Curious to know what a foundry is and how they produce metal castings? Why are foundries so important for manufacturing — particularly for manufacturing machinery like CNC Machine Tools?
In this article, you will learn all about the fascinating world of foundries and metal casting. We will cover the following topics:
- Definition of a Foundry
- Raw Materials used in Casting
- Machines Deployed in Casting
- Casting Process
- Casting Technology Best Practices
- Finished Products of Foundries
- Hwacheon’s Investment in Foundry and Casting Technology
Ready to explore the world of foundries and metal casting? Put on your heat protecting gear, don your helmets and let’s step inside!
Definition of a Foundry
A foundry is a custom-built facility that produce metal castings. This is done by melting metals at very high heat into liquid in a furnace, pouring the molten metal into molds, followed by a controlled cooling process, removal of the casted part from excess material after the metal solidifies, and a final cooling step.
Note that temperatures of the melted metals can reach up to 1500°C (2700°F) or even higher, depending on the types of material to be melted.
What Are the Raw Materials Used in a Foundry?
There are many different types of metals (or mixtures of alloys) used as casting materials. They may include metals like iron, stainless steel, carbon steel, or alloys made with copper, nickel, and aluminium.
At Hwacheon Machine Tools, we produce a mixture of different casting materials such as Ductile Cast Iron, Nodular Cast Iron, Gray Cast Iron, High Silicon Cast Iron, Low Thermal Expansive Cast Iron, and Special Cast Iron.
To reduce our environmental impact, up to 55 percent of the raw material used may be scrap metal. The remaining materials would be pig iron (20 percent) and recovery iron (25 percent).
Sand is commonly used to build mold frames in casting (sand casting). In our case, we use sand from Saudi Arabia, which is known to be superior in casting processes.
What Are the Machines and Equipment Used in Casting?
Various machines and systems are used to optimize a foundry. These may include melting equipment, molding making machines (which can be CNC machine tools), sand processing equipment, heat treatment equipment, as well as testing and inspection equipment.
For the new Hwacheon Foundry, we use the following top-of-the-line machines and equipment (from South Korea, USA and UK):
- Melting Equipment: Electric furnaces that are 3 tonne and 6 tonne each (Inductotherm – USA)
- Mold Making Machines: Hwacheon Machine Tools like the SIRIUS-2500 5AX
- Sand Processing Equipment: OMEGA (UK)
- Heat Treatment Equipment: 10 Tonne Annealing Treatment Equipment (South Korea)
- Testing and Inspection Equipment: Spectro Meter, Universal Testing Machine, Ro-Tap Shaker, Brinell Hardness Test Machine, and Metallograph
As you can see, the process of producing metal castings in a foundry requires significant investment in machines and equipment!
What is the Process of Metal Casting Like?
Now that we’ve got the raw materials and the needed machines settled, the next step involves the actual production process of casting itself.
Hwacheon Foundry deploys the following processes to produce metal castings.
Liquid casting material is melted up to temperatures of 1,380°C to 1,420°C. The material may comprise a mix of scrap metal (55%) + pig iron (20%) + recovery scrap (25%). Other combinations of raw materials may also be used depending on the casting to be made.
#2 Mold Creation and Machining
The pattern is created, either machined by special wood mold making machines or, in our case by Hwacheon CNC Machining Centres. Sand is then packed around the pattern, forming a sand mold which is a replica of the external shape of the later casting. Hwacheon uses the Furan sand casting method due to its key advantage in producing diverse sizes and shapes.
#3 Prepare and Assemble Mold
The sand mold is prepared and assembled for the molten metal to be poured into.
#4 Pouring Molten Metal into Mold
At the filling stations, the liquid metal is poured into the mold.
After filling, the extremely hot mold frames (you can literally see flames shooting out!) are put on a slow and long cooling circle.
#6 Remove Casting from Mold
When the molten metal in the mold is cooled and solidified, the final shape of the casting is formed. The sand mold can be “broken” or “shake out” to retrieve the actual casting part.
#7 Trim Excess from Casting
Excess materials stuck to the surface of the casting are removed by thorough cleaning and deburring, followed by painting (using protection paint).
#8 Finishing of Final Products
Towards the last step, quality checks and tests are made. A composition analysis using a Spectro Meter is done (to check material mix), followed by a material test using a Universal Testing Machine and Brinell Hardness Test Machine, before ending with a microstructure test (a Metallograph is used).
After the product is finished, it is important to keep the castings properly stored in cool conditions in a separate area.
Best Practices in Casting Technology
To ensure that you get the best results in casting, it is important to use the latest technology. Let us share some of the best practices that we adopt here at Hwacheon Foundry.
#1 Adopt Sand-Casting Technology
Hwacheon uses the sand casting method rather than other materials like wax, plaster, or die-cast. This Is due to the following reasons:
- Sand casting allows you to achieve high rigid casting and surface stability with a small amount of binder.
- Kneaded sand is highly liquid, hence reducing manufacturing time because no firing process is required.
- The high heat resistance and low gas generation in sand casting results in fewer casting defects.
- You do not need a separate process for removing casting from mold — just hit it to break it!
- You can recover more than 95% of the sand used — this makes sand both resource saving and pollution protecting.
- The molding process of sand does not require highly skilled operators.
- Sand casting makes it feasible for mass production as well as large-sized casting.
#2 Manage the Entire Process
Beyond this, Hwacheon also adopts these other best practices in casting technology:
First, we focus on achieving high quality throughout the entire automation process.
Second, we adopt strict Quality Control (QC) management, making sure that only high-quality materials (scrap, pig iron) are used. We also adopt controlled measurements to achieve precise melting temperatures for the materials.
Third, we ensure that the temperature is controlled through looking at the dissolution temperature and pouring temperature.
Fourth, we adopt leading edge cooling control measures. These include an auto cooling tunnel which prevents cracks by slowing the cooling process – an important consideration as rapid cooling will result in tensions in the material as well as potential cracks. Typically, the cooling time for casting is more than 24 hours. This may hit 48 hours for castings that weigh over 3 tonnes.
Fifth, we use a customised heat treatment facility, ensuring that Hwacheon products are suitable for high speed and high precision machines.
#3 Be Mindful of the Minor Details
Wait, there is more. To ensure high quality sand-casting, you should also take care of the following.
Start by carefully choose the best sand quality. This should include:
- Particle size control
- Sand composition management
- Dust control
Next, think about the melting quality of your materials:
- Scrap quality: No stain, no Mn (Manganese)
- Pig iron quality: Must have low Mn (Manganese), P (Phosphorus), and Ti (Titanium)
- Dose control: Measure all materials in the exact amounts
- Temperature control: Keep to the right degree for melting, and pouring
Finally, consider the cooling quality of your materials. Remember that rapid cooling can introduce cracks and fractures in your castings!
What are the Finished Products of Foundries?
Last, but certainly not least, what are the finished products made in foundries?
For Hwacheon Foundry, about 30 percent of our finished products are used for manufacturing Hwacheon’s CNC Machine Tools. These include casting for machine beds, columns, saddles, bed frames, spindle housing and other components.
Our foundry also supplies components to reputable companies around the world. They include:
- Machinery and its parts
- Robot arms and bodies
- Railway transportation parts
- Semiconductor equipment components (low heat expansion casting)
- Corrosion resistant components (e.g. HSCI, stainless pickling electrode plates, cathodic protection electrodes)
- Ship engine parts
- Solar energy system components,
- Many other machinery parts
Why Hwacheon Invests in The Foundry Business
Hwacheon takes pride in having our own foundry due to the importance of casting used in all industries.
Our late founder and honorary chairman, Mr Kwon Seung Gwan himself, started work as an apprentice mold maker in a foundry in his teens. His grit, determination and attention to quality resulted in taking over the ownership of the foundry in 1945, back when Hwacheon first started.
Casting material forms the very basic parts in all of industries. The process of casting continually expands with shifts in technology. Our foundry isn’t just Hwacheon Group’s birth right — it also lays the foundation of future industries.
The advantages of using Hwacheon castings on our CNC machines (based on customers’ feedback) include:
- Ability to achieve high rigidity, performance, speed and precision
- No ageing deformation while maintaining high speed and precision
- High cutting performance
- Durability and longevity
- Ability to keep up to our delivery schedule
Hwacheon’s New 21,000 sqm Foundry
Hwacheon has recently invested USD28.7 million in a state-of-the-art facility in the Daema Industrial Zone.
This new facility occupies a total land size of 73,000 sqm, with a built-up factory space of 21,000 sqm, making it one of the largest foundries of its kind in South Korea. Starting production on 22 December 2021, our foundry currently employs 120 employees, and runs at a capacity of about 1,000 tonnes per month.
You may be keen to know that the heaviest part that we can cast is a staggering 8 tonnes! Our total capacity for the facility is 12,000 tonnes per year at this point.
Hwacheon decided shortly before the Covid-19 pandemic on this new investment so that we can develop a permanent and reliable raw material business for the future. This is part of Hwacheon’s unique advantage.
Take a look at Hwacheon’s new foundry! Watch video here:
Our Future Plans in Casting Manufacturing
“Hwacheon understands the goals and objectives of casting components in manufacturing because many of our operations are just like yours” – President Kim Ki Tae
President Kim, a pioneer in the metalworking industry, is the key person transforming Hwacheon Foundry to what it is today. He has worn multiple hats during his 35-year tenure with Hwacheon – in machine tools manufacturing, R&D, as well as leadership of the new Hwacheon Foundry.
A firm believer in having our own foundry, President Kim is committed to continuing to deepen our expertise and knowledge in casting manufacturing.
Hwacheon has invested and will continue to invest in production facilities that combine production know-how (accumulated over decades of experience) with the latest casting technology and automation system.
Hwacheon will further nurture our talents through continuous industry-university cooperation and technical cooperation projects with both universities and institutes. Our human resources are the company’s most important assets — hence, we will continually cultivate excellent skilled workers.