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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.