The society of manufacturing engineers (SME) announced its Additive Manufacturing Community awards at the RAPID + TCT event, held May 9-11, 2017 at the David L. Lawrence Convention Center in Pittsburgh. In its 27th year, RAPID + TCT is North America’s preeminent event for discovery, innovation and networking in additive manufacturing.
The Industry Achievement Award, established in 2008 by SME’s Additive Manufacturing Community, was developed to recognize an individual, team or company for outstanding accomplishments that have had significant impact within the additive manufacturing industry or in any industry through the application of additive manufacturing technologies. As the name suggests, the award recognizes achievements that have been implemented or deployed in a commercial/industrial environment rather than research investigative work. Winners are selected with consideration for the scope and scale of benefits realized and the potential future impact their work will have on the industry.
This year, the community has recognized Dieter Schwarze, PhD, of SLM Solutions with the 2017 Industry Achievement Award because of his significant and continued impact on additive manufacturing through development of processes and technology applied in industry. In 1989, Schwarze began his research and development work on additive manufacturing and its commercialization. He is one of the primary inventors of selective laser melting. Schwarze holds several patents and studied physics at the University of Paderborn.
“Dr. Schwarze has been instrumental in the development and expansion of global additive manufacturing,” said Mihaela Vlasea, PhD, assistant professor in the Mechanical and Mechatronics Engineering Department at the University of Waterloo and an advisor to SME’s Additive Manufacturing Community. “The impact of his research, development and application of groundbreaking technologies just cannot be overstated. We’re proud to recognize him with this award.”
A timeline of the invention of selective laser melting from Dr. Dieter Schwarze:
Stereolithography (SLA), an additive manufacturing method in which a pattern of ultraviolet light from a 3-D CAD model is directed to the surface of a vat filled with photo-sensitive liquid resin, was patented by Charles Hull. The light reacts with the resin, causing it to harden and then the part is lowered slightly so another resin layer overspreads the top and the process repeats until it the object grows, layer by layer. Once the object is complete, the sticky resin must be cleaned off using chemical agents, and it then requires curing in a UV oven for strength. Sometimes this curing action does not reach completely inside the piece, leaving parts that are easily broken.
Dieter Schwarze read an article in Laser Focus World reporting on Hull’s stereolithography technology, and began investigating it along with his partner Matthias Fockele at their company F&S (Fockele & Schwarze) Stereolithographietechnik GmbH inPaderborn, Germany.
Binder jet printing, another type of additive manufacturing, was patented by researchers at the Massachusetts Institute of Technology (MIT). In this method, a liquid binder is “printed” in successive layers on a bed of powder, using a print head similar to ink jet printers for paper. One characteristic of parts produced by all the rapid prototyping technologies of that time was their fragility, making their longevity seem impossible.
A European research group led by Jürgen Peterseim working at the German company Krupp Forschungsinstitut GmbH, in Essen, began investigating whether it was possible to melt metal powder with a laser, in order to perform what today we call additive manufacturing. The EU project had the number BRE20216 and was called “Rapid Prototyping Metal Components.”
The Krupp researchers succeeded in producing simple structures, but Krupp halted the project at the end of 1994 for unknown reasons. The company made two presentations of their invention, including one on March 17, 1994, to a small group of about 20 people, and a second one at the 5th EC Conference “RTD on Industrial Technologies” in Brussels, December 6-8, 1994, and never pursued a patent.
The Krupp invention did not use scanners to direct the laser beam in a pattern over the powder surface, as in modern SLM machines. Instead, it used an x-y stage that moved the powder bed itself back and forth beneath the laser. It also had an open process chamber, unlike the standard hermetically sealed build chamber in today’s machines.
Three scientists at theFraunhofer ILT—Wilhelm Meiners, Andres Gasser and Konrad Wissenbach,—began a project with the aim of producing parts from pure metal powder. They approached Schwarze and Fockele to see if they were interested in working on a new technology that produced “parts that wouldn’t break if they fell off the table.”
Back in 1989, Schwarze and Fockele had begun experimenting with rapid prototyping using stereolithography. They built their first proprietary machine using galvanometer scanners moving a UV laser beam controlled by their own software and hardware products. Unlike other stereolithography technologies, the mechanical, electronical and software components they developed were, in principal, able to work with materials other than liquid resins, and their open software structure allowed for a larger variety of research capabilities.
The Fraunhofer researchers wanted to develop an additive manufacturing method that would work for state-of-the-art metal materials used in the tooling and metal parts industry at that time. Stainless steel was the first candidate, with other materials added later.
The two groups joined forces and from 1995 to approximately 1998, basic research was done both at Fraunhofer ILT and at F&S. The software, written by F&S, was open system and worked with any kind of CAD software. Schwarze and Fockele delivered both the hardware and the software to the Fraunhofer ILT researchers. This cooperative effort eventually led to the first automated rapid prototyping machine using pure metal powder to produce metal components.
A German patent was granted to Fraunhofer ILT researchers Wilhem Meiners, Konrad Wissenbach and Andres Gasser, for the ILT SLM (base patent, DE 19649865). Schwarze and Fockele were co-inventors of the technology and produced their own line of SLM machines later on.
It is unknown whether the Fraunhofer researchers had knowledge of the Krupp work before starting their own. But even if they had known, their work went much deeper into the process, developing useful results that form the basis of most of the metal additive manufacturing machines now on the market.
The first commercial SLM machine was delivered by F&S to Trumpf, a German laser manufacturer located near Stuttgart, Germany. The early SLM machines took more than a day to produce a matchbook-sized part (approximately 1 cm x 3 cm x 2 cm) using a 12 W laser. The same part now could be produced in about half an hour using a high power 400 W laser machine. Meanwhile, the laser spot diameter and the layer thickness for today’s machines have changed very little over time.
F&S entered into a commercial partnership with MCP HEK GmbH, located in Luebeck on the Baltic Sea in northern Germany. MCP HEK was looking for a technology using metal in an additive manufacturing process, and according to their agreement, F&S produced the machines and MCP HEK marketed them.
Schwarze and Fockele registered the trademark “SLM,” which now is used worldwide by SLM Solutions GmbH, and in Germany by both SLM Solutions and Matthias Fockele’s new company, Realizer GmbH. The term “SLM” has become more or less mainstream, so that many use it even for machines made by other manufacturers.
MCP HEK GmbH was renamed MTT Technologies GmbH, and the company decided to design and produce a completely new line of machines to meet the needs of the market, incorporating all the latest technology features.
The SLM 250 HL (HL for Hansestadt Luebeck), the first in the series, was faster in speed and more reliable, and became the standard product portfolio for the company at that time. The number 250 stood for the dimensions in millimeters of the build chamber in the x, y and z directions. The SLM 250 HL used a single 400-watt laser.
MTT Technologies GmbH was renamed SLM Solutions GmbH. The company introduced the larger build volume SLM 280 HL, a follow-up to the SLM 250 HL.
SLM Solutions introduced its flagship machine, the SLM 500 HL, which includes four lasers of 700 watts each, for a combined power of 2,800 watts—the most powerful production machine available for additive manufacturing today. The system is designed for continuous operation, so that once a part is complete, the build container can be moved out and replaced with another one, with a down time of only half an hour.
The SLM 500 also features a unique continuously recirculating closed-loop powder flow system with a metal pipeline conveyor moving the machine’s overflow powder to a sieving station and back. The system is completely enclosed so that no human contact with the powder is required, and the machine chassis itself does not need to include a half-ton powder container.