I’ve spoken with the good people at 3D printing and software provider Materialise several times over the past month.

During our most recent conversation, I realized something that I’m sure most everyone else in the manufacturing universe already knows: Additive manufacturing (AM) is extremely complex stuff.

Thank you, Captain Obvious.

During my four decades in manufacturing—first on manual equipment then CNC—I’ve been well aware of the need for stable, predictable processes.

Two weeks into my handscrew apprenticeship, for example, my one-time mentor, John, told me, “It doesn’t matter how you do it, as long as you do it the same way every time.”

Following that aphorism might make for a less interesting sex life, but it’s the key to consistent part accuracy. This is why I’ve always tried to follow the scientific method when operating a machine tool, tweaking a feed rate here, a carbide grade there, making one change at a time and documenting the results until machining nirvana was achieved. But I never gave this practice much thought as it pertains to AM. After all, industrial 3D printers are basically black boxes, right? There are no spinning cutters, no flying chips—just a laser beam hovering above a vat of resinous goo or bed of metal or plastic powder. Close the door, push the button, and come back hours or days later to a completed workpiece. Hopefully.

It’s the root word “hope” that’s worth discussing. Where machining and fabricating are well-understood technologies, with their practitioners enjoying roughly a century of knowledge and know-how from which to draw upon, 3D printing people are like the first screw machine operators, trying to figure out how to adjust all those scary-looking cams and knobs and slides without crashing a machine that costs way more than most people’s annual salary.

Worse, machinists and fabricators can have the worst work day of their life and not worry about altering the fundamental mechanical properties of the parts they’re producing. Additive manufacturers? Not so much.

Too little laser power, too much speed, less-than-pristine raw material, and the invisible structures within the burgeoning workpiece may not be what the customer bargained for, potentially failing months or years later.

Granted, I’m not giving proper credit to the tremendous technology that 3D printer builders have included in their wares or to the advanced simulation and optimization software that’s available to additive manufacturers. These tools might not guarantee success, but they certainly carry their users well down its path.

Still, the moral to this story is clear: Consistency is king, and an additive manufacturer must embrace the scientific method as no manufacturer has done before.

Even an old handscrew operator knows that.

（From: the Fabricator）