Hey, a little while ago we went through all our scrap in our machine shop and have quite a lot of it. We have a few options but I saw a few teams melt down and cast their scrap and I think a few even make it into fresh stock and was curious as to if they would say it was worth it compared to selling the scrap or sending it off to a recycling company. Also we do have a sponsorship with an aluminum recycling company but to my knowledge it’s mostly/only for aluminum cans and I don’t know if they would accept small bits of metal and chips from the lathe and mill.
My main thought is creating any size block for milling and maybe try making smaller 1/4 inch plates from scrap. Haven’t run the math but this might even save some money and time compared to ordering stock.
For reference, we have a 4x8 CNC router that can handle pretty intense surface milling operations but we also have a manual mill for smaller parts.
Have any other teams tried this? If so how did it go and what did you do? And does it seem worth it to try?
I would recommend selling it to a scrap company. Give your aluminum recycler a call—I’m pretty sure they would be happy to accept aluminum chips as long as they were not intermixed with other materials.
In general it is very difficult to control the casting process sufficiently on a small scale to get quality materials. It’s also quite unsafe given the temperatures involved.
We have a foundry as a part of our Industrial Arts Program. We have used it in combination with 3d printed molds for wheels, hubs, and a few oddball rough castings to make custom items over the years. Unless you have all the equipment on hand, it isn’t worth the time and effort that goes into it. If you have all the equipment (sand, tamping equipment, furnace, safe location for pouring, crucibles, full safety equipment, and more) it probably still isn’t worth it over just buying new stock. If your chips aren’t clean, you won’t be happy. It takes a LOT of chips to make something worthwhile and they are very difficult to get into the crucible cleanly.
If you decide you want to pursue it still, you will need chemicals to ensure that you don’t have contamination, porosity, and other issues crop up. Some say borax is enough, but it typically isn’t.
That said, we do have a nice board that we made that shows the steps to get from 3d printed to a finished hex hub when Andymark was out of stock many moons ago. By the time we finished it they were restocked and have one day shipping…
In response to both, the school does not have many of the materials required so I do see the issue there, I personally have all the materials needed and have done some hobbyist foundry work which is how I thought of it in the first place. We are fairly well funded but honestly I do see safety as a potential concern as well assuming we would have more than just 1-2 students working the foundries. Our team is also generally huge and safety and material control is already a challenge for us in the machine shop.
About material, we have a large mix of both chips and larger scrap, right now there’s about a HomeDepot bucket of fluffy lathe chips and about half that of smaller mill chips. The majority of material comes from a bucket with roughly 50lbs of various scrap pieces. I don’t know overall how clean it is, I know steel and aluminum are kept separate and we haven’t done paint yet so that’s not an issue either, how clean would we need our scrap to be for a company to accept it? Would patina/paint be an issue? And what about parts with welds as we have a lot of welded parts. If that’s not an issue than I suppose a company is a better option. I was told however that the exchange rate for aluminum scrap isn’t great per pound however, is this something y’all have had experience with? Part of the reason I considered it was we’re large enough to have a dedicated group to this and therefore the time trade off isn’t a major concern, but I suppose that doesn’t matter when McMaster and AndyMark have next day shipping.
Any volume a FRC team produces (plastic, aluminum, or otherwise) pales in comparison to even the smallest machine shops. Extrusion is difficult to keep tolerances on and as has been mentioned before, extremely hard to get the desired material properties when foreign matter is involved.
If you want to use this as a learning experience for some interested students/mentors that’s perfectly fine. The economics are not there for doing your own reprocessing at any meaningful amount, even if it were all heavily subsidized by the school (existing equipment, infrastructure, expertise, power, etc).
If it were me I would just take the scrap to a recycling facility and buy new stuff.
Pick one or two hard things, outsource the rest. Unless I had a large contingent of students intent on metallurgy (at scale none the less, or at least larger than jewelry) this is not one of the hard things I would pick to be competitive. Even then it is probably cheaper and easier to go on a extended field trip to an actual plant.
When I worked at a sign company we pitched the chips straight into the dumpster by the bushel every day- probably not proper, but it was mixed material. Offcuts for polycarb, acrylic, aluminum, polymetal, etc. were all were separated and sent out for processing (some at a loss for the company). FRC’s impact is pretty small by comparison.
Obviously teams should still take effort to reduce your overall footprint, but don’t greenwash yourselves either.
They’ll take it no matter what. You’ll get the same rate either way as you have no way to guarantee the alloy you are scrapping with certainty they would require. Paint might knock it down a grade or two. But the amount of money you’ll get won’t be enough to make you happy, it’s more about not putting it in a landfill
If you don’t have a relationship with a recycling company and you want to recycle, any machine shop near you will have a relationship with a recycling company. Contact them and ask if you can get their info, or perhaps simply ask if you can give them your scraps in exchange for a small discount on parts you can’t make yourself.
Edit: I should add, when I was working at a machine shop, this company was pretty low volume in terms of scraps and we still had the recycling guys come every 2 to 3 weeks. Every job was large volume, but the company mostly cuts down stock into more manageable pieces, so the amount of material turned into chips relative to shipped out is really low.
To try and respond to some of these comments (thank you guys this has been very helpful!)
Now that I’m looking into it, would we just dump the scrap off at their location or do we need to drop it off somewhere, also until we do inevitably get rid of it, any suggestions for storage? The HomeDepot buckets and bins aren’t super ideal and we probably need something a little more permanent.
And (re)cycling (haha) back to recycling companies since that’s been a common suggestion, we are sponsored/in partnership with Novelis and I was told we can essentially trade in aluminum cans for discounted or free stock, I imagine I could talk with them to arrange a similar deal with regular scrap and if not then I’ll look around the area for some other groups.
And another thought for the original topic talking about melting down and recasting material, it likely would be more of a passion project and not something integral to our team, we really need stuff for members to do especially in the off season and there was talk about producing our own stock from scrap during the off season so we order less and turn all the odds and ends into useable plates or rods.
Rods where the other big topic since for some reason there is a phobia of buying round stock for the lathe and as of now I’ve been turning down a lot of hub shaft for any round parts, which I hate doing.
The problem here is making the resulting material as useful as purchased stock. Contaminants are an issue (so you actually get 6061 out for 6061 in) as well as uniformity in casting, which is difficult to achieve in small batches. Commercially produced aluminum is made in huge castings that are then finished/extruded to get consistent material composition. In addition, nearly all commercially sold extrusions (including bar/rod stock) are tempered (T6) which is yet another processing step that is hard to do in-house.
What? Why? Round stock is so much easier to work with in a lathe than anything else…
According to my friend, one of the material science labs at my university bought a humongous block of aluminum and then spent >$1000 in water jet time just to cut it into rods. Somehow it was supposed to be cheaper than just buying the rods themselves.
Furthermore, it set us back a week since we were forced to wait to cut our bellypan and intake plate after our material already arrived (and then it still cost us $150 for the school’s machine shop to cut them).
Trust me I don’t like it either, and fortunately half ish of the parts made in the lathe are made from hex shaft, it’s only been a few this year that require an internal hex shape and/or larger OD features and what we had on hand was hub shaft.
The reason (I think) we don’t order rod stock is one, why this whole thread exists, we’re worried we’re gonna buy a lot and waste it furthering our ever growing pile of aluminum scrap, and two the team does spend a little too much money elsewhere and then when metal stock tends to be kinda pricey people start second guessing the need to buy it. In the end however they’re not the ones machining the part so I get why they don’t have a problem with a bijillion interrupted cuts while turning down hub shaft.
You can’t avoid this unless you don’t do any machining at all, I don’t see the point.
If you need to get rid of your scrap, contact the company you’re already working with, if they can’t help here then they should know someone who can and will.
Man, as one of the machinists on our team I wholeheartedly agree, the thing about a 120+ member team is that the departments are so separated and know increasingly less about each other so many of them have very little understanding about what goes on in the shop, for them scrap just means waste or failed parts
Well we already have something like 10 makerbot method X printers and a fancy big one we can’t even use/don’t want to so I mean why not lol.
Yeah it’s a weird dynamic, honestly the pressure to deal with scrap comes more from the school admin, it’s just that the higher leadership of the team and other random members sorta agree with them. This year the CNC router is gonna get used way more so I think they’ll learn to relax a little bit when we start burning through plate stock.
This whole scrap thing is really just one of the weird effects of having most members not understand machining
I’ll take the big one. The Makerbots are scrap (see the Makerbot Thread), so if the team’s complaining about scrap, getting rid of those would be a start.
This is something that can easily be set up. Also, you mentioned you’re using something like Home Depot buckets? That’s a bit small, perhaps look into a larger more consolidated form of storage to make admin happy (as a sort of “we’re working on it but it will take some time” step).
ngl, y’all really need someone to give a talk on machining at some point. Everyone needs to know how it works just to understand the limitations.
I mostly do mechanical design and I’ve spent hours and hours studying machining techniques to further my understanding of design so that I can design things that are easy to make and waste less material.
