Front End Module

[Chr1s]

Could anyone with front end module experience give some of the pro's and cons of it.

Is there a way to get around having a million and one part numbers due to all the different options ?

On vehicles with open frt architecture how did you control the rails.

Many thanks,

 

[GregLocock]

What tolerance do you think you'll manage on the rails? (in x and y)

You have to release one part number for each variant, otherwise you won't be able to control your stock.

Pros: makes life easy for the assembly plant. You may be replacing expensive labor with cheap, or offshore, labor.

cons: you are paying someone else to do the assembly plant's job, so you are reducing your potential profit. The engineering may not be done to your standards. Any changes will cost you more eg run-out of old level parts will probably be charged directly to the change, rather than using a draw-down plan. In my experience full service suppliers are not.

From a more theoretical standpoint, assuming you are using a perimeter frame, the structure will not be as efficient as if the equivalent metal were part of the body itself. The tolerance at the bolted joints, and the crash breakaway requirements, are both going to militate against efficient joints.



Cheers

Greg Locock

 

[Chr1s]

Currently the rails are held to +/- 0.5mm using the current crossmember, once that is removed they spring up to 10mm.
Ideally we'd like to removed the crossmember to be able to access the engine compartment. However the BIW is suppost to be carry over, with out a big re-design the structure is lost. So it may turn into half hearted module, leaving the crossmember in place.

 

[GregLocock]

Ten is a bit much. Think about how you will maintain front to rear axle alignment with a mounting system that can accomodate that much error.

To be honest unless you are redesigning the whole thing I doubt you'll get much value from a half-way house.

Cheers

Greg Locock

 

[Chr1s]

Where do vehicles that do not have a front crossmember get the structure to control the rails ?
I know there are vehicles out there that get built with open architecture.

 

[GregLocock]

Ours does, for example. It has two longitudinals poking foreward from the firewall, with nothing of any great integrity between them until the x members get bolted on. Maybe you could hold them apart with the bumper bar?

I don't know how they control it, but it is done somehow, much tighter than your tolerance.

Cheers

Greg Locock

 

[sean01]

I know that a well known german manufacturer uses the process that you are referring to - although I'm not sure if the either of the two vehicles I know its used on are available in the US yet.

Basically the modular front end has a carrier arm across the front of it , which bolts to the front longits on assembly to the main BIW- the entire front end module is held to a tolerance of +/-3mm. Prior to assembly the longits are held in place in the assembly fixture itself, and the front end module is brought into place on a special lineside assembly 'crane' with positioning sensos.

I would agree with Greg though that you have to design for this process from the beginning - not only in terms of the actual components themselves - but also the manufacturing process as well. Any re-design that tackles one and not both is doomed to fail.

best wishes


sean