Hybrid Additive Machining Produces Accurate Parts from Metal Powders

Matsuura’s hybrid additive/subtractive machining produces highly accurate parts from metal powders that are melted and sintered using a laser while surfaces are precisely milled at high speeds. This technology allows the ability to "grow" a metal component in layers with complex internal features and fine mill those internal features, as the layers are added, to give a perfect surface finish are what makes the Lumex Series such a distinctive, unique and remarkable production platform and machine tool. Watch the video as Director Lumex NA Tom Houle, along with Lester Jones, vice president and COO of Custom Mold & Design, demonstrates this technology in Matsuura’s booth at last year’s Amerimold.

Houle: Matsuura started building CNC machining centers in 1934. We’re a third-generation family owned Japanese company headquartered in Fukui City, Japan. The fourth Matsuura generation just joined the company last September. So, we have that strong family continuance going. In the early ‘70s, we launched five-axis CNC machining and to this day are one of the world leaders in highly accurate five-axis machining centers. In 1999, we started developing a powder bed fusion CNC machining center, an additive hybrid machine. In August of 2017, Matsuura built a showroom, a demonstration center and started selling and marketing the Lumex series of hybrid additive manufacturing systems. One hundred percent focused on the injection mold industry today, we feel the one-machine-one-process concept is certainly a benefit and can demonstrate a significant return on investment to very high-end injection moldmaking technology companies.

The process is a center powder bed fusion based system with a 45 thousand rpm Maxia spindle, Matsuura’s own proprietary spindle technology. We grow the part, or laser center, 10 layers at a time. So, 20 thousands of thickness and then we go in and machine that centered material back to finish machine-like tolerances and machine-like surface finishes. All of the parts you see in our display cases are as produced on our machine. And as they come out of the machine directly without any post-processing.

On the laser centering side, our process parameters are designed and developed to achieve full material properties without a heat treatment process. As centered, they come out at 36 rockwell it can be heat aged, for 485˚C for three hours to a 53 rockwell hardness. Materials available are a maraging M300, which is a European tool standard, a low carbon, high chromium content steel. We also have 316 and 17 for stainless commercially available, as well as cobalt chrome and aluminum. The aluminum is a reactive powder so it takes an option on the machine. All other tool steels run in our standard machining center.

We have an integrated Lumex CAM software, which is constantly being improved and updated by Matsuura. We have a team of software developers in Japan, releasing every six months a new version of the software. Most of the efforts have been around improving the machining and reducing the machining time. Our cycle time is about one-third centering and about two-thirds machining. So, because we're a machine tool company, that's where our focus has been and where we continue to make improvements.

Now some of the applications—certainly the biggest application is conformal cooling to improve part quality, to reduce cycle time and provide a big return on investment. There's a white paper that's available to pick up, created by Custom Mold on a particular application, detailing the possible return on investment in implementing conformal cooling. This allows the customer to heat and cool the mold rapidly to prevent the problems with heat shock. Because we're machining as we grow the part, we can get very fine detail without EDM. In a lot of cases, we can virtually eliminate the use of EDM for deep ribs and deep pockets.

The other exciting technology is because it's a dense part, we can control the density of the material by laser parameters. So, we have built a porous vent on top of this drill point. In an application, here's the finished part, you can see that the ping pong ball will spin. So that is acting as a vent, and you can see the air coming through the porous vent. Imagine the implications for a silicone injection mold, where you can shut off the party line and still let the silica material vent right through the porous structure. If I turn the air off, this liquid won't leak through the vents. So, keeping them clean and the longevity of vents, we're finding is very beneficial compared to other technologies that's possible that are possible.

Jones: We've been working with Matsuura on the Lumex process for about eight to 10 months. We spent a lot of time with their application engineers in our facility, which has been very beneficial, producing actual cores and cavities. We put together a battery case. It was an existing tool and most of the applications that we've had, when we build a new mold, we don't have the opportunity typically to build it in a conventional manner and build it with the additive process. So, we're taking existing tools that were built conventionally, building new components through the additive process to demonstrate the benefits of conformal cooling. In this particular study, we were able to take a part that had an 18 second cooling time, and reduce that down to 10 seconds. So, we took eight seconds out of the cooling time cycle and actually improved the warp condition in the part. So, it ended up making a better part and saved eight seconds for every cycle.

Through our calculations with the cost structures that we have in place and about 80–85 thousand pieces we'd have that new core paid for. So, it demonstrates the opportunity to really save some money and make those parts a lot more economical. We look at our business as trying to help our customers, the molders that use the tools that we build, to provide the best quality tool that will make the best quality parts and the most efficient processes. So, the conformal cooling applications really allow us to get at both those things; be able to attack the warp and sink areas, those kinds of things. A lot of medical components will end up—an inhaler, as an example may have some passageways that have some really bad plastic conditions where the wall sections are thicker than one would like—to be able to cool that and reduce the warp and sink that might occur in that kind of part and at the same time reduce the cycle time really brings benefits to the end user by reducing those costs.

Houle: We believe the Lumex series addresses three major problems or major issues facing moldmakers today.

Number one: trying to find a skilled labor force. This machine uses a different set of skills that are more readily available than seasoned journeymen moldmakers. We're having a very difficult time finding moldmakers, especially in the Midwest. Our president on the machining center side says we could sell many more five-axis machine centers if we could supply a machinist with them. So, this technology, one-machine-one-process allows that issue to be addressed.

It also addresses some efficiency issues. It's meant to run 24/7, lights out and provide progress as you're sleeping. 

And then lastly, it makes us more efficient and more competitive for our customers or for the moldmaker customers on the molding side with the conformal cooling and the application of unique technologies that are not available in any other platform.