By: Stefan Ritt, SLM Solutions
Engineers have developed today’s metal additive manufacturing systems to be faster and to print large objects.
Increasingly, additive manufacturing technologies are accepted in the production industry and gaining ground at the shop floor levels. Together with the acceptance of the basic technological parameters, the constant call for higher machine productivity came fast.
However, patience just is not the engineer’s best friend.
These conditions triggered the run on the largest, fastest and biggest machine among the manufacturers of Selective Laser Melting equipment you could find in Frankfurt-Germany in December last year, at the Euromold show. For Euromold 2013, still the global indicator for technological development in this field, even more companies will show big platform systems, so say the industry whispers through the grapevine.
One compact concept in this game is coming from SLM solutions GmbH in Northern Germany, which is a doubling of the previous version of the 2+2=4 Laser assortment to a maximum of 2,8 KW laser power, resulting in a calculated build speed of above 70 ccm per hour. To increase the build speed the engineers thought about a few special concepts.
A 400 W and a 1 KW laser work in one optical track and are operated alternatively. After the 400 W laser builds the outside contour of a part in 3 to 5 layers, the 1000 W laser melts the core area through all layers in one go. That saves melting time in the whole build significantly.
Double track optics
Two optical tracks with two lasers each project on the build area at the same time. The machine can be set to build one big part or multiple small parts and the buildup will happen simultaneously in different areas of the powder bed. Another accelerator!
Two way powder feed
Due to a specific design of the powder feeding mechanism, it can feed powder both ways—in the forward move as well as in the reverse movement. That saves 50% of auxiliary cycle time in the process. Just imagine half time at 200,000 layers. Savings are in hours easily.
Pushing for speed and size on one end, though, creates new challenges with high weights and volume on the other side.
To escape this “engineering catch 22” a removable build volume was designed. It not only allows an easier access to the large and heavy weight products, it also allows reduced standstill of the machine as a new volume can be installed and another build process started while the first part is removed and cleaned.
SEPIA (Simple Easy Powder Input Appliance)
The huge hunger for powder while building big parts fast presented the next challenge for the engineers.
Specific semi-manual devices had to be designed to move and handle the powder containers without problems while preparing and refilling the SLM 500 HL machine.
Simplified gas filter
As these machines, no matter which manufacturer, all work under protective gas atmosphere, this consequently must be filtered in circulation during the build process. Automotive industry not only presents 100 years of engineering but also quite a few smart ideas. So, why not just adapt a truck filter cartridge from known manufacturers. Easy to get, easy to use, easy to replace. If life only always would be like that.
PSA 500 – automated build volume unpacking and sieving station
Once a huge and heavy part is built, one has to think about how to handle a few hundred kilograms of weight. Obviously, one cannot handle it with just two hands from a more or less strong person.
The PSA 500, which will debut at Euromold this year, combines the powder removal and sieving as well as recirculating it into the powder tank for the next build.
A fully automatic powder-filtering unit is equipped with a special screw system for emptying the process chamber overflow containers and refilling the powder container under an inert gas atmosphere.
The electrically operated build volume is carried out to a container station to empty the whole build powder into a funnel. From this device the powder is forward controlled to the vibration sieving system.
The sieved GO grain powder passes into steel container, which is fixed in position inside the sieving system. The system is equipped with an additional ultrasonic device to support the sieving procedure. The sieving process runs automatically and does not influence the parallel running build process of the SLM system, which reduces the ancillary times.
Fine mesh filters and sieves are standard and commercially available products and pre-assembled with a 100 µm mesh insert. Fresh powder is brought through a screw system from the main reservoir either direct to the re-coater or a defined powder volume above the system.
Global aerospace industry is finally getting a tool to produce the three-dimensional parts their engineers have thought about for the next generation air- and spacecraft.
If an industry is willing to invest a small amount per kilogram for weight savings, these are the right toys for the big boys to reduce the buy to fly ratio significantly!
For example, GE has invested massively into this technology in the US and abroad since last year and will continue to do so as openly stated in their various press releases.
Medical implants are as unique as each patient. If an open heart surgery session would cost between $50,000 and $100,000 who would complain about a few thousand dollars for the implant if it fits the patient perfectly instead of close? Just think about walking around with a “nearly perfect fit” hip implant; it does not sound encouraging, however it is today´s routine!
Striker, for example, did research on how to make use of this technology and various combat veterans with multiple injuries from IED´s could benefit from implants made by this new technology.
We are all lucky to witness a fundamental change in production and it is not overdone to call this a small second industrial revolution, ironically a bit of a reverse of the first one.
Natural resources are limited, the awareness of that fact is rising and educated and experienced experts are becoming a rare species due to changes in society and educational structures. MPF