Excessive tolerancing

[Rstewart]

So I've been at my new gig as a manufacturing eng at a new company two weeks now.
My role is mainly processes and non-conformance reports along with work instructions in an MES system. 
Holy Shit, the engineering here is making these parts damn near impossible to manufacture.  Almost every thread call-out is a 3B and surface profile tolerances where they are Not needed.  I mean they have a .005 profile tolerance on a place that isn't touching a mating part?? 
This is a big place that is extremely successful, but Jesus the $$$ they are wasting on rework or scrap is just STUPID. Why has this not been addressed is beyond me.  I can see if these are drawings from the outside, but no we are doing the engineering.
Who else is in a place like this?

[Brian]

When I see stuff like this I imagine that folks (engineering?) don't truly understand what's important about their designs, so they resort to "CYA" sorts of behaviors....

I tell my customers that I don't mind if they keep moving the decimal point to the left on their drawings so long as they don't mind us moving the decimal point to the right on our invoices....LOL.

Now that I'm cranky and middle aged I've (finally) come to the conclusion that common sense is actually no  longer "common."

[Tim Johnson]

So I've been at my new gig as a manufacturing eng at a new company two weeks now.
My role is mainly processes and non-conformance reports along with work instructions in an MES system. 
Holy Shit, the engineering here is making these parts damn near impossible to manufacture.  Almost every thread call-out is a 3B and surface profile tolerances where they are Not needed.  I mean they have a .005 profile tolerance on a place that isn't touching a mating part?? 
This is a big place that is extremely successful, but Jesus the $$$ they are wasting on rework or scrap is just STUPID. Why has this not been addressed is beyond me.  I can see if these are drawings from the outside, but no we are doing the engineering.
Who else is in a place like this?

We typically have good communication with our engineers. Most of the time we get included in the first few design meetings to have representation for the machine shop along with the fabrication shop and assembly.

[Matthew Hajicek]

https://www.kellertechnology.com/blog/how-dimensional-tolerances-impact-part-production-costs/

[Brian]

We typically have good communication with our engineers. Most of the time we get included in the first few design meetings to have representation for the machine shop along with the fabrication shop and assembly.

I'm fortunate to have a few customers like that, too, and I think many folks underestimate the value of a *true* partnership with customers/vendors/co-workers. It's not always easy, or even possible, to understand the driving parameters of any particular project or part, and if one is open and humble enough to solicit the input of others (and actually *listen*, not just go thru the motions) it can be illuminating and mutually beneficial. It's best if this can be done during the earlier stages of a design before too many decisions become set in stone, but there are many ways to skin the cat as they say....

[CNCAppsJames]

IF there is only one measure of a successful Manufacturing Engineer it is that they bring value to a company by evaluating a part's form, fit, and function, then tolerance appropriately. 

The good ones have the potential to save companies 10's, 100's, or 1,000's of times their annual salary. 

[Brian]

Reading everybody's comments got me thinking: I wonder what % of us here could say that their input is valued or solicited by others in their organization (or by their customers), and what % of us just have to "shut up and make it"? Do you feel valued as an employee/vendor or are you perceived as just another cog in the process?

[JParis]

Reading everybody's comments got me thinking: I wonder what % of us here could say that their input is valued or solicited by others in their organization (or by their customers), and what % of us just have to "shut up and make it"? Do you feel valued as an employee/vendor or are you perceived as just another cog in the process?

As I just got promoted to Manufacturing Engineering Manager it an interesting time for this question.

They have just redone the release process for ECRs and new releases, all of the mew manufacturing parts now run through me and the Director of Ops....

I spent the early part of this previous week working with an mechanical engineer to get a part build in a way that was reasonable to manufacture, so I have a definite skin in the game. One of the big habits I am going to try to break over some time is the tolerancing on threaded holes. All too often we have seen .002" or .003" true position callouts on threaded holes. Those end up costing us BIGLY and that is something that needs to change. I recently had a part, complex and I worked with the original designer to get some features changed so that we would 2D mill them as opposed to 3D milling and final blending with a .015" ballmill...the company decided that since these parts even as altered we going to require too m any machine resources based on projected quantities needed, that they would take a look at a company casting and providing complete & plated parts.

They redesigned said part for casting, then becasue the casting house is 16+ weeks out just for samples it was decided to create and "as cast" version to be machined to give us parts needed for assembly and sale as well as a hedge against the casting house failing.

I wound up having to go back again and get ALL of the changes I had already made, made again....

I definitely have pull in the game to get somethings changed.

Getting engineering to "buy in" to your changes I have learned that many times if you explain the "as is" issue and offer a viable solution they will change.

As a Tier 1 supplier to military, we have some things that are sold to them that we cannot change lest we have to go through the entire first article/acceptance again...they are locked contracts.

[Rstewart]

We typically have good communication with our engineers. Most of the time we get included in the first few design meetings to have representation for the machine shop along with the fabrication shop and assembly.

This is how it was where I came from.  But I was the one actually making the parts there.  Engineering listened 90% of the time, that made things flow much better.

[CNCAppsJames]

That's no joke. TP is a much better definition for fastener fit than plus/minus, but the fact few cartoonists truly understand evwn the basic principles of GD&T and how if applied properly can actually save money is just mind blowing. The "engineers" our universities are turning out generally speaking aren't even close to being up to snuff. It's no wonder (aside from it being really hard) we are having a hard time getting humans back to the moon and beyond. Our degreed and licensed engineers just aren't up to the task.

JM2CFWIW 

[Rstewart]

I mean this field is in the defense industry, so I get the massive amount of checks, documentation, inspection, and all that.  What I just can't understand is WHY we're engineering these parts/assemblies with a metric shit-ton of profile tolerances and GD&T positional Everywhere.  Most* of this stuff will be beaten, pried, or vise gripped by soldiers somewhere.  I have worked with that side as well, there's NO such thing as solider proofing anything LOL.

[CADCAM396]

I am only valued after they have done it there way, failed and am asked to fix it.
sad way to approach things but keeps me buisy. first time around am asked to make components blind to overall form fit function and intention.
second time get to dig my heels into the project and getter done.

[RobertELee]

second time get to dig my heels into the project and getter done.

And have it on the bosses desk by 2:00!

[CADCAM396]

wow you have played this game before.
by the time it circles back to me all lead time is sucked out of the job. most times i am lucky if we arnt a year late

[Jeff]

We have a customer that sometimes cranks up the tolerance callouts, and if it's too much for us to handle to meet the delivery date or that tolerance would involve something like additional jig grinding we usually call them and they'll either change it or tell us to give it our best effort as it's not as critical as their engineer drew it up to be.
Also this customer LOVES to call out 32 micro or better all over. It's comical. And it's a good thing that they are super flexible on the MFG side of things.