenarios.
With its excellent optical properties, mechanical strength, and processability, acrylic has become the material of choice for transparent and decorative plastic components across various industries. However, producing high-quality acrylic injection molded parts requires strict control over every aspect of the process — from material drying and melt temperature management to mold polishing and gate design.
In Acrylic Injection Molding, every detail matters. Properly managing the pmma injection molding temperature, ensuring uniform mold heating, and maintaining ideal injection speeds are crucial to achieving bubble-free, high-transparency parts. Furthermore, selecting the right mold steel, applying precision surface treatments, and optimizing the cooling and venting systems can significantly improve part quality and reduce production costs.
If you are looking for a reliable partner to develop acrylic injection molded products or to customize precision molds, we sincerely invite you to connect with us. As a professional injection mold manufacturer with 23 years of industry experience, we specialize in delivering high-quality, high-efficiency tooling solutions and molding services. Our goal is to help you bring your product to market faster and ensure stable mass production.
Contact us today — we look forward to collaborating with you for mutual success.
