Basic Technology Of Sand Casting

- Jul 10, 2017 -

Sand casting (also known as sand mold casting): Molten liquid metal in the sand mold molding process. Steel, iron and most non-ferrous alloy castings can be obtained by sand casting, because the sand mold used for molding materials cheap and easy to produce, mold casting is simple, suitable for the castings of the single piece production and small production, has long been a metal casting production of the basic technology.

Process Cost: Tooling cost (low), single piece Cost (medium)

Typical products: Construction of metal fixtures, transport parts, furniture, lamps, Sand Casting engines and so on

Production fit: Suitable for single and small batch production

Quality: Low precision of molding surface, but suitable for hollow and porous parts casting

Speed: One-piece cycle moderate (5min-30min), depending on the proficiency of the operator

Applicable materials

1. Suitable for ferrous metals and nonferrous alloys, Sand Casting the most commonly used materials are: iron, steel, copper alloy, aluminum alloy

2. Magnesium has also been used more and more in recent years in sand casting, especially in aerospace.

Design Considerations

1. The drawing angle should be controlled between 1°-5° (2° is usually appropriate)

2. Part wall thickness should be controlled between 2.5mm-130mm (1in-5.12in)

3. Different metal cooling shrinkage rate is not the same. For example, the shrinkage rate of steel is almost twice times that of aluminum and iron, Sand Casting and the shrinkage rate of brass is 50% higher than that of aluminum, and the shrinkage is proportional to the volume of the parts.

The mould used in sand casting is generally composed of the outer sand type and the core. In order to improve the surface quality of castings, a coating is usually painted on sand and core surfaces. The main components of the coating are high refractoriness, high-temperature chemical stability of good powder materials and binders, but also add a convenient coating of the carrier (water or other solvents) and a variety of additives.

Design of sand mould casting process

Objective: In order to obtain a sound qualified castings, reduce the work load of casting, reduce the cost of castings, in the production preparation process of sand casting, Sand Casting it is necessary to formulate the casting process plan rationally and draw the casting process drawing.

Casting process diagram: In the part diagram with a variety of process symbols to show the casting process of the graphics, these include: casting position, mold fractal surface, the number, shape, fixed method and core order of the core, machining allowance, starting mode slope, shrinkage rate, gating system, riser, cold iron size and arrangement, etc. The casting process diagram is the basic process document for the design, preparation, casting and castings inspection of the shape (core box). According to the casting process diagram, combined with the selected modeling method, it can be drawn out of the shape of the picture and the box.