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2020.9.15
When you determining a manufacturing process for metal parts, die casting process is an option. In this article, let’s get started in the overview of die casting and understand the basics of this technology, including its definition, types, tools, pros & cons, as well as comparison with the injection molding process.
Die casting is a manufacturing process that produces metal parts with complex geometries through forcing molten metal material such as aluminum and zinc into a mold cavity under high pressure. The mold is also known as die. The die casting process requires a die casting machine, dies or molds, metal material and a furnace, the metal is melted in the furnace and then injected into dies in the die casting machine, it will rapidly cool and solidify into the final cast products.
A die is a specialized tool used in die casting process to shape the metal, dies are often made from hardened tool steel that has been machined to the net shape or near the net shape of the die casting parts. Two dies are used in die casting, one is the cover die and another is the ejector die, where they meet is called the parting line. The ejector die usually contains the ejector pins and the runner, which is the path from the sprue or shot hole to the cavity. The cover die contains a sprue or shot hole, for the molten metal to flow into the dies.
The two main die casting types are hot-chamber and cold-chamber die casting, involves hot chamber machines and cold chamber machines respectively, both of them are available at Diecasting-mould.com.
– Hot chamber die casting: uses alloys with low melting temperatures, such as zinc.
– Cold chamber die casting: uses for alloys with high melting temperatures, such as aluminum.
The casting equipment and metal dies make die casting are more ideal for high-volume production because its capital cost is large and the manufacturing process is relatively simple, it’s especially suitable for small and medium-sized castings. Overall, die casting is an efficient and economical production process that can offer products for various industries, most common applications of die casting parts including thin-walled enclosures, metal housings of appliances, automobile components, and more.
Pros of Die Casting:
– Higher production speed or rate than other casting processes
– Dimensional accuracy and stability
– Repeatable reproduction
– Little or not machining is required
– Suitable for part designs of varying complexity
– Reduced cost in the long run
– Less waste in material
– Thin wall castings have a stronger structure and lighter weight
– Integral parts simplified assembly
Cons of Die Casting:
– The initial investment is high, not cheap to start with small volume production
– Porosity will be caused if the air is not evacuated completely from the die cavity
– Restricted to metals with good fluidity
– In most cases, it’s only appropriate for non-ferrous alloys
– Not suitable for heavy castings
Actually, the process and stages of injection moulding and die casting is similar, the main difference is the used material. Also, they have own advantages and disadvantages. Which one to choose? If you have determined which kind of material to use, the answer is apparent, but if do not know which material to end with, you should learn more about these two techniques.
Main Difference
Die casting process uses metal raw materials while injection molding uses plastic or polymers.
Benefits of Die Casting:
– High accuracy and tighter tolerance
– Complex designs can be cast easily
– Die castings are stronger, stiffer, more stable and more heat resistant than plastic injection moldings
– Metal castings are completely resistant to ultra-violet rays, weathering and stress-cracking in the presence of reagents
Benefits of Injection Molding:
– Plastic molded parts may cheaper based on a unit volume
– Plastic injection molding parts are good electrical insulators
– Higher flexibility in the molding process
– Can accommodate different plastic or polymer materials
– Fillers can be used in plastic molds to increase strength
Which process should you choose? Die casting is only limited to materials with high fluidity under high pressure and the size and weight of castings are also be restricted. Both of these two methods have heavy initial investment and minimal expense in manual labor and waste material, if you are put the priority on your design accuracy and it involves high complexity, you should look for a die casting manufacturer, if you want to order large amount of parts with affordable price, injection molding also can be the way to go.