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Injection Molding Design Box at Early Stage – March 5,2019

Danke Mold is designing an injection molding design box.

Product  designer or mechanical engineers may be confronted with many injection  molding manufacturing concerns when designing parts. The box can be a  very good reference for injection molding design for manufacturing. It  covers most of the injection molding concerns, and also the suggestions  or solutions.



We  just finished at the early stage of 3D model creating and going to 3D  print it for model verification. Some upfront information that, the  Injection Molding design box including the following details:

1) Bosses design:

Bosses  and screw holes are very common features at injection molding parts.  But they can get issues easily. We listed a series of bad bosses or  screw holes design, while also a series of good designs, for comparison.

2) Uneven wall thickness:

We set 3 areas for different wall thickness.

One  is 50% of the part wall with right angle corner, one is 50% of the part  wall with gradually changing corner, the last one is 25% of a part wall  with the right angle.

It’s  for understanding the material flow at different wall thickness and  features. So that to avoid the short shot in part design.

3) Rib thickness of part wall:

Ribs  can help increase the part strength, or for assembly. However, sometime  ribs will cause uneven shrinkage at the part surfaces.

We  set 4 ribs’ design for reference. They are with different rib  thickness: 1.0mm, 1.5mm, 2.0mm, 2.5mm. We can see the different  shrinkage at the bottom of the part.

4) Core out:

Thick  wall is also confronted at injection molding part design. They would  cause many injection molding defects. For example, uneven shrinkage,  porosity, deformation, and etc.

Core-out is an injection molding design suggestion. It can help better material flowing and avoid most of the thick wall issues.

5) Surface Finishes:

We put 4 textured surfaces at the rough texture region, and 4 smooth surfaces at smooth areas.

At  the texture areas, they are Fine texture, Light texture, Medium Texture  and Rough Texture. It’s the most common texture that we help our  customer in most of the plastic injection molding jobs.

At the smooth surfaces, they are cutter marks, cutter mark removed, glossy, and high glossy.

For  quick-turn injection molding, we think that the surface finishes can  cover more than 95% requirements of injection molding parts.

6) Undercuts of snap:

Snaps  is usually with undercuts, which undercuts usually with lifter tooling  structure, which will push up the tooling cost. While shut-off tooling  structure is to simplify the tooling structure and then the tooling  cost.

It’s one more option for product  designer at designing the snaps. If without cosmetic concern, simplified  structure avoiding undercuts is much more preferred.

7) Side holes at Hinge:

Side  holes at the hinge are often simplified as shut-off structure. We  illustrate how to simply the part design. The theory is basically the  same as undercuts.

If without  simplifying, it will need long side-action distance, and then a  hydraulic slider to achieve the function. It will have the tooling price  much higher.  

8) Traditional gate type: Sprue gate, and Pinpoint gate:

For  injection molding parts, we always would like to have our customer be  attention to the gate marks. The gate position will affect the tooling  structure, molding production window, and then the tooling cost and unit  price. One more important thing is that, if the part is with cosmetic  concern, maybe we would have to be careful at the gate style.

We  put 2 gate styles for reference here. Sprue gate and PinPoint gate.  They are in wide common use at quick-turn plastic injection molding.


After  3D printing, we may adjust the 3D model again. If satisfied, we will  start making rapid tooling and run some low-volume injection molding  production for some samples. Would you have any injection molding design  inquiries, contact us via info@dankemold.com, or visit our website www.dankemold.com.

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Sales Engineer: Jade Du

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