Looking for any machinists or people in-the-know that can provide input on how much it would cost, including material, for a job shop to create the part below. This is purely an estimation exercise and we don’t need to be accurate - I’m just looking for a ball park number.
Essentially, the part is a 0.25" thick aluminum plate that is about 14x10 inches. Features are a 0.125" chamfer on the front face, a 1" hole through the ~center, and then on the back there is a depressed facing operation to accept a hinge mount with 6 holes drilled into that area with tapping. There are also 2 small holes drilled ont he back for magnets. So essentially both faces need to be machined, so this is at least a two step operation.
Again, just looking for a rough guess, doesn’t have to be accurate as I will use this # to price a part that I am making. Volume for the part would be 20 units at a time per order.
Thanks!
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I’m not gonna be able to give you a price but other important details are probably…
-Are the holes for the magnets drilled all the way through, or only part of the way? Are they glued or pressed in?
-How are the two large faces finished? Is that the surface they had when the raw stock was purchased or are they sanded/blasted/etc?
-What are the tolerances on the thickness of the sheet? How about the outside dimensions? And the diameter of the large hole.
I realize no one likes thinking of all those details early on but afaik they do change the tools you use, the raw material purchased, and how the part is made, and all that will drive the price. All those details are things that end up on a print before you can get an official quote.
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Fair ask, thanks.
Magnet holes are not drilled through the entire thickness. The magnets appear to be press fit in? Not sure how that works considering magnets are typically brittle.
We can disregard finishing for now, this is essentially the raw finish out of the machines, maybe after being run through a sander. It doesn’t appear to be anodized. We can ignore the magnet insertion operation as well and just consider the drilling of the holes for the magnets. I’m really just looking for the material + machining costs.
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You should be able to use just a half sheet of standard plate stock You’ll need 2,800 sq inches of finished material, a 48" x 72" piece is 3,456 and accounts for shape drop off and machining loss. Looks like it’s just a door so strength is not an issue. While 5250 series has great formability and welding characteristics, isn’t great for machining (although for something this simple, probably not an issue). 6061 machines really well.
Ball park cost:
So call it $25/part for material.
If you have a drawing in a format they can do CAM directly from, that will save you money as they won’t have to redo.
Run time won’t be much, setup minimal. If the tolerances for lenght and width aren’t real tight (say ± .015"), they’ll be able shear the panels net avoiding machining them out. Each piece will then have temp tooling (mainly edge locating) to hold in place while machining, probably need one sacrificial piece piece since it has through holes (this will allow hole to be machined completely through and and .125" into sacrificial - holes will be milled not drilled), this hopefully can be made from the major piece blanks cut from.
I used to be the Quality manager for job shop in FW, this is typical of what work would be required and goes into bid. So make your guess how long each of these takes to do, then multiply by shop rate, which I’d guess would be $75 on the very very low side, and $100-$125/hr more typical:
- CAD & CAM time
- Work order planning time One time cost if same vendor used. They own the CAM.
- Material acquisition cost
- Material blanking by a shear for 20 pcs and sacrificial part
- Initial set-up time
- Running 40 pieces (20 each side)
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- If hole tapping can be done on CNC big cost savings, if done as 120 separate ops, cost goes up, if fast say 60 seconds per hole part to part so that’s 2 hours of work vs about 10 seconds or 20 minutes of machine run time)
- Deburring edges
- Surface finishing (sanding)
- Final Inspection - very basic mainly edge finish and appearance. Operator on first piece at each step will check dimension.
- Packaging FOD protection
Assumes no material certs required, no other surface treatment such as anodize or paint.
This doesn’t give you a number but will probably explain the sticker shock when you get quote. Short runs are expensive.
@nicksilva @artg_dms This look about right?
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This is a really great response, I appreciate you putting in the time to write out so much detail. Thanks!
I was guessing that the cost would be somewhere in the 150-200 dollar range. However, I entered the .STEP into Xometry and got an estimate of just $60 for a 20 part run using ‘standard’ delivery time (US manufacture) and $35 per part from China if it isn’t time critical. I was really surprised by how low the quote was.
While I worked in China twice for over 5+ years, no ideas how they would cost it out. If material certs are important - good luck. We brought in all our own metals to a bonded warehouse because we didn’t trust them (aerospace).
Right now manufacturing in China has really been hit hard, so prices are probably good.
If you can spot weld the hinge on, you’ll save a lot: no holes drill and tap, no fasteners to install.
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This is really out of my expertise, however some things got my attention.
If you shear cut the plates there will be a “bend” along those edges and possibly a bend in the overall piece.
May be laser / plasma cut?
Drilling, tapping, etc. will be fast on cnc like the Haas.
Will require some kind of fixture to hold plate.
The accuracy / tolerances of the raw plate will determine how the fixture is made and will affect the accuracy of the holes drilled. And the consistency of one plate to another.
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Protolab quote came back at ~185 bucks a part. This is more in line with what I was thinking.
