Question On Responsibilities: 1

[Keith1029]

Question On Responsibilities:
Just so I can make sure that I am not the one in the wrong; I encountered the following situation:
1. One member of our company completed a design and drawing of a part and submitted that part for quoting with the intention that it would receive bending as a method of manufacture (although no method of manufacture was specified on the drawing).
2. A quote was received from a third party machine shop for the finished piece.
(For the case of full disclosure it should be noted that our company was aware that the machine shop was doing the machining, but subcontracting the bending of the part in order to provide us with the finished product.)
3. We did not provide a flat pattern with bending locations, rather just the drawing of the intended finished part.
4. The part received machining and then went for bending at which point it cracked along the bend. The lack of ductility in the metal was cited as the cause.
5. The supplier claims that the parts “unfitness for manufacture” is the result of the design engineer (which makes me wonder what happens if a non-engineer brings them a job) and we should pay for the cost and materials invested in the part up to this point.
My point of view is that the manufacturer provided a specific quote for a specific end product that was not provided. As the customer (and not an expert in their manufacturing process) I can’t see how I can be expected to pay for parts not delivered. I think this understanding applies for any damage done to any (new) piece regardless of whether or not part of it’s manufacture was sub contracted (unless expressly noted in the contract)
So the question becomes, with whom does the responsibility for the cost (time and materials) to this point lie? Is there any legal precedence specifying specific responsibilities? And am I to close to the situation to be seeing it objectively?

-Keith

 

[Keith1029]

Sorry - probably wrong forum (any direction to better will be gladly accepted).

 

[MintJulep]

A quote is a vendor's binding commitment that they can make the part quoted upon for the price quoted.

If they failed to do their due diligence before providing the quote too bad for them.

But instead of getting into a pissing contest a more reasonable course of action would be "let's talk about ways to change the design, materials or process to get parts that will work."

 

[hydtools]

My first response would be that if the vendor has enough expertise to claim "unfit for manufacture" they should not have quoted the job. Having quoted the job, they should deliver.

If the bending subcontractor has enough expertise to claim " unfit for manufacture", they should have refused the bending job. By accepting the job they bear responsibility to deliver.

On the other hand, your company should have design expertise to design the part, understanding the manufacturing processes and/or communicating with the vendors during the design of the part in order to specify a manufacturable part. Not just draw a part and throw it 'over the wall' hoping all will be well.

Ted

 

[1gibson]

If the vendor does not deliver an acceptable part, why would they get paid? They did not fulfill the contract, simple enough.

You stated you did not specify a method of manufacture. BUT, if you specified the type of raw material (ASTM for plate) and not just a general material description (3XX stainless steel) and the part can't be manufactured from that raw material type (plate).... It blurs the lines a bit, because you have (effectively, this could be debated) specified the method of manufacture. But they still should not have quoted it if they can't produce it, and I do not think you are liable if they can't meet their commitment.

Really, it sounds like this discussion should be taking place between the machine shop and the vendor who made the bends. Not the customer and the machine shop.

Can the part be heated (without distorting machined areas) before bending to eliminate the cracking?
Can the raw material be stress relieved before machining, to eliminate the cracking?

These are details that should not need to be specified by the customer. If a customer did specify them, then the vendor might ask why you were having someone else make the part when you knew exactly how to do it yourself.

 

[Keith1029]

Thanks guys, I think we are all on the same page (nobody wins a pissing contest). I just wanted a sanity check when the vendor was so insistant that they had no responsibility over their subcontractor or the manufacturability of the quoted part.

 

[TheTick]

I've been on the vendor end of estimating. It was part of my job to make sure that the customers' parts were manufacturable, and to provide alternatives if that was not the case.

Unless the drawing calls for a crack in the bend, send the parts back to the vendor and permanently part ways.

 

[Walterke]

Who chose the material?
Did you give up a specific kind of material or just, for example 'steel'?
If you did give a specific material, what are the suggested minimal bend radii for the thickness you used?
Is it a common material? (=are the bending people familiar with the material)

NX 7.5
Teamcenter 8

 

[MikeHalloran]

How did you get involved in this mess? I.e. negotiation should have ended with the buyer or the designer.


Mike Halloran
Pembroke Pines, FL, USA

 

[drawoh]

Keith1029,

What was the material and how was it to be bent?

This matters. For example, I have seen drawings call up sheet metal parts out of Aluminium 6061-T6, which sheet metal shops refuse to work with. If it were cut out by a machine shop and then sent out for bending, the sheet metal people would not get the opportunity to reject the material, and it would crack upon bending.

The only way your office has zero responsibility in this mess is if you specified the correct materials and bends.

If you want to bend metal, design the part to be punched out, and send everything to a sheet metal shop. The good shops will call you and ask for the material to be changed.

This is the right forum for your question. This covers manufacturing, design and documentation practise, and probably, office politics.

JHG

 

[Keith1029]

Yes the designer specified a material and condition, although not a specific type or stock and the condition was for final part only.

Granted a confrontation was not desired and we did arrive at a professional understanding with the supplier, but the situation did bring up the desire for this academic discussion.

Obviously it is best practice to design parts that work and can be manufactured, and it should be the designer’s responsibility to ensure this. The point of contention is that I feel the quoting process (for any type of job) represents the following conversation:
“Can you make this?”
“Yes, and it will cost you this.” or “No, and here is why.” Or, as has been pointed out, the really good service provider says “Yes, but here is how you could make it for cheaper if the design permits”
I believe that this quoting process, constitutes the appropriate research by the designer, who need not be required to be intelligent nor an engineer (although it helps to be both ), into if the design is able to be produced, and by what means.

Drawoh, I think I can see where you are coming from, but have to disagree with you, citing Mint Julep’s logic. To use your material example you say “which sheet metal shops refuse to work with” the question would become “why didn’t the sheet metal shop refuse to work with it in that case”.

Case 1:
If the customer went to the stamper then received the stamped part then went to the bender, and the bender broke the part then the it seems the obvious answer as the customer would be pay the stamper, then haggle with the bender for why it cracked, how to fix it and why they quoted on a part that they could not produce (did the customer supply the flat pattern with bending locations and tool callouts and procedures? Why did the bender accept the job if he knew the material callout and that it couldn’t be bent? Was the full material callout actually supplied? etc.).

Case 2:
If the bending shop is a sub-contractor of the stamper, who has quoted a completed product, and they stamp the part and then take it to the bender who cracks it. I would say that the responsibility shifts down one level and the stamper would then haggle with the bender for why it cracked, how to fix it and why they quoted on a part they could not produce. The customer need not know anything about the bending process, the company that is doing it, how much it costs, how or any other information as the stamper has committed to the completed product under their quote.
This, of course would be true for any contractor, sub-contractor relationship regardless of what type of product/service was being provided.

IMHO, it is the responsibility of the designer to define form and material specification to fit function. Only then can a manufacturer that can provide that product be selected. To the statement that “only if you supplied the correct material and bends [would you have no responsibility]” I would say that the correct bends (type and location) should not be supplied at all (by ASME Y14.5-2009 1.4.e) and that the “correctness” of the material would be based on function and could be correct whether it is metal, cardboard, or concrete. If the material is not useable for that specific method of manufacturing then the onus would be on the manufacturer to say that “we can’t actually make this out of this material” and refuse quoting.

Is this flawed logic?

 

[bigTomHanks]

Interesting situation, here is my take on things. Behind every successful product/design are a lot of little failures. Failure is a part of everything that we do and a lot is learned from a failure. I think that everyone involved holds some responsibility for what has happened here. The engineer for not being a manufacturing expert, the machine shop for quoting a job based on a process that they do not know will work, and the bender for taking the work as well. The most unfortunate thing about this whole situation is the way that everyone has reacted to it. It seems like there are a lot of people pointing fingers when they should all be huddled around to find out what to do to make the part successful. Someone here is trying to protect their company/job by not taking a hit for this deal. Fact of the matter is that each company is dependent on the others success to get the end product made. The end product is what will get everyone paid and all should be working toward that goal. There may be structural issues with someone involved in this deal and if they keep this up then I suspect they won't be in business very long because their suppliers will abandon them. I hope everyone works out their differences and the hit for this job is spread to all involved in some way.

 

[desertfox]

Hi Keith1029

I'm inclined to agree with you're logic, the designer is responsible for laying down what the final component should look like and the material grade.
The drawing doesn't normally convey the method of manufacture and nor does it need too, unless the designer seeks a particular method.
The supplier who quoted to manufacture the component had both the drawing and the material specification I assume and so if they or their sub-contractor felt there was a problem, either with the design or material they should have approached yourself at that point.
They have quoted to make that component against the drawing supplied and so thats what you should receive.

desertfox

 

[Cockroach]

The third party vendor, the one chosen by your machine shop to do the bend, is responsible. They have failed to provide services required by the machine shop, hence their customer.

The fact that the bend failed due to material brittleness should have been realized by the third party vendor. I dispute the notion he is not an expert in his field. He supplies bending services in this case, to the machine shop. They should of realized the standard practice is to apply heat to the zone of the bend and fold over a mandrel. The joint is then cooled down in air to room temperature in order to mitigate thermal stresses. The purpose of the heat is to provide ductility and have the material relax during the bend process.

You the customer, are right to ask for the machine shop to supply the piece as quoted. The machine shop is right to ask that third party vendor to pay for a replacement piece and provide the bend. The dispute is between the machine shop and the third party shop, NOT you the customer waiting for the product.

As a professional engineer supplying machine design consulting services and product, my machine shop would insist the third party become good with their services. Ultimately I would loose the monies on material time and you, my customer. But as a machine shop owner, I would not tell that third party how to do their job. A print does not tell the machine shop how to manufacture a product, so too does the print not dictate how the bend should be produced. That area of specialization, recognized to be beyond the machine shop skill, hence them seeking and hiring a third party to do so, puts the onus on that third party shop selling "bending services".

I agree with earlier responses, the third party is responsible to the second party for restitution of material and machine shop services to date of accepting the piece. You as the end reciever of the product are unfortunately, left to wait for resolution the the bend dispute.

Happens all the time!

Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada

 

[drawoh]

I got a call from a machine shop today asking if I really wanted 10-24UNC thread inserts in a part. It turns out I wanted 10-32UNF. I need to figure out how things got switched.

Obviously, if the parts had been delivered with the 10-24UNC inserts, it would have been my own damn fault. I really appreciate that the fabricator was paying attention.

In the OP's case, we have not been told enough about the material and process to properly understand the error.

[ol]
[li]Possibly, the OP's engineer designed the part wrong, or at least, badly. We do not know how obvious or dumb the mistake was.[/li]
[li]The primary vendor failed to detect the fabrication problem. The bending was possibly outside their area of expertise. [/li]
[li]The secondary vendor failed to detect the fabrication problem. Perhaps they were not told all the details. When you get into the multiple expertise things, communications are absolutely critical.[/li]
[/ol]

The vendors bear responsibility for not fabricating the part properly. The designer still is responsible for the original design. If you are designing something tricky, you can always call the shop ahead of time and get comments on your preliminary drawings. To do mechanical design, you must have some understanding of the fabrication process.

JHG

 

[eng1ne]

To me, this has much less to do with 'legal responsibility' and much more to do with, as others have alluded to, "how to win friends and influence people!"

The very fact that a 'responsible entity' is being sought rings alarm bells.

Of course, I don't know the individuals involved, and you can't reason with unreasonable people - but there might have been a win-win opportunity somewhere in this whole scenario. Finding that would have negated any need for finding a responsible party - all parties would have accepted their own responsibility and worked together to achieve an outcome fit for all.

Aside from that and from an objective point of view, the bending shop is responsible.

If I ask for a 1 nano metre radius on cast iron, I expect not just a refusal to quote, but hope for other suggestions.

Perhaps the bending shop were not familiar with the material grade? Perhaps the machining process had induced unanticipated stress?

Several times I have designed machined components that I trusted my supplier would deliver based on the fact they quoted; and several times they have called to advise they are having problems machining certain features. My response would be: thanks for trying and thanks for letting me know; you are the expert, what do you suggest?

Often I either had to change the design, or work with them to find another solution.

But I guarantee that if my response had been: you haven't fulfilled your legal responsibility, you are not the expert you claim to be and I'm not going to give you the opportunity to make any suggestions to resolve it - I would have to go through the whole purchasing cycle again to possibly end up at the same point with another supplier having run over schedule by 200% at a greater cost.