Mechanical

The common types of patterns are 1.          Single piece pattern 2.       Split piece pattern 3.        Loose piece pattern 4.       Gated pattern 5.         Match pattern 6.         Sweep pattern 7.       Cope and drag pattern 8.        Skeleton pattern 9.       Shell pattern 10.   Follow board pattern   Single piece pattern:                This is the simplest type of pattern, exactly like the desired casting. For making a mould, the pattern is accommodated either in cope or drag. Used for producing a few large castings, for example, stuffing box of steam engine.        Split ...

PATTERNS:              From the design, provided by an engineer or designer, a skilled pattern maker builds a pattern of the object to be produced, using wood, metal, or plastic; other materials to be used can be polystyrene or even sand strickled into shape. The metal to be cast will contract during solidification, and this may be non-uniform due to uneven cooling. Therefore, the pattern must be slightly larger than the finished product, a difference known as contraction allowance. Pattern-makers are able to produce suitable patterns using ‘contraction rules’. Different scaled rules are used for different metals because different metals/alloys contract at different rates. Patterns also have core prints; these create registers within the moulds, into which are placed sand cores. Sand cores are used to create undercut profiles and holes which cannot be moulded.                  Paths for the entrance of...

 Properties of a Sand Casting Mixture:         Type and Content of Binder and Other Additives:                  As mentioned, controlling the type and content of the sand binder and other additives is the key to controlling the properties of the casting's mould sand mixture. Moisture Content:                Moisture content affects the other properties of the mixture such as strength and permeability. Too much moisture can cause steam bubbles to be entrapped in the metal casting. Grain Size:                    Particle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials. This is different from the crystallite size, which refers to the size of a single crystal inside a particle or g...

                          Sand Casting                    Casting is the process of production of objects by pouring molten into the cavity called a mould which is the negative, or mirror image of the object, and allowing it to cool and solidify. Sand casting is means of producing rough metal casting using a mould usually made from sand formed around a replica of the object to be cast (called a pattern) that is removed once the sand has been compacted. Sand castings not further worked by polishing are readily recognized by the sand-like texture imparted by the mould. As the accuracy of casting is limited by imperfections in the mould making process there will be extra material to be removed by grinding or machining, more than is required by other more accurate casting processes. Furthermore because the mould is destroyed in order to retrieve the object, a new mould must b...

                                         CASTING                   Casting process is based on the property of a liquid to take up the shape of the vessel containing it. Molten metal poured into a mould flows into the corners and fills all the voids. When metal solidifies it takes the shape of the mould not exactly the same because solid being denses there is reduction of volume. For obtaining correct dimension, provision needs to be made for shrinkage of metal. Hollow components can be produced by inserting a core into the cavity in the mould.                Casting is one of the most versatile forms of mechanical process for producing components, because there is no limit to the size, shape and intricacy of the article that can be produced by Casting. It offers one of the cheapest methods a...