Development of the process of sand casting

The purpose of the work is to familiarize with the main stages of the design of the process of making a casting in sandy form.

Source Data:

- drawing of the part with specifications for its manufacture (see Fig. 1);

- production type: piece;

- grade of casting alloy: SCH 21.

To perform the work, you must:

1. Select the molding method, select the mold casting position, and assign parting planes.

2. assign machining allowances to all machined surfaces of the part, surfacing and forming slopes. Develop casting drawing;

3. Develop a model drawing

4. Develop a rod drawing (if required)

5. calculate the runner system;

6. Develop a mold assembly drawing.

Select mold casting position and define parting planes

In unit manufacturing, a manual molding method is used. The technique of molding is in two supports, according to an integral model using a wooden model kit. We use a non-detachable model to increase the accuracy of the shape assembly.

The casting of the part is arranged vertically in order to minimize the labor intensity of the production of the part, provide ease of manufacture and assembly of the mold and ensure that the model can be removed from the mold without breaking the mold.

The central hole (∅60) must be made using a rod. Holes in the flange (for fasteners), due to the small diameter, can be cast irrationally, they will be made mechanically. Given the type of production - small-scale - we accept manual molding in two supports according to a split model using a wooden model kit.

Purpose of machining allowances

Let us assume that in this case the casting belongs to the second accuracy class. A casting sketch for the example is shown in Figure 2.

The allowance value is strictly regulated and summarized in tables, using the values ​ ​ of which, we determine the allowance values ​ ​ for this part (see Table 1).

The linear shrinkage value for CH 21 is 1%.

Conclusion

As a result of the work, the casting position in the mold was determined, connectors, and model shapes were assigned; machining allowances are assigned to all machined surfaces of the part, shrinkage allowances, surges and forming slopes. The dimensions of the rod signs were also determined and the runner system was calculated. Included in the graphics are sketches of the part, cast, model, rod, and mold assembly. Thus, we got acquainted with the main stages of designing the process of making sand casting.