How To Prevent Plastic Injection Mold Parts Shrinkage
Why we need to discuss this blog “How To Prevent Plastic Injection Mold Parts Shrinkage” today, This year, we have made plenty of plastic enclosed components with ABS, PE, Nylon for our global customers. For better meet customer’s requirements- high quality and lower costs, have compared CNC machining and injection mold process, of course, when our customers have thousands of orders. As usual, we have built injection molding to produce than CNC machining manufacturing. But, sometime, we have encountered main problem on the mold processes which is shrinkage, since our CNC machining can make products of wall thickness is more, like 10mm, 20mm, or more.
However, if we will choose the injection mold, the wall thickness is limited, most of them are 2-3mm, or 4mm, 6mm, most of them are based on product feature, if this is too thick, then when we will inject part, then product surface is easy shrinkage. In order to know these information, Creatingway takes this article to share with you these issues, and how to resolve them, or avoid the shrinkage issues.
Below are some of reasons on plastic parts shrinkage issues
Today, we will take ABS material as one example to explain this case for Plastic Injection Mold.
- Plastic shrinkage is its inherent characteristic—- thermal expansion and contraction
The temperature is very high when the plastic molded, once the plastic parts are formed, the temperature is low and the volume will be reduced.
In general, the shrinkage rate of ABS material is five thousandths in plastic injection mold.
- Under the same injection pressure, the shrinkage rate of the thickness of the wall is larger than that of the thin areas.
- The same mold, the same area of the parts, ABS plastic injection pressure smaller is easier to shrink than the bigger one.
- According to the specific structure and the flow analysis. When the same structure out of the gate is easy to shrink than the near one, it’s mainly that the pressure is smaller and hard to steady the pressure when the farther distance, so natural shrink too much.
- At the same time, when your gate accessories wall thickness is very thick, it also may cause shrinkage.
The injection parameter maybe will lead shrinkage issue
- Slowly shot speed
- Low shot pressure
- Insufficient pressure time
- High the raw material temperature
- Low the nozzle temperature
- Open the molding too early, cooling insufficient
- The thickness design of the molding cavity is inconformity
How to resolve or avoid the shrinkage issues for plastic injection mold
- Optimize the mold transport water and enhance the cooling effects.
- Reasonable reduce the wall thickness
- Reduce the plasticizing temperature
- Increasing injection pressure speed, meanwhile keep pressure, speed and extension of pressure time.
- Improve back pressure.
Too low mold temperature can also result in shrinkage of products, which can be used to stabilize mold temperature by shortening the molding cycles or adding mold temperature. Creatingway will take more these article to work with you on more engineering information and skills.
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