Die Casting vs Investment Casting: What's the Difference?
Since the 1890s, casting has been a vital manufacturing technique. Today, die casting and investment casting are the two most prevalent casting technologies. Though they share fundamental principles, their specific differences are noteworthy.
Die casting involves forcefully injecting molten metal into cold cavities at high pressure. In contrast, investment casting requires injecting wax into an aluminum cavity. Investment casting usually uses molds for multiple cycles of reuse to create metal parts with exceptional surface finishes. Die casting, however, is economical for large production volumes and non-ferrous parts.
Understanding the different casting methods is crucial, whether you are working on new part fabrication or increasing production. This knowledge will guide you in selecting the appropriate casting method for specific applications. In this article, we will explore the differences and similarities between die casting and investment casting to enhance your understanding of production options.
What is Die Casting?
Die casting is a manufacturing technique that involves melting and injecting non-ferrous alloys into molds using a die-casting machine. A unique characteristic of die casting is the permanence of the mold, meaning it doesn't have to be remade at every cycle. It is one of the most efficient methods for producing non-ferrous metal parts.
Types of Die Casting
There are two types of die casting: hot chamber and cold chamber die casting.
Hot Chamber Die Casting
Used for metal alloys with low melting points. The metal is melted in a furnace, usually attached to a machine, and then injected at high pressure into the die using a hydraulic system. This process is fast, with the cycle varying depending on the part's size and weight. It is best suited for low melting point metals like lead, zinc, magnesium, and tin alloys.
Cold Chamber Die Casting
Here, the molten metal is transferred into the cold chamber before being injected into the die. The pressure increases significantly, and the molten metal solidifies rapidly, forming the final casting. This method is ideal for various applications due to its flexibility in weight and size.
Die Casting Operations
The primary difference between hot and cold chamber methods lies in the metal, machinery, and furnace location. High melting point metals require more energy and a robust furnace. Otherwise, the casting process is similar.
The die-casting process involves a steel die containing the pattern used to create a part. The molds, usually created in two or more sections, are mounted on a machine and held together tightly. The molten metal is inserted into the die, and once cooled, the casting is ejected. This process is repeated to create as many parts as needed.
Die Casting Application Industries
Die casting is widely used in various industries, including automotive, landscaping, recreation, and healthcare. Its design flexibility and metal options make it a favorable choice worldwide:
Automotive industry for vehicle transmission, entertainment system housing, and engine components to its GPS
Landscaping and recreation industry to create outboard gear cases, RV chassis, marine undercuts, and hydrostatic axles to outfit their products.
The healthcare industry provides hospital equipment controls, blood analysis machines, peristaltic pumps, and surgical devices.
Advantages of Die Casting
Some major benefits of the die-casting process include the following;
High production rate: Die casting is one of the best ways to produce consistent and reliable parts rapidly.
Dimensional accuracy: Die casting produces parts that can maintain dimensional accuracy for a long period. This will eliminate the need for further machining.
Ability to produce complex shapes: Due casting can create near-net-shape parts with little secondary machines.
Good surface finish: Die casting has smooth and fine crystalline surfaces that help to reduce your total cycle time.
Consistency in properties: When it comes to properties, die casting has consistent rigid, fine, and durable properties.
Relative cost-effectiveness: Die casting is cost-effective in high volumes.
Disadvantages of Die Casting
Risk of porosity and inclusions
Limitations on large part size
Limitations on part thickness
Lower corrosion resistance
Microstructural limitations
Lower tensile strength compared to other methods
What is Investment Casting?
Investment casting, also known as precision and lost wax casting, uses metal to produce specific parts with excellent finishes, minimizing material waste.
Investment Casting Operation Steps
To understand the uniqueness of investment casting, below is a detailed description of the casting process;
1.Design a Wax Pattern
You can either design your desired part by building a wax injection die or using 3D printing. If you are using a wax injection die, the metal die should be constructed from aluminum. If you are using 3D printing, you need a CAD model to send the product specifications to the printer for printing.
2.Wax Assembly
Here, wax patterns are attached to a sprue before they are constructed into a tree. Imperfections found in the wax are also removed so it resembles the finished part.
3.Ceramic Coating
At this point, the wax pattern is dipped into a ceramic slurry to create a shell around the wax. At the initial stage, fine material is used to preserve the smallest details of the pattern before subsequently using coarse ceramic materials that provide strength and hardness to the mold. When the mold reaches its desired thickness, it is then allowed to set and harden.
4.Dewaxing
Here, the ceramic mold is placed upside down in a furnace to allow the wax from its initial state to melt and evaporate. Extra care should be placed during this stage to ensure the extra stress from the heat does not affect the mold.
5.Casting
Casting involves pouring the metal into the mold to create the cast part. The mold is then allowed to sit with the molten metal until it solidifies.
6.Divesting
Here, the ceramic cell is removed and cleaned till there is no sign of the casting process. This can be done either by vibration, media blasting, water ejecting, or vibration.
7.Finishing
This stage involved the removal of impurities either using hand tooling or welding.
8.Testing
At this final stage, the parts are inspected using both visual and fluorescent penetrate inspections that can identify surface or subsurface defects. The entire process is then repeated to include additional parts.
Investment Casting Application Industries
Many industries are utilizing the process of investment casting. Some of these industries include;
Firearm industry which produces triggers, hammers, and other precision parts
Aerospace and power generation industry produces complex cooling systems and turbine blades with intricate shapes
Oil and Gas industry that creates safety and pressure relief components for their equipment
Advantages of Investment Casting
Below are some of the benefits of investment casting;
High precision: The parts and components of investment casting have a high tolerance.
Ability to produce complex shapes: It is suitable for parts and components that have complex geometry.
Wide range of material choices: It is designed for both ferrous and non-ferrous metals.
Disadvantages of Investment Casting
Higher cost compared to other methods
Limitations on part size and thickness
Limited post-pour machining
Wastage of casting material
What is The Difference Between Investment Casting and Die Casting?
A detailed comparison between die casting and investment casting reveals differences in casting processes, materials used, design complexity, component size, surface finish, production volume, tolerance, and production time. The table below summarizes these aspects.
| Die Casting | Investment Casting | |
|---|---|---|
| Casting Process | Molten metal is applied to the die cavity at high-pressure | Molds are created using liquid ceramic slurry |
| Materials used | Non-ferrous metal | Ferrous and non-ferrous metal |
| Design complexity | Considerable flexibility | High design flexibility |
| Component size | Large parts | Smaller or medium-sized parts |
| Surface finish | Good surface finish | Excellent surface finish |
| Production volume | Over 10,000 pcs | Less than 10,000 pcs |
| Tolerance | standard tolerance of +/-0.010 inch and precision tolerance of about +/-0.002 inch | +/-0.005 inches |
| Production time | At least 100 shots per minute | Hours of casting |
Die Casting vs Investment Casting: Difference in Stages
Now we will discuss a detailed explanation of their differences in:
1.Casting Process
The die-casting process usually starts with injecting liquid metal into the cavity, usually in a shape similar to the desired product, at high pressure. The molten metal is placed on a sleeve and forced into the die cavity using a piston. As soon as the metal cools off, its component is removed to provide a complete finish.
The process of investment casting, on the other hand, starts by designing a wax pattern that can produce the desired end product. This pattern is consistently attached to sprue bottoms and dipped into a ceramic mold. As soon as the ceramic hardens, taking the casting shape, the mold is heated to melt the wax. The mold is then filled with the metal cavity till it cools and solidifies. In the end, the mold is broken, and the cast is removed.
2.Materials Used
Non-ferrous metals are mostly used for die-casting. This includes aluminum, copper, magnesium alloys, zinc, and lead. Investment casting uses both ferrous and non-ferrous metals like stainless steel, zinc, aluminum, etc. Generally, investment casting opposes more material options compared to die casting.
3.Design Complexity
Die casting offers larger production of components with good dimensional results; however, investment casting helps you achieve more precise dimensions, complex geometries, and thin-walled components.
4.Component Size
Die casting allows you to produce components and has a little size limitation. However, investment casting can only accommodate components from 0.02 kg to 100 kg. While you can get any past size with die casting, investment casting has some limitations to the size of the parts.
5.Surface Finish
Surface finishing with die casting is good enough but may require additional machining to attain its desired result. However, the surface finishing of investment casting is better with precise tolerance and about 125 micro finishes. You may not need any secondary machining with investment casting.
6.Production Volume
If you are working on high-volume projects with a large production run of about 10,000 pcs or more; you should use die casting. This is because the process offers consistency and can produce 100 to 2,000 parts in an hour. Investment casting, on the other hand, is more suitable for low-production runs with less than 10,000 pcs.
7.Tolerances
Both die and investment casting offer tight and good tolerance; however, this depends on the material used and the shape of the parts. Die casting is the best option for large pieces because it provides a standard tolerance of +/-0.010 inch and a precision tolerance of about +/-0.002 inch. Investment casting is suitable for smaller components of about +/-0.005 inches.
8.Production Time
Die casting can produce about 3 to 4 shots in a minute and about 45 to 100 shots a minute for smaller components. In contrast, investment casting is time-consuming and would require hours of casting with extra labor.
How to Choose the Best Casting Method for Your Application
Selecting the best casting method depends on factors such as cost, product quantity, surface finish, manufacturing time and fulfillment speed, shape and size, and strength. Careful consideration of these aspects will guide you in achieving the desired results.
Cost: Die casting is generally more economical for large production volumes, as it's a faster process and the molds are permanent. Investment casting, on the other hand, may involve higher costs, particularly for small production runs. The method involves creating new molds for each cycle, and the process is more labor-intensive.
Product Quantity: If you're producing a large quantity of parts, die casting is usually more appropriate. It's designed for high production rates, and the machinery can produce hundreds or even thousands of parts in an hour. Investment casting is typically used for lower volumes and small production runs, where the complexity and precision outweigh the need for speed.
Surface Finish: Investment casting offers an exceptional surface finish and is able to maintain intricate details. This makes it suitable for parts that require a high level of precision and aesthetic quality. Die casting also provides a good surface finish, but it may require additional machining or treatment to reach the desired level of detail.
Time and Speed: Die casting is a faster method, capable of producing many parts quickly. It’s ideal for applications where time is a critical factor. Investment casting is a slower, more deliberate process. It involves multiple stages, including designing a wax pattern, creating a ceramic mold, and carefully pouring the metal. This method is best suited when quality and precision are prioritized over speed.
Shape and Size: Die casting allows for considerable flexibility in shape and size and is used for large parts. Investment casting, on the other hand, excels with small, complex shapes. The process can create intricate features that might be challenging or impossible with die casting.
Strength: Both methods offer reliable strength, but the specific requirements of the component might favor one over the other. Die casting is used for non-ferrous metals and offers consistent rigidity and durability. Investment casting allows for both ferrous and non-ferrous metals and can cater to specific strength and hardness needs.
Application-Specific Needs: Understanding the final application of the part is crucial. If the part requires a complex design with fine details, investment casting may be the best option. If the application demands large quantities with cost-effectiveness, die casting might be more appropriate.
In conclusion, the decision between die casting and investment casting is multifaceted and should be made with careful consideration of the factors mentioned above. Aligning the chosen method with the specific requirements and constraints of the project ensures that the manufacturing process is both efficient and effective in meeting the desired outcomes.
If you're interested in exploring these casting methods further, please visit the following pages:
Die Casting at Teamsworld: Learn more about our state-of-the-art die casting capabilities and how we can support your large-scale production needs.
Investment Casting at Teamsworld: Discover the precision and intricacy of investment casting with our expert team, and find out how we can help you create complex and detailed components.
Feel free to contact us with any questions or to discuss your specific project requirements. Our team of experts is ready to assist you in choosing the best casting method for your application.