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Popular science of plastic materials - UHMWPE mold processing

release time:2023-09-08publisher:

The advantages of UHMWPE mold processing

1, the loss of raw materials is small, will not cause too much loss (usually 2% to 5% of the product quality).

2, the internal stress of the product is very low, and the warping deformation is also very small, and the mechanical properties are more stable.

3, the wear of the mold cavity is very small, and the maintenance cost of the mold is low.

4, the cost of molding equipment is low, the mold structure is simple, and the manufacturing cost is usually lower than that of injection mold or transfer molding mold.

5, can be formed larger flat products. The size of the product that can be molded is determined only by the clamping force of the existing mold press and the size of the template.

6. The shrinkage rate of the product is small and the repeatability is good.

7, can be placed in a given template on the number of mold cavity mold, high productivity.

8, can adapt to automatic feeding and automatic removal of products.

9, high production efficiency, easy to achieve professional and automated production.

10, the product size accuracy is high, good repeatability.

11, the surface is smooth, no secondary modification.

12, can form a complex structure of products.

13, mass production, relatively low price

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UHMNWPE molding process

1, calcination molding processing technology

Powder epoxy resin, molecular weight is not limited; Pulverized epoxy resin is ground into irregularly shaped blank material (such as rod, plate, wheel, sleeve, etc.), the working pressure is 42MPa, the pressure holding is 30~90 seconds, and the thermal expansion and cooling contraction rate of the mold is 1~3%; After calcination at 250~300℃, the calcination time is set at 1 hour /10mino according to the actual thickness.

2, extrusion molding processing technology

UHMWPE epoxy resin should be blended with LDPE, LCP or modifiers to improve liquidity. The machine adopts the plunger pump type and the same direction twin-screw extruder to prevent the defects of low friction resistance and very easy deviation of raw materials. Extrusion temperature 180~200℃, screw speed ratio 10~15R/min; Single-screw extruder can be used for simple goods, but it is necessary to increase the production and processing ancillary equipment and increase the rated power of the motor.

3, injection molding processing technology

UHMWPE epoxy resin blended with LDPE, LCP or additives should be selected. The screw and abrasive tools of the plastic machine need to be improved. Injection pressure above 12OMPa, screw speed ratio 40~60r/min, barrel environment temperature 180~220℃, mold temperature 85~110℃.

4, extrusion molding a press molding

First extrusion melting embryo, and then pour into the grinding tool, to make the required goods.

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UHMWPE sheet molding process

1. Premix

HMWPE raw material adopts the special wear-resistant self-lubricating formula technology of Tagla, which can meet the processing requirements of Tagla guide rail, profile and parts after high speed mixing.

2. Add material

According to the need to add a specified amount of material to the mold, and the amount of material directly affects the thickness of the product. If the amount of feeding is large, the plate size is thick; If the amount of feed is small, the sheet size is thin.

3. Close the mold

After feeding, even if the positive mold and the negative mold phase closed. When closing the mold, use fast first, and change to slow speed when the negative and positive mold contact quickly. The operation method of fast first and slow later is conducive to shortening the non-production time, preventing mold scratches, and avoiding the UHMWPE raw materials in the mold groove from being taken out by air due to too fast closing. When the mold is closed, the pressure can be increased to heat and pressure the raw material.

4. Exhaust

When molding UHMWPE raw materials, in order to exclude the air in the mold, after the plastic reaction in the mold cavity of the plastic mold is carried out for an appropriate time, the pressure release mold exhaust can be released for a short time. The exhaust operation can avoid the stratification and bubbles inside the product; However, the exhaust is too late, because the material surface has melted gas can not be discharged.

5. Heat and maintain pressure

It is kept at the molding temperature for a period of time, so that the UHMWPE raw material is fully melted at high temperature and pressure.

6. Release mold

Demoulding is usually done by ejecting the rod and then demoulding the UHMWPE sheet.

7, mold blowing

After demoulding, usually use compressed air to blow the cavity and the die surface of the mold, if the fixed object on the mold is tight, it can also be cleaned with a copper knife or copper brush, and even need to use a polishing brush.

8. Post-processing

In order to further improve the quality of the products, while reducing or eliminating the internal stress of the products, to achieve the consistent stability requirements of the size of the wear-resistant chain guide rail, profiled profiles and parts.


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