From undersized to oversized

3D PrintingTech displayed a 12-ft. plastic bottle it built in six sections.

The production of big and small parts intrigues me. The reason is because making an unconventionally sized part requires an extra dose of manufacturing know-how.

Extra thought must be given to handling oversized parts, for example, to prevent them from toppling and injuring operators. And large−often asymmetrical−workpieces can be difficult or impossible to mount on machines.

Smaller parts also pose workholding challenges. Typically they are too small to incorporate surfaces suitable for securing them to a machine. An additional concern is gripping force. Even the smallest amount of overgripping torque can damage a tiny workpiece.

My interest in oversized and undersized stuff extends to 3D-printed parts.

The largest printed object I saw in the 3D/Additive Manufacturing Pavilion at FABTECH® 2018, held Nov. 6-8 in Atlanta, was a 12-foot bottle. The smallest was a 4-millimeter-diameter gear.

3D PrintingTech, Atlanta, produced the bottle. It measures 12 ft. high by 3 ft. wide by 2 ft. deep and has 3-mm-thick walls printed from approximately 36 kilograms of PLA. The build time was 200 hours, said founding partner Josh Stover.

The shop used a 300-series Workbench Pro from 3D Platform to print the big bottle, which serves as the master for a mold. Stover said the shop separated the design into six sections to accommodate the 3D printer’s 1- by 1- by 0.7-m build envelope.

The smallest 3D-printed part I saw at FABTECH was a gear at the Nanogrande Inc. booth. Made of a tin-bismuth alloy powder on the Montreal company’s MPL-1 printing system, it measures 4 mm in diameter and comprises 25 layers, each 5 microns thick.

According to the company’s CEO, Juan Schneider, the MPL-1 can deposit layers with a thickness equaling that of the build-powder particles. He credited the company’s Power Layering Technology™ for allowing this by overcoming the van der Waal forces that limit the compaction of particles.

Before introduction of the technology, said Schneider, particles less than 17 µm turned into “clumpy mud” when printed.

“With this approach, we can easily print with particles as small as a nanometer, but also particles of 5 microns, [which is] what the industrial sector is currently seeking,” he said. “At this size, the particles stick to each other, virtually eliminating the need for support structures typical to 3D printing.”

Nanogrande produced a 4-mm-dia. gear (inset) by laying down 25 5-micron-thick layers of powder metal. Company CEO Juan Schneider stands by the MPL-1 printer used to build the gear.