Due to various reasons, the wax mold produced by the wax pressing machine will have some defects, mainly including the following:
- full of dissatisfaction
The main reason is that the temperature of the wax material is low, the injection speed is slow, and the pressing temperature is low, which causes the wax material to cool quickly during the flow process, which is manifested in the corners and edges or the thin-walled part of the wax mold. Rounded corners appear, similar to underpouring of metal castings.
- Bubbles
One is surface air bubbles, that is, subcutaneous air bubbles visible to the naked eye, with individual distribution, some
Densely distributed; the other is the bubbles in the deep layer of the wax model, usually concentrated and larger bubbles, which cannot be seen by the naked eye, but bulged from the part of the wax model, appearing in the central part of the wax model and the last cooling part, This is the release of the internal pressure, the result of the expansion of the gas.
- Surface wrinkles
Due to insufficient wax temperature, low injection speed, improper coordination of wax movement and molding temperature; or due to damage or uncleanness of the inner surface of the molding; improper placement of the chilled metal block, etc., leaving motion on the surface of the wax mold Mark of. Deep texture, similar to cold insulation defects in metal castings; slight wrinkles can be removed by grinding. In addition, around the core, and the holes, sometimes there are slightly concave seams. The meeting of the two wax streams is not well fused, which is the result of insufficient temperature and pressure of the wax material.
- Rough surface
Because the injection pressure is too small or the injection speed is not enough, the contact density between the wax material and the inner surface of the molding is not enough, and the surface state of the molding cannot be faithfully reflected, and there are serious wrinkles.
- Shrinkage
The surface of the wax mold is concave, mainly because the injection pressure and time are not enough, or the temperature of the wax material is high, the cooling time is not enough, and sometimes there is too much release agent, which may also reduce the properties of the wax material. Surface shrinkage involves a large area and is difficult to repair.
- Deformation
After the wax mold is removed from the molding, in addition to the shrinkage and changes in size, it is artificially deformed due to improper removal techniques; it is common for the wax mold to be flexed due to changes in the temperature field due to the cooling of the wax mold. Therefore, the wax model just taken out from the pressing should still be placed carefully. Usually, it is flat based on a larger plane. If necessary, a shape suitable for the deformed part is used to make a metal block embedded in the wax model to prevent deformation. cool down. It is also possible that the wax material is too soft, the molding components are not suitable, etc.
- Hairy wings (shackles)
This is one of the most common defects, that is, a thin wax piece escapes at the compressing part, the junction of the compressing block, the connection between the core and the core seat, etc. The main reasons for this are insufficient molding accuracy, the molding parting surface or the joint surface of the inner parts of the molding being damaged or adhered to dirty objects, the molding force is not enough, and the injection pressure is too high. Or the temperature of the wax is too high. The fins must be completely removed before the wax model can be used.
- Adhesion
The adhesion of the wax mold to the mold is caused by the lack of a release agent, the temperature of the wax and the mold being too high, or the mold being damaged and the mold is not clean.
