INTRODUCTION
Do you know that vacuum die casting produces finely detailed and durable metal parts? This casting method, known for its strength involves creating a vacuum environment to ensure quality castings are free from defects such as porosity and impurities associated with traditional casting techniques.While vacuum die casting is commonly associated with the production of metal cast, it is also utilized is the production of plastic casts that have found use across various industries including the healthcare industry. This article gives insights into vacuum die casting, common machinery employed, vacuum casting process, the advantages and applications of the technique as well as service providers in this field. So, keep reading!
WHAT IS VACUUM DIE CASTING
Vacuum die casting is a manufacturing technique that uses a vacuum to produce quality casts for better performance. Unlike traditional die casting methods, where liquid metal is injected into a die mold cavity with pressure, the vacuum casting process ensures that a vacuum system removes the air and gases in the die cavity before injecting the molten metal or plastic.
This process by-passes the shortcomings of other die casting methods by providing a regulated environment that reduces defects in the final product. Vacuum die casting’s main strength is in its ability to create a vacuum inside the mold cavity before and during injection of the liquid metal.
Reducing the presence of air and other gases trapped in the molten metal prevent issues, such as, presence of air bubbles, poor mechanical strength, and reduced mechanical density. The vacuum also ensures that the liquid metal flows freely into all the areas of the die cavity while avoiding gas entrapment and the defects in the solidified metal component. This yield cast components with good surface finishing and accurate dimensions.
Furthermore, the vacuum die casting technique controls the solidification process of the molten metal. The regulated vacuum chamber permits uniform cooling rate and uniform material characteristics throughout the whole cast component. This consistency is fundamental for applications that require ultra-precision and consistency.
The vacuum casting process uses non-ferrous metals such as zinc and aluminum alloys. These metals offer beneficial properties, including excellent fluidity in their molten state, easy casting process, and improved mechanical characteristics in the finished product. These cast parts exhibit impressive heat resistance, which is a property of the alloys utilized.It is important to note that the vacuum environment can either be established when the molten medium is introduced into the mold cavity (at the same time) or it can be established after the molten medium has been introduced into the vacuum casting machine.
VACUUM DIE CASTING ADVANTAGES
Vacuum die casting confers various advantages over the traditional die casting methods. The air-free environment in the mold cavity provides good quality and effective cast components. Some vacuum casting advantages include:
Smooth Finish of the Final Product
The vacuum environment removes air and gases in the liquid metal, which helps minimize surface defects or pores such as pinholes and rough textures, thus resulting in smoother finishes. This surface quality of vacuum die casting is valuable mainly for products that have to be aesthetically pleasing. Hence, vacuum die casting contributes to quality appearance of products and its overall performance.
Improved mechanical properties
The vacuum chamber reduces the rate at which the molten metal is exposed to oxygen. This reduction in oxidation causes cast components produced through vacuum die casting to have high tensile strength compared to products of traditional die casting.
The improved mechanical properties are accessible because the vacuum efficiently removes gases that can cause porosity de-valuing the material. This characteristic is vital for applications whose elements undergo stress or high load.
Low/ Elimination of Defects and Wastes
Removing the air and gases in the vacuum chamber reduces inconsistencies commonly associated with metal cast parts. The vacuum casting process results to fewer rejected products as the final products meet the required specifications and, overall, there is less material waste. Vacuum die casting also provides a more effective production process, saving cost and time.
Vacuum Casting Advantage on Filling Pressure
The vacuum environment helps to control filling pressure. Filling pressure is a term that refers to pressure used to inject the liquid metal into the mold cavity so incomplete filling can be minimized. This control ensures that the filling is uniform and the turbulence experienced by the molten metal while filling is reduced as it fills appropriately with low pressure compared to traditional die casting.
Less Environmental Impact
Vacuum die casting usually produces fewer emissions than conventional die casting. The vacuum ensures that the chemicals and fluxes used to manage oxidation make the process smooth and, in the long run, reduce gas emissions in the environment when the final products are in use.
Vacuum die casting is the most appropriate for applications exposed to high temperatures. The gas-free cast property usually results in good thermal conductivity and resistance, allowing the die to maintain its integrity under high temperatures.
VACUUM DIE CASTING APPLICATION
Vacuum die casting, a metal casting operation with many benefits, produces high-quality and durable components, especially where precision and durability are essential. By utilizing vacuum die casting techniques, industries can produce high-quality components that require excellent mechanical characteristics, complex designs, and minimal flaws. Here are some products and applications where vacuum die casting is notably beneficial.
Aircraft Components
Vacuum die casting is crucial in producing aerospace parts such as aircraft engine components, turbine blades, and other structural parts. These components must tolerate harsh conditions so they can function effectively. This method’s mechanical strength and decreased porosity characteristics are essential for these heavy-duty applications.
Automobile Manufacturing
Components such as transmission housing and engine blocks are manufactured with vacuum die casting. This method offers advantages for the automotive sector by producing parts that demand high strength and exact specifications. The technique ensures weight reduction, optimal part performance, and, in the long run, conservation of fuel and safety.
Defense Technology
Reliable and durable components are vital in the military system, and this process helps produce items for military vehicles, weapon systems, and other protective gear. Its augmented mechanical features and defect-free properties make it ideal for defense applications.
Medical Devices
Surgical instruments and prosthetic equipment are examples of products made from vacuum die casting. These products, and many others, are essential in the medical field as the accurate measurements and weight specifications that vacuum casting employs give people prosthetic body parts or equipment that can function accurately for their body.
Electronic Systems and Gadgets
Vacuum die casting produces electronic devices, especially those that require good electrical conductivity and thermal regulation.
Industrial Equipment
This equipment involves the use of resilient components that can endure substantial wear and tear. This method can be used in manufacturing of gears, and structural components for industrial machinery.Household products such as cookware, decoration items, and jewelry are vacuum casting products as the smooth finish ensures aesthetically appealing productions. Other applications of vacuum die casting are in the construction of agricultural equipment, sports equipment (e.g., bicycle parts), telecommunications, and the marine industry (for boats, ships, housings, etc.).
VACUUM CASTING PROCESS
The vacuum casting process makes products by pouring the cast material, usually molten metal (such as zinc, aluminum, magnesium, etc.) into a mold cavity, similar to injection molding. However, unlike injection molding and other traditional casting techniques, the vacuum chamber is created under the mold cavity before the metal is injected into it.
This technique of metal casting involves various vital steps, all of which are important for the functionality and quality of the final product. The following are steps involved in vacuum die casting:
Creation of a 3D model of the Cast Component
Design the components to be produced using computer-aided design (CAD) software. This 3D component can highlight its shapes, dimensions, and features before production. This prototype helps make any essential modifications before creating the final product mold.
Metal Melting
The metal alloy has to be melted adequately in a furnace to reach its liquid state. Aluminum, magnesium, and zinc are the common alloys used in vacuum casting. Additionally, you must carefully control the melting temperature to ensure the metal achieves its intended properties.
Construction of the Mold Cavity
We make the mold from high-strength alloy steel, which handles hot molten metal and shapes the final product. Treat the mold’s inner surface correctly or coat it well so that you can release the metal part smoothly after cooling and solidifying to form the final product. This also helps the mold last longer and reduces wear and tear.
Set up of Vacuum Chamber
The unique characteristic of vacuum die casting is the vacuum chamber. The vacuum is created inside the mold cavity to provide a controlled environment around the mold free of air and gases, eliminating gas entrapment, as mentioned earlier.
Injection of the Metal
In the vacuum casting process, molten metal is injected or infused into the mold cavity and this must be done under intense pressure. The already-made vacuum helps fill every part of the mold cavity with the molten metal in a smooth process.
Cooling and Solidification
Cooling begins after the mold cavity has been filled. The vacuum aids in regulating the cooling rate. The cooling rate influences the casting’s mechanical properties, as proper cooling produces consistent solidification, which gives the product strength and durability.
Ejection and Assessment
The cast can be ejected using ejection pins or mechanical devices to ensure the cast component is adequately removed from the mold cavity. Assessing the cast and comparing it with the 3D model is essential to ensure that all the specifications are met for quality assurance. Dimensional measurement, visual inspections, and so on are done during this stage.
VACUUM CASTING MACHINE
The vacuum casting machine in conjunction with master models and 3D printers fabricates plastic or metal parts for small-scale production runs.
Every vacuum casting machine comprises a vacuum chamber, electrical control module, melting chamber, mixer, and metal injector. The process begins in the melting chamber where the metals are heated into liquid according to the melting points of the metals used. Different metals and colors may be combined based on the desired product. De-aeration follows shortly for about 50-60 seconds.
After mixing, the metal injector injects the mixture into the mold under vacuum. In the vacuum chamber, gravity spreads the molten metal throughout the mold. This unique feature of the vacuum casting process distinguishes it from other manufacturing technologies.
Auxiliary Equipment for Vacuum Casting
Auxiliary equipment for vacuum die casting includes squeeze pins, a mold temperature controller, and the jet cooling machine. The squeeze pins help to minimize shrinkage during the molding process by ensuring proper placement.
Temperature is regulated in vacuum die casting via the 320o C Oil-mold temperature controller. This implies the controller uses an oil base and a working temperature as high as 320O C. Other die-casting machines may use water-based temperature controllers which operate at lower temperatures to prevent fire outbreaks.
The jet cooling machine minimizes porosity and shrinkage normally associated with casting at high temperatures. The cooling system in die-casting machines helps to prevent thermal fatigue of metals which might cause them to shrink. The sequential cooling and high-pressure capacity associated with the jet cooling system eliminates hot areas in deep regions of the core pins and inserts.
VACUUM DIE CASTING METAL
The vacuum die casting process begins by preparing the molten metal to be poured into the mold cavities. In the case of metals, metal alloys with moderate temperatures and densities are usually preferred. Some of these metals include:
Aluminum alloys
Most die-casting industries utilize aluminum alloy as the molten medium. They usually contain silicon, magnesium, zinc, and copper to enhance the flexibility and strength of the aluminum. Aluminum alloys are used in applications where weight reduction is necessary. For instance, in the creation of aerospace parts. A380 and ADC12 are common aluminum alloys used in vacuum die casting.
Magnesium alloys
Magnesium alloys are used to cast structural components with minimal weight. AZ91D and AM60B are magnesium alloys used in die casting. These magnesium alloys are known for their excellent strength and good thermal conductivity.
Zinc alloys
Zinc alloys are used across various industries where cast parts with complex details are needed. In vacuum die casting the zinc can be combined with other metal alloys depending on the application of the cast parts. An example of such a blend is the Zamak series.
Copper alloys
Copper alloys are employed in the vacuum casting process. However, Copper-Nickel alloys are not used due to the extreme temperatures required to melt the metal. They are used in applications that require high electrical and thermal conductivity. Overall, copper alloys are more common in other die-casting processes such as sand casting and centrifugal casting than in vacuum die-casting. Brass and Bronze are the common copper alloys employed in casting processes.
Vacuum die casting can be done with several metal alloys; however, aluminum remains the most applied in many vacuum die casting factories.
VACUUM DIE CASTING MOLD DESIGN
Vacuum die casting molds are integrated into a vacuum environment within the vacuum die casting machine where vacuum and gravity are relied on to remove all gases within the metal that might result in shrinkage affect the porosity of the metal or cause imperfections in the final products.
Types of Vacuum Die Casting Mold Designs
Depending on the application of the cast products and the production scale, the following are types of vacuum die-casting mold designs:
Single Molds
These molds produce one cast part per cycle. Single mold designs are used to create large casts with complex cavities or casts with regions that require tight tolerances. The simplicity of this mold allows for high dimensional accuracy and easy control of molten metal into a single cavity. It is also an inexpensive design compared to other molds.
Multi-cavity Mold Design
Some vacuum die casting processes utilize single molds with various cavities. The multi-cavity mold is a complicated version of the single mold design and facilitates the production of various cast parts of the same geometry per cycle. It is therefore more time-efficient than single mold designs and helpful in large-scale productions. Uniformity is also achieved to a large extent with this design.
Family Mold Design
Unlike the multi-cavity mold design, the family molds also have numerous cavities but each with dissimilar shapes and sizes. The different casts created from the cavities form a component cast part, hence the name family mold design. It saves time and reduces the production cost.
Insert Molds
Insert molds come in handy when the desired cast product requires a combination of different materials such as plastic and metal. This design enables prefabricated or bought-in parts to be inserted into the mold before the casting begins. Insert mold design requires a great level of expertise and control during casting. Integrating different materials enhances the strength and flexibility of the final product.
VACUUM CASTING VS. INJECTION MOLDING
There are various die casting techniques employed in fabricating plastic and metal cast parts used in automotive, aerospace and electronics industries. However, factors such as the production scale and the ultra-precision of the products largely determine the technique to be used. Vacuum die casting and injection molding are two major techniques utilized in metal cast productions. The following are the differences between the two techniques.
Vacuum Casting
The vacuum die-casting process is required for rapid prototyping and other small-scale production of metal parts. Unlike traditional die casting, it involves pouring liquid or melted metal into a mold under a vacuum. Vacuum casting molds are commonly made from steel or nickel materials. The mold is a replica of a “master pattern” bearing the geometry and number of cavities the mold is intended to have. A 3D printer or CNC machine produces the mold when the master pattern is dipped in the molten medium.
In contrast to Injection molding, vacuum casting process yields are smaller. This is because it requires a significant level of manual labor. Injection molding on the other hand is an automated process requiring minimal manual intervention thus it yields more metal casts per cycle.
Overall, the vacuum casting process is an inexpensive manufacturing technology when compared to injection molding. The most expensive aspect of vacuum die casting is the cost of the printers or CNC machine used to replicate the master pattern.
Injection Molding
Injection molding utilizes high pressure to form ultra-precise metal and plastic parts. Unlike vacuum casting where gravity spreads the molten media within the mold cavities, injection molding uses force to fill out the mold cavities. The Injection molds are made from hardened steel or aluminum which are relatively expensive. Due to the difference in the durability of the mold materials and the degree of precision being targeted in the final products, injection molds may take longer time to perfect.
CNC machining and electric discharge machining (EDM) are employed in fabricating injection molds.Injection molding is much preferred to the vacuum casting process because it minimizes production time and allows for repeatability. This implies that several metal parts can be produced per cycle depending on the number of cavities in the mold. The pressurized filling mechanism of the cavities and the rapid rate of cooling contribute significantly to its time efficiency. Thus, it is commonly employed in large-scale production of metal casts.
PROFESSIONAL DIE CASTING MOLD MANUFACTURER AND VACUUM CASTING FACTORY – RAIDY MOLD
Raidy Mold is a Chinese Mold manufacturing company with over 30 years of experience in the die-casting industry. Some of their services and products include:
Aluminum Die Casting
Raidy Mold specializes in the mass production of durable and lightweight aluminum die-casting molds and cast parts used in automotive, aerospace, and electronics applications. Their casting procedures allow for repeatability and follow stringent standards based on the application of the final product.
Vacuum Casting and Plastic Injection Molding Services
Raidy Mold is equipped with advanced laboratories and state-of-the-art equipment that facilitate the production of flexible plastic parts made from plastic injection molds and vacuum casting for the creation of metals casts used in automotive, consumer packaging industries, and also in medical devices. Medical devices such as pacemakers with complex specifications are made on a large scale using various mold designs manufactured by Raidy Mold. Each product is tailored according to client’s request.
In addition to offering vacuum die casting services, Raidy Mold also manufactures vacuum-casting machines. Unlike the traditional die-casting machine, Raidy Mold’s vacuum die-casting machines improve the intrinsic quality of the casting as well as the yield rate by eliminating air and gases via the installment of a vacuum channel. The vacuum has a high-precision vacuum sensor and an anti-oil absorption system to minimize shrinkage and porosity in the final products.
CONCLUSION
This article has discussed vacuum die casting, the pros and cons involved in the vacuum casting process, vacuum die casting machine, mold designs, auxiliary equipment, vacuum die casting manufacturers as well as the difference between the vacuum casting process and injection molding in terms of lead times, production scale and the likes. The information in this article will help you decide on the casting process best suited for your product.
Raidy Mold dies casting manufacturer is an excellent choice for various die-casting services, especially vacuum casting. These vacuum casting services range from the sale of various cast parts to mold design services and the sale of vacuum casting machines. Their excellent expertise and track record of producing quality products make Raidy Mold your first stop for your die-casting products. Contact Raidy Mold today for your vacuum die-casting services.
