Lost Wax Casting

The lost wax method or lost wax casting method is a production process in ancient China. In modern times it is still the method used to bring out the finest details of metalwork. Such products are often difficult to manufacture due to the cumbersome design. The lost wax method enables any metal to fully and faithfully reproduce the appearance of its wax model. Therefore, this method is still widely used in sculpture, jewelry processing, dentistry and industrial restoration. The lost wax method is very demanding and expensive, but it rewards the craftsman with the beauty and originality of the finished product.

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

Lost wax casting basic situation

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:

High manganese steel, high chromium steel, high nickel steel, carbon steel, alloy steel, stainless steel, gray iron, cast iron, cast steel, cast aluminum, cast copper, etc. can be customized according to customer requirements.

Lost Wax Casting Process

Lost wax casting process is not only suitable for precision casting of various types and alloys, but also produces castings with higher dimensional accuracy and surface quality than other precision casting methods. Castings that are not easy to process can be cast by investment precision casting.

Investment casting is developed on the basis of ancient wax casting. As an ancient civilization, China is one of the countries that used this technology earlier. As far back as hundreds of BC, the ancient working people of our country created this lost wax precision casting technology, which is used for precision casting with various fine patterns. And the bells and tripods and utensils and other products, such as the tomb of Zenghou Yi in the Spring and Autumn Period, etc. The base of the statue of Zeng Houyi's tomb is a number of intertwined dragons. They are connected end to end and interlaced up and down to form a multi-layered moiré-like pattern hollowed out in the middle. These patterns are difficult to produce by ordinary precision casting techniques, and the lost wax method is used to produce these patterns. The precision casting process can take advantage of the fact that paraffin has no strength and is easy to carve. With ordinary tools, you can carve the same paraffin material as the tomb plate of Zeng Houyi, and then add a pouring system, paint, dewax, Pouring, you can get the exquisite tomb plate of Zeng Houyi.

The practical application of modern investment casting methods in industrial production was in the 1940s. The development of aviation jet engines at that time required the manufacture of heat-resistant alloy parts with complex shapes, precise dimensions and smooth surfaces, such as blades, impellers, and nozzles. Since the heat-resistant alloy materials are difficult to machine and the shapes of the parts are complex, it is impossible or difficult to manufacture them by other methods. Therefore, it is necessary to find a new precise molding process, so the lost wax precision casting handed down from ancient times is used for reference. The improvement of the technology, the modern investment casting method has obtained important development on the basis of the ancient technology. Therefore, the development of the aviation industry has promoted the application of investment casting, and the continuous improvement and perfection of investment casting has also created favorable conditions for the aviation industry to further improve its performance.

my country began to apply investment casting in industrial production in the 1950s and 1960s. Since then, this advanced precision casting process has been greatly developed, and has been widely used in aviation, automobiles, machine tools, ships, internal combustion engines, gas turbines, telecommunication equipment, weapons, medical equipment and cutting tools and other manufacturing industries. Manufacture of arts and crafts.

The so-called investment casting process, simply put, is to use fusible materials (such as wax or plastic) to make fusible models (referred to as investment models or models), and apply several layers of special refractory coatings on them. After hardening to form an integral mold shell, the mold is melted from the mold shell with steam or hot water, then the mold shell is placed in a sand box, filled with dry sand molding around it, and finally the mold is placed in a roasting furnace for High-temperature roasting (for example, when a high-strength mold is used, the mold after demolding can be directly fired without molding), after the mold or mold is fired, molten metal is poured into it to obtain a casting.

The dimensional accuracy of investment castings is relatively high, generally reaching CT4-6 (CT10~13 for sand casting and CT5~7 for die casting). Of course, due to the complex process of investment casting, there are many factors that affect the dimensional accuracy of castings. For example, the shrinkage of the mold material, the deformation of the investment mold, the linear change of the shell during the heating and cooling process, the shrinkage rate of the alloy and the deformation of the casting during the solidification process, etc., so although the dimensional accuracy of ordinary investment castings is high, However, its consistency still needs to be improved (the dimensional consistency of castings using medium and high temperature waxes is much improved).

When pressing the investment mold, a mold with a high surface finish of the cavity is used, so the surface finish of the investment mold is also relatively high. In addition, the shell is made of high temperature-resistant special binder and refractory paint prepared from refractory materials, which is coated and hung on the investment mold, and the inner surface of the cavity that is in direct contact with the molten metal has a high smoothness. Therefore, the surface finish of investment castings is higher than that of general precision castings, generally reaching Ra.1.6~3.2μm.

Product Advantages

The biggest advantage of investment casting is that investment castings have high dimensional accuracy and surface finish, so machining work can be reduced, but a little machining allowance can be left on the parts with higher requirements, even some castings Only grinding and polishing allowance are left, and it can be used without machining. It can be seen that the use of investment casting method can save a lot of machine tool equipment and processing time, and greatly save metal raw materials.

Another advantage of the investment casting method is that it can precision cast complex castings of various alloys, especially high temperature alloy castings. For example, the blade of a jet engine has a streamlined outline and an inner cavity for cooling, which can hardly be formed by machining. Production by investment casting process can not only achieve mass production, ensure the consistency of castings, but also avoid the stress concentration of residual knife lines after machining.

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

Lost wax casting is now called investment precision casting. It is a precision casting process with little or no cutting. It is an excellent process technology in the precision casting industry. It is widely used. It is not only suitable for high melting point metals, various The precision casting of various alloys, and the dimensional accuracy and surface quality of the castings produced are higher than those of other precision casting methods, and even the complex, high temperature resistant and difficult to process castings that are difficult to be cast by other precision casting methods. In my country, investment casting has been applied to industrial production since the 1950s and 1960s. Since then, this advanced precision casting process has achieved tremendous development, and has been used in aviation, automobiles, machine tools, ships, internal combustion engines, It is widely used in manufacturing industries such as gas turbines, telecommunications equipment, weapons, medical equipment and knives, and is also used in the manufacture of arts and crafts today.