There are many steps and things to consider when manufacturing products through the technique of casting and the casting process. This guide explains the process involved with casting and benefits of using this popular forming method.
In casting, a molten metal or other material fills a mold , then cools and hardens into a desired shape. However, a manufacturer must plan out post-cast steps to ensure effective results. Proper care should be taken at each step to deliver a final product that maintains proper quality and integrity.
Benefits of the Casting Process
Casting is but one method of metal shaping, as there are many other options, including welding, forging, stamping, extrusion and machining. Before settling on casting, you should first understand the benefits that the process provides over these other techniques. The casting process:
●
Ability to create complex geometries: Liquid metal facilitates construction of intricate designs, in either simple or complex geometries.
●
Fast production cycles: Once the casting tools are in order, very little maintenance and downtime is necessary. This makes casting an option for mass production applications.
●
Workability of hard metals: Casting is often one of the only viable manufacturing processes for hard metals that are not malleable enough for solid state shaping.
●
Reduced assembly: Oftentimes, casting can creatle items in a single, complete component, eliminating the need to assemble multiple pieces.
●
Minimal sizing restraints: Casting can create extremely small to extremely large parts, even up to 200 tons.
●
Versatile surface textures: Casting molds can be designed to deliver smooth, semi-smooth or rough surface textures.
Types of Casting Processes
There are several different casting methods, each of which requires slight variations in the process. The categorization of the different types of processes are based on the material used to make the molds. Casting options include:
● Sand casting
● Plaster casting
● Shell molding
● Wax casting
● Die casting
● Centrifugal casting
Basic Steps in Casting Process
While each casting method creates unique challenges and process enhancements, all techniques retain the same basic steps. These steps are:
● Patternmaking
● Coremaking
● Molding
● Melting and pouring
● Finishing
● Patternmaking
To create a casting mold, a manufacturer must first design a physical model. The process of fabricating this model is called patternmaking. Using computer-assisted design (CAD) systems, the manufacturer designs dimensions and geometry of a mold, and then packs an aggregate material, such as sand, concrete or plastic, around the pattern. Once the pattern is removed, the mold cavity in the sand can be filled.
Coremaking
Many part designs require the inclusion of cores in the casting mold. Cores are solid materials placed inside the mold cavity to create interior surfaces of a casting. For example, a metal pipefitting will require a cylindrical core inside the mold cavity to create the hollow construction of the component's interior.
Molding
At this point, the manufacturer can create the casting mold. A material such as sand, plaster or wax is used in expendable mold casting, whereas metal and other durable materials are used in non-expendable mold casting techniques. The material fills the casting mold model and is allowed to harden, at which point the manufacturer removes it from the cavity and the casting of the component can now begin.
Melting and Pouring
Metal must be properly melted prior to being placed in the mold. Typically, this is done by using what is known as a crucible. Crucibles are containers made of porcelain or another melt-resistance substance in which a manufacturer can heat a metal beyond its melting point. Once properly melted, the molten metal is poured into the casting mold to cool and harden.
Finishing
Because metal can sometimes fill in cracks in a casting mold or sprues, the pouring channel for the mold, manufacturers must often finish the metal following casting. This can be accomplished through a variety of finishing techniques, including sanding, grinding and buffing. Once proper appearance and surface texture has been achieved, further post-treatment processes such as painting or electroplating may be necessary for some applications.
Things to Consider When Casting
There are numerous factors that need to be considered to ensure proper size, shape and integrity of the final component. Some of these factors include:
●
Type of material: each metal and casting material retains specific characteristics (hardness, melting point, density, etc.) that will affect the casting process.
●
Cooling rate: This factor depends largely on the type of material from which you craft the mold. Proper cooling is necessary to minimize gas porosity and other negative properties that can result from a fast cooling rate.
● Shrinkage: As castings cool, they shrink. To ensure proper component size and integrity, you can utilize risers to feed additional molten metal into the cavity. An oversized mold may also be useful in some applications.
ABOUT KEVA
Keva Casting is a professional casting company that focuses on Construction, Machinery, Automobile, Hardware, Pipeline and many other industries.
We provide top quality products with the best service based on our complete production chain including our own mold design, advanced production techniques, and full management of the supply chain. Keva Casting has two factories located in Zhucheng, China's Shandong province.
We use "shell molding", which is a new technique that has been developed in recent years.This new technique has simplified production procedures and reduced air pollution compared with traditional sand casting and investment casting. Shell making and core making are faster to ensure production in enormous quantities. The dimensions and surface finishing are satisfactory for all kinds of industrial requirements. Besides supplying our own formwork & scaffolding systems, our casting products also supply OEM services in various industries.