Manual modeling definition – all modeling operations completed by hand or hand tools are called manual modeling.
Advantages and disadvantages: flexible manual molding operation, simple process equipment (pattern, core box, sand box, etc.), short production preparation time, strong adaptability, molding quality can generally meet the process requirements, but low productivity, high labor intensity, sand casting quality, so it is mainly used for single piece and small batch production.
Classification application scope: there are many kinds of manual molding methods. In actual production, the appropriate molding methods can be selected according to the structural characteristics, production batch and production conditions of sand castings.
Classification by sandbox characteristics
Two box modeling
Main features:
It is the most basic method of molding. The mold is composed of upper box and lower box, which is easy to operate.
Scope of application:
Various production batches and sand castings of various sizes.
Three box modeling
Main features:
The mold is made up of upper, middle and lower boxes. The height of the middle box shall be suitable for the distance between the two parting surfaces of the sand casting. The operation of three box molding is laborious, and it needs to be equipped with a suitable sand box.
Scope of application:
Small batch production of single piece. Sand castings with two parting surfaces.
Stripping molding
Main features:
The sand box shall be removed from the detachable box for molding and used for new molding again before pouring after the mold is closed. Many molds can be made repeatedly with one sand box to save sand box. It is necessary to fill the surrounding of the mold with molding sand or add a box on the mold to prevent the wrong mold during pouring.
Scope of application:
Production of small sand castings. Because the sand box has no box belt, the size of the sand box is less than 400 mm × 400 mm × 150 mm.
Pit modeling
Main features:
In the sand pit below the ground, no sand box or upper box is used. The large sand casting needs to be paved with coke under the sand bed, and the air outlet pipe is buried, so as to draw air during pouring. The cost and time of manufacturing sand box are reduced, but the molding costs labor and requires high technology.
Scope of application:
The sand box is insufficient, or the production batch is not large, and the quality requirements are not high, such as sand box iron, furnace grate, core bone, etc.
Classification by pattern features
Whole mold design
Main features:
The pattern is integral, the parting surface is flat, and the mold cavity is all in a sand box. The mould is simple and the sand casting will not produce wrong mould defects.
Scope of application:
Sand casting with a maximum section at one end and a flat surface.
Dredging molding
Main features:
The pattern is integral and the parting surface is curved. In order to lift the pattern, the molding sand that hinders the lifting of the mold is dug by hand. Molding costs labor and low productivity, requiring high technical level of workers.
Scope of application:
Small batch production of single piece. Sand casting whose parting surface is not flat.
Fake box molding
Main features:
In order to overcome the shortcomings of the sand digging molding, a bottom tire which is consistent with the parting surface is made in advance before the molding, and then the bottom tire is made on the bottom tire. Because the bottom tire does not participate in pouring, it is called false box. It is simpler than sand digging, and its parting surface is neat.
Scope of application:
Sand castings that need to be sanded in batch production.
Parting molding
Main features:
The pattern is divided into two parts along the maximum cross section. The cavity is located in the upper and lower two sand molds. The shape is simple and labor-saving.
Scope of application:
Sand casting with the largest section in the middle.
Movable block molding
Main features:
There are small bosses, ribs, etc. on the sand casting that hinder the mold lifting. During die making, these parts are made into movable (i.e. movable block). When lifting the mold, first take out the main body shape, and then take out the movable block from the side. Molding costs labor, and the technical level of workers is high.
Scope of application:
Small batch production of single piece. Sand castings with protrusions that are difficult to lift.
Scraper molding
Main features:
Use scraper instead of solid shape. It can reduce the cost of pattern, save wood and shorten the production cycle. However, the low productivity requires high technical level of workers.
Scope of application:
Small batch production of single piece of large and medium-sized sand castings with equal cross-section or revolving body, such as pulley, cast pipe, elbow, etc.