Guest blogger Brad Done discusses how 3D printing supports metal manufacturing.
3D printing has captured the imaginations of many, inciting dreams of a printer in every household—able to print everything from a cup of coffee to a new kitchen faucet at the touch of a button. While advances have been made in terms of speed, surface quality and material selections, the dream is far from a reality. And that’s okay.
When it comes to scaled industrial and commercial production—specifically in metal manufacturing—3D printing still has a way to go. Some barriers include the high cost of production and object size limitations.
This will not always be the case. 3D printing already offers great value for many intricate, low-volume or one-off productions, especially where customization is beneficial. But when we look at the manufacturing technology we already have in place, it’s likely that 3D printing will complement rather than replace them.
3D printing and metal manufacturing
Metal casting is a manufacturing method that offers similar benefits to 3D printing. The freedom of design is especially valuable, as it helps eliminate additional fabrication design and processes that can take time and cost money. Users can eliminate mountings, brackets, fasteners and sectioned parts by casting or printing several components into one part.
Casting methods have evolved through centuries of practice and development. Aspects such as material selection, alloying, phase control, heat treatment and design techniques have been refined for centuries to meet specific product applications. It is unlikely that a new method or technology, no matter how revolutionary, will make this industry obsolete overnight.
Here are a couple of examples of how 3D printing supports metal manufacturing.
Investment casting. Investment casting is a versatile process that produces castings at high volumes with exceptional surface qualities. The process typically requires that a die be machined to produce wax patterns used to create disposable molds—often hundreds, if not thousands, of disposable molds—using materials that can be reused throughout the production process. We haven’t seen 3D printing offer this type of quality product at this type of scale (yet).
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Where 3D printing can—and does—offer benefit is in the development phase. 3D printers can create wax patterns without the use of a die. Printing patterns for large-scale production would likely be costly and time consuming—especially for products with high-volume geometries. But during the prototyping phase, it avoids spending resources on tooling a pattern-making die that won’t be needed until full production.
Sand casting. Sand casting is the most widely used casting method in North America. A pattern must be made in the exact form of the final product. The pattern is then used to produce disposable sand molds. Like investment casting, sand casting offers exceptional freedom in designing products. It is also highly economical for both small and large production volumes.
Depending on how many parts are being made, patterns can be made from plastic, wood or metal. Traditionally, foundries use pattern makers—either in-house or contracted—to produce patterns from technical drawings. But now, 3D printers can create patterns to be used directly for large-scale production. Depending on the design stage and the scope of final production, different printing technologies can make patterns of different materials—plastics for shorter runs, and metal for longer runs where more durability is needed.
There are also specialized printers that create working sand molds and cores that can be used for molten metal. These printers use resin to bind layer after layer of silica sand particles, essentially gluing them together into a solid mold. These molds can be used like other sand molds, supporting a range of metals. Again, the technology likely won’t be cost-effective for large production runs, but can help during the prototyping phase—or for smaller, one-off types of productions.
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What about DMLS?
These days, direct metal laser sintering (DMLS) equipment and procedures produce exceptional products using a range of metal materials—including aluminum, stainless steel and titanium. Products made using DMLS are strong, durable and heat resistant—and they feature densities comparable to, if not better than, those made through casting. DMLS products can also be heat treated, machined, electroplated and polished like any cast product.
Where does DMLS fall short? While the technology is great for producing small parts with complex geometries, it is comparably slow and expensive for producing large volumes. There are a few factors to consider here. For one, materials are often more expensive when purchased as 3D printer inputs than as base raw materials. For another, once the proper mold-materials have been prepared, casting still offers better economy of scale.
Again, DMLS will be valuable for short-run and one-off projects—especially where complex geometries and ongoing customization are required. We’ll also see designers change product configurations to limit complexities to small components to be printed—while using other methods to produce bulkier housings.
3D printing for the near future
3D printing will definitely have a role in low-run and one-shot production, especially where customization is desired. The reality, however, is that most products manufactured in the world are standard parts. Casting, as well as machining and working with pre-fabricated materials, will have a major cost advantage for standard production for quite some time.
Brad Done is the vice president at Reliance Foundry Co Ltd. He has more than 25 years’ experience in manufacturing in North America and overseas.
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