Precision Die Casting
Precision Die Casting
Die casting is the process of forcing molten metal into a mould cavity under high pressure. In precision die casting, the mould cavity is usually made with two steel dies that have been created into the desired shape by a machine.
At EKO, die castings are manufactured with non-ferrous metals such as aluminum, zinc, and tin-based alloys. The type of metal that is being cast determines the type of machine used (hot chamber/cold chamber) to make the cast.
Die casting is a manufacturing process that is suitable for high volume items. As metal dies and casting equipment make up a large part of capital costs, the incremental cost per item tends to be very low.
Our precision die-casting process ensures that the products that we manufacture have excellent surface finishing and good dimensional consistency with precise measurements.
Die Casting Material
Alloys that are suitable for die casting are those that are corrosion resistant and have optimal density. Our engineers assess the mechanical properties such as strength, hardness and elongation when picking the right alloy to use for your die-cast.
The most common die casting alloys are aluminium, magnesium, zinc and copper.
Here at EKO, we use a variety of Aluminium & Zinc materials to support customer requirements in order to meet the quality of the specified products
Aluminium die casting alloys or so-called “ADC/LM” (follow with the code ADC12/LM1) are lightweight. It offers good corrosion resistance, ease of casting, good mechanical properties and dimensional stability. It also has excellent shielding properties, high electrical conductivity and is durable enough to achieve high quality finishing characteristics.
Complete recycling of aluminium die castings is also possible. Many companies choose aluminium alloys because of its durability and lightweightedness.
- ADC 1
- ADC 3
- ADC 10
- ADC 12
Zinc or so-called “Zamak” have high strength and hardness with an excellent electrical conductivity. Apart from this, Zinc has characteristics such as high thermal conductivity, accuracy and stability during casting. It has an excellent thin wall capability resulting in the ability to achieve high quality finishing characteristics.
It is also possible for complete recycling when the zinc die casting is no longer usable.
- Zamak 3
- Zamak 5
Precision Die Casting Process
Precision die casting involves five main steps:
Clamping
The two halves of the die are clamped together with enough force to keep it secure when the metal is injected.
Injection
Molten metal is injected into the die. The transfer method of the metal depends on whether a hot chamber machine or cold chamber casting machine is used.
Cooling
The molten metal is allowed to cool and solidify when it enters the die cavity.
Ejection
Once the cooling time has passed, the two halves of the die will be opened and the casting is pushed out with an ejection mechanism.
Trimming
Excess material will be trimmed from the casting.
Die casting has far-reaching applications. Manufacturing industries such as automobile, aerospace
and power tools industries are all heavily reliant on the die casting processes.
Types Of Die Casting
There are two main types of die casting manufacturer processes that are commonly used
Hot Chamber Die Casting
In hot chamber die casting, the injection mechanism’s cylinder chamber is completely immersed in the molten metal. The direct immersion results in a fast, convenient mould injection that leads to high production rates. Hot chamber die casting removes the need to transfer metal from a separate furnace. It is a casting process that works well for items that use metals with low melting points such as zinc, lead and tin.
Cold Chamber Die Casting
In cold chamber die casting, the molten metal is ladled into the injection system. This means the injection mechanism is not immersed in molten metal. Cold chamber die casting is generally slower than hot chamber die casting. However it is great for alloys with high melting temperatures such as brass, aluminium, and magnesium.
The type of die casting needed is dependent on the project or product and its application. Our team at EKO will ensure that the right process is used for your application.
The manufacturing industries are constantly changing–there’s always a new technology promising to make manufacturing floors more efficient than ever. It also helps to keep abreast of technological developments and ensure that your business is taking advantage of the latest innovations to improve productivity.
Why Use Precision Die Casting?
Here are a few reasons to consider precision die casting over other manufacturing processes:
- It is efficient and economical for high volume production runs.
- It can create a broad range of complex shapes and components.
- Die casted parts have a long service life.
- Die casted parts have close tolerances, and dimensional accuracy.
- There are multiple finishing techniques.
Automated processes guarantee consistency in the finished product.
Die Casting vs Other Manufacturing Processes
Die Casting vs Sand Casting
Die casted parts require less machining, have thinner walls and are more dimensionally precise than sand casted parts. Sand casting has lower tolling setup costs, making it suitable for small quantity requirements.
Die Casting vs Plastic Injection
Die Casting vs Forging
Die Casting vs Screw Machining
Die casting is able to produce finished parts that are high in accuracy, complex and have attractive finishes. Here’s how die castings compare with other manufacturing processes.
HERE AT EKO, We do cast either in Aluminium or Zinc with our latest Hot & Cold Chamber Machine
Cold Chamber Casting
- Toyo 800 Tonnage
- Toyo 350 Tonnage
- Toyo 250 Tonnage
- Toyo 125 Tonnage
- ** Vacuum System
Hot Chamber Casting
- Producer 130 Tonnage
Surface Improvement & Finishing Process
With robust technology in hand, EKO supports the secondary process with a variety of equipment to turn the castings into high quality products.
EKO also offer a variety of Surface finishing to every single part that we produce such as:
- Tumbling
- Shot Blast
- Sand Blast
- Hairline
- Powder Coating
- Impregnation
- Wet Paint
- ED Coating
- Trivalent Chromate
- Electroless Nickel
- Anodizing
Lastly before we ship finishing parts out to customers, we offer in-house appearance add ons such as:
- Silk Screen Printing
- Tempo Print
- Laser Engraving
- Mechanical Assembly
Our Precision Die Casting Works
Frequently Asked Questions About Precision Die Casting
If die-cast components are an integral part of your business, choosing a manufacturer that you can rely on is paramount. Factors such as handling capacity, turnaround time, material selections, cost, communication, experience and whether the company is equipped with the right tools should be taken into consideration. Check out our blog post for a more detailed guide to choosing the right die casting company.
When compared to its counterparts, precision die casting may appear to be relatively expensive. However, it can be an efficient and economical process – especially for mass productions. Moreover, working with EKO will give you access to one of the most competitive rates in the market.
It ultimately depends on your application and design. With greater precision, zinc alloys are excellent for smaller and more intricate shapes. They also offer superior finishing. However, aluminium alloys remain as the most commonly used alloy for their affordability and wide availability.
Die casting: Process, Equipment, Uses, and More
The first die casting machine came into existence in 1838, which was a manually operated device. It used an alloy of tin and lead for casting letters. There were further iterations in 1846 and 1886 which had an integrated die casting machine. These poured liquid lead into the line molds with brass letter dies.
Die casting was limited to the printing industry for the first few decades until Herman H. Doehler unveiled the Doehler Die Casting Company in the year 1908. It manufactured die-cast parts and was a market leader until 1998.
It was in 1925 when we first got the glimpse of what a modern die casting machine can look like, which was developed by Louis H. Morin and Joseph Soss in the USA. Since then, we have seen several breakthroughs in this industry with machines becoming more powerful and efficient in due course.
In this article, we discuss the basics of die casting.
What is the die casting process?
Die casting is an automated process of melting alloys (usually those with low melting points) into liquid state and pressing them under high pressure into molds. A pressure of about 150 to 1200 bars is used with a filling speed of 540km/hr.
The process differs from sand casting in the aspect that metal molds are used which can be reused.
Die casting comprises four different processes – die preparation, filling, ejection, and shakeout. For the first part, the operator sprays a lubricant (water-based is the most common, but manufacturers use water-in-oil or oil-in-water too) over the mold cavity. It ensures keeping the temperature in control and easy removal of the finished product.
Post lubrication, the die gets sealed, and the molten metal passes through the pipes at a high pressure of 1,500 to 25,400 psi. The pressure level remains intact until the liquid solidifies and takes the shape of the cast.
Once the solidification is complete, the operator opens the cast, and the ejector pin removes the shot. The last step, i.e. shakeout, involves separating the scrap from the finished product. The manufacturer can use sawing, grinding, or other relevant processes to free the cast from the gate, sprues, flash, and runners.
The scrap is separated and can be melted for reuse, which leads to the yield being close to 67 percent.
Once the shakeout is complete, the finished product is tested for misruns, cold shuts, or any other possible defects.
The process
There are two different processes used in die casting – hot chamber and cold chamber. To begin, the mold is brushed/sprayed with a release agent to ensure easy removal after the process is complete. Irrespective of the process in use, the liquid first passes through a casting chamber where a piston presses it into the mold through single or multiple channels.
Tooling for die casting
Two parts mainly form a die casting – one is cover die half, and the other is the ejector die half. Both of them meet at the parting line. The former contains the sprue or shot hole, allowing the metal to travel to the die. The latter has the ejector pins, and the runner which comes in between the cover die half and the mold cavity.
The cover die attaches to the platen of the machine located at its front. The ejector die stays with the movable platen. Also present are two cavity inserts, which are bolted into the die halves and are easily replaceable.
Manufacturers design the dies in such a way that the finished product will stay in the ejector half after the process is complete. The ejector pins, driven by a pin plate, ejects them and retracts back to their original position.
Cores and slides also form a part of the machine. The former creates holes or other specific designs and can be fixed, loose, or movable, depending on the need. Slides function similar to movable cores and are useful in undercutting the surface.
Types of die casting machines
Following are the types of die casting machines that find usage in different circumstances –
Hot chamber die casting machine
In a hot chamber die casting method, the liquid passes through the valve into the chamber and is pressed at high speed into the mold by the piston. Here the chamber is in constant contact with the liquid metal and the casting set is placed within the melt.
In this process, the operator immerses the injection machine in the metal liquid. A gooseneck attaches the machine to a metal feed system. The die is then closed, and the piston rises to open the port, allowing liquid to fill the container.
Cold chamber die casting machine
In cold chamber die casting method, the casting equipment is placed outside the melt. The casting chamber uses channels to press the liquid into the mold. The process is best suited for alloys with a high melting point.
Here, the metal is first converted into liquid in a separate furnace. The operator then transfers the same to the casting machine and feeds it in the chamber. The machine then pushes a pressurized plunger to force the liquid into the cavity.
Low-pressure die casting
Mostly used for aluminium components, the low pressure die casting involves the mold placed vertically above the molten metal bath, and a riser tube connects them. Because of the pressure, the liquid is pulled in the mold, and the non-existence of feeders ensures high yields.
High-pressure die casting
In high-pressure die casting, the metal liquid is injected at high speed and high pressure in the mold. It results in a cast that has superior surface finish, uniform, and high precision.
Vacuum die casting (VPC)
A relatively new variation known for achieving low porosity and high strength, the vacuum die casting is similar to low-pressure die casting. Here the location of the mold and the molten metal bath is interchanged, and the chamber creates a vacuum, forcing the liquid into the cavity.
Squeeze die casting
The squeeze die casting is appropriate for liquids with low fluidity. It is mostly used for aluminium and aids in fiber replacement.
Semi-solid die casting
Also known as Thixoforming, the semi-solid die casting is useful in delivering high precision casts. It offers minimal porosity and maximum density.
Advantages and disadvantages of die casting
Following are the pros and cons while using a die casting machine.
Advantages
- Higher yield because the molten metal is injected at a very high speed in the dies.
- Ability to attain the finish of order of 1.1 microns conveniently.
- Lower waste material generation.
- The mold is reusable ensuring lower scrap.
- High accuracy and repeatable reproduction of different complexities because of the presence of moving parts.
- Die-casting parts can be created with close adherence to given specifications.
Disadvantages
- It isn’t easy to cast low-fluidity metals.
- Most casting processes will result in a small amount of porosity in the finished dies. Some of them need additional treatment to ensure sustaining cracks or exfoliation.
- The setup is limited to a maximum weight which prevents casting for all sizes and requirements.
- If there is air trapped inside the cavity, it can lead to defects.
- It is economical only when you set it up for large-scale production.
Die casting materials
There are four primary alloys that we usually find useful for die casting – aluminum, magnesium, copper, and zinc.
Apart from having specific characteristics, these offer good corrosion resistance, high strength, and high thermal and electrical conductivity, making them an apt choice.
Also, these are non-ferrous, and their composition ensures excellent flexibility in terms of usage. Most die cast alloys are fully recyclable and can withstand high temperature with ease.
Uses of die casting- fields of application
Most manufacturers opt for die cast when they want to manufacture homogeneous products on a large scale. A good casting ensures that the quality doesn’t deteriorate during the manufacturing process.
The die casting application is most suitable for producing very thin items (newspapers, alloy sheets, etc.).
Because of their ability to maintain quality over some time, they find usage in a myriad of industries, with automotive and press being the most common.
Also, the following industries are known to use die cast for its production purposes –
- Furniture
- Electronics
- Machinery
- Lighting technology
- Power tools &
- Aerospace
Defects in die casting
Here are the probable flaws that may bug you during die casting –
- Flashing issues because of injection pressure being too high or clamp force being below par.
- Creation of bubbles because of non-uniform cooling rate or injection temperature being high.
- Hot tearing is caused because of uneven cooling rate.
- Ejector marks on the casting caused because of high ejection force or cooling time being too short.
- Unfilled sections because of slow injection, low pouring temperature, or insufficient volume.
Conclusion
The modern-day die casting industry is a highly competitive one. The European counterparts are struggling to match with their Asian competitors, specifically China and India. The whole industry is trying hard to improve the manufacturing process and achieve a scrap rate of zero percent.
With digitization 4.0, the vehement integration of digital technologies and processes which offer better efficiency and control, we expect the industry to flourish and reach new heights. The future of die casting revolves around the ability to create novel products with high clamping force and a variety of usage.
At EKO, we offer precision die casting that is made possible because of the deployment of the latest technology phenomenon and ensuring that the processes are optimized to make use of them efficiently. We offer a plethora of surface finishing for every product that comes out of our machines and offer customization such as laser engraving, tempo print, and others.
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