Centrifugal Casting

Centrifugal casting is a casting method that can pour liquid metal into a rotating mold, and at the same time fill and solidify into a casting under centrifugal action. It is more suitable for the production of small batches to large batches of rotating body-shaped products, or pipe fittings of various diameters.

The processing characteristics are that the steel castings produced have high dimensional accuracy, smooth surface, dense organization, and high production efficiency, which is more suitable for gray cast iron and ductile cast iron to produce castings. Zhongwei Precision has been committed to the foundry industry for 20 years. Specializing in the production of various centrifugal castings.

Product Description

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. Bronze centrifugal casting: sand casting, centrifugal casting, deburring, sand blasting, machining, heat treatment, leak testing, surface treatment, etc.

4. Available materials:

Other materials: cast iron, cast steel, cast aluminum, cast copper, alloy steel, etc. can be customized according to customer requirements.

According to the country, please check the corresponding national material grade in the table.

Craftsmanship

Metal filtration, pouring temperature, mold rotation speed, solidification under slag, coating use, casting release, gating system, pouring dosing, etc. are the process problems that must be determined or solved in centrifugal casting production, because they directly affect the quality and quality of castings. Productivity.

1. Metal filter

Some alloy liquids have more scum that is difficult to remove, and various filters can be placed in the pouring system to remove the slag, such as foam ceramic filters, glass wire filters, etc.

2. Pouring temperature

Centrifugal castings are mostly tubular, sleeve-shaped and annular parts. The resistance encountered when the molten metal is filled is small, and the centrifugal pressure or centrifugal force enhances the filling ability of the molten metal. Therefore, the pouring temperature during centrifugal casting can be higher than that of gravity pouring. 5~10°C lower.

3. Mold speed

It is an important process factor in centrifugal casting. Different castings and different casting processes have different casting speeds when castings are formed.

Too low casting speed will lead to poor filling of molten metal during vertical centrifugal casting, and the phenomenon of molten metal raining during horizontal centrifugal casting, and will also cause looseness, slag inclusions, and uneven unevenness on the inner surface of the casting.

If the rotational speed of the casting mold is too high, defects such as cracks and segregation are prone to appear on the castings. The outer surface of the sand centrifugal castings will form defects such as expansion boxes, which will also cause the machine to experience large vibration, increased wear, and excessive power consumption. Therefore, the selection principle of the casting speed should be to select the smallest value under the premise of ensuring the quality of the casting.

4. Slag utilization

In order to overcome the defect of subcutaneous shrinkage caused by bidirectional solidification of thick-walled centrifugal castings, the slag-forming agent can be poured into the mold together with the molten metal during pouring, and the slag covers the inner surface of the casting to prevent heat dissipation on the inner surface and create a Outward-inward sequential coagulation conditions eliminate subcutaneous shrinkage. At the same time, the slagging agent can also play the role of refining molten metal.

The method of pouring the slag-forming agent is: when pouring, sprinkle powdery slag-forming agent in the pouring tank; pour the molten slag into the mold together with the molten metal.

5. Use of paint

The composition of coatings for centrifugal metal molds is similar to that of gravity mold casting. When casting slender centrifugal castings, it is difficult to remove the residual coating on the working surface of the casting mold, so the residual strength of the binder in the coating composition after high temperature work should be as low as possible to facilitate removal.

6. Casting release

In order to improve production efficiency, under the premise of ensuring quality, castings should be demolded as soon as possible. Sometimes in order to prevent cracking of castings, the castings after demolding should be immediately put into a holding furnace or buried in a sand pile to cool down. For some castings that are not easy to demould and need slow cooling and crack prevention, the casting mold with castings can be removed from the centrifugal casting machine immediately after the casting mold stops rotating, buried in the sand pile to cool slowly, and it can be stripped when it reaches room temperature. type.

7. Pouring system

The pouring system in centrifugal casting mainly refers to the pouring cup that accepts the metal and the pouring trough connected to it, and sometimes also includes the pouring channel in the mold. When designing the gating system, the following principles should be paid attention to:

① When pouring castings with long length and large diameter, the pouring system should make the molten metal spread quickly and evenly on the inner surface of the mold;

② When pouring easily oxidized metal liquid or using centrifugal sand mold, the pouring tank should make the metal liquid fill the mold in a balanced manner, reduce the splash of the metal liquid as much as possible, and reduce the erosion of the sand mold;

③ When pouring and forming castings, the runner in the mold should enable the molten metal to flow into the cavity smoothly;

④After the pouring is finished, there should be no metal and slag left in the pouring cup and pouring trough. Residual metal and slag, if any, should also be easy to remove.

8. Dosing

The inner diameter of centrifugal castings is often determined by the amount of molten metal poured. Therefore, during centrifugal casting, the amount of molten metal poured into the mold must be controlled to ensure the inner diameter. Installation of pressure sensors on the ladle rack for centrifugal casting, automatic quantitative casting, and quantitative casting of electromagnetic pumps in thermal insulation induction furnaces have also been applied in production.

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.

Product Application

Centrifugal casting is suitable for the following casting fields:

1. Bimetal cast iron roll;

2. Heat-resistant steel roller table at the bottom of the heating furnace;

3. Special steel seamless steel pipe;

4. Brake drum, piston ring blank, copper alloy worm gear;

5. Impellers, metal dentures, gold and silver mesons, small valves, cast aluminum motor rotors and other special-shaped castings;

6. Other industrial fields.