The German manufacturing company Trumpf, which has a specialist Laser division, has been actively involved in producing metal additive manufacturing machines for some years. It has developed a range of machines using laser metal deposition or LDM technology and more recently has turned its attention to developing an alternative approach, laser metal fusing or LMF.
This is not Trumpf's first foray into LFM, having previously worked on this technology back in 1999. But as the market for additively manufacturing parts has steadily grown, so Trumpf has once again turned to LMF. It has developed a range of TruPrint 3D printers, starting with the TruPrint 1000, which was first previewed at the end of 2015. The company used the recent Formnext show in Frankfurt, Germany to launch its new TruPrint 3000 and to show a beta version of its TruPrint 5000.
The process uses lasers to generate complete parts layer by layer in a powder bed. It’s suitable for the production of complex parts, such as those with internal channels and hollow spaces. Likely markets include the aerospace industry as well as dental applications such as crowns and bridges and for making tools and molds.
Trumpf has developed a modular cylinder concept to eliminate manual handling of the metal powder for better safety. There are different cylinders for powder supply and overflow and the cylinders are also used as the build area. The powder is loaded into the supply cylinder and a lid put on so that it can be handled safely. The supply cylinder is loaded into the TruPrint. Some powder is transferred to the build chamber and fused by the laser to form the first layer of the part. Any unused powder is removed to an overflow chamber and the process is repeated until the part is built up one layer at a time. The entire unit with all three cylinders is enclosed in a chamber that is filled with gas and with just 0.1 percent of oxygen to prevent any risk of explosion. The cylinders can be swapped out easily to keep the machine supplied with powder and when the part is finished it’s simply a matter of removing the build cylinder so that a fresh cylinder can be used in its place while the actual parts are unloaded elsewhere.
This, of course, means that the build area is limited to the size of the cylinder. The original Trumpf machine, the TruPrint 1000 took cylinders that were just 100mm in both diameter and height.
New metal machines
At Formnext, Trumpf showed off a new, larger version, the TruPrint 3000. It’s equipped with a single 500 watt laser. But more importantly this has a much larger cylinder – 300mm in diameter and 400mm high, which is designed for the production of much larger parts. The TP3000 takes two supply cylinders, meaning it can hold up to 75 liters of powder, easily enough to finish any given job without having to stop for refilling. The supply and overflow cylinders can be changed out without interrupting the manufacturing process.
Trumpf has also shown off an early version of its TruPrint 5000, which is essentially a version of the 3000 with more lasers. As such it takes the same size cylinders but can be fitted with up to three 500-watt lasers. Daniel Giek, an engineer from the product development for Trumpf’s Additive Manufacturing division, says that each laser can cover the entire build area, explaining: “So they can use each laser for separate parts or together on one part. There are no overlapping marks from switching lasers because they can all reach the entire build.”
The system automatically determines the ideal laser paths so that all three lasers can always expose multiple parts. The lasers can also be assigned to specific parts so that one laser can produce part of an object, such as the outer casing, without creating any overlapping seams.
The TP5000 has a built-in preheating function so that it can operate at higher temperatures – up to 500ºC – where the TP3000 is limited to 220ºC. Giek explains: “So we can address more materials and reduce tensions inside the materials even more.”
This is due to be available later next year.
To complement these printers Trumpf has also developed a range of ancillary equipment. This includes an automated sieve station that’s capable of refining several hundred kilograms of powder every hour.
The Trumpf printers are suitable for a wide range of metal powders from different sources including steel, nickel-based alloys, titanium or aluminum. Giek says: “Our philosophy is to be open because we understand that customers will have special alloys and materials and will have to do their own process optimization.”
There’s also an unpacking station where new parts can be removed from the machine, cleaned and detached from the substrate plate. The build cylinder fits directly into this and it has safety gloves and sight protection to protect the operators from direct contact with the powder. Any excess material is sent back to the sieving station.
All the various machines appear to have similar interfaces. Giek adds: “We try to give customers a modular system so they can use the same handling for multiple machines.”
Trumpf also announced a partnership with Siemens at the recent Formnext show. The two companies will work together to develop a software solution for the design and preparation of 3D printed metal parts. Essentially this means integrating Trumpf’s powder-bed-based laser metal fusion (LMF) process into Siemens NX software, which Trumpf will sell alongside its printers as TruTops Print with NX. It will mean having a complete software solution from design through to production. All the different stages will use a standardized user interface and there will be no need for any third party software for part design or data preparation.
Tony Hemmelgarn, president and CEO of Siemens PLM Software, says: “There will be no need for data conversion because the tools for design, simulation, 3D printing and NC programming of metal parts are integrated into one system.”
Frederik Schaal, who works on advanced research and development for Trumpf’s Additive Manufacturing division, says that it also include process monitoring. The system records a range of parameters such as how much powder is used and how long each part takes, which can be stored on a server. Schaal says: “It’s a lot of data so we give the customers the choice as to what to record.”
In conclusion, the TruPrint range is shaping up nicely with the 1000 being a useful entry level machine for small parts manufacturing, the 3000 offering a much bigger jump in size and the 5000 with its multiple lasers representing a considerable jump in productivity. But the most interesting element is the modular approach, starting with the cylinders, which can be reused from one machine to the next, through to the range of ancillary equipment designed to service multiple production machines and all tied up with a complete software workflow courtesy of the partnership with Siemens.
All of this gives Trumpf a range of options, given that the company also has its Laser metal deposition machines, though these are mainly targeted at repairing items such as turbine blisks. The decision to develop the TruPrint LMF range speaks to Trumpf's confidence that the market is ready for serial metal part production.