By Ivy Max
The New age of metal casting explained.
If you ask any well-versed metalworker that has been engaged in the field for a considerable amount of time, their opinions on metal casting might only skew towards the more modern methods and procedures that they follow today. Modern metal casting, however, just like the tip of an Antarctic iceberg, only represents a fraction of the entire field. This piece is going to take a brief at the old and contrast it with the new.
Metal casting, at least in theory, is quite simple. The worker pours melted metal into a mold, cools and removes the mold to reveal the finished piece. The mold holds the metal to a certain shape until it melts.
Generally, metal casting adheres to the following steps thus:
- Master pattern and corebox fabrication
- Creation of the mold and the core
- Melting the alloy
- Pouring the molten metal gently into the already created mold
- Solidifying the metal
- Breaking the mold and removing the finished product
- Finishing touches
Usually, other information sources will go into deep detail on the above mentioned processes but as it is not the focal point of this piece, we can just move on and address the intended crux of the piece.
In the 20th century, the rise of demand for automotives and other heavy equipment meant that more cutting-edge methods for metal casting needed to be developed – and developed they were. Following the advent of steel, Ford motors flow production techniques pioneered the new age of metal casting – one that was able to meet the demand for mass-market production. Both world wars only served to consolidate the need for mass-market metal casting.
The modern metal casting processes have a multitude of underlying methods, some of which are easier and less complicated than others. Some have roots dating back hundreds of years while others are relatively new, having been invented less than a century ago. Some of these are:
- Investment Casting: This technique represents the oldest metal casting technique that is still in use until date.Investment casting is metal casting process that involves covering a wax pattern shaped like the final product in refractory material, then melting out the wax and replacing it with molten metal.
- Green Sand Casting: Greensand casting is an extremely versatile metalcasting method. It is a quick method with low tooling costs where moist, clay-bonded sand is compacted around a pattern to, forming a mold. The resulting molds can be used to cast nearly any alloy, and the majority of sand used to form the mold can be reused.
- Shell Mold: This methodwas invented in the mid-20th century by a German engineer, and was subsequently perfected by mass-market manufacturers in the U.S. and Europe. The process involves coating a pattern with sand grains that are resin-coated, allowing them tobond to one another with the application of heat. Shell mold casting provides a high degree of precision and excellent repeatability.
- Airset casting: This, like many others, is a variation of sand casting. Airset casting–also known as no-bake casting uses chemically-bonded sand that solidifies at room temperature. The process can indeed be more time-consuming than regular greensand casting or shell molding because it requires more time for molds to solidify, but the required tooling is inexpensive.
- Die Casting: Die casting is another casting method utilizing reusable molds. In contrast to permanent mold casting, die casting employs high-pressure injection to quickly and completely fill the mold cavity. Die casting can provide excellent casting parameters, but startup costs often limit its use to high-volume runs.
In the United States of America alone, Metal casting as an industry, is worth more than $33b and it also happens to be directly responsible for the creation of more than 300,000 jobs, most of which are crucial to the manufacturing sector and by extension,, the functioning of the economy as a whole. In fact, it is estimated that casting as a method is required in more than 90% of durable consumer good.
With strong education sector relationships and ties to government aid and support, the metal casting industry enjoys both the best in research and development as well as ample government funding.
Contrary to the popular belief that metal casting is a relic of the past, it actually is perfectly melding into 21st century technologies. Accompanying technologies like 3D printing and CNC machining meld perfectly with traditional metal casting methods that together, manufacture products that ensure the highest utility and durability for consumers.
