Solving the Manufacturing Equation for Metal Parts

Eletter Product

Proto Labs now produces metal parts using both additive and subtractive processes, the number of offerings continue to multiply, and metal parts are being produced by all three of our divisions. With metal injection molding (MIM), magnesium thixomolding, three-axis milling and turning, and direct metal laser sintering (DMLS), the challenge becomes how to create the right manufacturing equation that best works for your product. Each has its strengths, and depending on your needs, chances are that you may use more than one process during the development of your product.

Metal Injection Molding
Metal injection molding (MIM) is a metalworking process for creating fully dense, net-shape metal parts starting when metal powder suspended in a binder matrix (or feedstock) is injected into a tool, in a process very similar to injection molding, resulting in a green part. The green part is then debinded to remove most of the polymer carrier, resulting in a brown part. The brown part is heated in a furnace in a process called sintering to remove the remaining binder and form a fully dense (typically, 97 percent) metal part. MIM is a mature, established manufacturing process for molding relatively small metal parts.

Magnesium Thixomolding
Thixomolding is a specialized process for making parts out of magnesium. It produces fully dense parts by injecting a gel-like slurry of chipped magnesium into a steel mold under high pressure and allowing the material to cool and solidify. It produces net shape parts that are very true to the CAD models from which molds are made. They are affordable, strong, light, and similar to parts produced by magnesium die casting, but they can have thinner walls, finer detail and less surface porosity.

CNC Machining
Firstcut CNC Machining can manufacture parts in as fast as the day they were ordered with engineering-grade plastic and metal materials for improved selection, part functionality and cosmetic appearance. We employ both three-axis milling and turning.

Our three-axis milling process allows for milling from up to six orthogonal sides of the part to machine as many features as possible. Our turning process includes live tooling to create off-axis holes, flats, slots and grooves. Final milled and turned parts are used as high-quality prototypes, jigs, fixtures, one-offs and in end-use applications.

Direct Metal Laser Sintering
Direct metal laser sintering (DMLS) is one of three additive processes available at Proto Labs. DMLS uses a laser system that draws onto a surface of atomized metal powder. Where it draws, it welds the powder into a solid. After each layer, a blade adds a fresh layer of powder and repeats the process until a final metal part is formed.

DMLS can use a variety of alloys, allowing prototypes to be functional hardware made out of the same material as production components. Since the components are built layer by layer, it is possible to design internal features and passages that could not be cast or otherwise machined. DMLS produces full-strength, functional metal parts with the same ease and speed as plastic parts, with the potential to transition into metal injection molding when increased production is needed.

Solving the Equation
Choosing among the available metal-forming technologies can be a complicated process. Magnesium, for example, can be formed either by machining or by thixomolding. The former would be the most cost-effective process for low volumes, the latter for higher volumes. For very small numbers of parts in a variety of engineering-grade materials, machining is a good choice. If, however, the parts have features that cannot be produced by three-axis milling or turning, DMLS would be a better approach. If you want low-cost steel parts in larger numbers, MIM is an excellent choice.