Drawing Resources For Plastic Manufacturing

[Myint Mo]

Hi I am a fresh graduate mechanical engineer and currently helping one of my friend's plastic molding business. I have to create 3D model of small plastic containers such as nasal inhaler and prepare 2D drawing to send to mold designer. What I am looking for is any resources for 2D technical drawing of plastic wears compliance with industrial standards. Since I am a fresh graduate and not familiar with plastic manufacturing. So I need some sample drawings as reference.

 

[drawoh]

Myint Mo,

You need to read up on GD&T and on plastics manufacturing tolerances. My issue with plastic drawings I have seen is that geometry is too free-hand, and you cannot define it to the point of doing effective inspection. Absolutely read up on GD&T.

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JHG

 

[gb2835]

So in the end it really depends on the mold maker for how detailed (if any) 2D drawings should be. In the past my drawings have only shown design specific features for the mold (rib thickness, various fillets at the inner corners, draft, threads if they are present, etc.) and locations of any locking or hole features. As @drawoh mentioned, GD&T is the best way to establish the locations of locking and hole features. Fortunately due to the nature of plastics and mating components the tolerances are fairly loose and can be easy/cheap to inspect.

On the other hand, I've heard of mold makers requiring fully defined 2D drawings. This can be tough if the plastics have a lot of non critical features (aesthetics, locations of ribs, etc.). You should be able to find plenty of mold makers that don't require this though.

On the other other hand, some mold makers don't need 2D drawings at all. This can work if the design is simple enough and locations of features is not paramount. If you can 3D print the design on an FDM and it works then you *probably* don't need drawings.

My suggestion would be to detail the drawings to what you feel is necessary and send it out as a quote/evaluation package, even mentioning it is your first time. I've done this in the past when working on new manufacturing/processing projects and ended up working with decent shops willing to point some things out to me.