February 2, 2023

Why You Should Do Prototype to Verify Part Design Before Mold Making?

Do Prototype to Verify Part Design Before Mold Making

This is a bad case that happened a few years ago. This is a loss for both the client and our-self. The mold is modified again and again, at first we are not aware of that there will be such a long way to go before we committed to taking the job. We also know little of the client or we were able to make greater efforts to pull things back on right track.


“Hi Tim,
What I know about tooling here in UK is that you always make the tool in a way that if adjustments are needed
. It can be done always. It’s easier to take away metal than add metal, I am sure you work this way yes? Please confirm you are ready to proceed.”

Our reply:

“Hi Steven, 
Easier to add steel than reduce steel
. Yes, when it is necessary, we leave some ” safe steel” for further adjustment. But none of these is as important as the part design itself to determine the success of your project. Please focus on your part design, please let me know worry about mold making, you need to double check your design before tool making. Have you done prototype to verify your design?  Do you have an assembly drawing to show which go with which? 
If you are ready to move forward, please send me the finalized part drawing, and the approved quotation sheet (or issue an official PO if you can)
. We will provide PI for deposit accordingly,  then we can start DFM process.”

After the mold is completed and samples submitted, we have spend quite a long time to do injection mold modifications due to many times part design changes.  

part design changes1

Our replay:

“Hi Steven,
We have spent more than one month to modify the mold due to frequently design changes , please help to double check and confirm if this is the final drawing. If you couldn’t confirm that, l strongly propose you to make a prototype to verify your updated design. It will cost you way more money and time to modify the injection mold than making prototype to verify your design. 

Following are the detail of all the modifications with the cost.
Please feel free to let me know if you need any further clarification.

detail of all the modifications with the cost

Modification Comes again

“Hello Steven,
Please could you advise the reason of changing plastic resin to ABS and ABS/PC ?  These 2 type of resin is weaker than POM
. Considering this is an export mold project, our Job is making you a mold,  verifying the alternative resin is not in our plan. Do you think you can do this resin verification after the mold transferred to UK ?  
Also please confirm the modification you mentioned is the last time modification.
Since we just made a change over this area once last time, changing it again is difficult.  Please confirm if this change 7.5 to 5mm is a must.  l strongly propose you to do 3D printing or CNC machine prototype before modification, that would save your cost, time. 
Sorry l have to say so, but please give us a confirm information what to do
. My people are getting lost right now, we don’t know if we should continue modification or we should stop to wait your new instructions raised up like each 2-3 days a new requirement.”

At last we made 5 times of modification before shipping the mold to the customers. The good news is the final result is still not bad. To be honest, no injection mold maker enjoy a work like this but sometimes it do happens. Part of the reason is immature design, some of the injection mold buyer are not aware of this is the case. But majorly l think the injection mold maker or injection molder, as the professionals, should be able to be careful and smart enough to help the clients out of this trouble as much as possible.

Why You Should Do Prototype003

Feedback :

“Hi Tim,
They look excellent! Thank you for the hard work and professionalism that your company demonstrates.”

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