Medical Device Link.

Micromachining

Less machining is one of the biggest attractions of a new technique for making small parts. Mark Two Engineering Inc.’s 4th Dimension technology is a proprietary process capable of producing components used in minimally invasive surgical procedures. The “4th Dimension” is product development and manufacturing time, which can be significantly reduced by the new process, according to Greg Murphy, CEO of Mark Two.

An investment casting technique, 4th Dimension Technology relies on acrylic part patterns. Instead of a master mold, however, a 3-D printer is used to create an acrylic pattern layer by layer from CAD data, a process similar to stereolithography. Once created, a pattern is coated with a ceramic material and baked in an oven to produce a cavity for casting stainless steel or other metals.

Murphy describes 4th Dimension Technology as microcasting. “Most casters cast bigger parts. We’re working in the realm of very small parts.” How small? He claims the technique has been used to cast complex parts with dimensions of less than 2 mm and tolerances as low as ±0.0005 in.

The 4th Dimension technique can produce tiny, complex parts that meet, or nearly meet, customer requirements, according to Murphy. Then, if necessary, conventional processes such as milling, turning, and wire EDM are used to bring some part features into closer tolerance. “But when parts come out of the process near net shape, you don’t have to spend so much time machining everything,” he says.

By eliminating the hard tooling required for conventional investment casting, 4th Dimension Technology saves time and money, Murphy says. For example, he notes, the process allows rapid prototyping iterations that can slash product development time from months to weeks.

One problem so far: convincing skeptical customers that the process actually works as advertised. “Most of them don’t really believe parts can be made this way—until we show them,” Murphy reports.