Lost Wax Investment Castings for Automobiles

Lost wax investment castings for automobiles mainly include the following technological processes: core making - wax mold making - molding, waxing and firing - melting, pouring and casting processing. The wax mold of the object to be cast is made of wax, and the prepared mud is applied on the surface of the wax mold or poured with fine mud to form a mud shell, and then the surface of the mud shell is coated with refractory material. Heating and baking make the wax mold melt and flow out to form a cavity, and then pour copper liquid into the cavity, and the casting can be obtained after solidification.

Product Description

Basic situation of Lost wax investment castings for automobiles:

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.

Production Process

The lost wax method first uses a wax material mixed with beeswax, rosin and tallow to carve the product to be cast (wax type), then pour the mud washed out of clay onto the wax type, sprinkle quartz sand, crushed plant fibers, sawdust (sawdust slag) )Wait. After drying, pour clay and yellow mud to mix the mud washed out, and then sprinkle sand. After repeatedly forming the shell on the wax mold, the shell is heated on the fire. When heated, the wax melts into a liquid state and escapes from the mold. After that, the mold shell is sintered (it cannot be potterized, so the sintering temperature is generally not more than 800 °C), and then the molten metal liquid is poured into the mold shell for casting. After cooling, the shell is knocked off, and the cast product is exactly the same as the wax shape.

Lost wax method is a precision casting method of bronze and other metal objects, which is still used in modern industry. It is known that the earliest artifacts cast by the lost wax method in China belonged to the late Spring and Autumn Period, such as the copper ban in the tomb of Chu in Xichuan, Henan, and the exquisite craftsmanship indicates that it was not the original production. As for the production of exquisite and exquisite, Chu made the greatest contribution, and the honor plate of Zenghou Yi's tomb is also the most praised. However, the application of the lost wax method is not popular enough, and there are still not many works seen today. This is related to the limited amount of beeswax and the overly complicated production. Perhaps it is also because the effect is amazing, but it is difficult to elicit a general aesthetic pleasure connection.

Generally, sand casting is made of wooden molds or prototypes. The sand molds must be made into two halves and then put together. The molds must be able to be taken out from the half of the sand molds. The lost wax method does not have to take out the mold, so it can cast objects with very complex shapes. Modern precision casting uses very fine foundry sand. It also makes wax molds first, then sprays the sand onto the molds, and fires the sand molds at high temperature to make very fine and complex molds. Very precise parts are directly cast, eliminating the need for machining.

The specific process of lost wax casting:

Lost wax method, also known as "investment method", is a precision casting method for bronze and other metal utensils. The method is to use beeswax to make a casting model, and then use other refractory materials to fill the mud core and form the outer model. After heating and baking, the wax model is completely melted and lost, so that the entire casting model becomes an empty shell. Then pour the molten liquid into it and cast it into utensils. The utensils cast by the lost wax method can be exquisitely carved and have the effect of hollowing out.

The principle of Chinese lost-wax casting technology originated from the burning-loss method, which was first seen in the middle and late Shang Dynasty. The bronze statues and plates unearthed from the tomb of Marquis Yi of Zeng in Suixian County, Hubei Province are the earliest lost wax castings known to China, dating from the fifth century BC.

Lost Wax Casting Process

1.Model making. Artists or moldmakers create original models in wax, clay, or other materials. Waxes and oil-based clays are more commonly used because these materials are softer.

2. Invert. Cast the original model. Generally, there is a rigid outer mold plus a softer inner mold, and the inner mold is the exact negative shape of the original model. The inner mold is usually made of latex, urethane rubber or silicone and is supported by the outer mold. The outer mold can be made of plaster, but it can also be made of fiberglass or other materials. Most molds are made from at least two pieces, and during construction, some spacers are placed between the parts to allow the molds to fit back together accurately. If there are long, thin sections extending out, they tend to be cut from the original model and molded separately. Sometimes many molds are required to rebuild the original model, especially for large models.

3. Cast wax. Once the mold is complete, the molten wax is poured into it and shaken to form a uniform coating on the inside surface, usually about 1/8 inch (3mm) thick. Another method is to fill the entire mold with molten wax and let it cool until the desired thickness is set on the surface of the mold. The rest of the wax is then poured out again, and the mold is turned upside down to allow the wax layer to cool and harden. Using this method it is more difficult to control the overall thickness of the wax layer.

4. Remove the wax. Remove the hollow wax version of the original model from the mold. The mold can be reused to make multiple copies, limited only by the durability of the mold.

5. Polished. Polish each hollow wax replica, erasing the parting lines with a heated metal tool. The surface of the wax model must not have any defects, it will look like the finished product. Individually molded wax patterns can now be heated and grouped together.

6. Open the runner. The wax replica is made into a tree-like wax tree that will eventually provide a path for the molten casting material to flow and allow air to escape. There is usually a wax "cup" starting at the top and the wax pattern is attached at various points by wax columns.

7. Sizing. The wax tree is dipped into a silica slurry and then into sandy stucco, or crystalline silica of a certain grain size. The slurry and grit combination is called a ceramic mold. Dry and repeat the process until at least half an inch of coating covers the entire part. The larger the object, the thicker the shell needs to be.

8. Burn off. The ceramic shell coating is placed in a kiln, and the heat hardens the silica coating into a shell, melting the wax and expelling it. The molten wax can be recovered and reused, but is generally simply burned. The shape of the original item is now the inside of the hardened ceramic shell, the negative shape formerly occupied by wax. The feed tube is now also hollow.

9. Test. Let the ceramic shell cool, then test to see if water flows freely through the feeder and exhaust. Cracks or leaks can be repaired with thick refractory paste. To test the thickness, holes can be punched in the casing and then patched.

10. Pouring. Reheat the shell in the kiln to reinforce the patch and remove all moisture, then place the mouth up into a bucket filled with sand. The metal is melted in a crucible in a furnace and carefully poured into the shell. The case has to be hot or the temperature difference will destroy it. The filled shells are then cooled.

11. Demoulding. The casing was knocked off to remove rough castings. The metal gate is also cut off and recycled for the next pour.

12. Metal polishing. Finally, the metal casting is ground and polished

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

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.

Lost wax investment castings for automobiles have been widely used in aviation, automobiles, machine tools, ships, internal combustion engines, gas turbines, telecommunication instruments, weapons, medical instruments and cutting tools and other manufacturing industries, and are also used in the manufacture of arts and crafts.