The metal casting process can create anything from tiny fasteners to large industrial components, all through a five-step procedure. It happens by creating a pattern and making a mold, melting and transferring the metal and finishing, cleaning, polish and inspecting the casting. While metal casting is a straightforward practice, it requires specialized skills and techniques to perfect.
At Hengchang Foundry, we have the mastery and technology to form objects of various sizes for different industries like heavy equipment and transportation. No matter the complexity of the parts you require, our professional team can produce tailored castings to deliver unique parts for your application.
What is the metal casting process? Continue reading to learn what to know about metal casting and how our metal casting services work.
When talking about a pattern, we aren’t referencing one you trace on a piece of paper. Instead, metal casting foundries refer to patterns as a replica of the object they’re casting. This pattern helps form the mold cavity, which can be made of wood, plastic, aluminum and many other suitable materials. Making a pattern is a crucial first step because the accuracy of the mold determines the accuracy of the final product.
The four steps in producing a precise pattern include:
Depending on the type of material being poured into each mold, the final, solid product will distort to a certain degree. For example, it may shrink compared to the original size of the mold. This is why each pattern has allowances for slight alterations. Additionally, patterns require a draft, or a vertical tapered wall, where professionals can extract the pattern without tampering with the molded product.
It’s now time to create the mold, which is a hollow shape that will form the metal later on in the process. While some molds are expendable, others are nonexpendable.
An expendable mold means you can’t use it again. In that case, materials like sand, plaster foam or plastic make up the mold, and they’re destroyed during the casting process. Alternatively, you can use nonexpendable molds indefinitely, as they’re often made of aluminium.
Both expendable and nonexpendable molds can support different pattern complexities and materials.
While we use a multitude of materials for metal casting, they all fall under one of two categories — ferrous and non-ferrous metals. The metals used in metal casting can include iron, zinc, aluminum, tin, copper, lead alloys and others. While a ferrous metal contains malleable iron or steel, a non-ferrous metal contains nonmalleable metal, such as copper, nickel or aluminum.
After selecting the appropriate metal type, we load it into the furnace where temperatures rise until it reaches the material’s melting point. At Warner Brothers Foundry Company, we use gas furnaces during the metal casting process, though there are two other common types of furnaces for metal casting — electric arc and induction.
Using electric furnaces is our preferred method for metal casting because it burns cleanly and efficiently. Electric furnaces also allow us to heat the metal to the necessary temperatures without using high amounts of electricity. Electric furnaces are more efficient for our process, which keeps costs lower on our end and allows us to offer lower prices on your end.
Once the material melts down, it’s transferred to a large ladle before it reaches the mold. Through gates and risers, or openings in the mold, workers or machines pour the liquid material into the mold. Once it takes shape, solidifies and cools, we eject the casting from the mold, removing excess metal from the gate and rider system before moving to the next step in the process.
Understanding how long metal casting takes depends on the material — some may cool within minutes, and others take several days.
This stage involves making the final touches and cleaning each individual part. At Hengchang Foundry Company, we go in and remove excess metal parts and begin the cleaning process, using different tools to clear away particles and dirt. The final product is the same proportion and shape as the original pattern used during step one.
Additionally, some products may require a heat treatment, such as rail clamp, hydraulic cylinder, buffer. This process alters the properties of the material through a heating and cooling technique where the metal becomes more resilient. These treatments are ideal for applications that may endure extreme weight, wet environments or freezing temperatures.
The metal casting process ends with an inspection to ensure everything is complete and up to our standards. During the final stage, we check the part’s physical structure and integrity to ensure it’ll hold up and perform the expected job.
There are destructive and nondestructive testing methods, which are put in place depending on the casting’s specifications. In particular, visual inspections include looking for cracks, accuracy and surface finishes, and more in-depth testing checks tensile strength, hardness and ductility, among other components.
No matter the industry, we inspect everything from trailer hitches and industrial equipment to small automotive parts. In the end, you’ll have a durable component that’s suited to your unique needs and operations.
Human beings left the Stone Age behind roughly 4,000 years ago when the Bronze Age began, although some foundries go back even further. The team at Cast Technologies takes great pride in coming from a long line of skilled craftsmen that reaches back to the ancient world. We are today using processes based on the same principles as those used by our ancient ancestors to radically change and modernize the world. While people might think of things like electricity, the printing press and computers as the building blocks of the contemporary world, the truth is our way of life rests to a very large degree on the work of foundries: Automotive, air travel and energy production are just three industries that heavily depend on cast items. You depend on multiple cast items every day of your life.
Naturally, modern foundries bear little resemblance to the primitive technologies that man invented to make weapons and tools from simple bronze alloys, but the ideas are much the same: Melt a mixture of metals together and pour the liquid into some kind of mold. Making a bronze spearhead uses much the same technology still used for making parts for a power generator.
The ancients made things like weapons and plows, allowing them to put aside their more primitive stone tools. Today, foundries make an almost infinite number of items we rely on in modern life, including car engines, pipes, chains, aircraft parts, tools and many other metal components. Of course, foundries today aren’t limited to bronze, but can cast countless metal alloys depending on the characteristics required by the finished item.
Foundries have evolved considerably, thanks to advances in technology and the science of metallurgy. Initially, charcoal fires were used to power little furnaces hot enough to melt metal, but now gas or electric heat are used to power more advanced furnaces.
Early foundries were a dangerous work environment, but modernization and mechanization have made them much less hazardous. For example, pouring molten metals into molds via a robot or other automated equipment is much safer than pouring by hand using a ladle.
Another change in foundries involves the methods used to placing the molten metals into molds. Traditional gravity pours are still used, but there are other methods available now, including vacuum or pressurized gas pours.
Imagine you are living a few thousand years ago and you wanted to cast a simple item, such as a flat disk, in metal. The easiest method would be something called sand casting.
You might start by carving something called a pattern from wood. Once you had your desired shape just as you wanted it, you could sink it into a sandpit and then — very carefully! — you would remove your wooden model from the sand. Done right, this would leave a perfect impression of your wooden model in the sand.
Next, you would prepare your metal according to the characteristics you wanted your finished item to have. Perhaps you’d follow the ancient recipe of one part tin to nine parts copper. You’d need a small furnace, a clay melting pot and of course a hot charcoal fire for melting. Yes, primitive charcoal-fired furnaces can indeed get hot enough to melt copper and tin together, although it’s much easier to achieve the necessary temperatures in a modern foundry.
Once your metals had melted together, you’d carefully pour your mixture into the sand cavity and let the metal cool. Finally, you’d remove the solidified metal disk from the sand. If all went well, you’d have a perfect metal copy of your wooden disk.
Now let’s imagine you wanted to make a more complex casting. You might want to make your item in two different sections, a top and bottom. This is called a split pattern, and the upper section is called the cope, while the bottom section is called the drag.
Even more complex designs can be made using something called a core. The core is inserted into the mold to create a hollow area.
Now imagine you needed your item to have a smoother finish. You could smooth it out by sanding or grinding. Today, you might sandblast the surface, sand it or machine it smooth with a grinder. This same general process is used in making everything from the simplest tiny items, such as jewelry, to the most complex and large parts weighing hundreds of pounds, such as wind turbine blades.
After the item comes out of the mold, further processes may be used if necessary. Cast Technologies has an on-site machine shop to add the finishing touches to any component.
We will analyze all aspects of your metal casting project to ensure meet your delivery timeable with the quantity, quality, price and repeatability your demand.
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