Notes from Windward: #62

Solar Powered Induction Foundry

     A foundry melts metal to pour into molds in order to create things. For six years before our move to Washington, we operated a foundry in North Las Vegas, Nevada. When we moved, we packed up that equipment and brought it north. Most of it is still stored away awaiting the construction of a proper building in which to house the furnace and set up the equipment.

     Most metal is melted using a flame of some sort, whereas induction melting uses an electrical coil to induce an electronic field in the metal. This field is turned on and off two thousand times a second, which has the molecular effect of bending the metal back and forth thereby heating it.

     Induction heating has a number of key advantages, notably speed, purity and efficiency. Our seventy kilowatt furnace can take thirty pounds of brass from room temperature to pour tempuratue in six minutes. By being so fast and by not blowing a flame on the metal, the induction melting process causes very little oxidation of the metal or time for the lower boiling constituents like zinc to gas off. And since the energy is going into melting the metal instead of heating a large volume of exhaust gases and a large furnace assembly, induction uses only a fraction of the energy required to melt a pound of metal in a combustion furnace.

     In Nevada, we used a diesel powered 100 Kilowatt generator to provide electricity for the furnance. The generator produced three phase alternating currrent which the unit converted to direct current internally. Our plan now is to go solid-state usuing photovoltaic panels to charge a battery array. That will allow us to by-pass the massive rectifiers which are literally the size of hockey pucks and waste so much energy that they have to be water cooled.

     It's going to be really nifty to be able to cast sculpture by harnessing the power of the sun.

     There are two key uses that we have in mind for the foundry: artistic castings and equipment salvage.

     Because of the ultra clean metal that the furnace produces, it's ideal for casting bronze art work, and having casting capacity on site would provide a key resource to people wanting to express their artistic talents in a medium that isn't readily available otherwise.      Because of the electronic nature of the heating process, it's not subject to the temperature limitations that come with flame based heating systems with the result that induction can melt just about any metal you care to put in the crucible. That means that we can take a scrap car and use the brake drums to cast a dutch oven, the steel gears to cast a replacement part for the tractor or the aluminum transmission housing to cast a pump housing. The great thing about induction is that it just doesn't care what you put in the pot; it will melt it in short order.

     There's a world of old equipment out there that's going to waste because key parts are no longer available. Sometimes there are work-arounds available; the rest of the time you have to start from scratch, and a foundry is where you do that.

Solar Powered Induction Foundry

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