Wax Tree Grouping Process of Investment Casting
After the wax mold has been trimmed, a wax tree is required for further operation.
In the wax tree, the wax molds are prepared in a certain order, and are sequentially layered and welded on a wax rod in the circumferential direction, so that a wax tree shaped like a big tree is finally obtained. The basic requirement of the wax tree is that the wax molds should be arranged in order, the key is that the wax molds cannot be in contact with each other. Given maintaining a certain gap, a good wax tree should have as many wax molds as possible, i.e. one wax tree should try to "plant" the maximum number of wax molds, which can meet the needs of mass production.
The wax tree must be "planted" on a round rubber base. The diameter of this rubber base is matched to the inner diameter of the stainless steel cylinder. The general rubber base has a diameter of 3, 3.5, and 4 inches. The center of the base has a raised circular recess having a diameter comparable to that of the wax tree. The first step of "planting a wax tree" is to pour some of the melted wax liquid into the head of the wax rod and insert it into the recessed hole of the base to make the wax rod and the concave hole firmly. In the second step, the wax pattern is welded to the wax rod layer by layer, starting from the bottom of the wax rod (from bottom to top) or from the head of the wax rod (from top to bottom). If the technique of "planting trees" is more skillful the difference between the two methods is small, otherwise it’s recommended to start from the head of the wax rod because this method has advantage that it can prevent melted wax droplets from falling onto the welded wax mold, so that it can avoid unnecessary rework.
The following procedures should be noted for the operation of the wax tree.
1)The wax pattern route of the wax tree generally has an angle of 45° with the wax rod, that is, the direction of the wax pattern is inclined upward. Only in this way can the metal water be smoothly injected into the mold. This angle can be appropriately adjusted according to the size and complexity of the wax pattern, and the small and complicated wax pattern can reduce the angle; on the contrary, the larger wax pattern can increase the angle.
2)Before the wax tree is planted, the rubber base should be weighed first. After the wax tree is finished, weigh it again. The weight of the wax tree can be obtained by subtracting the results of the two weighing. By converting the weight of the wax tree to the weight of the metal in terms of the density ratio of the wax to the cast metal, it is possible to estimate how much metal is required to be cast.
3)After the wax tree is finished, it must be checked whether the wax pattern has been firmly connected. If not, it is easy to cause the wax mold to fall off when pouring, which affects the casting process. Finally, it should be checked if there is enough gap between the wax molds. If the wax molds are stuck together, they should be separated. If there are dripping wax drops on the wax tree, they should be removed with a blade.
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