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Reliable Casting Suppliers in China

United Kingdom | General information | Popularity - 0/10
Casting is a hot manufacturing process of metal forming, that is: melting metal, manufacturing mold (core), pouring liquid metal into the mold and after solidification to obtain metal products (castings) with desired shape, size and performance. The casting industry always enjoys the title of "Mother of Industry" and occupies a very important position in the economy.
Casting products are widely used in various industries, such as, automobiles, mining, metallurgy, machinery, power generation, rail transit, ships, aerospace and etc. Castings is the core component of industries mentioned above.
There have 2 raw materials categories for castings: ferrous metals (cast iron and cast steel) and non-ferrous metals (aluminum, magnesium, copper, zinc and others). Although the global non-ferrous metal castings grows rapidly, black metal casting is still the mainstream. In recent years, the output of ferrous metal castings, such as , gray cast iron, ductile cast iron and stainless steel casting parts accounts for more than 80% of the total output. And in ferrous metal castings, gray cast iron is the main material. So does the main material of Chinese castings. The ratio of gray cast iron is about 41.8%, the ductile cast iron accounts for about 28.7%, the aluminum (magnesium) alloy accounts for about 14.5% and the rest takes 3.3%.
In downstream application, the automotive industry is the largest demand field for castings in China. The demand for construction machinery, casting pipes and pipe fittings and rail transportation industries has been increasing, while the demand for industries, such as agricultural machinery, machine tools and tools has been declining. At the same time, the export volume is gradually expanding every year and products are mainly exported to the United States, UK, Germany, India and other countries and regions.
At present, although China's casting production is far higher than other countries, the average output of single company is lower than that of western countries. China has a huge number of casting manufactures. In 2019, the number of casting manufacturers in mainland is about 15,000. Among these casting factories, 30%(about 4,500 factories), takes 80% of the total casting output. Casting Companies China
China's casting industry is large but not so strong and only a few large-scale casting companies have competitive advantages in scale, technology and process. Their downstream applications involves two or more industries and these industries even refer to more subdivided applications. But large amount of middle and small casting factories are in full competition in low-end products. Actually their production tech and management level remains at the level of 10 years ago. Small casting companies only produce one or two single application products. Except for a few benchmark casting companies, it is difficult for the remaining companies to export castings directly because of hidden quality issues.
Investment casting
Investment casting is also called lost wax casting, or known as precision casting in China. And it is a universal name for the process of obtaining precision-sized castings. The products produced by this process are precise, complex and close to the final shape of the part and can be used directly without or with little CNC machining treatment. Comparing with the traditional sand casting process, the casting size obtained by precision casting is more accurate and the surface finish is much better.
(1) High precision: the castings has high dimensional accuracy, fine surface roughness value, the dimensional accuracy of the casting can reach to 4-6, and the surface roughness can reach to 0.4-3.2μm, which could greatly reduce the machining allowance of the casting and reduce production costs.
(2) Investment casting could be used for complex shapes and it is difficult to be processed by other casting methods. The wall thickness is close to 0.4mm and the minimum hole diameter could be less than 1.0mm.
(3) Carbon steel, stainless steel, alloy steel, copper alloy, aluminum alloy, high temperature alloy, titanium alloy and precious metal can be produced by precision casting. Since alloy materials is difficult to forge, weld and cut, it is ideally suitable for precision casting process.
(4) High production flexibility and strong adaptability; investment casting can be used for mass production but also be used for small batch or even single piece of production (but the production efficiency is quite low).
Most first-generation investment casting manufacturers in China are joint-ventures or wholly-owned investment from Taiwan, Japan and other places. Most of them use silica sol shell making technology and are mainly distributed in coastal areas or its surrounding areas, such as Shandong, Jiangsu, Shanxi, Anhui , Guangdong and other provinces. Reliable Casting Suppliers in China
After 20 years development, the 2nd generation and the 3rd generation investment casting manufacturers in China have already well developed and taken most export business. High level equipment and facilities, the quality control system established, product quality can reach similar level of western companies’ but with strong competition on TCO and service. They can be considered as potential suppliers to produce their own products to replace foreign products.
Many precision casting factories use different technical routes. According to different quality requirements, prices and delivery time of castings, these factories need take correct selection of the right casting technology to meet customers’ needs. In recent years, in order to provide samples quickly, many investment casting manufacturers in china use 3D printing to make shells, which greatly speed up the prototyping process and provide fast solutions for customers to develop new products.
Shell Molding
Shell molding, also known as shell-mold casting, is a process of expendable mold casting that uses resin-covered sand to form the mold. This process has greater dimensional precision, high productivity and less labor costs advantages when comparing with sand casting. It is used for tiny to medium components that require high precision.
Shell mold casting is a sand-like metal casting method, in which molten metal is poured into an expendable mold. The mold, however, is a thin-walled shell produced by adding a sand-resin combination around a motif in shell mold casting.
Shell mold casting enables both ferrous and non-ferrous metals to be used. For instance, cast iron, coal steel, alloy steel, stainless steel, aluminum alloys and metal alloys are widely used. Typical components are small size to medium size and involve elevated precision, such as equipment housings, heads of the cylinder, linking wires and arms of the lever.
The big advantages for shell molding process is high productivity, less labor costs, good surface finishes, low tooling and equipment cost, short lead time. While it also has disadvantages, such as possible high porosity and often needs secondary machining. If performs manually, high labor costs occurs. There are fewer shell molding manufacturers in mainland China. When we visit some shell molding suppliers, we realize that these potential suppliers need keep monitoring on daily basis for quality control.
Sand casting
Sand casting, also known as sand molded casting, is the most commonly used casting process. It is suitable for all kinds of materials, most Ferro-alloys and non-ferrous alloy can be used for sand casting. The weight of castings can be from tens of grams to tens of tons. The biggest advantage of sand casting is: low production cost. The disadvantage of sand casting is that it could only produce castings with simple structure; the surface roughness is low, the metallurgy of the castings and the internal density is low. Casting mold can be produced by hand or by machine. Manual molding is suitable for single piece, small batch and complex shapes. Machine modeling can greatly improve the surface accuracy and dimensional accuracy but with large investment at the very beginning.
As China tightens environmental protection in recent years, many small and medium-sized OEM sand casting parts manufacturers have been forced to close down because they fail to meet the minimum environmental protection standards. Therefore, there are fewer sand casting factories than before. Currently, the sand casting factories are mainly in northern China. But, the Yangtze River Delta region still retains some sand casting manufacturers and aluminum sand casting manufacturers.
Low-pressure casting & gravity die casting
Casting material: non-ferrous metals
Casting quality: tens of grams to tens of kilograms
Casting surface quality: good
Casting structure: complex
Production cost: higher cost (because of upfront cost on mold)
Scope of application: small batches, prefer large and medium-sized non-ferrous alloy castings, thin-walled castings
Low-pressure casting is a casting method, in which liquid metal fills the mold and solidifies into a casting under the action of low-pressure gas. Low-pressure casting is primarily used for the production of aluminum alloy castings.
In gravity die casting, molten aluminum is poured into a metallic tool. The casting temperature is about 750℃. The tolerances and surface finish are good. The use of sand cores in gravity die casting enables casting of very complex components.
Gravity die casting method is a competitive casting method when production quantity is relatively small or when heat treatment is needed to improve the mechanical properties. This casting method gives better tolerances and surface finish than sand casting. The tooling cost of this method is somewhat higher than by sand casting.
Because process chain is short and it is not difficult to control quality, suppliers’ ability of low-pressure aluminum castings and gravity die casting are mature; not only casting process, most suppliers provide series of post finishing of polishing, machining anodizing and other processes. Furthermore, new technology development capabilities of both low-pressure casting and gravity casting are also strong. After a period of running-in, it can be considered as a qualified supplier.
Lost Foam Casting
Lost foam casting (LFC) is a casting method used to create solid metal parts from molten metal. When a part is created through casting, a mold is used to produce the desired shape. In lost-foam casting, the mold is made from polystyrene foam, which is lost during the casting process as the liquid metal melts it and replaces its shape — hence gets name “lost-foam.”
Lost foam casting is a new process with almost no margin and accurate forming. This process does not need to take a mold, has no parting surface and no sand core, so the casting has no flash, burrs and draft slope and reduces the core due to dimensional error caused by combination.
The above casting methods have different process characteristics. In casting production, different castings choose corresponding casting methods.
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