khoeysr

I always thought that most, if not all, of the parts in a GM vehicle were produced by someone other than GM (including their subsidiaries, such as Delphi back in the day). Where I am going is although Bowling Green puts this stuff together, they are assembling other people's parts. Many of the problems that we are hearing about may be pinned on the suppliers.
The only thing on the C7 that is built at BG is the aluminum frame, and supposedly even that has some subassemblies.

So am I close, or just way off here?

BlueOx

khoeysr

I guess I am OK with the parts thing.

So maybe GM should get less heat for the occasional bugs we are hearing about?

Glen e

not really..it's gonna happen, but QC checks and parts reviews should catch any batches that are bad..Chev is still ultimately responsible TO YOU..

talon90

Nope, you are pretty spot on. Bowling Green is an "Assembly Plant" there are parts plants, manufacturing plants and assembly plants. Some of the plants are more vertically integrated, some do their own stamping, molding and sub-assembly work. Bowling Green is adding verticle integration but it is at a low level compared to some. They paint parts molded and supplied by other vendors. They do make the frame (previous models they finish assembled the frame) but they are primarily taking purchased components and assembling them in to a Corvette.

There are many levels of QC always taking place but to maintain an efficient operation the norm is to move as much of the inspection and non value added work as far upstream as you can. The expectation needs to be that a supplier can and is doing what they signed up to do. Too much reliance on that upstream process can lead to problems (not saying that is the case here) but you must try to give your vendors the benefit of the doubt.

$$$frumnuttin'

partially correct. There is another faction not to be overlooked. Engineering Proveout. You must first realize a car is a collection of systems....you know; braking, exhaust, engine, chassis, body, and so on. Before Bowling Green ever gets into their role, all of these systems had to be proven to work, AND...here is the big one...had to be proven to work TOGETHER! That is, with no glitches, no cross talk, no interference with each other's function. And, they have to do this under a myriad of conditions: cold start, extreme heat, high speed, continuous operation, heavy duty, high mechanical stress, long term exposure, intense weather, high altitude...you get the idea I'm sure.

The Catch 22 is these functions have to be proven out for the most part on prototype parts and mocked up systems/test vehicles. The assumption is, if a part meets specification then it gets released. This is true for all cars in all car companies. However, a prototype part does not represent the part as manufactured under high volume production. This is where the glitches appear, such as poor dimensional tolerances, stresses in plastic parts, lubrication issues under extreme pressure or temperature (high and low), line-to-line fitment issues, fastener torque/tension issues, and so on.

Each part is "owned" by a Product Engineer back at GM's Tech Center. He, along with the supplier of said part, work together to design a component to meet the vehicle intent by creating the prototype part, then testing it under simulated vehicle test conditions in the laboratory and/or on test mules (past or current vehicles) as part of the 'system' I mentioned above. At some point near the final approval deadline of all of these components it becomes time to work with the factory to determine how all of it will be assembled. On a brand new 'platform' (C7) 1000's of issues come into play. The entire assembly line has to be re-worked. I'll stop here, because I think that point has been emphasized and described elsewhere.

I hope this helps you understand how complex this whole business is. I left out all the approval processes up and down the management totem pole, the influence of Styling, the battles between Purchasing trying to control cost against the wishes of Engineering to input the latest materials and systems, and so much more. But it is such an exciting industry, even more so for those working at GM on C7 and its suppliers.

Jerry
35 years automotive Materials Engineer

Macguy

Thanks for this info, interesting stuff. Then there are the software issues and integration with the h/w, complex business making an auto, esp. something like a C7.

zipcode

Very informative to those not in the industry. Thanks for taking time to share this

VIN666

And then you need to consider that each and every little part that gets supplied by someone gets pressure to be cheaper / lighter / better all the time.
Suppliers have sub-suppliers, those have raw material suppliers and so on and so forth.
If you were to draw up all the organizations involved in one single car, your head would spin. That little graphic up there covers maybe 5% tops.

torquetube

The buck stops with GM. They spec the parts, select and qualify the suppliers, and are the final integrator.