Advantages and Disadvantages of General Sand Casting Process
Sand casting is a sand casting used to make large parts such as gray cast iron, ductile iron, stainless steel and other types of steel. The main steps include painting, moulding, core making, styling, melting and pouring, cleaning and more.
The basic raw materials for ordinary sand casting are foundry sand and sand binder. The external sand type used in sand casting is divided into three types: clay wet sand type, clay dry sand type and chemical hardening sand type.
Selection of process parameters
1, processing allowance
The so-called machining allowance is the surface on the casting that needs to be machined. A certain machining allowance should be set in advance. The size depends on the type of casting alloy, the molding method, the size of the casting and the position of the machined surface in the mold. .
2, the draft angle
In order to facilitate the removal of the pattern from the mold, the slope applied to the vertical wall perpendicular to the parting surface is referred to as the draft angle.
3, casting fillet
In order to prevent the casting from generating stresses and cracks at the joints and corners of the wall, to prevent sharp corner damage of the mold and to generate blisters, the joints and corner portions of the casting wall should be designed to be rounded when designing the casting.
4, core head
In order to ensure the positioning, fixing and venting of the core in the mold, the core and the core are designed.
5, shrinkage margin
Due to the cooling shrinkage of the casting after casting, this part of the shrinkage dimension is added when making the pattern.
Advantages:
1. Clay is rich in resources and cheap. Most of the used clay wet sand can be recycled after proper sand treatment;
2. The cycle for manufacturing the mold is short and the work efficiency is high;
3. Mixed sand can be used for a long time;
4. Adaptability is very wide. Small pieces, large pieces, simple pieces, complicated parts, single pieces, large quantities can be used;
Disadvantages and limitations:
1. Because each sand mold can only be poured once, the mold is damaged after obtaining the casting, and must be reshaped, so the production efficiency of sand casting is low;
2. The rigidity of the molding machine mold is not high, and the dimensional accuracy of the casting is poor;
3. Castings are prone to defects such as sand washing, sand inclusion, and porosity.
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