Metal casting is the process in which liquid metal is poured into a mold containing a hollow cavity of the desired shape and then allowed to cool and solidify. The origins of this process date back about 5,600 years to ancient Mesopotamia – and except for a few modern innovations in the molds themselves – the process has remained relatively unchanged since then.
Today, thousands of everyday objects from doorknobs, jewelry, and toys, to automotive and aerospace parts are designed and cast using the lost-wax, plaster mold, or sand cast techniques. Each one of these objects, parts and pieces have one thing in common—their complex shapes that make them difficult or uneconomical to manufacture by any other method.
While bronze was the preferred metal of choice for thousands of years, a 2016 survey by Foundry Management & Technology Magazine shows that steel (of any alloy or quality) along with gray iron are the highest used metals at 20.9% each. Ductile iron follows next at 18.6% with aluminum in the fourth position at 17.8%. Bronze along with brass have fallen to 9.3% with the remaining 12.4% considered “other” alloys such as magnesium, titanium, stainless steel, etc.
Growth
According to the survey, a majority of all respondents expect that they will see better results in 2017 — i.e., ship more tons of castings — than in 2016. More than one-third believe that tons/shipped will remain even from 2016 through 2017.
Foundries working with ductile iron, gray iron, and steel are equally as likely to forecast increased shipment volumes in 2017 as they are to call for decreased volumes. Aluminum operations are nearly 10 percent more likely to forecast an increase in shipments.
Of those companies with optimistic sales expectations, nearly 30 percent indicated that they would be investing between $100,000 to over $5 million in upgrades to process and testing equipment. However, employment growth is not likely to be in the picture as nearly one-quarter of the companies reported that robotics technology is high on their list of improvements.
Details in the Design
Indeed, the challenge for today’s foundry is to develop new and more efficient processes and material designs that will meet the technology of tomorrow.
Until now, the process of perfecting a part for mass production has required the development of a mold, casting a prototype, testing, and then a series of refinements until the end product meets the exact specifications. It can take anywhere from a week to a month to cast a specific metal part, depending on the complexity of the design. That process, if duplicated several times, can cost thousands of dollars as well as many weeks or months of lost time. Preventing defects and avoiding what can be extraordinarily costly rework is the key to efficiency at an operation where single manufactured pieces can weigh up to a ton.
New technologies such as 3D scanning and 3D measurement instruments along with 3D printing are dramatically changing the way products are designed, constructed, and perfected. By using point-cloud software with a 3D scanning attachment, exact measurements are uploaded to a computer, modifications are made, and a 3D printed model is produced within hours or a day. This technology enables supremely fast, accurate, and reliable prototypes to be made.
The 3D design and printing process increases the total design time but dramatically reduces the overall cost of the end product. By reducing the number of prototypes that are needed to perfect the design you’re left with an increased supply of viable prototypes as well as less wasted product.
The Future
Not only does 3D design and printing make the process of metal casting more efficient and cost-effective, it also provides innovative breakthroughs that were not possible even five years ago.
Modern transportation has evolved from heavy forged steel parts to lighter composite materials that offer better gas mileage but sacrifice some of the structural integrity that protects occupants. Recently, a breakthrough in casting steel with a foam-like structure could challenge traditional wrought-steel applications. These porous metals made of aluminum and titanium are becoming increasingly popular as stiff but lightweight materials for use in structural components for the automobile and aircraft industries.
Steel foams, as they are called, exhibit excellent stiffness-to-weight ratios with a variable density lightweight steel plate weight at least 20% less than a comparable solid plate. In particular, steel foam panels have higher bending stiffness than solid steel sheets of the same weight. The basic objective of the development process of metallic foams is the combination of physical and mechanical properties expected from metallic foams such as high stiffness, low specific weight, high gas permeability, low thermal conductivity, unusual acoustic properties, high impact absorption capacity, and good electrical insulating properties.
As foundry operations evolve into the modern world of automated technology, General Kinematics, the leading manufacturer of foundry production equipment, is also working to provide the most innovative and advanced techniques for process level automation.
