UF and collection planes in ISO GPS

[greenimi]

ISO GPS system:
Can UF and collection plane be applied together?
(UF above the tolerance indicator and collection plane as a supplemental indicator)

I don't have access to all ISO GPS standards, but in the ones I have I cannot find an applicable example where UF and Collection plane are used together.

Is it feasible? Is it legal? Any good examples?

Thank you so much and have a great day/ weekend

 

[3DDave]

Questions are often a sign that someone is paying attention and a five minute call on a part that takes 20 hours to make and saves that part from being scrap? Priceless, when there is a tight schedule.

Speaking of price - suppose there are 40 machinists, 5 process/manufacturing engineers, and 10 QA guys. Do you send all 40 machinists out for a 40 hour course for ASME Y14.5 and another 40 hour course for ISO GPS (you do seem to use both) plus a 10 hour refresher course once a year for each? At year 2 that will be 100 hours of classroom instruction each or 4000 man-hours total vs. a 5 minute phone call to engineering. Include the process/manufacturing engineers and that's an additional 500 hours.

How efficient is that? Not including losing up to 4500 man hours of billable/production time over the first two years?

Alternatively, sending 10 QA persons for that fifty hours of training is just 1000 man hours, 4.5 times more effective, but QA is more likely to have already learned this before being hired and won't need that level of training. Or just have them make a 5 minute phone call on the back of a 10 hour refresher course.

This doesn't count the cost of licensing or buying copies of the ASME Y14.5 and ISO GPS for all 55 manufacturing employees or the time they may take thumbing through it/scrolling through it at the jig-bore were they not to ask questions.

If one is cost-conscious this should have been totaled up.

 

[Burunduk]

We don't send employees to external courses or invite an external trainer for dimensioning and tolerancing. This is a field learned on the job, during the training period, with a structured program developed by a team of experienced employees who also mentor the new employee through this learning process. There is no comparison to an external course. It offers huge cost savings, and employees who go through the training take it seriously. In companies that purchase courses, employees attend just to fill a seat, knowing that no one will expect them to implement the guidelines of an external instructor who has no idea about the company's products and no involvement in the company's work outside of the training they provide.

 

[3DDave]

"This is a field learned on the job" so you expect questions because you have don't have experts doing the training and passing along whatever telephone game distortions come from one person's misunderstanding becoming the next person's sole source of certainty.

Do you also teach them math on the job or do you depend on external instruction by people who have no idea what math is done in your company?

What "guidelines"? This is a standardized form of communication; it has rules. Are the rules in your company different from the rules in the standards? GM used to have a guidance booklet on "don't do this" sort of things, like don't use concentricity, but rules are rules. To understand guidelines and exceptions one should understand the reason for the rules.

Is this like, take a day and learn 400-1000 pages of information?

Are you in charge of this cost saving in-house training activity?

 

[Burunduk]

You can doubt it all you want, but this method has proven itself. New hires who come from companies that did provide external training in dimensioning and tolerancing discover and admit that one of the things they lack for quick integration into the job is knowledge in, yes, dimensioning and tolerancing, simply because at their previous workplace, they didn't really apply what the external instructor taught. In contrast, with us, it is part of the job and not just theory. The trainer is also a colleague who does the same work as the trainee daily and is available for support and help continuously also after the training period.

Because part of the training involves extensive use of the standard document itself (as opposed to the training manuals of the external instructors), the additional source of certainty becomes the standard. However, there is also a professional library with up to date literature on the subject available to employees.

 

[3DDave]

"In contrast, with us, it is part of the job and not just theory."

That's familiarity via repetition. Same as most skills. They only know the slice that is commonly used and, it is likely, the passing of information from mouth to ear means that the pool of options remains small. Typical in-house training has one or two sent to the initial class, returning with good recall of 80%, misunderstanding 10%, and that is repeated by the students who come away with 64% and misunderstanding 20%. Without independent verification, who is to catch the missed and incorrect parts?

It's why I am a fan of the Variation Systems Analysis software; not sure where they were sold to. It doesn't forget, doesn't guess, cannot be convinced. It reports what the actual potential results will be. For certain your training doesn't include any better than the old RMS combinations of absolute limit analysis or figure in actual production variation in deciding how to allocate costs to various features and potential processes.

My take - ask the engineer directly what they meant if there is any uncertainty. Maybe the engineer did make an error; it can happen. Maybe the notation could be changed to be less or not ambiguous. Going to the training person who told the worker what something meant means that the engineer never finds out about it and now is the same, potentially incorrect opinion doubled. Still going to be cheaper than continuing training really is.

How is it with this very effective cost-free training that the new symbology adds anything to the cost? Isn't it free?

 

[Burunduk]

To wrap up the tangent:

It's important to ask questions. You can direct your questions to the design engineer responsible for the drawing, the instructor who taught tolerancing, or both—depending on the situation. However, the primary communication between design engineers, production, and inspection can't rely mainly on phone calls, emails, or meetings. If everyone spends just 5 minutes calling each other about every issue, we'll all be bogged down with clarifications, and the organization won't function efficiently.

There needs to be a common language conveyed through the drawings, and these drawings should serve as the main and clear means of communication. That's what standards are for, and employees need to be trained to work according to these standards.

It's management's responsibility to choose the right product definition standard for the organization. If the standard is cumbersome and unclear, it defeats the purpose. On that note, I remind you that you're still waiting for an expert's response regarding the collection plane.

 

[3DDave]

That's all a great non-response. Truisms, near "begs-the-question" statements. It's got nothing.

How does a minor change in symbology become a large an impediment to a well trained organization that apparently craves dimensioning and tolerancing time in the classroom? How long are the classes? Does it depend on group-think to get to answers or is there tolerance analysis software in use to prove the allocations and predict product acceptance rates based on prior factory variation?

This seems more like a job-shop where there are only a small number of tools and a want for designs tailored to the limitations.

The ISO GPS standard appears generally to be clear, at the least for typical use cases. As most standards go, edge cases are often a problem. It also doesn't appear to be cumbersome. The format of the ISO GPS is significantly more direct than the witches brew that Y14.5 has become. Even if it is unclear and cumbersome, what purpose does it defeat? It remains a standard.

Since you imply it's, what, "cumbersome and unclear" then it is your management's responsibility to choose the right product definition and not ISO GPS. Therefore you have never had to deal with what you management is responsible to avoid. Maybe you have a problem with your management?

 

[Burunduk]

We don't use ISO GPS for product definition and internal purposes. Product definition and training are per ASME Y14.5-2018.
We have some of the main ISO GPS documents available for interpreting customer drawings. With that said I have yet to see a customer drawing that uses those relatively new indicators (collection plane or intersection plane).
When we get these there will likely be questions and misunderstandings.
But I have the feeling it won't happen soon; Drawings referencing ISO tend to look like they aren't made to any standard at all. Considering the complexity and cryptic nature of this method relative to Y14.5, not surprising.