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Low volume exterior trim processes

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RCDLtd

Automotive
Jul 18, 2003
153
Is there anyone that has previously researched and crunched the numbers to determine cost effective, low-volume processes for plastic (or composite) exterior parts.

For instance, taking a mass-produced PP, Injection molded bumper as a starting point and looking for an alternative process to replace that bumper with a new deisgn for a total volume of around 3000 vehicles.

The new bumper must use a carry-over fixing strategy so the complicated B surface, requiring all the sliders, must carry-over to accomdate.

The volume, to me, seems is too high for traditional hand-layup methods to be cost effective so I've concentrated on "molded" options.

The volume, to me, seems too low to support expensive injection mold tools so I've looked at low-cost tooling options.

Where I've got to is RRIM using PU. The tooling cost is mid-priced so a good start. The molding price is very reasonable so it starts to look even better. But then there is the painting and finishing and it seems that so much hand finishing is required to get the bumpers to the standard of the OEM PP part that the piece price goes through the roof.

Anyone have similar experience with RRIM finishing or do I need to find another supplier?

Any alternative processess that can be suggested to be worth researching?

Thanks in advance.
 
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Hi RCDltd,

We are currently researching this method also at the moment for a small project of a similar volume.

Our experience of the RRIM process seems to be similar to yours - and ultimately we have abandoned its use and gone to paint spraying of a semi-automatic lay-up composite structure. We bond the b-surface fixing detail onto the back of the membrane prior to curing in an autoclave.

Another technology we are researching is the use of a vac-formed part. In particular vac-forming of a colour matched membrane. Then similar to the composite method - we bond fixing detal onto the back of the surface. While this is in its initial stages of development, providing the design of the bumper (shape and depth of draw) can be tailored to suit the process, we are confident that we can install it to a small scale production run.

A sublte point that we had to learn when investigating and developing these processes though was to make sure we fully understood the way in which money was being accounted for - in one particular instance for an exterior bump strip we thought that continuous moulding was too expensive - until we realised that our methoud for writing of capital expenditure was over 6 months as opposed to 8 years !

hope this helps


sean
 
Sean,

Thanks for the feedback, it gives me a bit of confidence that we haven't missed something.

I to have looked at an acrylic capped (and coloured) vac forming process but unfortunately we can't alter the form sufficiently to produce in this manner. It looked very good, and with the acrylic capping there is no chance of seeing any witness lines on the A surface from the bonded B surface features.

We have just started to look at a composite route similar to the one you describe, I'm not yet convinced about the low speed damagability aspect though but it is early days. Do you know of any current production vehicles using this process on bumper facias?

I haven't completely given up on RRIM yet though, I'm now looking at the possibility of a resin B surface tool, it offers a reasonable saving on the overall tooling cost.

Thanks again.
 
We are currently supplying pieces like that by thermoforming. It is good for low volume because of the tooling costs and part quality. Because you only need a 1 sided tool it is less expensive than other processes. We are painting the parts rather than using film so it is easier to design the part. Also there are fewer inventory and quality problems. We have made a couple of new brackets and added fastening points to the backsides where needed.
 
Hi RCDLtd,
I believe you replied to a thread I posted yesterday re: help on a cad/database program. Can you contact me directly at peters@hawaii.rr.com on this? Thanx very much ,Look forward to hearing from you.Peter
 
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