To get the improved casting method to compensate casting shrinkage and deformity by means of location change of asbestos liner in customary casting ring, the author performed an experimentation as follows.
By using the experimental wax pattern former that has been used in author's pervious study, 74 peices of same sized wax patterns were made of sheet wax.
Each of the patterns was invested into the casting ring which was lined with asbestos ribbon by means of applying 4 types of the location in the ring.
After gold alloy casting body was made, each margin of the casting body was measured with a micrometer.
@ES The followings are the summarized results obtained:
@EN 1. In the usual asbestos lining method of exposing both mangins of the ring, the ideal compensation for the casting shrinkage and deformity can't be made.
2. The shrinkage and deformity phenamenon is showen much in the case that the ring has more exposed margins in both sides out of liner than in the case that it has less exposed margins.
3. The apparently shrunken area in the casting body is the one which was located near the exposed ring margin out of liner. On the other hand, the area which was located far from the exposed margin has a tendency toward reflexible expansion.
4. vertical(axial direction of the casting ring) expansion of the casting body is also disturbed in the case that the ring had exposed margins in both sides out of liner.
5. According to the phenamena mensioned above, the casting body has a tendency of shrinkage toward trapezoid deformity.
6. As the exposed ring margin is smaller and as the location of wax pattern in the ring is deeper, the compensation for the casting shrinkage and deformity in the casting body is more efficient.
7. In the cast that only the crucible side of the ring has the exposed margin out of liner, the wax patten is invested deep in the ring and the ring heating temporature is controled adequately, the casting body can expand to the almost original
size in
all directions without any deformity.
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