Vendor creates additional drawings for approval - Standard?

[jdmmech]

I have been working with an injection molding company in Taiwan for several years. They are not ISO so I am curious as to the reasoning for the additional drawings they create. We send them 3D models and drawings of injection molded parts as well as 2D drawings of overmolded cables. They recreate these drawings to include their part numbers and then send the drawings to me for approval before they continue with the PO. No additional dimensions are added, and tolerances are sometimes missing or exaggerated. There is not another vendor I work with who does this, but since I am still young in my career, I am curious if this is standard anywhere else. I have little control of who we do business with, otherwise I would love to work local and get this question answered the 1st time I asked them. This is time consuming and unnecessary in my opinion.

Thanks for any input!!

 

[KENAT]

Some vendors will do this - especially if they are using non standard processes or exotic materials...

Some of our precision ceramic vendors for instance do this.

Often it's translating the drawings to local 'standards', and possibly tweaking them to suit their process etc. Not sure this is the case here.

Do they actually ask for design/tolerance changes to suit their process or just make mistakes when recreating your drawings?

Posting guidelines faq731-376

http://eng-tips.com/market.cfm?

(probably not aimed specifically at you)
What is Engineering anyway: faq1088-1484​

 

[jdmmech]

On cables they would ask for tolerance changes at times. On the molded parts, material & tolerances are just missing from the block. Trailing zeros removed (metric). This company makes products extremely similar to the ones I send them, and it uses the same material.

I am less opposed to reviewing them knowing that other vendors also do this, but will continue to ask for a reason. Thanks!

 

[looslib]

If you are using trailing zeros for tolerance specs on metric drawings, that violates ASME Y14.5.
They are removing them to give them more tolerance and be in complaince with the spec.

I think they want you to approve their retoleranced prints to give themselves an out if the parts meet their print but not yours.


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