I have been involved with a number of metalwork design projects lately and I'm increasingly finding myself asking for quotations for small prototype runs (often one-off jobs) to verify the validity of a design.
The kind of items I'm talking about are small items like electronic product enclosures, mounting plates for screwing PCBs onto etc. Items that would probably fit into a shoebox and are made of machined or folded plastic, aluminium, mild steel. Not heavy engineering, so no welding etc.
Question: How would a large custom metalwork manufacturing company (1000+ employees let's say) interpret my design files and what steps would they be likely to take in order to estimate costs for a small run of prototype units?
If I give them a 3D STEP file (output from Solidworks for instance), how would they evaluate the complexity of the design and convert that to a list of costs such as tooling charges, material costs and setup-time costs etc?
What I think might happen:
- They load the STEP file, find the smallest stock material size that fits the design - this gives the materials cost.
- An engineer analyses the features in the design and does the CAM toolpath generation and other operations at this level. This becomes NRE tooling costs and production line job-change costs.
- Shipping costs are estimated based on the final object's size, shape and weight.
But this sounds like it would take a long time to organise and would be expensive in terms of man-hours, which they would want to avoid since I haven't given them any money yet. Quite often the quote comes back to me within a couple of days, which suggests that they might simply be "eyeballing" the project, guessing the price and adding a wavy-hand percentage to cover the guesswork.
How does this kind of thing work in this industry? I have asked one of our smaller manufacturers but they seemed reluctant to answer this sort of question as if it was some kind of closely guarded secret. I want to stay on their good side so I stopped asking :)
I'd like to hear details from those with experience in custom machining, sheet metal fabrication (stamping, folding etc) and other related activities.