The foundry business has been under siege for the last ten years, perhaps more. Actually here in Philadelphia, in the 60’s there were at least thirty major foundries. Now there’s only 1 major producer. But the casting procedure is growing on a worldwide basis. It’s the spine of producing the great majority of our metal products. Let’s have a quick look at the benefits and drawbacks of five casting processes.
1] Sand Casting
Sand casting is among the oldest processes.
As the name indicates. A fine kind of sand is utilized as the mould. Metal is poured ( gravity feed ) into the mould. After the material has cooled, the frame is released and the sand falls away. Leaving the parts to be ground and cleaned. This sort of casting is the most basic of all. But it’s got an incredible advantage. This is the least costly and perhaps the sole way to make huge castings. Castings that weigh fifty lbs, up to thousand of pounds are made using this strategy.
2] Investment Casting
Compared with sand casting, this process yields a rather more exact, complicated part. IC process has been utilized for centuries to make jewellery.
To make an investment casting, a tool is machined out of aluminium. Then wax is injected into the tool. The tool then produces a wax model that’s a precise copy ( with some allowances for shrinkage ) of the part to be made. The wax is then assembled with other waxes on a tree. Dependent on the scale of the part, each tree becomes ten – two hundred pieces. After the tree is absolutely assembled, it is dipped in five coats of ceramic slurry.
After the ceramic stiffens, the wax is soft out of the tree. Now you have got a tree which is prepared for amalgamate to be poured in. This is a gravity fed process which is acceptable for an array of alloys – ferrous and non-ferrous. Investment casting gives you an exceedingly definite casting with a particularly smooth finish. It is glorious for making parts that weigh less than ten lbs.
3] Graphite Mould Casting
This is also a gravity feed process with graphite getting used to make the molds for this process. A hole ( negative model of the part ) is machined into 2 big blocks of graphite. These 2 halves are aligned to each other and placed in a semi-automatic press. The method yields precision castings which are wonderful for huge thin covers and bases for instrumentation. So saving the price of intensive machining.
4] Metal Injection Molding
This is a comparatively new process ( thirty years of age ) utilised for making tiny parts. The tooling for this process is virtually precisely like tooling for plastic injection molding. Once the green part has been moulded, they’re debound and sintered. This process is making headway in the medical device field. It’s major downside is that tooling is really dear, $25,000 and up. However it does give you great precision and a comparatively low piece price for high volume elements.
5] Pressure Die Casting
Steel toughened tools are extensively utilized for this process. $25,000 and more is a normal price for a die cast tooling. It is by a large margin the most inexpensive way to cast aluminium, zinc and magnesium parts. Die casting is a very automated process and so awfully capital radical. But similar machines are found internationally. Making the die casting process a world business.