Tag Archive for: PMMA injection moulding

PMMA injection molding

Polymethyl Methacrylate (PMMA) Plastics Material

PMMA plastics is commonly known as polymethyl methacrylate, acrylic and so on and its chemical name is polymethyl methacrylate. PMMA plastic material has some defects such as low surface hardness, easy to snag, low impact resistance, poor molding liquidity performance.

So PMMA’s modification appears one after another such as copolymerization between methyl methacrylate and styrene and butadiene, a blend of PMMA and PC, etc. 372 PMMA is the copolymer of methyl methacrylate and styrene. If you add a small amount of nitrile rubber (about 50%) in the 372 PMMA, it will become 373 PMMA.PMMA injection molding parts

The fluidity of PMMA plastics is poorer than that of PS, ABS and its melt viscosity is rather sensitive to the change of temperature. In molding, it changes the melt viscosity mainly from the injection molding temperature. PMMA is an amorphous polymer, the melt temperature is above 160 Celsius degree and the decomposition temperature can reach 270 Celsius degree.

  1. Processing of plastic
    PMMA has a certain degree of water absorption of 0.3-0.4%. The injection molding moisture must be less than 0.1%. Typically, it is 0.04%. The presence of moisture makes the melt bubbles, gas lines, and low transparency.
    So it should be dried. Dying temperature is 80-90 Celsius degree and drying time is 3 hours or above. In some cases, the utilization of recycled materials can reach 100%. The actual quantity depends on the requirements for quality. Usually, it can reach 30%, you should make sure there is no pollution of recycled materials, or it will influence the transparency and the nature of the finished products.
  2. Selection of injection molding machine
    The PMMA material doesn’t have special requirements for the injection molding machine. Due to the great melt viscosity, it requires the grooves deeper and nozzle hole a larger diameter. If you need higher strength requirements of products, you should use a larger aspect ratio of the screw to implement low-temperature plastics. In addition, PMMA must use drying hopper to store material.
  3. Design of plastic mold and gate location
    PMMA’s Mold temperature can be 60 -80 Celsius degree, The diameter of the sprue should match up with the internal taper. The optimum angle is 5 to 7, if the products of injecting molding are 4mm or more, the angle should be 7, the diameter of the mainstream channel is 8 to 10 mm, the overall length of the gate should not exceed 50 mm.

For the products with wall thickness less than 4mm, the diameter of the flow channel (runner) should be 6-8mm. For the wall thickness is more than 4mm, the diameter of the runner should be 8-12mm. Depth of runner, fan-shaped and tabs-shaped gate should be 0.7 to 0.9 (it is the wall thickness of product), the diameter of pin gate should be 0.8 to 2mm;

The product with lower viscosity should choose the smaller size. The common venting hole’s depth is 0.05 to 0.07mm, width is 6mm, the stripping slope 30′-1, cavity portions are between 35′-1 and 30.

  1. Melt temperature
    You can use the air injection method to measure temperature ranging from 210-270 Celsius degree, which depends on the information provided by the supplier.
  2. Injection temperature
    You can use rapid injection to avoid generating a high degree of internal stress. It’s suitable to use multi-level injection, such as slow – fast – slow, etc.. When injecting the thick parts, you should use the slow speed.
  3. Dwell time
    If the temperature is 260 Celsius degree, the dwell time is within 10 minutes. If the temperature is 270 Celsius degree, the dwell time is within 8 minutes.

Sincere Tech has special injection molding machines for PMMA plastic injection molding service, each year we produce millions of PMMA plastic molding parts for our customers. If you are looking for a PMMA injection molding service or any other customer molding service, welcome to send us an email.

PMMA injection molding

Injection Molding Technology of Polymethyl Methacrylate (PMMA)

PMMA is commonly known as polymethyl methacrylate, acrylic and so on and its chemical name is polymethyl methacrylate. PMMA has some defects such as low surface hardness, easy to snag, low impact resistance, poor molding liquidity performance, so PMMA’s modification appears one after another such as copolymerization between methyl methacrylate and styrene and butadiene, a blend of PMMA and PC, etc. 372 PMMA is the copolymer of methyl methacrylate and styrene. If you add a small amount of nitrile rubber (about 50%) in the 372 PMMA, it will become 373 PMMA.PMMA injection molding parts

The fluidity of PMMA is poorer than that of PS, ABS and its melt viscosity is rather sensitive to the change of temperature. In molding, it changes the melt viscosity mainly from the injection temperature. PMMA is an amorphous polymer, the melt temperature is above 160 Celsius degree and the decomposition temperature can reach 270 Celsius degree.

  1. Processing of plastic
    PMMA has a certain degree of water absorption of 0.3-0.4%. The injection molding moisture must be less than 0.1%. Typically, it is 0.04%. The presence of moisture makes the melt bubbles, gas lines, and low transparency. So it should be dried. Dying temperature is 80-90 Celsius degree and drying time is 3 hours or above. In some cases, the utilization of recycled materials can reach 100%. The actual quantity depends on the requirements for quality. Usually, it can reach 30%, you should make sure there is no pollution of recycled materials, or it will influence the transparency and the nature of the finished products.
  2. Selection of injection molding machine
    The PMMA material doesn’t have special requirements for the injection molding machine. Due to the great melt viscosity, it requires the grooves deeper and nozzle hole a larger diameter. If you need higher strength requirements of products, you should use a larger aspect ratio of the screw to implement low-temperature plastics. In addition, PMMA must use drying hopper to store material.
  3. Design of mold and gate
    Mold temperature can be 60 -80 Celsius degree, The diameter of the sprue should match up with the internal taper. The optimum angle is 5 to 7, if the products of injecting molding are 4mm or more, the angle should be 7, the diameter of the mainstream channel is 8 to 10 mm, the overall length of the gate should not exceed 50 mm.

For the products with wall thickness less than 4mm, the diameter of the flow channel should be 6-8mm. For the wall thickness is more than 4mm, the diameter of the flow channel should be 8-12mm. Depth of gon, fan-shaped and tabs-shaped gate should be 0.7 to 0.9t(t is the wall thickness of product), the diameter of pin gate should be 0.8to 2mm; The product with lower viscosity should choose the smaller size. The common venting hole’s depth is 0.05 to 0.07mm, width is 6mm, the stripping slope 30′-1, cavity portions are between 35′-1 and 30.

  1. Melt temperature
    You can use the air injection method to measure temperature ranging from 210-270 Celsius degree, which depends on the information provided by the supplier.
  2. Injection temperature
    You can use rapid injection to avoid generating a high degree of internal stress. It’s suitable to use multi-level injection, such as slow – fast – slow, etc. When injecting the thick parts, you should use the slow speed.
  3. Dwell time
    If the temperature is 260 Celsius degree, the dwell time is within 10 minutes. If the temperature is 270 Celsius degree, the dwell time is within 8 minutes.

Sincere Tech has special injection molding machines for PMMA injection molding service, each year we produce millions of PMMA plastic molding parts for our customers. If you are looking for a PMMA injection molding service or any other customer molding service, welcome to send us an email.

PMMA injection molding

What Is PMMA Injection Molding?

Polymethyl methacrylate (PMMA) injection molding is a process where organic glass/acrylic is injected into a cavity to form a particular product upon cooling and hardening. The molds produced by PMMA injection molding are used to make car windows, aquariums, and screens for mobile phones. Acrylic is preferred to glass because it has better abrasion resistance.

Applications of PMMA Injection Molding

Undoubtedly, a higher percentage of the plastic/glass products that we use in our daily lives are manufactured using polymethyl methacrylate. Acrylic injection molding is used to produce the following items:
1. Eyeglass lenses
2. Plexiglass windows
3. Fashion accessories such as bracelets
4. Mobile phone casings
5. Computer and electronics casings
6. Vehicle windshields
7. Lamps holders
Below are a few of Acrylic injection molding parts we made before, if you have any project that needs PMMA molding products, welcome to send us your data, we will offer you the best quality with our expert experience of PMMA molding service

Advantages of PMMA Injection Molding (acrylic molding)

1. It Produces Scratch-Resistant Products
Research has confirmed that acrylic molding materials are more scratch-resistant than other glass products. In this manner, the molding process generates products that can maintain their lustrous appearances for long without degradation.
2. It Produces Light Products
Acrylic has a density of 1.185 grams per cubic centimeters. On the other hand, glass has a density of 2.4 grams per cubic centimeters. As a result, PMMA plastic molding produces products that can be used as lightweight alternatives to glass.
3. PMMA Injection Molding Can Produce Complex Designs
The injection molding develops advanced shapes that cannot be generated by other injection molding processes such as metal injection molding. Furthermore, the PMMA injection molding process can reproduce a significant number of products that are identical in terms of shape, size, and weight.
4. High Production Efficiency
The PMMA injection molding process is faster than metal injection molding. As a result, more production units can be produced through this process in a given time. Technical analyses have confirmed that PMMA injection molding plants have shorter cycle times, which increase the overall production output of the industry.
5. Enhancement of Color Flexibility
Acrylic plastic injection molding produces items that can be mixed with resins to create a wide variety of colored products. In contrast, this feature is not present in other processes such as metal/glass injection molding.

6, Speical material for high requirement of transparent plastic molding.

PMMA material called Acrylic, or Plexiglass, Transmittance is up to 92%, is high then the glass, that means Acrylic molding is one of the best options for high requirement transparent injection molding parts, such as glass, Optical glass, lens, car lights, transparent pipes, etcPMMA plastic molding
Disadvantages of Acrylic plastic Injection Molding
1. The materials produced have a lower resistance to impact compared to those produced by metal injection molding.
2. The heat resistance of most products produced by the PMMA injection process is low (About 80 Degrees Celsius).
3. Most items produced by the process have lower mechanical strengths, which limit their loading capacities.
4. Some acrylic products have poor chemical resistance, which makes them prone to react with organic compounds.
Conclusion
Given the above points, it is essential to understand how the PMMA injection molding works, its applications, advantages, and, disadvantages. Also, knowledge is vital at helping you appreciate the PMMA injection molding process.
If you want to see more transparent plastic molding parts please go to our transparent plastic molding page, if you have any project that needs PMMA injection molding or any other custom mold and molding parts, you are welcome to send us an email, we will offer you the best option solution.
SINCERE TECH have been made millions of PMMA injection molding parts, to make PMMA plastic molding parts is not easy, you always will meet the problem from time to time, but with our professional rich experience, any issue will be solved in no time.