Design engineers should be fluid dynamics specialist to inject plastic MOLDED parts without any bottleneck.
Rules For Designing Plastic Molded Parts Without any Problem:-
The following rules will help all the engineers to avoid problems when designing injection-molded plastic parts:
Rule 1: Consistent with the wall thickness
The thickness of the walls of the plastic part should be the same.
This is the most basic design parameter, and its strict adherence will eliminate many manufacturing problems.
The Parts with uniform walls will not warp, will Fill properly and will fit together because the variable shrinkage is minimal.
The thickness difference of the wall in high mold shrinkage plastic should not exceed 10%.
In fact, even minor inequality can present processing and quality problems.
Rule 2: Provide proper gate Location
If the thickness of the separation wall cannot be avoided, then the designers should be provided for the proper gate space.
If this is not supplied, it would be almost impossible to get a similar pack of the molded part.
The most effective gate is the place when entering the thickest part of the melt cavity and then flows into narrow areas.
Rule 3: Set optimum wall thickness
Theoretically, there is no maximum wall thickness for injection-fitting parts.
But the designer is more concerned with determining the minimum wall thickness because the thin ones are almost always less expensive.
Two factors contribute to this: First, thin parts require less plastic material, and secondly, they are rapidly cooling.
In order to determine the most suitable wall thickness, engineers should first consider the product requirements.
Normally, the strength determines the wall thickness. Engineers can also opt for optimal wall thickness to rely on a limited analysis.
Rule 4: Generally radius corners
During injection molding, the molten plastic has to be twisted or cornered.
Plastic flows from round corners will be easy, so engineers should liberally straighten the corners of all the parts.
On the contrary, there is stressed stress inside the sharp corners – especially during the cooling process when the top of the part tries to shrink and the material pulls against the corners.
If the inside and out of a part is equal to half of the thickness of the nominal wall, then a uniform wall can be obtained around the corner.
Both sides of the corner will display the same amount of shrinkage, and the marks of sync will be completely saved.
Apart from this, the first rule of plastic design – the thickness of the same wall will be followed.
As the plastic goes around a well proportional corner, it will not be subject to sudden change in the area and direction.
The cavity packing pressure remains constant. It leads to a strong, retarded stable corner, which will oppose the post-mold warpage.
Rule 5: Select the appropriate draft angle
From a cost and manufacturability standpoint, the ideal draft angle is the biggest angle, which will not reduce customer satisfaction with the product.
It is difficult to determine the minimum allowable angle.
There are authorizations on plastic material suppliers and molders, what is the most acceptable draft.
In most instances, 1 ° per side will be adequate, but better between 2 ° and 5 ° per side.
If the design is not compatible with 1 °, then allow 0.5 ° on each side. Even a small draft angle, such as 0.25 °, is better for none.
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