Casting process, Pattern, Casting Defects
- 1. CASTING Metal Casting is one of the oldest materials shaping methods . Casting means pouring molten metal into a mould with a cavity of the shape to be made, and allowing it to solidify.
- 2. ADVANTAGES Molten material can flow into very small sections so that intricate shapes can be made by this process. As a result, many other operations, such as machining, forging, and welding, can be minimized or eliminated. It is possible to cast practically any material that is ferrous or non-ferrous. As the metal can be placed exactly where it is required, large saving in weight can be achieved. The necessary tools required for casting molds are very simple and inexpensive. As a result, for production of a small lot, it is the ideal process. Size and weight of the product is not a limitation for the casting process.
- 3. LIMITATIONS Dimensional accuracy and surface finish of the castings made by sand casting processes are a limitation to this technique. Many new casting processes have been developed which can take into consideration the aspects of dimensional accuracy and surface finish. Some of these processes are die casting process, investment casting process, vacuum-sealed molding process, and shell molding process. The metal casting process is a labor intensive process
- 4. STEPS CASTING PROCESS 1. PATTERN MAKING 2. CORE MAKING 3. SAND PREPARATION & MOLDING 4. MELTING AND POURING 5. SOLIDIFICATION & COOLING 6. CLEANING
- 5. PATTERN The pattern is the principal tool during the casting process. It is the replica of the object to be made by the casting process, with some modifications. The main modifications are the addition of pattern allowances, and the provision of core prints. If the casting is to be hollow, additional patterns called cores are used to create these cavities in the finished product. The quality of the casting produced depends upon the material of the pattern, its design, and construction. The costs of the pattern and the related equipment are reflected in the cost of the casting. The use of an expensive pattern is justified when the quantity of castings required is substantial.
- 6. FUNCTIONS OF THE PATTERN A pattern prepares a mold cavity for the purpose of making a casting. A pattern may contain projections known as core prints if the casting requires a core and need to be made hollow. Runner, gates, and risers used for feeding molten metal in the mold cavity may form a part of the pattern. Patterns properly made and having finished and smooth surfaces reduce casting defects. A properly constructed pattern minimizes the overall cost of the castings.
- 7. PATTERN MATERIAL Easily worked, shaped and joined. Light in weight . Strong , hard and durable. Resistant to wear and abrasion, to corrosion and to chemical reaction. Dimensionally stable and unaffected by variation and humidity. Available at low cost . Such that it can be repaired easily and economically or even re- used. Having ability to take a good surface finish .
- 8. Materials for Making Patterns WOOD METALS PLASTICS PLASTER WAX
- 9. TYPES OF PATTERN 1. Single-piece pattern 2. Split pattern 3. Multi piece pattern 4. Gated pattern 5. Cope and drag pattern 6. Match plate pattern 7. Loose-piece pattern 8. Sweep pattern 9. Skeleton pattern
- 10. GATING SYSTEM Gating system means all the passages through which the molten metal enters the mould cavity. The elements connected with a gating system are : Pouring basin Sprue Sprue base well Runner Ingate Riser
- 11. TYPES OF GATES TOP GATE BOTTOM GATE PARTING GATE STEP GATE
- 12. RISER Most of the foundry alloys shrink during solidification. As a result of this volumetric shrinkage during solidification, voids are likely to form in the castings so these needs the additional molten metal. Hence a reservoir of molten metal is to be maintained from which the metal can flow readily into the casting when the need arises. These reservoirs are called risers. TYPES OF RISERS OPEN RISER BLIND RISER
- 13. CASTING DEFECTS BLOW HOLES POROSITY SHRINKAGE MISRUNS AND COLD SHUTS INCLUSIONS CUTS AND WASHES METAL PENETRATION FUSION SHIFT SWELLS
- 14. Applications of Casting in AE Parts for Sunroofs Chassis Parts Transmission Components Vehicle Interior Components Air-Conditioning Systems Engine Parts Brake Systems and Hardware Power Steering Systems Fuel Intake Parts Other Mechanical Parts
- 15. Thank you