Dandong Dawang is a professional Shell mould castings factory in china. Shell mould castings are prevalent in most machine manufacturing industries, and the shell moulding process is a cost-effective solution. Every metal casting must undergo a tricky and complex process in the casting industry. Based on the model design’s complexity, engineers determine the types of the metal casting process. In this case, shell moulding is one of the best solutions for complex and more significant products.
Application of shell mould casting
Shell mould casting is famous for a wide range of industrial applications. Some best examples of shell mould castings are gearbox housing, cylinder head, hydraulic or pneumatic valve bodies, truck hoods, small boats, camshafts, engine blocks, automotive transmission parts, break beams, manifolds connecting rods, lever arms, bathtubs, drum shells, body panes, etc.
Besides the products mentioned above, the agricultural, automotive, petrochemical, and construction industries require shell mould casting to create the machinery for their respective fields.
Shell Moulding Process
Shell moulding is a similar sand casting process except for their respective mould types. The sand-casting process uses an expandable mould, whereas shell moulding uses a ready-made thin-walled shell. Shell moulding vs sand casting elaborately describes the difference between these two casting processes.
However, a typical shell moulding requires five different components to complete the process: a pattern for the mould, an oven for heating the casting pattern, a sand-resin mixture, molten metal, and a moulding box or dump box. The tooling process creates reusable shell mould patterns that integrate higher production. However, the following headings are the four primary steps for shell mould casting manufacturing.
Step1: Creating the Pattern
The shell moulding process begins with the specialized tooling process, where a tooling machine creates an individual mould from a pattern. Typically, wood, metal, wax, plaster, or plastics are suitable pattern materials for casting tooling. In the case of shell mould manufacturing, cast iron is famous for creating reusable casting patterns.
Step 2: Shell Mould Manufacturing
Later the process divides these patterns into two equal parts. In this case, an oven heats each half of the casting patterns at 175 degrees to 370 degrees. After the heating process, the operator applies specialized lubricants on the surface of the hot casting pattern to facilitate removal. Now, an operator clamps the heated casting pattern into a dump box. It is important to note that this dump box already contains silica sands and thermosetting resin.
Now the surrounding resin-covered sand starts making a shell around the casting pattern. This shell usually becomes 10 to 20 mm thick. The thickness of the casting shell depends on the clamping duration and the temperature of the hot casting pattern. Later, the operator puts the dump box with the casting pattern into an oven and again heats it. This curing process increases the overall tensile strength of the shell from 2.4 MPa to 3.1 MPa. After the heating stage, the operator brings out the dump box from the oven and ejects the casting pattern from the mould. Now, this half mould is ready for assembly.
Step 3: Shell Mould Assembly
The assembly process’s simplicity depends on the mould design’s complexity. At this stage, a plain design comes with two halves of moulds. On the other hand, in some cases, the process might require more than two moulds. For most complex structures, multiple cores might be necessary. In that case, the operator inserts the mould parts in the respective places before closing the final pieces.
However, glue or clamping is typically suitable for shell mould assembly to complete shell mould structure. During the assembly process, the operator ensures all the cavities and gating systems for pouring smelting metal. After the inspection, the newly assembled shell mould is ready for the next step.
Step 4:Smelting and pouring
Smelting metal is an energy-intensive process to refine raw metals into pure metal. The method removes the impurities, such as debris or slag, during the smelting process. Heat and chemical-reducing agents are popular mediums for the smelting process. When the hot metal turns into liquid form and all the slags are removed, it is ready to be poured into the shell mould.
After smelting, an operator or automated machine pours the liquid metal into the shell mould through the gating systems. In a shell mould, no matter what kind of metal you are using, all get into liquid form and solidify inside the shell mould. Therefore, you can get all types of shapes and designs from all different kinds of metals of various mechanical properties.
Step:5 Cleaning and inspection
Before reaching the final stage, the liquid metal turns into a solid shape through unique cooling methods. Solidification is a significant step for every foundry as vital casting defects appear at this stage. However, metal shrinkage is one of this stage’s most common casting defects.
After the solidification process, the operator breaks the mould and removes the metal from it. After removing the rough castings from the mould requires trimming and cleaning. The trimming process ensures no excess metal or sand from the mould remains on the surface of the rough castings. After the inspections, the final rough castings are ready for final finishing.
Shell Moulding in Dawang Casting
Dawang Castings started planning for shell moulding production in 2018. The aim was to use precoated sand made of phenolic resin and pearl sand to conduct the shell moulding casting research. Our team in charge of this research underwent many tests and mass productions that upgraded to a mature shell moulding casting technology.
However, Dawang casting can now produce high-quality shell moulding castings in a cost-effective solution with finer details. We are preparing the automated production line for the complete shell moulding process. By 2023, Dawang Casting will officially launch its shell moulding mass production.
1. Equipment Capacity
At present, six automatic double-station core shooting machine sets and two single-station core shooting machine sets are available at Dawang Castings. These machines can produce a variety of castings with an overall dimension of 1000mm x 1000 mm and a unit weight of no more than 100Kg thanks to their 1200mm × 1200 mm maximum tooling installation capacity.
2. Quality Assurance
Dawang Castings’s first goal is to ensure the products’ quality. We maintained our reputation by providing the best quality products for decades. However, to reduce the impact of human factors and guarantee product consistency, the production process uses a combination of parameterized control and standardized procedures.
3. Latest tooling facility
Dawang Castings continues to invest in cutting-edge technology to produce increasingly complicated parts for its clients. As a result, we can create any casting, even those with intricate moulds. However, the tooling in Dawang Castings is made of high-quality alloy cast iron, which has a small thermal expansion coefficient, small thermal deformation, good strength, and wear resistance, so the accuracy and consistency of the product are well guaranteed.
Shell moulding is an upgraded version of the traditional sand-casting system. Therefore, we expect a lot of benefits from the shell castings. However, the following points are some of the most popular advantages you might expect from shell castings.
- Easy and cost-effective:Shell moulding is easy to operate and requires less sand than traditional sand casting. As a result, shell castings are cost-effective.
- Quality surface finishes:Resin-covered sand creates high-quality and smooth surface-finished shell castings. As a result, it reduces the additional machining for final finishing, reducing the overall cost.
- Dimensional Accuracy on rough castings is high:Shell moulding uses rigid and hard moulding material that does not allow the molten material to swell. As a result, the final rough shell castings come with smaller dimensional tolerances that do not require additional machining, reducing the cost. In typical shell moulding, up to .25mm dimensional tolerance is possible.
- Complex shell castings and thin wall thickness:Shell moulding can produce a thin wall thickness of less than 5mm, which is hard for sand casting. Besides, the shell moulding process performs the casting process through hot shells and cold moulds, which can produce different complex shapes.
- Require less labour and skills:An automated machine performs the job in typical shell moulding. As a result, this process requires fewer workers, reducing product costs. In addition, as the casting machines are automated, it does not require high operating skills.
Shell moulding is an upgraded version of the sand casting technique. Sand casting typically uses expandable mould, whereas shell moulding uses a ready-made thin-walled shell. The following points are the direct comparisons of shell moulding vs sand casting.
|Shell Moulding||Sand Casting|
|Creates a thick shell around the casting pattern||It doesn’t need such a technique, and it’s simply expandable|
|Creates a more refined surface finish||Produces a rough surface that needs further machining|
|Produces tighter tolerances||Have fewer tolerances|
|Suitable for small and medium-sized castings||Suitable for medium and large-size castings|
|Has high geometrical accuracy||Has low geometrical accuracy|
|Works both for ferrous and non-ferrous metals||Works both for ferrous and non-ferrous metals|
|Easy and cost-effective solution||Easy and cost-effective solution|
Shell moulding is also famous as shell mould casting. Shell moulding is a metal moulding process that uses a sand-base mould and a thin-walled (10 to 20 mm) shell to create different complex metal shell castings. Most industries use resin-covered sand for shell moulding. Compared to the sand-casting process, shell moulding produces better dimensional accurate products with lower labour costs and higher productivity.
A typical shell moulding process works with ferrous and non-ferrous metals, such as cast iron, alloy steel, carbon steel, stainless steel, etc. Usually, shell moulding is ideal for small and medium-sized metal castings in most cases. In some cases, this process also creates larger metal shell castings.