Die casting has been around for a long time and it continues to evolve. This casting method is indispensable in product development because of its high efficiency. Die casting is accurate and produces parts with good surface finishing such as aircraft engine components, automotive body parts, and electronic enclosures.
However, the high cost of die casting makes it prohibiting for many businesses despite its numerous benefits. If you are wondering why die casting costs so much then you are in the right place. This article will explain the types of die casting techniques in detail, reasons why die casting is expensive to carry out, and how to calculate die casting costs.
What is Die Casting
Die casting is a manufacturing technique that forces molten metal into a mold under pressure. As the metal cools and solidifies, the result is a strong and durable part. Die casting is a versatile metal fabrication process. It is compatible with many engineering materials including aluminum, brass, magnesium, zinc, and copper. With this technique, you can be sure of parts with high precision and excellent surface quality.
Additionally, die casting is relatively fast and is a cost-effective option for large-volume production. However, die casting comes with high tooling costs which may be challenging for small businesses. The final parts are also susceptible to defects if the process is not well controlled.
Types of Die Casting
There are different types of die casting processes you can use in product development. They work in different ways and have unique peculiarities. Let’s look at the common types of die casting available
Gravity Die Casting
Gravity die casting is a common die casting technique. Here, the molten metal fills the mold exclusively under the force of gravity. Gravity die casting is a permanent casting method because it uses reusable molds which are usually made of steel. Because there is no application of external pressure, the molten metal fills up every corner of the mold which reduces porosity. However, gravity die casting comes with size limitations. It is also slower when compared with other die casting techniques.
Pressure Die Casting
As the name implies, you carry out this process under pressure. The amount of pressure you use depends on the particular type of pressure die casting process. In high-pressure die casting, you inject the molten metal into the mold at a pressure ranging from 15000 to 25,000 PSI. This technique is fast and allows for the production of parts with thin walls. Low-pressure die casting, on the other hand, uses a pressure of around 3 to 15 PSI. Because of the low pressure, it has a slower casting cycle.
Vacuum Die Casting
Vacuum die casting is a precision manufacturing process that produces repeatable parts. You carry out this process in a vacuum environment. The use of a controlled environment helps to remove air and gasses. Hence, the metal fills up the die evenly and completely. Vacuum die casting limits gas entrapment and the formation of pores in the final part. Additionally, the final castings are dimensionally accurate with an enhanced surface finish. However, the use of vacuum increases cost and process complexity.
Squeeze Die Casting
Squeeze die casting is a hybrid process that combines the peculiarities of casting and forging. It uses two dies that are squeezed together after introducing the molten metal. After injecting the metal into the lower die, the upper die applies pressure to create the desired shape. The final parts are strong and come with a better grain structure. Furthermore, you can use squeeze die casting for parts with complex shapes and designs. The main limitation of squeeze die casting is the difficulty in producing thin walls.
Why Is Die Casting So Expensive
One of the challenges of die casting is the high cost this technique comes with. Die casting products are expensive because of the intricacies of the process. There are many reasons behind this.
- Die casting has high tooling costs. The molds and dies are made using computer numerical control technology that comes with high-priced software and machinery. Furthermore, the material for these molds is usually steel which is expensive.
- Another reason for the high cost of die casting is the costly metal alloys used. Die casting requires metals of the highest grade and purity possible. Alloy preparation to remove impurities are additional expenses.
- Furthermore, some die casting processes, especially those with high-pressure requirements, need specialized machinery. Some require a controlled environment which further increases capital.
- The labor costs of die casting can be on the high side. Some techniques need highly skilled engineers and operators to carry them out. You must be experienced to be able to troubleshoot if problems arise.
- Die casting is expensive because of the high energy and operational costs. The process of melting the metal can be energy-intensive. This energy cost further increases as the melting point of the metal increases.
- The waste die casting process generates when molten metal solidifies in runner systems and overflow areas also adds up. The process of recycling these metal waste can be expensive.
How to Calculate Die Casting Cost
Die casting cost varies and depends on many variables. Let’s look at an extensive breakdown of the cost of die casting.
Tooling Costs
The cost of tooling depends on how many parts you can produce with a single die. For instance, if the total cost of manufacturing the die is $20,000 it can cast 10,000 parts. The tooling cost is $20,000 divided by 10,000 which is $2. When calculating tooling costs, you should also factor in expenses associated with setup and maintenance.
Material Costs
The cost of the material differs and depends on the particular metal you are using. Material expenses cover the basic costs, the use of additives, and scrap.
Machine Operation Costs
For most suppliers, the cost of operating casting machines and equipment is charged per hour. This cost depends on many factors including the size of the casting, part complexity, and energy consumption rate. To calculate the machine cost per part, multiply the hourly rate by cycle time. You then divide by the parts produced per cycle.
Labor Costs
Labor costs include direct labor cost per part, setup, machinery maintenance, and quality checks. You also have to consider the region and skill levels when calculating labor costs. To get the individual part labor costs, multiply the hourly labor rate by cycle time. Thereafter, divide by the number of parts produced per cycle.
Secondary Processing Costs
You should also consider the expenses you would incur when finishing the final castings. These include the cost of trimming and deburring. Depending on your project requirements, secondary processing may also include machining and heat treatment. Add them up to get the secondary processing cost per part.
Quality Control and Inspection Costs
The cost of quality control and inspection is significant. It includes those associated with in-process and periodic checks. Furthermore, you should also factor in the rejection rate and rework. At times, die casting produces parts that you have to rework before taking them to market.
Total Cost of Die casting = Tooling cost + Material cost + Machine cost + Labor Cost + Secondary processing cost + Quality control cost.
Conclusion
Die casting is a high-precision casting technique that uses a permanent mold for part fabrication. However, one of the setbacks of die casting is the high cost, especially for low-volume production. There are some ways you can reduce the cost of die casting and improve overall efficiency. To do this, optimize die design and use multi-cavity dies if possible. Furthermore, implement lean manufacturing, select the right die casting metal, and use energy-efficient equipment.
