Oh, we can do this! Extrusion Part 2
So, we’ve decided that our Empire Lamp was going to be our first big project out of our new shop. The will was always there, now we had to figure out the way: sourcing an extrusion company and paying for it. Neither one was going to be a small feat.
This extrusion was a non-negotiable if we wanted to make this lamp. It makes up the body of the lamp, the design’s most distinctive feature, and there really is no other feasible route to making the shape but with this process.
When we said earlier that much of the design was based around how it would be manufactured, this is the primary element we were talking about.
“What is an extrusion?” It’s an industrial manufacturing process, most often used with plastics and aluminum, where stock material or “billet” is heated to a high temperature in a furnace to make it more pliable. The billet is then forced through an opening called a “die” using a hydraulic ram, at great pressure, to make continuous lengths of material. The die being a cross-section of the desired geometry. These continuous lengths are then cut to specific lengths at the facility and shipped to a customer that will often modify the lengths by machining further features into the shape, such as holes or slots, to make a finished product. This is a very efficient and accurate process- no material is wasted.
The fact that we are a very small company that needs a very small quantity of material manufactured and this is a large-scale process mostly used to make large volumes of parts for large companies, so when quoting, extrusion companies want to know how much material you want to run, which is designated in tons. To make enough lengths of extrusion to make 100 lamps, we needed roughly 1/2 ton of material extruded, but most companies have minimums of 2-5 tons. The first few bids we got were hilariously expensive.
Several quotes later, we found someone who would work with our little 1/2 ton job, would ship to Maine, for a reasonable price. Finding this good partner, funny enough, involved going back to Cali.
Ok, so we found someone to do it! From there the process involves having a custom die made of our shape, usually out of a tool steel of some kind and then pay for the stock/billet material that will make the extrusion.
Here is our drawing to them and the confirmation drawing we received back with our “OK to fabricate” signature. Then we crossed our fingers it gets here without damage, and toast to
“Yeah, we can do this!”
Our original design had a wall thickness of 3/4” (.750”), but we were informed that this would make the part too heavy for the cooling tables that the lengths would roll onto after extrusion.
So we had to modify our design and reduce the wall thickness to 7/16” (.4375”). We just needed enough
thickness so that we could machine back at our shop a rounded-over edge on to the top and bottom of the body and we felt like 7/16” was enough to do that.
Two months later, on a beautiful fall day here in Maine, 108 feet of extrusion cut into 6 foot lengths arrived in our driveway. After high fives, we loaded them in the back barn and we now feel on our way, with a dream realized, and lots of really cool work ahead.
So, we got to work immediately.
Here is our first cut and the process of machining a body to be ready for the polisher: