You’re Wrong: 5 Common Misconceptions About DMLS
The U.S. Department of Veterans Affairs approved three more years of funding for the "Luke" DEKA Prosthetic Arm, which includes actuated fingers and control via a foot-operated joystick, shoulder-operated joystick or myoelectric switches operated by brain impulses (harnessing the power of the neuron-musculature that remains after an amputation). Credit EOS & DEKA
Direct metal laser sintering (DMLS), the additive manufacturing technology that many have heard of and few understand. DMLS uses a focused laser beam to melt and fuse metal powders into a solid part in 20 micron layers (30 microns for a new titanium alloy powder).
Complex 3-D CAD geometries, in a matter of hours, without any tooling? Many think it sounds too good to be true, but here are five of the most common misconceptions surrounding DMLS technology.
1. DMLS Is For Prototyping, Not Manufacturing
Actually, many industries manufacture with DMLS now; including: dental labs and suppliers, aerospace companies, shoe and jewelry designers, tool and moldmakers —and even Formula One racing teams.
2. Laser-Sintering Is Complicated
Laser-sintering is automated and easy to learn. The software creates cross sections from 3-D CAD models, or from 3-D scans.
The laser-sintering system lays down a precise layer of metal powder and melts the powder in the shape of the cross-section. Then the build platform lowers the exact thickness of the layer, and the process repeats until the part is complete.
No tooling needs to be designed; no tool paths need to be programmed. DMLS equipment can run unattended.
3. DMLS Parts Are Not As Strong As Traditional Metal Parts
DMLS parts typically have characteristics of strength, hardness and durability; and are at least comparable to cast or forged parts from the same kind of metal.
This titanium humeral mount was "grown" in DMLS as a single piece for an experimental prosthetic from DEKA.
In many cases, the rapid solidification rate, after the laser melting, creates a very fine crystal structure with strengthsuperior to forged components. The freedom of design allows parts to be designed and built hollow, or with fill structures to produce even higher strength-to-weight ratios.
4. DMLS Can’t Do Anything New
DMLS can do many things other processes can’t. It can create extremely complex geometries that would baffle machinists and moldmakers alike.
It can create multiple customized versions of a product in the same batch — or dozens of different products at once. It can eliminate the need for some secondary processes, for instance by "growing" a threaded bolt-hole or a cooling channel at the same time that it manufactures the part.
In addition, DMLS offers nearly unlimited design potential, because it is an additive manufacturing process — there are no concerns about tool paths, draft angles or mold lines to worry about. It is a catalyst for design-driven manufacturing as opposed to manufacturing-constrained design.
A cobalt chrome combustor can for aerospace (Courtesy Morris Technologies).
When used for appropriate manufacturing tasks, DMLS is less expensive than machining or casting.
For short production runs, DMLS is often cheaper than methods that require an initial tool or die.
For projects that demand mass customization or involve geometries too intricate to machine, cast or mold readily, DMLS offers a viable alternative.
In addition, the design possibilities of DMLS often allow a higher-value product to be produced.