Milling-turning machining for innovative micro-parts

Amorphology, a NASA spin-off company, is a leader in applying advanced materials and manufacturing technologies to improve non-lubricated micro gears for robotics and other industrial applications using “amorphous” metals. » innovative products such as loose metallic glasses.

These materials have advanced characteristics compared to steel, titanium and aluminum, for example, and the company’s patents (for several metal alloys) are based on the development of gears for space and d other extremely cold temperature applications.

Amorphous metals are a class of non-crystalline alloys that cut and chip differently than other materials, and in the company’s quest to find a machine capable of producing the micro gears, it performed machining tests with several machine vendors – including Starrag – to evaluate the accuracy, cycle times and overall capabilities of the machines when cutting a relatively unknown alloy.

“We focused on finding the best machine to meet our rapid prototyping, mold insert cutting, and post-processing needs,” says Jason Riley, COO of Amorphology. The Starrag Bumotec s191H turn-mill machining center outperformed all competitors.

After receiving the CAD files of the prototype gears and carrying out tests using a cutting tool developed by Starrag at the machine tool builder’s sites in Switzerland and the United States, several batches of samples were products.

Amorphology was impressed with the results and in discussions with Starrag about how the two companies could cooperate to grow their respective businesses, it was agreed that Amorphology would introduce the Bumotec at its Pasadena, California location for customers of both companies can see it.

Amorphology is set up to fabricate a wide variety of parts on the machine, from mold inserts to prototype gears, as well as other production bulk metal glasses and traditional metal parts.

“We are aiming for high-precision parts with tolerances often around 5 µm on certain dimensions,” continues Mr. Riley. “Most of our work is focused on rapid prototyping and relatively small batch production quantities of around 100 parts per month. The Bumotec offers mill-turn capabilities that we currently don’t have, as well as higher production capacity.

Amorphology points out that the Bumotec s191H can “offer a unique value proposition”, either by machining single parts or producing hundreds of components in a lights out scenario.

In addition to manufacturing gears for aerospace uses, Amorphology’s products are also used in cobots, robots, and medical devices. For example, most cobots use strain wave gears – the main component being a flexspline which is a complex thin-walled part.

Starrag Bumotec s191H milling-turning machining center working area

The s191H is part of a family of Bumotec turn-mill machining centers for high-precision machining of often complex parts in a single setup.

With a 65mm bar capacity, bar feed system and high pressure (3hp) coolant, the s191H can achieve very precise (±2.5µm) machining solutions within its d X, Y and Z axes of 410 mm, 200 mm and 400 mm respectively, thanks to linear drives and high-level thermal stability.

Additionally, its main spindle is complemented by a sub-spindle that can rotate in the horizontal and vertical planes for multi-process/task routines. Tool magazine options extend up to 90 locations on a machine that has fast travel speeds of 50m/min and a spindle speed of 30,000 (or 40,000) rpm which also helps to its ultra-fast cycle times.

Many of Amorphology’s cobots, robots, and medical device parts can be cast or injection molded, but sometimes these micro parts must be post-processed to extremely high tolerances. Starrag Bumotec has its roots in designing machines for the Swiss watch industry and as a result the machines are exceptionally adept at producing small, high value gears.

Speaking on behalf of Amorphology, Mr. Riley concludes, “We expect the Bumotec s191H to machine lubrication-free micro gears. While we will machine our proprietary alloys to very small sizes in cases where production quantities do not require injection molding, we will also use the machine to help develop parameters for amorphous metals. And as we move forward, we will be the only company in the world with such knowledge.