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Are you being asked to quote secondary machining operations on a handful of 3D-printed metal parts? If so, how do you cut these parts?

Kip Hanson is a contributing editor for Cutting Tool Engineering magazine. Contact him by phone at (520) 548-7328 or via e-mail at kip@kahmco.net.

According to industry experts—such as the additive-manufacturing consulting firm Wohlers Associates, Fort Collins, Colo., and simulation and product development experts Phoenix Analysis and Design Technologies (PADT)—3D-printed metal from laser-based powder-bed fusion systems cuts no differently than a billet of 17-4 PH stainless steel, titanium, Inconel or one of the many other alloys available today.

Another test dealt with more of a real-world application on steel over wood. This is similar to what you might see with the fastening of a Simpson Strong-Tie product. The goal was to see what happens in your typical impact driver application when the bit suddenly makes a hard stop against steel (with the driver still torquing behind it). The results weren’t pretty for most of the competition, but the Milwaukee Shockwave bits seemed to do way better than the first generation models, driving in dozens of screws. We’ll have to get these in-house and do some of our own testing applications, but what we saw looked very promising.

Another thing Utley mentioned is part stress. The 3D printing process generates tremendous temperature differentials as the powdered metal melts and rapidly cools, layer by layer, until the workpiece is complete. That’s why Proto Labs heat-treats nearly all 3D-printed metal parts. Without this secondary stress-relief process, it’s possible the part would curl up like a potato chip during machining.

There’s also a unique tip design that keeps the bit from walking, and an integrated wear indicator to let you know when it’s time to change out the bit.

We saw a ductility test of a Shockwave bit vs three competitors using a specialized machine that measured twisting force (torque) applied to the bits while locked down into a secured fastener and torqued to insane levels. This was a very entertaining demo that really showed off the capabilities of the new Milwaukee Shockwave bits as well as the limitations of some of the competition in this particular area.

When he's not playing with the latest power tool, Clint DeBoer enjoys life as a husband, father, and is an avid reader—especially the Bible. He loves Jesus, has a degree in recording engineering, and has been involved in multimedia and/or online publishing in one form or another since 1992.

Getting and testing some of these new bits will be a lot of work—but also a lot of fun. Accessories make all the difference—it’s where the rubber meets the road. Needless to say (but we’ll do it anyway), it’s great to see advances made in the area of impact bits, wood & metal drill bits, and SDS bits for concrete.

The competition were all second generation accessories, including one standard bit and two impact-rated bits (we recognized several products from our original impact rated bits testing article. The results were enlightening, with the Milwaukee bit showing far more ductility before breaking than the others (it handled a lot more torque). The Milwaukee bits also broke right at the “Shock zone” area in the middle of the bit (where it was designed to break) whereas the other bits broke at the tip. The new second generation Shockwave bits will be available in Phillips, square, Torx, hex, and Milwaukee’s patented ECX tips (in various sizes for each).

“The sintering process creates some pretty extreme internal stresses,” Utley said. “Even without machining, it’s important to remove them if you’re going to produce a stable part.”

New to market are the Milwaukee Red Helix twist drill bits which use a continuously variable helix that ejects material (both metal and wood) at a remarkable rate. They utilize a 135 degree split point bit that holds in place really well to resist walking, and there’s also a nice chip breaker to keep the debris flowing.

Bonding of adjacent surfaces in a mass of particles by molecular or atomic attraction on heating at high temperatures below the melting temperature of any constituent in the material. Sintering strengthens and increases the density of a powder mass and recrystallizes powder metals.

This titanium hip implant looks like tough stuff, but the most-difficult thing about machining parts like these is fixturing them. Image courtesy of McClay Tooling.

But not so fast. Mark Fisher, workshop manager at Christchurch, New Zealand, machine shop McClay Tooling Ltd., agreed that the 3D-printed titanium hip implants the company machines are virtually indistinguishable from titanium bar stock, except for their “slightly harder skin.” For these parts, McClay designed proprietary cutters that it operates at feeds and speeds Fisher is unable to discuss. He is, however, willing to point out the difficulties faced in fixturing these parts due to their complex, organic shapes, a factor that also presents challenges during 5-axis machining operations.

Substances having metallic properties and being composed of two or more chemical elements of which at least one is a metal.

Milwaukee announced 300 new accessory products in three different categories (concrete, metal, and wood). First up was the second generation of Milwaukee Shockwave bits which use a custom alloy 76 steel that can resist high shock. The heat treatment used is 4x longer than the original Shockwave bits. For a great overview of what to expect with respect to impact-ready bits, check out our article Impact Rated Bits: Dispelling the Myth.

Pro Tool Reviews is a successful online publication that has been providing tool reviews and industry news since 2008. In today’s world of Internet news and online content, we found that more and more professionals researched a large majority of their major power tool purchases online. That piqued our interest.

New M/2 2-cutter and MX4 4-cutter SDS-Plus and SDS-Max drill bits have some very unique features that should give them more speed and longer life than previous models. First, the new bits come with an enhanced rebar guard that keeps you from locking up should you hit some rebar. There’s also integrated breaker points that pulverize material faster during boring. Finally, like the Red Helix drill bits, the Milwaukee M/2 and MX4 SDS bits utilize a variable flute design to get more material out faster and deliver more holes drilled per battery charge.

It’s also available with a Shockwave hex shank so you can toss it in your impact driver and go to town when needed (as a lot of guys do since it’s so convenient).

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The second generation Milwaukee Shockwave accessories will launch in September 2015 at various price points and will be packaged both as smaller bit packs as well as in larger kits.

A quick Google search returns images of some cool-looking components, but what’s with all the curvy geometries and gnarly surface finishes that, at first glance, appear rougher than corn cobs? 3D-printed parts must be tough to machine, right?

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Eric Utley, applications engineer at Minneapolis-based Proto Labs’ Morrisville, N.C., location, said 3D-printed metals are “like machining a sand-casted part” and agreed that fixturing is probably the biggest struggle. “You have to wrap your head around how to hold these parts, where you’re going to touch off and make sure you’re machining what actually needs machining. That said, one of the beauties of 3D printing is that it’s usually easy to design in part-locating surfaces, provided you think about it in advance.”

“In general, for parts printed using powder-bed laser melting processes, we recommend the standard speeds, feed rates and cutting tools found in the Machinery’s Handbook,” said Rey Chu, principal of PADT, Tempe, Ariz.