Multiple Features With Only One Toleranced on the Print

[dwright48313]

I am so glad this forum is back. I have been getting information from this site throughout most of my quality career. Sorry off topic...

Ok I have a question, I have a print with three separate although identical slots and on this print they only section cut and dimension one of them. It does not say "3x" or "3 places" (although other dimensions on the print do) or TYP to tell me that I need to measure all three. As a person who had been in Quality forever my instinct tells me I need to measure all 3 anyway to be on the safe side however the layout tech did not read it this way and now the customer is saying that one of the slots that were not checked is not to print. Because all 3 are not dimensioned and toleranced so these other 2 dimensions have to be to print? I always erred on the side of caution and assumed that it is intended however I don’t know if that is actually true or not. Thanks everyone for your help!!

 

[Miner]

Re: Multiple Features With Only One Toleranced

This was probably an omission on the part of the drafter. However, common sense would tell you that all three must be measured.

 

[dwright48313]

Re: Multiple Features With Only One Toleranced

This was probably an omission on the part of the drafter. However, common sense would tell you that all three must be measured.

Thanks for your quick reply! I agree and that is what I would do however that is not what the print says so it not what was done. So are we, if it is not specifically called out, required to meet it. We have 2 out of 3 slots that are not to print which would have been caught if they were measured on the first offs or at PPAP however the Layout Tech stands behind his decision that they are not required to be measured or be to print.

This was not the only duplicate feature that was not dimensioned. There are 6 Air Flow Vents (there are 3 at the top of the part and 3 at the bottom of the part) and only the bottom air flow vents are dimensioned for Length, Width, and Height as well as distance (from the bottom of the vents to the bottom of the part) however there was a callout for Perpendicularity in relation to these vents that stated 6x. So of course only the 3 on the bottom were measured for the L, W, H, and distance (distance from bottom of vents to bottom of part) but all 6 were measured for Perpendicularity as the print stated. Luckily the sizes of all 6 vents were not an issue however they are saying that the distance from the top of those vents to the top of the part (the bottom reversed) are not to print. Again that distance is not called out on the top of the part.

So now my boss is telling me that the Layout Tech is right and we only have to meet the dimensions specified on the drawing so he will not be fixing the tool. In order to get everything where I want it to be, which is everything to print regardless, I need to give him more than it's implied and it is common sense. I have to give him proof that the layout tech was wrong not to measure each feature. I scoured through the notes and I did not see anything where is it a requirement to meet the print and all it says is "For unspecified dimensions see Math Data". There are not ANSI or ISO or any other dimensional standards listed either. This is why I am at a loss.

 

[Stijloor]

Re: Multiple Features With Only One Toleranced

These issues (I feel your pain) should have been addressed during the contract review stage. Suppliers (External Providers) are often too anxious to get the work and very hesitant to ask questions of the Customer. Just to be sure, prior to PPAP submission, contact the Authorized Customer Representative for clarification and resolution.

 

[Eredhel]

Re: Multiple Features With Only One Toleranced

Is this a part that is designed by your company, or is it one designed by someone else?

 

[dwright48313]

Re: Multiple Features With Only One Toleranced

I agree Stijloor it should have been addressed prior but like you said they are in a hurry to quote and get the work and then I am left dealing with the fallout. I am finding that this is pretty common with this customer's prints as almost all of their prints are designed this same way. Moving forward our Quality Manager and Layout Techs here and at our other locations have been made aware that if there are more than one of the same features (or if the other side is a mirror image of the dimensioned side) all features are to be measured regardless of whether or not it is called out. Unfortunately I deal less and less with the APQP part until there is an issue but now I see that I have to get back to being more involved.

Erdhel this print was drawn and designed by our Customer and as I said above as I looked through some of their prints I see that it is a pretty common practice for them.

 

[Emmyd]

Re: Multiple Features With Only One Toleranced

As part of the quoting process, do you do any type of feasibility review on the prints and models? This is where we would raise that flag. I believe that the tool shop that built the tools should have used the CAD model in the tool design. I'd review the CAD model to see if it matched the print -most designers put on the prints that the CAD models are master and should be consulted for missing nominal dimensions. I would closely review the notes on the prints because if they put that verbiage on the prints then you have to go a bit deeper to decide if the tools need to be fixed. Then it becomes a matter of the CAD matching the print and which takes precedence.

Hope this helps!

 

[dwright48313]

Re: Multiple Features With Only One Toleranced

While there is a Feasibility Form included with the quotes there has been a trend where most parts are quoted to 3D Data now with alot of TBD's because prints are not available at that time. The tools are made to CAD/Math Data/Stp Files/3D Data/whatever and when the drawing is available they go back and update the Feasibility. To be honest from what I can see of their review process they review the print for CC's,SC's, and Attribute callouts to see if a fixture is needed or if it is possible to meet the requirements. Then it is checked for note, grain, material, and any other testing requirements. Sure they review dimensions in case the print has unilateral tolerances so that they can get the those areas of the tool NOT built to nominal but no one has ever really took the time to ask the customer if one dimension applies to all features. In fact I have heard the owner say the less toleranced dimensions on the print the better for me. As for the notes the print does state that "Math Data is Master, Drawing is for Inspection Only" but the data is theoretically perfect so it does not define any tolerances for those dimensions not specifically toleranced. I did verify that the Data does match the dimensions that we are being questioned about, that was the first thing I did, and we are not out of tolerance by any more than + 0.1. The print lists the dimensioned slot as 2.45mm +/- 0.1 and slots that were not toleranced and checked are checking at 2.62mm so I would say if Math Data is the master we are pretty close in size but I have nothing to say one way or another whether or not we are to print. Urgg this is so hard. I am playing the "well I guess you are technically right but is being right worth losing a long time customer" card to get what I want fixed until I can find some firm proof he has to fix it...lol.

 

[Emmyd]

Re: Multiple Features With Only One Toleranced

While there is a Feasibility Form included with the quotes there has been a trend where most parts are quoted to 3D Data now with alot of TBD's because prints are not available at that time. The tools are made to CAD/Math Data/Stp Files/3D Data/whatever and when the drawing is available they go back and update the Feasibility. To be honest from what I can see of their review process they review the print for CC's,SC's, and Attribute callouts to see if a fixture is needed or if it is possible to meet the requirements. Then it is checked for note, grain, material, and any other testing requirements. Sure they review dimensions in case the print has unilateral tolerances so that they can get the those areas of the tool NOT built to nominal but no one has ever really took the time to ask the customer if one dimension applies to all features. In fact I have heard the owner say the less toleranced dimensions on the print the better for me. As for the notes the print does state that "Math Data is Master, Drawing is for Inspection Only" but the data is theoretically perfect so it does not define any tolerances for those dimensions not specifically toleranced. I did verify that the Data does match the dimensions that we are being questioned about, that was the first thing I did, and we are not out of tolerance by any more than + 0.1. The print lists the dimensioned slot as 2.45mm +/- 0.1 and slots that were not toleranced and checked are checking at 2.62mm) so I would say if Math Data is the master we are pretty close in size.

In this case, there should be a general tolerance called out on the print - either in the notes back to the datums or in the titleblock. I understand the idea that less dimensioning on the print is better, but if your customer is now debating the measurements a dialogue needs to be opened up between you and the customer to determine what is important and should be measured.
But, if there is a general tolerance on the print and assuming that 3D model is at nominal - how do the undimensioned features check against that?
We see things like this all the time on our prints, we still will check them on the first article inspection and apply the general tolerance to make sure we are at least producing parts to the intent of the print.

 

[dwright48313]

Re: Multiple Features With Only One Toleranced

In this case, there should be a general tolerance called out on the print - either in the notes back to the datums or in the titleblock. I understand the idea that less dimensioning on the print is better, but if your customer is now debating the measurements a dialogue needs to be opened up between you and the customer to determine what is important and should be measured.
But, if there is a general tolerance on the print and assuming that 3D model is at nominal - how do the undimensioned features check against that?
We see things like this all the time on our prints, we still will check them on the first article inspection and apply the general tolerance to make sure we are at least producing parts to the intent of the print.

Fortunately for me the general tolerance is the same as the listed tolerance which is +/- 0.1 mm so I can get the customer what he wants. That works for me. I will explain it that way and update our Feasibility/Print Review Checklist to include the question "Do all identical or mirror features have dimensions/tolerances applied?". This way we will be flagged to go back to the customer and have it confirmed so that they can update the print (cough...cough...yeah right..) or get something in writing I hope that can confirm that these dimensions need to be measured and to print.

Thank you all so much for your help!!!