What are the parameters of plexiglass injection molding process? What parameters of plexiglass are s

1. PMMA barrel temperature feeding area 60 80 (70).

District 1 150 200 (190).

District 2 180 220 (210).

District 3 200 250 (230).

District 4 200 250 (230).

District 5 200 250 (230).

Nozzle 200 250 (230).

The temperature in parentheses is recommended as a basic set point, the stroke utilization is 35 and 65, and the ratio of module flow length to wall thickness is 50:1 to 100:1

Melt temperature 220 250

Barrel constant temperature 170

Mold temperature 40 80

2. PMMA injection pressure.

High injection pressure is required due to poor fluidity, holding pressure 100 170MPa (1000 1700bar); For thick cross-section products, high holding pressure and long holding time are required, such as lenses (injection pressure of 40 60, 2 3min).

Back pressure Requires relatively high back pressure: 10 30 MPa (100 300 bar); Insufficient back pressure can easily cause voids or gray-black markings in the product.

Injection speed depends on cross-section thickness and flow length: thick cross-section products require extremely low injection speeds to achieve a suitable pre-flow effect; Multi-stage injection: Slow to fast speeds are recommended near the gate to obtain good surface quality.

Residual material 2 6 mm, depending on metering stroke and screw diameter.

Pre-drying absolutely needs to be dried at a temperature of 80 for 4 hours because the water absorption is up to 1

**Rate allowed, as long as the material has been properly dried and pigments added; The products produced by adding recycled materials no longer have good optical quality.

3. PMMA shrinkage.

Gate system requires a large gate size due to poor resin flow; For lenses, the gate should be smaller than the cross-sectional thickness of the outer contour of the lens; The gate diameter should be at least as large as the cross-section thickness of the part; In order to obtain a good surface quality near the gate, sharp edges between the gate and the article should be avoided; For effective pressure transfer over long distances, the gate (cross-section) should be short, round, or square; Do not use wide or thin gate cross-sections.

4. There is no need to clean the machine during downtime.

Barrel equipment Standard screw, special geometric dimensions are required for optical parts; Non-reverse ring, straight through the nozzle.

Generally, the wall thickness of PMMA in the injection grade is not a big problem.

Acrylic, also known as PMMA or plexiglass, its injection molding process is as follows.

1. Plastic treatment.

PMMA has a certain water absorption, and its water absorption rate is up to, and the injection molding must be at the following temperature, usually. The presence of moisture causes bubbles, streaks, and reduced transparency in the melt. So it is necessary to carry out a drying process. The drying temperature is 80-90 for more than 3 hours.

In some cases, the material can be used 100%, and the actual amount depends on the quality requirements, usually more than 30%, and the material should avoid contamination, otherwise it will affect the transparency and the nature of the finished product.

2. Injection molding machine selection.

PMMA has no special requirements for injection molding machines. Because of its high melt viscosity, it requires a deep groove and a larger diameter nozzle hole. If the strength of the product is required to be high, a screw with a larger aspect ratio should be used for low-temperature plasticization.

In addition, PMMA must be stored in a dry hopper.

3. Mold and gate design.

The mold temperature can be 60 -80, the diameter of the sprue should match the inner taper, the best angle is 5 ° to 7 °, if you want to inject 4mm or more products, the angle should be 7 °, the diameter of the sprue is 8 to 10mm, and the overall length of the gate should not exceed 50mm. For products with a wall thickness of less than 4mm, the runner diameter should be 6-8mm.

For products with wall thickness greater than 4mm, the diameter of the runner should be 8-12mm. The depth of the gate, fan and vertical gate should be to the thickness of the product wall), and the diameter of the needle gate should be to 2mm; Smaller sizes should be used for low viscosity. Common vents are as deep as 6 mm wide.

The demoulding slope is 30 -1°, and the cavity part is between 35 -1° and 30°.

4. Melt temperature.

It can be measured by the air injection method: ranging from 210 to 270, depending on the information provided by the ** provider.

5. Injection temperature.

Fast injection can be used, but to avoid high internal stress, it is advisable to use multi-stage injection, such as slow-fast-slow, etc., and slow speed is used when injecting thick parts.

6. Length of stay.

If the temperature is 260, the maximum stay time is 10 minutes, and if the temperature is 270, the stay time cannot exceed 8 minutes.

The temperature of the mold, the moving mold and the fixed mold is about 80 degrees, the temperature of the material tube starts from the discharge port, the injection condition is high pressure and low speed, and the pressure holding is the same, high pressure and low speed, the cooling and pressure holding time can not be too short, otherwise the plastic products will shrink, the speed of the storage screw should be slow, the back pressure is not less than 20 kg, the drying temperature is about 85 degrees, not less than 4 hours, and these conditions are almost the same.

Acrylic injection molding is generally after the raw material is hot melted, injected into a special mold, molded and cooled after demoulding, acrylic injection molding in order to meet the product requirements, you can add an appropriate amount of additives for injection molding, such as adding toner, decorations, and injecting bubbles, for example: acrylic injection molding, which is to mix specific items with hot melt materials and mold.

Polymethyl methacrylate and slag ester, commonly known as plexiglass, are polymerized by monomer and are colorless and transparent (light transmittance greater than 92) lightfast plastics. It is easy to color, the surface hardness is large, the mechanical strength is also high, and when exposed to the outdoors for a long time, the defense file will not turn yellow like other plastics, but the impact strength is insufficient. The processing of polymethyl methacrylate is mainly injection molding and extrusion, but it can also be manufactured by monomer casting molding.

It is mainly used for optical instruments, lamps, building materials, etc., and can be used instead of ordinary glass.

In terms of strength and various conditions, plexiglass is better.

Acrylic plastic needs to be 270 to be played.

1. Hardness. Hardness is one of the parameters that best reflects the production process and technology of cast acrylic sheet, and is an important part of quality control. The hardness can reflect the purity of the raw material PMMA, the weather resistance of the plate and the high temperature resistance.

The hardness directly affects whether the plate will shrink, bend and deform, and whether the surface will crack during processing. Hardness is one of the hardness indicators to judge the quality of acrylic sheets, and the average Mohs hardness value is about one.

2. Thickness (acrylic tolerance).

There is an acrylic tolerance for the thickness of acrylic sheet, so the control of acrylic tolerance is an important embodiment of quality management and production technology. The production of acrylic has an international standard ISO7823

Tolerance requirements for cast plates: tolerance = (x thickness).

Tolerance requirements for extruded plates: tolerance = < 3 mm thickness: 10 %> 3 mm thickness: 5 %.

3. Transparency and whiteness.

Strict raw material selection, advanced formula follow-up and modern production technology ensure the excellent transparency and pure whiteness of the board. Crystal clear after flame polishing.

Between 200-260, slightly lower and higher depending on your acrylic grade.

At least 200 degrees or more, the melting point of acrylic is relatively high.

Acrylic. The material can be molded by injection molding.

The process of dissolving acrylic raw materials and pouring them into the mold is called acrylic injection molding. Goodbang.

Logos are generally made of acrylic panel blister to make car logos, and the injection acrylic process is less used, because injection molding is generally small scraps.

Injection molding: Injection molding uses pellets made by suspension polymerization, and the molding is carried out on ordinary plunger or screw injection molding machines. Table 1 is polymethyl methacrylate.

Typical process conditions for injection molding.

Note: Injection molded products also need post-treatment to eliminate internal stress, and the treatment is carried out in the 70-80 hot air circulation drying oven, and the processing time depends on the thickness of the product, generally about 4h.

Advantages: Acrylic is the best new material to be able to make sanitary ware after ceramics. Compared with traditional ceramic materials, acrylic has the following advantages in addition to its unparalleled high brightness:

Good toughness, not easy to break; Strong restorativeness, as long as you dip the toothpaste with soft foam, you can wipe the sanitary ware new; The texture is soft, and there is no cold and biting feeling in winter; The colors are bright and can meet the personality pursuit of different tastes. Use acrylic to make basins, bathtubs, toilets.

Not only is it beautiful and durable, but it is also environmentally friendly, and its radiation is almost the same as that of the human body's own bones. Acrylic sanitary ware first appeared in the United States and has occupied the entire international market.

of more than 70%.

Disadvantages: Due to the difficulty and high cost of acrylic production, there are many low-quality and low-cost substitutes on the market. These substitutes, also known as "acrylic", are actually ordinary organic panels or composite panels (also known as sandwich panels).

Ordinary organic board is made of ordinary plexiglass pyrolytic material and pigment, with low surface hardness, easy to fade, and poor polishing effect after grinding with fine sand. The composite board has only a thin layer of acrylic on the surface, and ABS plastic in the middle.

It is easy to delaminate due to the influence of thermal expansion and cold contraction during use. True and false acrylic can be identified from the subtle color difference and polishing effect of the plate section.

Acrylic material is a kind of plastic material, the characteristics are high transparency, scratch resistance, easy to mold, acrylic material can be molded by injection molding, basically acrylic products are produced by injection molding.

In the injection molding process, the parameters of the injection molding machine must be checked, and in addition, it is necessary to ensure that the raw materials and the machine are normal.

There are a lot of daily dismantling products made of plexiglass, and we can see cracked dates around us, and the injection molding products of Junyi Industry are beautiful and practical, and they can also be given to relatives and friends.