Defects of wax mold making for Investment Casting process

As it is known to all, Investment Casting is also known as lost- Wax Casting . Compared with other casting methods and parts forming methods, investment casting has the following advantages: high dimensional accuracy of castings, fine surface roughness values, dimensional accuracy of castings can reach 4-6 grades, surface roughness It can reach 0.4-3.2μm, which can greatly reduce the machining allowance of castings, and can realize no-margin manufacturing and reduce production costs; can cast castings with complex shapes that are difficult to be processed by other methods; alloy materials are not limited: such as carbon steel , stainless steel, alloy steel, copper alloy, aluminum alloy, superalloy, titanium alloy and precious metal materials can be produced by Precision Casting. For alloy materials that are difficult to forge, weld and cut, it is also suitable for precision casting. It can be used for mass production, as well as small batches or even single-piece production. Above all, it is really popular nowadays for investment casting. We SCZY LTD has done a lot of projects from different countries with investment casting process for different materials like: Stainless Steel Casting, Carbon Steel Casting, Brass Casting Parts,etc. Today we would like to talk about some regular defects which are prone to occur in the process of wax mold making for Investment Casting:

1. The wax mold is deformed. After the wax mold is taken out from the mold, in addition to the shrinkage and changes in size, it is sometimes artificially deformed due to incorrect removal methods; since the wax mold is flexed and deformed during cooling, it is common, so The wax mold just taken out from the molding should still be placed carefully, and it may also be caused by factors such as too soft wax material and unreasonable Molding Design.
2. The wax mold filling is not satisfied. The main reason is that the temperature of the wax material is too low, the injection speed is slow, and the molding 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 thinness of the wax mold. The wall part is not full, and the corners are rounded, which is very similar to the insufficient pouring of metal castings.

3. Wrinkles on the surface of the wax mold, because the temperature of the wax material is too low, the firing rate is too low, and the movement of the wax material is not properly matched with the pressing temperature; or because the inner surface of the pressing is damaged or not clean. It is the result of insufficient temperature and insufficient pressure of the wax material.
4. The surface of the wax mold is concave, mainly because the injection pressure and time are not enough, or the wax temperature is high, the cooling time is insufficient, and sometimes there is too much release waste.
5. The wax mold has seams, which is the most common defect, that is, there are very thin wax flakes at the joint of the pressing and forming, the joint of the pressing block, the connection between the core and the core seat, etc. out. The main reasons for this are that the molding accuracy is not enough, the molding parting surface or the joint surface of the inner parts of the molding is damaged or adhered to dirty objects, or the molding force is not enough, and the injection pressure is too high.
6. The wax mold is sticking to the molding, which is caused by no release waste, or the temperature of the wax and the molding are too high, or the inner surface of the molding is not clean enough.
7. Rough surface of the wax mold: because the injection pressure is too low, or the contact density between the wax material and the inner surface of the molding is not enough, serious wrinkles will appear.
8. Bubbles in the wax mold: One is the surface bubbles visible to the eyes, and the other is the bubbles inside the wax mold, which are usually large and cannot be seen with the naked eye, but can be found through the partial bulge of the wax mold. This is due to the expansion of the gas inside the wax mold.

investment casting

Shenzhen SCZY Technology Co., Ltd

Business Type: Manufacturer

Product Range: CNC Machining , CNC Machining Parts , Precision Machining, CNC Milling , CNC Turning Parts , Machining, Forging, Forging Parts , Investment Casting, Die Casting , Casting Parts, Sheet Metal Fabrication, Product Assembly Service...

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Email: sandy@sczyltd.com

Address: No. 1906, Vanke Center, Changqing South Road, Chang` An Town, Dong Guan City, Guangdong Province, PR China 523850