Lists of high pressure die casting manufacturers and detailed information about the process
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High pressure die casting (HPDC) is a process that includes injecting molten metal into a mold or die under considerable pressure to form implements, parts, and components. The dimensional accuracy, tight tolerances, and smooth surface finish of parts manufactured by high pressure die casting removes the need for any secondary processing. Parts’ manufacturers prefer high pressure die casting over other methods due to the quickness of the process, high volume production, and relative low cost.
The pressure for high pressure die casting is created using hydraulics and pressurized gas that drives a piston or ram that injects the molten metal into the mold. The clamping end of the mold absorbs the high pressure and holds the die tightly closed as the molten metal solidifies. The speed of the process can turn molten metal into solid near net shapes in a few seconds.
The choice of high pressure die casting as a manufacturing process is due to its ability to produce large, light alloy parts in high volume, rapidly and efficiently. In addition, the parts produced have excellent surface finishes, exceptional uniformity, and high-quality mechanical properties. Although deburring around holes to remove flash is necessary, in general, parts produced using high pressure die casting do not require any form of secondary processing. Complex and intricate shapes are cast as a single piece.
The die casting process has been used for over two hundred years to produce parts. The initial method involved pouring molten lead and tin into a mold and was used to manufacture type for California case printing presses. The industrial use of die casting began in the early 20th century and involved multiple dies to create a wide range of products. As the high pressure die casting process grew in popularity, different types of metals were introduced as well as more products.
Although the HPDC process is utilized differently for each manufacturer, there are basic steps to the process that are the foundation for every type. In addition, certain products require unique procedures due to the nature of the products and their use. The initial steps in high pressure die casting begin with a dialogue between the die casting company and their customer. Prior to meeting, customers have developed and designed products, the aspects of which are presented to high pressure die casting engineers.
All high pressure mold casting companies have an inventory of molds that they use to produce standard products. With new customers and new designs, molds have to be created. As with all industrial products, the process begins with a computer aided design (CAD) software or some other form of computer rendering. Engineers and customers work closely together on creating a design that has the right dimensional tolerances and configuration to fit a customer’s product.
Special attention to the design of the mold can alleviate any potential issues that may arise during the manufacturing process. Designers and engineers work closely together in order to get every aspect of the mold perfectly shaped and configured. Such attention to detail is necessary as a preventative measure regarding concern for waste and increasing costs.
The molding system includes the cavity, core, inserts, sliders, and pins. There are two halves to the cavity of the mold, which has the shape of the finished molded part. Steel plates and frames help combine the halves of the mold and its components for installation into the die casting machine.
A critical feature of the mold is the ejection system that ejects parts from the mold. On the reverse side of the mold is the runner system that delivers the molten metal to the mold cavity and impacts the pressure and speed of the movement of the molten metal. The final feature in the mold is the overflow system that removes pressure and has overflow and venting slots.
The types of high pressure die casting molds include prototype, rapid tooling, production, unit, and trim. Prototype molds or dies are a way of testing a die before machining a full on custom made die and are tested using gravity casting. Rapid tooling dies are produced quickly and are normally used for prototyping. Production dies are the main part of high pressure die casting. They are made of high-quality steel and are stored in holder blocks. Production dies can produce several thousand parts over multiple cycles.
Prior to attaching the mold to the high pressure die casting machine, various steps are required to prepare the surface of the mold for the acceptance of the molten metal. Although the metal for the mold and the metal to be injected are different, there is the potential that the injected metal may stick to the surface of the mold. To prevent such a scenario, a lubricant is applied to the interior walls of the mold. It regulates the temperature of the mold and serves as a film between the molten metal and the mold, making it easy to remove the finished casting.
When a customer requests the manufacture of a molded part, they stipulate the type of metal that they want used. As assortment of metals are used in the high pressure die casting process and include:
Metals for cold chamber high pressure die casting are ones with high melting points and include aluminum, brass, and magnesium. Hot chamber high pressure die casting works best with metals that have a low melting point, such as lead, zinc, tin, and magnesium.
The two methods used to inject molten metal into a die in high pressure die casting are hot chamber and cold chamber, which differ in how the metal for the process is melted. Both methods inject the molten metal into the die but are parts of different types of high pressure die casting machines. Although the final product in both cases is the same, the methods used for heating and melting the metal to be cast are extremely different.
Hot chamber high pressure die casting is ideal for metal alloys with low melting points, such as lead, zinc, tin, and some magnesium alloys. Known as a gooseneck machine because of its structure, hot chamber high pressure die casting machines include a furnace, burner, cylinder, piston, nozzle, gooseneck, die, and ejection pins.
The gooseneck, feed system, burner, and furnace are linked as one machine. Every step of the casting process is completed in a single machine. The metal alloy to be processed is loaded into the melting pot with the cylinder for the plunger located in the center of the pot. Heat is applied to the melting pot by the burner in the combustion chamber located underneath the melting pot.
During the heating and melting process, the molten metal is blocked from leaving the melting pot by the location of the plunger in the cylinder. When the metal has achieved the correct temperature, the plunger or piston is lifted allowing the molten metal to enter the cylinder through the intake port.
The next step is the aspect of the process that provides the pressure to force the molten metal along the gooseneck into the die cavity. Using the power of a hydraulic cylinder, the piston is forced down the cylinder and pushes the molten metal up the gooseneck. The key to the process is the amount of pressure placed on the molten metal, which ensures that all sections of the die are filled. The pressure from the piston continues until filling is complete.
Once every part of the die is filled, the pressure is maintained until the molten metal solidifies, which begins as soon as the molten metal touches the surface of the die. The initial cooling occurs at the surface of the die and thinner sections, progressing inward. The time of solidification varies in accordance with the type of metal being processed and design of the part.
Once the metal part has solidified and formed, the plunger is retracted. The dies separate or are pulled apart and the formed part is ejected. On the movable end of the mold are ejector pins that push out the completed solidified part.
Unlike hot chamber high pressure die casting, the furnace for creating the molten metal for cold high pressure die casting is separate from the mechanism of the casting process. Molten metal is heated, melted, and prepared in a gas fired or electric resistance furnace. Metal, in the form of ingots, is loaded into the furnace. When the metal reaches the correct consistency and acceptable molten level, it is removed from the furnace using a ladle.
Although the function of cold chamber high pressure die casting is the same as hot chamber high pressure die casting, the structure of a cold chamber high pressure die casting machine is simpler. The vertical plunger and cylinder are replaced with a shot chamber and ram. The shot chamber replaces the gooseneck as the mechanism for feeding the molten metal into the die, which has the same structure as that used in hot chamber die casting.
The molten metal is taken from the melting furnace in the ladle to the cold high pressure die casting machine and poured through a hole located on the top side of the shot chamber. The amount of molten metal in the ladle, which is referred to as a shot, is the exact amount necessary to fill the die.
As the hydraulic driven ram moves along the shot chamber, it covers the pouring hole. The intense pressure from the ram forces the molten metal to every portion of the die, which prevents air pockets and voids. The amount of pressure varies between 1500 psi and 25,000 psi. The level of pressure is maintained to prevent shrinkage and until total solidification. Metal is injected at hundred inches per second and quickly produces exceptionally high-quality parts. The cooling process for cold chamber high pressure die casting is completed quickly.
Casting ejection for cold high pressure die casting is essentially the same as that for hot chamber high pressure die casting. The die is opened, an ejector pins, located in the movable end of the die, push out the formed solidified casting from the die cavity.
Trimming is the process of removing excess material from the completed casting, in the form of flash or runners and gates. Flash is thin pieces of molten metal that is squeezed out of the die at the parting line as pressure is applied to the molten metal. When the completed casting is ejected from the die, it is trimmed to achieve its final shape. The process of trimming ensures dimensional accuracy and geometries that match the specifications of the casting’s design.
Proper trimming removes rough edges and any imperfections. The result of the process is a smooth finish and aesthetically pleasing appearance. Trimming, as with many aspects of casting, has to be completed carefully since over-trimming can weaken the structure of a casting and damage its integrity.
A method that has been introduced to increase the efficiency of trimming is trimming machines that are used for high pressure die casting and high-volume production. The process includes a trimming die that removes gates, risers, and burrs in one simple operation.
There are several methods of die casting, which include gravity die casting, vacuum die casting, sand casting, and pressure die casting. The choice of die casting process is critical to the production of parts and components. Each of the methods has capabilities and restrictions that have to be considered when choosing casting to produce a component.
Casting manufacturers help guide clients through the casting manufacturing process to inform them as to the benefits and considerations it provides. In the case of high and low pressure die casting, there are stipulations that restrict certain types of metals, volume of production, and the properties of castings.
Cost is a major consideration for both high and low pressure die casting. It is important for casting customers to know the cost of the casting process, which is weighed against the high quality of the products that are produced. Low pressure die casting involves alloys with low melting points and the production of castings that weigh 150 kg. High pressure die casting uses soft alloys and performs at high speeds.
Tooling costs is an issue for all forms of die casting due the expense of forming and shaping dies and molds. The design of a mold, its complexity, and the types of materials are initial costs for both types of die casting. The pressure related to high pressure die casting necessitates the use of strong and more robust metals. The tooling has to endure rapid injection, which increases design costs. Low pressure die casting uses less pressure, a factor that decreases the wear on molds and dies.
Production volume is a major factor in differentiating the capabilities of high and low pressure die casting. HPDC is automated and used for high volume production runs, which amortizes the tooling costs and lowers per unit costs. When thousands of parts and components are needed, high pressure die casting is the best choice.
The slower cycle times of low pressure die casting makes it best for small runs of a few hundred parts. The lower tooling costs helps to keep the per unit cost down. LPDC can be an alternative but requires careful consideration since large quantities can be very costly.
As is indicated by volume, high pressure die casting has faster cycle times, which is the reason it can produce higher volumes of parts. The speed of injection makes it possible to have faster part production. Normal cycle times for HPDC for average parts is 200 to 300 shots per hour. For very small parts, such as zipper teeth, shots per cycle increase into the thousands. Shorter cycle times mean that more parts are produced per hour, a factor that increases productivity and lowers labor costs.
The length of the process for low pressure die casting is longer. The controlled molten metal filling process increases cycle times, which ends in lower throughput. In addition, the slow process increases labor and operational costs. Large orders take several hours and delay delivery times.
Die casting is a high energy consumption process. The amount of energy used by HPDC compared to LPDC is significant. High pressure die casting requires a great deal of energy to create the pressure for the faster cycle times. This increases operational costs and can have an impact on certain areas.
Although the slowness of low pressure die casting results in shorter product runs and long cycle times, it has a benefit in regard to energy costs. The lower pressure of LPDC lowers energy costs per cycle. The greater factor that influences energy costs for LPDC is the breadth and scale of production, which increase energy costs.
Both high pressure and low pressure die casting are capable of producing complex geometries with the basic difference being quantities and time. The key to their success is close attention to the process to ensure accuracy and adherence to design parameters. A cost that may be added to both processes is post processing and additional finishing steps due to flash, runners, and gates, factors that influence more complex components.
The factor that sets high pressure die casting apart from other casting methods is the speed and accuracy of casting production. Speed seems to be a dictating factor in modern manufacturing. High pressure die casting is widely used due to its speed and accuracy. While other casting methods may take hours to produce components, high pressure die casting can complete the process in minutes.
Aside from the speed of high pressure die casting, there are benefits in regard to the components that are shaped by the process. From carefully crafted dies to high quality finishes, high pressure die casting offers several benefits that have made it an essential aspect of part production.
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The high production rate is what is constantly pushed as a benefit of high pressure die casting. The speed of the process makes it possible to produce large quantities of parts in a short time, which lowers per unit costs. The number of cycles per hour varies in accordance with the parts being produced but can be as many as several hundred up to several thousands. This increase in units lowers the cost of each unit.
One of the disadvantages of LPDC is the limitation on how small the thickness of part walls can be. The pressure placed on the molten metal as it is injected into the die cavity forces the molten metal to every portion of the die, regardless of the thinness or thickness of the die. Wall thicknesses for high pressure die casting can be less than 2 mm for aluminum and as thin as 1 mm for zinc.
Having the ability to produce components with significantly thin walls makes it possible to manufacture lightweight components with sufficient strength and durability. In the modern age, this includes a wide range of industries such as aerospace, automotive, and electronics. Weight has become a major issue for the auto issue and has always been a concern for aerospace.
High tolerances are one of the major reasons for the popularity of die casting in general and high pressure die casting in particular. The dies for high pressure die casting are made from H13 tooled steel and precision machined to the micron level to produce castings with exceptional tolerances.
The tolerances for zinc castings are between ±0.001 in and ±0.002 in. For aluminum, casting tolerances can be between ±0.002 in and ±0.004 in. Tolerances for castings is important to ensure the casting meets the functional requirements of an application. The types of tolerances in high pressure die casting are linear, flatness, and parting lines, a factor that is examined to ensure part precision.
Porosity is a major concern in all forms of die casting. Trapped gases and air inside a casting create pores, which become weak points. Although HPDC creates turbulence when injecting molten metal, fast solidification and high pressure minimize potential porosity. When considering a method for producing a part or component, it is essential that the chosen method does not allow porosity.
The presence of openings, spaces, or pores in a casting ensures component failure and damage. The main feature of high pressure die casting is the pressure under which the molten metal is injected and continued until solidification. The constancy of the pressure as it presses up against the molten metal limits the potentiality of porosity.
The engineers and designers at high pressure die casting companies work diligently to ensure that none of their molds will produce pores. Although the pressure of the process severely limits the potential for the inclusion of pores, the design and tooling of the die ensures the prevention of porosity.
In any metal working process, grain structure is a major concern since it determines the strength and durability of a part or component. In high pressure die casting, pressure is applied to the molten metal until the casting solidifies. The process is quick and efficient. The speed of the high pressure die casting process allows the matrix of a casting to be consistent with small grains that improve the properties of the casting.
When a metal is processed, its microstructure is changed. Changes in the microstructure influence a metal’s properties. Strength, toughness, ductility, hardness, corrosion resistance, the effects of high or low temperatures, and resistance to wear are impacted. During the design phase of high pressure die casting, engineers carefully examine how the procedure will affect the microstructure of the final product and what its capabilities will be.
One of the factors related to changing the microstructure of a metal is its strength to weight ratio. A feature of high pressure die casting castings is their thin walls that have a fine microstructure. It is this aspect of the castings that separates the process from other forms of casting. The result of the fine microstructure is castings that are exceptionally strong, durable, lightweight, and tough.
The smooth even surface finish of HPDC castings is achieved by fast fill times and the smooth walls of the dies. Castings, in secondary processing, are blasted, painted, anodized, chrome plated, and polished to a mirror finish. The process for high pressure die casting delivers components with a superior finish, excellent uniformity, and outstanding mechanical properties. The dimensional accuracy and exceptional surface finish generally does not require machining, which further enhances the production process and lowers cost.
When customers choose high pressure die casting, they have a vision of the surface finish that their product requires. Working with HPDC engineers, they outline the nature and use of the product with a description of the necessary finish. The surface of a product is dictated by the mold, metal, and any forms of coatings. Consideration of the surface finish is a necessity when selecting high pressure die casting as a process.
For many years, die casting was restricted as to the size of castings. With the advent of bigger and better machines, high pressure die casting is used to produce engine blocks on 4500 ton and 6500 ton HPDC machines. As the size of machines has increased, the size of parts has matched the improvement with parts of thousands of millimeters and several feet being produced.
Intricate and complex designs of a wide range of sizes and weights are rapidly being produced. The addition of the production process of HPDC is changing the face of modern industry. With the restriction on the process eliminated, HPDC can be used to produce any form of product at extremely high quality in line with manufacturing standards.
Many products require heat treatment to harden them and make them more durable. This aspect of production has not always been available for HPDC products until recently. The increasing use of HPDC as a production method has necessitated finding a method to heat the parts being produced. High volume production and exceptional grain structures have made high pressure die casting the first choice for part production. A caveat related to choosing the process was the inability of heat treating HPDC parts.
After dedicated research, engineers developed a method that is used to heat treat HPDC parts and make them usable for products requiring increased hardness. This revelation has further expanded the dependence on HPDC as a production method. In addition, conventional heat treating methods are used that include cooling a part and then reheating it in an oven.
Choosing the right metal for a high pressure die casting project is a critical aspect of the manufacturing process. Metal selection is included in the early phases of the design process since the type and properties of a metal determine how it can be included in an application. The choice of a metal is determined by a metal’s durability, strength, and overall quality.
High pressure die casting components are made of aluminum, magnesium, and zinc, which are chosen for their resistance to corrosion, high strength, and non-magnetic properties. Of the three metals, aluminum has become the most widely used due to its resistance to corrosion and rust.
The choice of a die casting metal is determined by the parameters of a project’s requirements and the application for which a product is being produced. The three factors customers use when selecting a metal are:
Magnesium is lighter than aluminum and easier to cast due to its fit with the process. Alloys of magnesium that are typically used in high pressure die cast are:
AZ91D – AZ91D has a high strength-to-weight ratio, corrosion resistance, and castability.
AM60 – AM60 includes strength, ductility, vibration dampening, and castability and is the first choice for casting auto parts.
AS41B and AE42 – AS41B and AE42 rare earth alloys with high-temperature, creep, corrosion, and ductility resistance but are very expensive alloys.
The benefits of magnesium include:
There are several factors that differentiate zinc from magnesium and aluminum. Its smooth surface finish provides high aesthetic appeal with tight tolerances. Zinc can be used to cast any type of product of any size. The alloys of zinc used for HPDC casting include:
Zamak 3 – Zamak 3 is known for its dimensional stability and ease of casting.
Zamak 2 – Zamak 2 is an expensive zinc alloy with great strength.
Zamak 5 – Zamak 5 is less ductile but has higher tensile strength.
The many benefits of zinc include:
Since its discovery in the 19th century, aluminum has become the most commonly used metal for a wide range of products and applications. Lightweight, corrosion resistant, and electrically conductive, aluminum is normally the first choice for the manufacture of castings. Certain grades of aluminum have strength and durability that is comparable to grades of steel. Aluminum alloys that are typically used for high pressure casting are:
A360 – A360 is used in die casting because of its excellent strength and heat resistance. It is a good choice for parts that require toughness and durability, such as automotive components and aircraft parts.
A380 – A380 is known for its fluidity, which makes it easy to cast complex shapes with thin walls. Its mechanical properties include high strength, corrosion resistance, and thermal conductivity.
A383 – A383 is a version of A380 with exceptional strength and good conductivity.
A413 – A413 is a good choice for applications that require excellent corrosion resistance and high strength.
A319 – A319 is commonly used for automotive and industrial applications.
A356 – A356 is widely used in high pressure casting due to its castability and strength.
There is a long list of benefits that manufacturers can provide regarding the use of aluminum. A short list of those benefits include:
The high quality of products produced by high pressure die casting has made it a production partner with a diverse set of industries. The speed at which components are produced and the quantities make HPDC ideal for the manufacturing of any size part or component. High pressure die casting has been around for many years and has been used to produce tight tolerance parts. In recent years, the diversity of the ways that HPDC can be used has been ever expanding as new and innovative methods of including it in the production of various applications are being discovered.
The auto industry purchases more castings than any other industry. Engine blocks, gearbox casings, oil sumps, engine mountings, and structural parts are manufactured using HPDC. The strength and durability of components produced using HPDC are unmatched by any other manufacturing method.
The emphasis that has been placed on auto manufacturers to lighten the weight of cars has required manufacturers to find ways to decrease car weight. High pressure die casting offers a solution by producing strong durable components that match weight requirements.
Central paradigms for the construction industry are strength, durability, and longevity. Unlike other industries where products have a time limit, buildings, materials, and structures are expected to last for many years. It is for these reasons that the construction industry uses components, parts, and other features produced by high pressure die casting. Window frames, roof superstructures, total building frames, bridges, and skyscrapers are constructed using HPDC castings. Components are lightweight, sturdy, strong, durable, and, above all, long lasting.
Referred to as structural components and structural die casting in the high pressure die casting industry, components produced for the construction have to meet the requirements of being lightweight and strong. In addition, they have to be dimensionally accurate with tight tolerances to fit into a structure's architectural design.
The aerospace industry has strict standards regarding the components used to construct aircraft. Many of the regulations are for safety reasons and the protection of occupants. HPDC is popular with the aerospace industry due to the process’ ability to produce intricate and complex designs. The planning and construction of aircraft is a carefully controlled and monitored process that examines, in detail, every step. The lightweight and superior quality of HPDC parts makes it the ideal process for aerospace manufacturing. Aside from the durability and strength of parts, the repeatability, consistency, and precision of the process is a perfect match.
Medical devices have strict stipulations regarding accuracy and precision. The proper assembly of such devices ensures high quality performance, safety, and adaptability. Ultrasound systems, pacemakers, dialysis equipment, and medical robots require intricate components that are produced by high pressure die casting. Manufactured components are designed to meet the high standards of medical professionals. The tools are lightweight and easy to handle in hospital rooms and surgical theaters.
In the renewable energy industry, high pressure die cast is used to manufacture piping, drilling equipment, valves, impellers, and brackets for solar panels. As with the construction industry, components for the energy sector have to be strong, durable, and long lasting to meet the requirements of sustainability.
There is a very long list of components that are produced for the electronics industry using high pressure die casting. From connectors and housings to heat sinks and handles and knobs, the HPDC supplies high quality products, parts, components, and tools. The choice of HPDC as a producer is due to the mechanical properties of components, their low cost, and their precision and complexity. In the majority of cases, zinc is the metal used to manufacture tools for the electronics industry.
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