Cast bronze bushings are the process of making bronze bushings by pouring the liquid copper alloy through melting into the cast model and obtaining the required shape and properties by cooling and solidifying.
We can get complex shapes and large castings, a large proportion of machinery manufacturing, such as machine tools accounted for 60 to 80%, 25% of the car, agricultural machinery accounted for 50 to 60%.
What are the common methods of cast bronze bushings?
We cast bronze bushings in three categories, mainly the following three ways, including centrifugal casting ranked first, this article is mainly about centrifugal casting, centrifugal casting has been widely used in the production of pipe, bearing, and bushing castings.
- Centrifugal casting (including cantilever centrifugal casting max φ3000-1000 (mm), torus centrifugal casting max φ3000-2500 (mm), vertical centrifugal casting max φ6000x 1000(mm)).
- Horizontal continuous casting, max φ180, φ180×120 (mm).
- Vertical metal mold casting, max φ1000×1500（mm).
Centrifugal cast bronze bushings
This is a casting method in which liquid bronze alloy is poured into a high-speed rotating cast centrifuge equipment and solidified and shaped by centrifugal force.
In the centrifugal casting process, the centrifuge speed, casting system, casting quantification, solidification under slag, metal filtration, coating of the inner wall of the model, casting temperature, casting off, etc.
Centrifuge speed of cast bronze bushings
This is an important process factor for bronze bushings in centrifugal casting, different bronze bushings/ bearings have different materials, temperatures, and speed differences, and the speed will have completely different results.
- Casting speed is too low: it will make the vertical centrifugal casting, liquid bronze alloy filling bad; horizontal centrifugal casting appears liquid bronze alloy appears rain, also will make the internal bronze bushings appear loose, slag, bronze bushings/ bearings internal surface uneven and other defects.
- Casting speed is too high: bronze bushings/ bearings on the easy to appear cracks, segregation, and other defects; sand centrifugal castings on the outside surface will form expansion box and other defects, but also make the machine appears large vibration, increased wear, excessive power consumption.
Casting system of cast bronze bushings
The casting system in centrifugal casting mainly refers to: the casting cup which receives the liquid bronze alloy, the casting trough connected with it, and the sprue in the casting mold. When designing the casting system, the following principles should be noted.
- When casting bronze bushings/ bronze bearings with long length and large diameter: the casting system should enable the bronze alloy liquid to be spread evenly on the inner surface of the mold relatively quickly.
- When casting bronze alloy liquid that is easy to oxidize or using centrifugal sand casting, the casting trough should make the bronze alloy liquid fill the mold in a balanced way, reduce the splash of bronze alloy liquid as much as possible and reduce the scouring of the sand mold.
- When casting forming castings, the sprue in the mold should enable the bronze alloy liquid to enter the cavity smoothly.
Casting quantity of bronze alloy liquid
The inner diameter of the bronze bushing/bearing is often determined by the amount of bronze alloy liquid cast, when in centrifugal casting, the amount of bronze alloy liquid in the model casting must be controlled to ensure the size of the inner diameter.
Use of slag
In order to overcome the thick-walled bronze bushings in centrifugal cast bronze bushings, the production of two-way solidification caused by subcutaneous shrinkage defects, can be cast in the slag-making agent and bronze alloy liquid poured into the model together, slag covering the inner surface of the casting to prevent the heat dissipation of the inner surface, creating outward-to-inward sequential solidification conditions, eliminating subcutaneous shrinkage.
Filtration of metal liquid
Some liquid bronze alloys have a lot of dross that is difficult to remove, so you can put various filters in the casting system to remove the dross, such as foam ceramic filters, glass wire filters, etc.
Coating of the inner wall of the model
When casting slender centrifugal castings, it is more difficult to remove the residual coating on the working surface of the model, so the residual strength of the binder in the coating group after working at a high temperature should be as low as possible to facilitate the removal.
The Temperature of cast bronze bushings
Centrifugal castings are mostly bronze bushings for the tubular, sleeve, and ring-shaped pieces.
Bronze alloy liquid filling mold encountered less resistance, and centrifugal pressure or centrifugal force to strengthen the filling capacity of the metal liquid.
Bronze bushing off model
In order to improve the production efficiency, under the premise of ensuring quality, the bronze bushings should be as early as possible.
In order to prevent the bronze bushing from cracking, the bronze bushing/bearings should not touch the cold water directly after demolding.
The advantages and disadvantages of casting bronze bushings.
Centrifugal cast bronze bushings
Features.
- Under the action of inertia force, slag, gas, inclusions, etc. are concentrated on the inner surface of the casting and other parts of the casting. The bronze bushing internal structure is excellent, with no pores, shrinkage, slag, and other defects, so the mechanical properties of the casting are better.
- Centrifugal casting does not require a gating system. When casting hollow castings, the core can be eliminated, with less investment in equipment and high efficiency.
Cast bronze bushings/ bronze bearings also requires knowledge of bronze bearings, such as: finer grain structure, bronze powder, wear resistance of finished bushing, other cast bronze products, corrosion resistant sliding shafts, bronze cast bar, etc.
Our bronze bushings, bronze seals, and bronze thrust washers are machined by computerized digital control.
These custom configurations machines are all housed in a constant temperature workshop to avoid high temperatures affecting machining accuracy.
The mechanical properties, compressive forces, physical properties, final porosity, Brinell hardness of the bronze bushings are all factory tested and require reduced friction prior to shipment.
Our overall efficiency in cast bronze bushings, bronze bearings is very good.
With over 20 years of experience in the production of bronze bushings, we have the right solution for every problem in terms of casting die set , durability, rotating speed, friction, corrosion, wear rate, and working closely between various departments.
The bearings meet the required tolerances by the drawings, have excellent machinability, and excellent advanced machining equipment.
