The Injection Molding Process of Acrylic is Briefly Introduced

Update:28-09-2019
Summary:

Established in 1988, Jiaxing Mirror Acrylic Technology […]

Established in 1988, Jiaxing Mirror Acrylic Technology Co., Ltd is a collection of large acrylic (PMMA) panels and custom acrylic aquarium into a professional company.

Acrylic products have a wide range of uses, so today we will take a brief look at the injection molding process of acrylic:

1. Treatment of plastics

PMMA has a certain degree of water absorption, which reaches 0.3-0.4%, while injection molding must have a humidity below 0.1%, usually 0.04%. The presence of water causes bubbles, air streaks, and reduced transparency in the melt. Therefore, drying treatment is required. The drying temperature is 80-90 DEG C, and the time is more than 3 hours.

Recycled materials can be used 100% in some cases, and the actual quantity depends on the quality requirements, usually over 30%. Recycled materials should avoid pollution, otherwise transparency and the properties of finished products will be affected.

2. Selection of Injection Molding Machines

PMMA has no special requirements for injection molding machines. Because of its high melt viscosity, it needs a deeper spiral groove and a larger diameter nozzle hole. If the strength of the product is required to be high, low-temperature plasticization shall be carried out with screws with larger length-diameter ratio. In addition, PMMA must be stored in a drying hopper.

3. Melting temperature

Measured by air-to-air injection method: from 210℃ to 270℃, depending on the information provided by the supplier.

Withdraw the backseat, make the injection machine nozzle leave the main runner bushing, and then manually perform plasticizing injection molding, which is the empty injection molding.

4. Injection temperature

Fast injection is available, but to avoid high internal stress, multi-stage injection, such as slow-fast-slow, etc., should be used. Slow injection is used for thick parts.

5. Residence time

If the temperature is 260℃, the residence time should not exceed 10 minutes at most, and if the temperature is 270℃, the residence time should not exceed 8 minutes.

If you want to know more about acrylic, you can click here: https://www.jmacrylic.com/