What kind of furnace is used to create alloys for aluminum die casting?

I have only been able to find information about how to create alloys or how to process them afterwards in the die casting process.

Any insight on which kind of furnace you use to create the initial alloy would be highly appreciated.

  • $\begingroup$ Are you asking about commercial furnaces or lab/personal furnaces? $\endgroup$
    – hazzey
    Jan 19 '16 at 21:31

Normally the production of specific alloys is a fairly specialised process and they would be bought in as ingots or other stock types from commercial manufacturer rather than being made as part of a manufacturing process. This is as much about the quality control and analysis required to produce a given alloy to a specification as the actual mechanics of melting and handling it.

When aluminium is refined from bauxite it is reduced by electrolysis, therefore aluminium refining plants are generally sited close to an economical source of electricity like a hydro-electric power station.

Once you have ingots of metallic aluminium it is relatively easy to melt and both gas fired and induction furnaces are commonly used. Aluminium is usually melted in a refractory ceramic crucible although steel crucibles can be used in some circumstances.

In order to produce a specific alloy you first need to know the composition of the metal you are starting with and then add the appropriate alloying elements in the correct proportions. Depending on the process flux may also be added to aid in separating out oxides and exclude atmospheric gasses (although aluminium is self-fluxing to a certain extent, in the sense that is quickly forms a tough oxide layer on the surface of the molten metal which is effective in excluding the atmosphere ), it may also be necessary to add material to scavenge unwanted impurities and (especially in the case of aluminium) to remove any dissolved gas.

Aluminium furnaces can be very simple indeed although, for obvious reasons the degree of sophistication will depend on the scale of production and the quality required from the finished product.

One special case is where magnesium is a significant alloying element, in this case the very high reactivity of magnesium requires special safety precautions as molten magnesium can burn uncontrollably in air and as such it is not generally wise to melt high magnesium alloys in an open furnace.

  • $\begingroup$ +1. Degassing is critically important to aluminum melting and pouring, as liquid aluminum has high hydrogen solubility but solid aluminum does not. As a result hydrogen comes out of solution in the final product resulting in microporosity and hydrogen embrittlement. Both of these generally result in high scrap rates. $\endgroup$
    – wwarriner
    Feb 16 '16 at 21:00

Aluminum is a metal that can be used in die casting to make parts easily. Many die casting techniques like permanent mold casting and sand casting are used for casting aluminum. Permanent mold casting is highly repeatable and helps to decrease the spin balancing processes and secondary machining operations. On the other hand, sand casting uses temporary molds that are made from wood or metal, making the tooling investment very low. However, per part prices are higher in the case of sand casting than permanent mold castings.

In the case of permanent mold casting techniques, the cycle times are short and this will decrease the per part price. However, tooling costs can be very high in this method. When compared to sand castings, permanent mold castings cool faster, offering a finer and uniform microstructure to the parts. This will help to boost the mechanical properties of the product by about twenty percent.

Gravity fed permanent metal molds is used these days to manufacture near net shaped parts from different alloys of aluminum. However, it is the duty of the die cast designer to ensure that it is profitable and possible to use permanent molds to manufacture the part. The die cast company should know the limits of the casting method to take full advantage of this die casting technique.

Source : http://pacdiecast.com/aluminum-die-casting/permanent-mold-casting-for-casting-aluminum-alloys/

  • $\begingroup$ -1. Doesn't address the question "What kind of furnace is used to create alloys for aluminum die casting?" It just explains casting, which is not what the question asked. $\endgroup$
    – JMac
    Apr 17 '17 at 14:39

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