Additive Manufacturing

SEP 2018

ADDITIVE MANUFACTURING is the magazine devoted to industrial applications of 3D printing and digital layering technology. We cover the promise and the challenges of this technology for making functional tooling and end-use production parts.

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SEPTEMBER 2018 Additive Manufacturing 14 TAKING SHAPE Okuma applications engineer Brad Fitzpatrick and senior applications engineer Paul Kingsley load metal powder into the feed system of Okuma's hybrid machine tool. suppression; maintaining humidity matching the powder requirements; wearing a res- pirator with the ability to filter metal powder; and cleaning with an "explosion-proof " vacuum featuring a self-contained motor. Kingsley offers some additional advice: • Prevent powder exposure. He stresses, "When dealing with powder, you need to wear a good respirator mask." This equipment is the most notable element of the new procedures that come with powder metal AM. He adds that he prefers to avoid any physical contact. "I'll wear latex gloves for any significant exposure to the powder, like cleaning the hopper." • Shop air should be out of reach. One common machine- shop practice needs to be off-limits. "You have to get used to not taking the air hose and blowing chips," he says. Doing this with a hybrid could create a safety hazard. "What makes powder dan- gerous is the right mix with air," he notes. It can ignite if it finds contact with the correct proportion of oxygen. • Safeguard against sparks. "You also have to watch ignition sources and leads," he says. The vacuum, for example, should be grounded to the machine. Anti-static floor mats are in order. • Keep the machine under control. "Our hybrid at Okuma is in a lab," he notes. "I am not the only person who uses it, but I am always present when someone does." This points to a valuable related procedure: Charge a safety champion with monitoring procedures for the additive machine. • Coolant is a friend. "When we're doing LMD, we're also do- ing machining," he says. Thanks to coolant, the latter assists with the safety of the former. It might seem coolant and a laser-based process would not work well together, but the flood coolant captures metal into a slurry that reduces the risk of the powder becoming airborne. The machine is protected against this slurry using the same features found in a machine for milling graphite. In the end, the safety procedures are straightforward. "Never be in a situation where you can breathe or ignite powder," he says. Working within these procedures requires diligence, but it becomes second nature. Users of powder-based metal AM, hybrid or otherwise, have discovered this. Safety is not the obstacle. What is the greater challenge of making effective use of a hybrid machine today? "Programming," he says. CAM software has not been developed to serve additive capability on a machine tool anywhere near as effectively as it can program the other operations the machine performs. Various software companies are working on this. But for now, programming a cycle that includes building features at various angles and machining those same features from different directions generally requires splitting the cycle into several different programs that can all be defined more simply. In short, with a hybrid, while any manufacturing team member can be expected to follow the safety procedures, not just anyone can write the tool paths. "This isn't some- thing you give your least experienced programmer," Kingsley says. "You need someone who can manipulate the software and not just operate it," because for the time being, some manual manipulation of the output of CAM is the way to obtain tool paths for additive operations.

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