Silica Sol Investment Casting

Investment casting, also known as lost wax casting, includes processes such as pressing wax, wax repairing, tree forming, dipping, wax melting, molten metal casting and post-processing. Lost wax casting is to use wax to make a wax mold of the part to be cast, and then coat the wax mold with mud, which is a mud mold. After the clay mold is dry, put it in hot water to melt the inner wax mold. Take out the clay mold that has melted the wax mold and then bake it into a pottery mold. Once roasted. Generally, the pouring gate is left when making the mud mold, and then the molten metal is poured from the pouring gate. After cooling, the required parts are made into Silica sol investment casting.

After more than ten years of precipitation, Qinhuangdao Zhongwei Precision Machinery Co., Ltd. has rich production experience in water glass lost wax precision casting, lost foam precision casting technology, silica sol precision casting technology, and shell sand casting technology. We expect manufacturers from all over the world to consult and negotiate business.

Product Description

Basic situation of Silica sol investment casting

1. Implementation standards: The company strictly implements ISO9001 & TS 16949 certification.

2. Product material standards: ISO, GB, ASTM, SAE, ISO, EN, DIN, JIS, BS

3. Main processes: sand casting, silica sol investment casting, water glass investment casting,shell casting,deburring, sand blasting, machining, heat treatment, leak testing, surface treatment, etc.

4. Available materials:

Titanium alloy, carbon steel, alloy steel, stainless steel, gray iron, cast iron, cast steel, cast aluminum, cast copper, etc. can be customized according to customer requirements.

Analysis Of Defective Castings

There are many different problems encountered in the production process of precision casting, and the problems and solutions encountered by Silica sol investment casting in the production process. Although it has been tried many times, it still cannot be poured. It is thought that it will not be able to form if it cannot be poured, but in fact it is not the case. In fact, it means that the casting cannot be poured, which means that the casting has shrinkage holes, and it is pressed and leaked after processing.

Casting System Design

The casting is pressed and leaked, indicating that the density of the casting is not enough, and there must be shrinkage pores inside the casting. So, why do castings have shrinkage pores? Generally speaking, the shrinkage porosity in the casting has a lot to do with the structure of the casting itself. For example, the wall thickness of the casting is uneven, and there are hot spots everywhere, so the riser or gate cannot be used for feeding, or the heat dissipation in the casting is uneven, and the local heat dissipation is poor, resulting in shrinkage and shrinkage of the casting. In fact, both of the above-mentioned phenomena exist in this casting, and there are too many holes in the structural design of this casting. Of course, this is required for the functionality of the part itself. However, it is precisely because of this design that the hot joints of the casting are spread all over the whole body of the casting, and the casting must be fed through the gate or riser, so as to achieve the purpose of dense casting and preventing leakage.

In addition, there are not many places where gates can be set on the surface of this Silica sol investment casting, but because there are too many holes in the casting, there are too many obstructions after the gate is designed, and it is easy to cause the molten metal to punch directly. It is taboo, so the forming of castings is a problem, and there is no need to talk about the layer of casting feeding. Therefore, if this casting is based on the current design structure, it is relatively difficult to process and form by the method of investment casting. Let's take a look at the two casting process designs shown in Figures 3 and 4. The height of the casting is not small, the size is about 250mm, and the vertical and horizontal distribution of the holes in the middle of the casting, the first top-casting gating system appears to have many problems. Not to mention the oxidation of the molten metal, only the splash of the molten metal will easily cause cold isolation and inclusion defects on the casting, and the inherent quality of the casting will definitely be greatly reduced. Compared with the first scheme, the second scheme looks relatively reasonable, but the structure of the casting itself makes the function of the gating system design unable to play out at all, therefore, the purpose of densification of the casting cannot be achieved.

So, how should this precision casting solve the existing problems?

1.Modify the existing product structure. The so-called modification here is not to change the part structure, but to change the casting structure to make it more suitable for the investment casting method. For example, block some of the holes and leave holes in one direction, so that the flow of molten metal is not hindered, making it possible to feed the casting. Or change it to the inner cooling iron method, and finally remove it by processing method.

2. Use the bottom injection type for the existing products, let the molten metal enter the casting cavity smoothly, put the largest surface on the lowest surface, and then increase the riser on the large surface. When pouring to the top surface of the casting, it is poured from the riser to improve the liquid metal feeding ability. Of course, if it can be supplemented by water cooling through the bottom hole, it would be better.

From the above situation, we can see how important the structural manufacturability of castings is. If these details can be handled well in the contract negotiation in the early stage, it will benefit a lot in the later production.

The above is a problem encountered in the production of precision casting, I hope to help everyone. Qinhuangdao Zhongwei Precision Machinery Co., Ltd. is an outstanding supplier of precision casting, precision casting, all-silica sol investment casting, and CNC machining. It provides joint development and one-stop customized services from mold manufacturing to precision casting production. We are committed to providing high-quality precision casting for China's high-end manufacturing industry. If you have any questions about precision casting and precision castings, please contact us!

Post Casting Process

1. Heat treatment: annealing, carbonization, tempering, quenching, normalizing, surface tempering

2. Processing equipment: CNC, WEDM, lathe, milling machine, drilling machine, grinder, etc.;

3. Surface treatment: powder spraying, chrome plating, painting, sandblasting, nickel plating, galvanizing, blackening, polishing, bluing, etc.

Moulds and Inspection Fixtures

1. Mold service life: usually semi-permanent. (except for lost foam).

2. Mold delivery time: 10-25 days, (according to product structure and product size).

3. Tooling and mold maintenance: Zhongwei is responsible for precision parts.

Quality Control

1. Quality control: the defective rate is less than 0.1%.

2. Samples and trial run will be 100% inspected during production and before shipment, sample inspection for mass production according to ISDO standards or customer requirements

3. Testing equipment: flaw detection, spectrum analyzer, golden image analyzer, three-coordinate measuring machine, hardness testing equipment, tensile testing machine;

4. Provide after-sales service.

5. The quality can be traced back.

Application

Silica sol investment casting uses batches of high-melting-point alloy precision castings, mass-produced, complex shapes, and small parts that are difficult to machine. Such as: blades, impellers, guides, guide wheels and automobiles, tractors, pneumatic tools, small parts on machine tools, and handicrafts of steam turbines, gas turbines, hydraulic engines, etc.