Difficult to do according to PPAP Manual? Big plastic parts, over 100 dimensions

[Mobobo]

hello all,
According to PPAP manual (3rd rev.), the supplier should submit full dimensions report, and I often ask 6pcs for the full dimensions.
But, for some big plastic parts, such as shroud (supporting the fan and motor to cool the engine of a car), it has over 100 dimensions, so the problem are:
the suppliers often don't submit the full dimensions report, even miss some SC and CC dimensions in print because those dimensions are difficult to check, like the "R" and angle, therefore, is it necessary to do full dimensions inspection? of course excepting the SC and CC.

 

[Jim Wynne]

hello all,
According to PPAP manual (3rd rev.), the supplier should submit full dimensions report, and I often ask 6pcs for the full dimensions.
But, for some big plastic parts, such as shroud (supporting the fan and motor to cool the engine of a car), it has over 100 dimensions, so the problem are:
the suppliers often don't submit the full dimensions report, even miss some SC and CC dimensions in print because those dimensions are difficult to check, like the "R" and angle, therefore, is it necessary to do full dimensions inspection? of course excepting the SC and CC.

If your customer expects compliance with the default requirements, your supplier is required to do a complete dimensional layout (including any requirements shown on the control plan that aren't referenced on the drawing) for at least one part from each position in a multiple-cavity tool, or just one part if the tool in single-cavity.

 

[Caster]

Miller time

hello all,
According to PPAP manual (3rd rev.), the supplier should submit full dimensions report, and I often ask 6pcs for the full dimensions.
But, for some big plastic parts, such as shroud (supporting the fan and motor to cool the engine of a car), it has over 100 dimensions, so the problem are:
the suppliers often don't submit the full dimensions report, even miss some SC and CC dimensions in print because those dimensions are difficult to check, like the "R" and angle, therefore, is it necessary to do full dimensions inspection? of course excepting the SC and CC.

Mobobo

My first quality job we had 2200 dimensions per mold. It was just awful.

My very smart boss got our layout people to meet with the customers layout people and the design responsible engineer over beers (back in the day when you could do that).

Once they got talking they found a lot of dimensions that neither knew how to measure and a lot that were meaningless (rads, etc). They agreed on a reduced inspection set. These dimensions MATTERED, and we got them right.

Everyone was happy except the customers buyer, he went ballistic. They are trained from birth to ask for more work for less money.

It's worth trying, but pick your customer contact carefully.

The basic idea behind PPAP is sound, check the part so you know it is right. But then the committee got to it and it grew to become impossible.

So make your own vital list. You know what will cause problems. Make sure you cover those. Then you and the customer are protected.

I'd be a little worried if your suppliers are not checking SC and CCs. If the part does not fit or someone gets hurt and you <or your supplier> did not verify these at PPAP....the lawyers will have a field day.

 

[cokyat]

I think that as a supplier, what we did in this particular problem was that we submitted a waiver to the customer together with a letter asking them which dimensions and parts are most critical to them that will cover the SC and CC, say for example, the part drawing indicates a width of 500mm (and were sub-divided into widths, 200mm, 150mm, and 150mm as indicated in the drawing), we asked them if it's ok to measure the 500mm instead of the three subdimensions. This can also apply to radii, angles or diameters.In short, simplifying the data will help lessen the full dimensional evaluation.

 

[Rob Nix]

Back in the late 70's I, as a young quality engineer for an injection molding outfit, did a LOT of dimensional layouts with +100 dimensions as part of our "PPAPs" (back then they were called source warrants, GM-1386, I.S.I.R.s, etc.). It was not uncommon. But I did try to use common sense. If 20 of the dimensions were radii, I just used a radius gage and rounded to the nearest fitting one. I focused my attention on accuracy to the critical dimensions.

Back to the present: Your concern is why so much more attention is being paid to Design for Manufacture/Assembly (DFM/DFA) and Geometric Dimensioning & Tolerancing (GD&T), where the suggestion is to use as many BASIC DIMENSIONS as possible, opening up tolerances as much as possible, and keying in on the functional dimensions (and those needed for durability). Problem is, the drawings are the customers, and getting them to make sensible revisions is not easy.

To make a short story long, Caster makes the right points: key in on the dimensions that matter.

 

[Mobobo]

thanks for all suggestion, all decisions based on the familiarity to parts and products, and the final goal is to ensure the security and function of the parts.