Installed capacity of 600 Metric Tons per annum of Shell Moulded Casting / Croning and an expansion capacity of 1500 Metric tons per annum.
Manufacturing shell moulded castings right from 350 grams to 18 kilograms per piece. Maximum casting dimensions: 800mm(L) x 500mm(W) x 460mm(H) Ideal for Complex shapes and high reproducibility.
The shell moulding process begins with the creation of a pattern. Different foundries use different techniques to produce patterns, but the goal is essentially the same. A pattern is an approximate replica of the part to be cast, taking into account projected shrinkage and other demands of the process. To create a two-part shell mould, in which two halves are combined to create a full mould, two patterns must be produced. One will create the bottom half of the mould or the drag, and the other will create the top half of the cope.
Next, the pattern needs its vital sister part: the core box. The core box is a tooling that forms the core, which then fits inside a mould so the casting can have a hollow cavity in the middle. Core boxes are created through a process very similar to that of patterns. Again, the core box (and the resulting core) must account for the metal shrinking as it cools in the mould.
Once the core box and the pattern are ready, it’s time to get ahold of some resin-coated sand. When heated to the appropriate temperature (around 550 degrees F), the resincoated sand grains bind together and begin to set. The core box is filled with sand and left to sit while the sand bonds and solidifies. Once enough sand has bonded against the walls of the core box, the rest of the sand is poured out, leaving a hollow core. Similarly, the pattern is heated to an appropriate temperature and covered in sand. The sand-covered pattern is then left to sit until the sand has bonded. Usually, the sand walls of a shell mould will be between 7 and 8mm thick. When both the core and the shell mould are cool and ready to go, they must be assembled. The mould is removed from its pattern and the core is removed from its core box. Then, the core is inserted into the drag and covered by the cope. The two halves are sealed using glue, or a combination of glue and other fasteners, and if everything’s been done right up to now, the shell mould is ready to get poured.
Pouring the casting is a lot like moving molten metal from a bucket to a teacup, except on a much larger scale and, fortunately, assisted by machinery. Prior to being poured, metal is heated in a furnace to extremely high temperatures. The exact temperature varies between materials, but steel alloy is usually poured at 3,000 degrees F. Once poured, the metal must sit until it’s solidified.
Once the metal is sufficiently cooled and solidified inside the mould, it’s time for a shakeout. Shakeout is basically exactly what it sounds like vibrating the mould and casting so that the sand breaks apart and falls away.
The finishing process for a shell mould casting varies widely depending on the part being cast, the materials used, and the foundry’s facilities. For example, some parts require machining. Some only need to be cut out of the moulds and have their rough edges ground down. Others need to be heat treated (see right). Others, requiring more strength, need to be heat treated several times. While the shell moulding process allows foundries to produce intricate parts, there are some cases when multiple pieces will be cast and welded together.
Castings are machined in-house using various numerical control CNC, VMC and VTL machines to achieve dimensional accuracy as per the drawings.
Finished products of investment casting are inspected visually & dimensionally as per customer supplied drawing, purchase order & technical datasheet.
