Defining Rework in the Prototype Stage


Randy Stewart


Before I ask my question I'll fill you in on the company. We are a low volume production and prototype supplier to the B3. We design and manufacture automotive body stampings. Part of our responsibility is to prove out production processes so we will utilize experimental means if requested. Additionally engineering change is our middle name we may incorporate as many as 6 in a part in a day. My question is concerning rework. I'll give you an example: We were making support rails (left & right hand) and found that the part design (customer supplied) was not feasible, we produced the tooling to make the part (fit & function) but it could not be manufactured to original design. We were given concessions and modified the part design on 1 hand, re-cut the tooling and proved out the process (customer paid) however, the customer had no more funding and would not pay for the re-cut of the other hand so we developed a hand rework process to correct the parts (remember this is prototype). The re-cut hand took 2 hours of hand fab to be qualified while the other hand took 8 hours of hand work to be qualified. Is there any rework here??????

Due to the prototype environment we do a great deal of hand fabrication because the customer does not like to pay for secondary tooling (flange, trim, hem dies, etc.). To what extent would you classify rework. Say a fender takes 3 hours to fab on an average, a job (different fender) comes through that takes you 7 hours to fab on average due to the dart depth and radius. Upon investigation you find that the dies are giving you the best part possible within the process limitations. Would you consider the added 4 hours rework???

All suggestions and ideas will be greatly appreciated.
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Good question!

I'm interested in the replies you get on this. I never considered 'rework' as applicable to the prototype stage before.

Randy Stewart

I know Marc, but when your deliverable is a prototype part it becomes your finished product. Here's another example: We are usually supplied the steel/aluminum to make the parts by our customer. A normal allocation is that we will use 20% of the material in the die prove out stage so if we are required to deliver 200 parts we would be given material for approximately 220 (I know simple math). Now, if due to poor die design we go over the allocation (basically scrap) it needs to be accounted for.:frust: :bonk:
You think this is different, try fulfilling the R&M requirements for a die design (not the die just the design) or kirksite tooling (prototype)!!!!!:confused:


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Yes - I understand where you're coming from and your logic. That's why I posted my response and why I'm particularly interested in responses from others. There's always a different way to look at something. You may also have noted I changed the thread title to reflect this.

Alf Gulford

Seems to me that what we're calling 'rework' here is actually a part of the normal and expected process, as opposed to taking an actual bad part and making it good again.


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Initially, I agreed with Alf's thining here, but then another thought came to mind.

So a little thinking out loud....

I go back to old time definitions of rework/repair....

Rework - performing additional work to a part to return it to an "in tolerance" condition.

Repair - performing modifications to an unusable part to make it usable.

Sounds like you do more repair than rework.

But if your business is prototype development, Alf is right, just part of the normal flow.

Did I muddy the waters?


Randy Stewart

No I don't think you've muddy the waters. What all of you have said is what I've been pondering. I may be wrong (wouldn't be the first or last time!!) but if we focus on what is our deliverable I think the excessive repair falls outside the "normal" process. Once a system/process is designed and established I feel that we should have some type of baseline to perform to. A minimum standard so to speak. Without that everything becomes foggy and you can't hold anything accountable. Just as "quality" is a moving standard or a bar that is raised all the time, our "minimum acceptable craftsmanship needs to be established. That's my take on it anyway. I may be trying to draw that line in the water instead of the sand here, but I feel that if there is nothing to compare it too then how can I ever establish some sort of continuous improvement?
Thanks for the discussion folks. This is a topic that I really want to look into and try to define.

M Greenaway

I am thinking that the scenario you describe is not re-work, it is simply additional processes to produce an acceptable product because the initial or primary process is incapable (for whatever reason), i.e. it is part of your normal production process.

Re-work stricly speaking is a disposition of non-conforming product. I would say that your product is not non-conforming because it is not finished. As it seems you cannot perform corrective action (because the customer wont pay ?) I cannot see what benefit calling your product non-conforming, and your subsequent actions re-work, will give you.

Dont think there is a right or wrong answer on this, just a matter of how you see it, and how you feel this extra work is best handled.

Randy Stewart

I cannot see what benefit calling your product non-conforming, and your subsequent actions re-work, will give you.
Good point. I have been focusing on a departments/processes output or their deliverable. I will have to break it down and identify the actual benefit. On the other hand, just because I can use a non-conforming panel/part as tryout in the next operation or develop dunnage with it, doesn't make it a "saleable" item.

Randy Stewart

Thanks for the input, it gave me something to think about. We do have operations where the "rework" is classical (i.e. N/C Mill the 2nd time because of bad program, improper laser proveout, etc.). However, and I believe this is where my hang up was, the area of what I have defined as "lost time/oportunity". This would include the time the additional hand work requires and the affect it has on capacity issues of subsequent jobs and so on.
Now the task is to identify the classical rework and get a handle on it. Once again thanks.
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