by Lara Copeland, contributing writer
The American Mold Builder
Fulfilling prototype to production needs with its additive manufacturing expertise on a daily basis, Incodema3D, a business segment of Incodema Group, has seen the radical changes made in the industry in recent years. When asked about the process, evolution and uses of metal 3D printing, Director of Additive Manufacturing Scott Volk shared the following insights.
How does 3D printing with metals work?
The Direct Metal Laser Sintering (DMLS) process begins with a 3D CAD model whereby an STL file is created and sent to the machine’s computer program. A technician works with this 3D model to properly orient the geometry for part building and adds support structure as appropriate. Once this “build file” has been completed, it is “sliced” into the layer thickness the machine will build in and downloaded to the DMLS machine, allowing the build to begin.
The DMLS machine uses a high-powered Yb-fiber optic laser. Inside the build chamber area is a material dispensing platform and a build platform, along with a recoater blade used to move new powder over the build platform. The technology fuses metal powder into a solid part by melting it locally using the focused laser beam. Parts are built up additively, layer by layer, typically using layers 20 to 60 micrometers thick.
How has metal 3D printing changed the mold building industry? How has it evolved since it was first introduced?
The industry has changed drastically since it was first introduced – in America, that was about 12 years ago, and in Europe that was roughly 16 to 17 years ago. Over that time, it’s gotten better by leaps and bounds, and huge improvements have been made both in terms of technology and materials.
When 3D printing first started, EOS had one material available on its machine – Direct Metal 20 (DM 20). It was a bronze-like material – a kind of copper metal compound – and it was a rough material. Shortly thereafter, stainless steel materials appeared on the market. As time has passed, the properties have continued to evolve. Cobalt chrome became popular for medical purposes, and Inconel was used for aerospace. Titanium arrived shortly after that, and now there are two different grades of titanium, three different grades of stainless steel, three grades of Inconel, tooling steel, cobalt chrome and much more. The availability of a variety of materials and their capabilities has improved dramatically over the years.
The technology also has been enhanced since the machines first became available. In the beginning, the control software was difficult to use, and over time competition has sprouted up. This fact has forced technology to get better faster. Today, there are quad 400-watt laser machines at 16-inch cube capacity, whereas before there were 200-watt lasers at 10×10 inches that were incredibly slow and could barely process certain materials. Now we have 1000-watt, single laser, 16-inch cube machines that can handle almost any material and build just about anything, up to high-speed quad laser machines that are fast and the same size (16 inches).
What is the difference between metal and plastic 3D printing? Why should metal be chosen over plastic?
As far as resolution, there is a big difference between the two materials. With most of the plastic technology, the layering is quite evident within the resolution. But in looking at the powder technology – and there are powder technologies in the plastic business as well – it’s a better surface finish for layers. The layers don’t necessarily translate into resolution or surface roughness with a powder machine. That’s why additive metal machines produce parts with a clean surface finish: There is very little layering effect. The metal equipment offers better resolution and surface roughness.
There really are no limits to what the metals can do. All the metals we use are the same type of materials that most people are accustomed to seeing. Although we only have certain grades of certain materials available, those grades are equivalent to the materials that could be ordered from any metals vendor. The properties are similar. The difference between the grades of materials stems from the welding process; we are looking at materials as if they were welded as opposed to being wrought materials that are machined. While there are some slight differences in properties and the way they are handled, it’s essentially the same materials.
Does additive offer any time savings?
That is a pretty big advantage for additive as well. The time it takes to procure stock, have it brought in to a traditional machine shop, carry out that machining – to get to the point where an additive part would be finished – is much longer than what an additive part would take to create.
For example, a 10-inch tool with any kind of intricate design in it in traditional manufacturing – if it’s standard and not rushed – could take potentially three to five weeks to create. On our machine, a 10-inch tool would take three to four days to build. Overall, the time savings is immense. The tool still must go through a considerable amount of finishing after the build, so it will still require some time in a machine shop. But the amount of time that goes into a tool that’s been made with additive is much less than starting from a blank stock of material.
What makes metal 3D printing a good choice for the mold building industry?
The biggest advantage is the ability to utilize conformal cooling. This helps with the control of shrink in parts, control of warpage, sink – all those four-letter words in the molding industry. Additive brings solutions for each of them. The conformal cooling idea isn’t just for cycle time; it’s also for accuracy within the parts themselves. If the overall thermal dynamics of a tool are controlled, the quality of the molded part also can be controlled.
Alongside that is the difference in materials. Maraging steel was a material that was used many years ago in the die casting business, but it was so expensive that in many cases it was never used again. However, because additive only uses the amount of material needed for the part itself, and waste material is no longer machined away – it brings back materials that were too expensive to use any other way. Maraging steel is a material that was suitable for core areas where there was a lot of heat buildup. It is used because it has a high CTE property, so it handles the thermal issues that other steels have difficulties with as far as transferring heat. It opens up a new range of possibilities to build cores with material that had previously been abandoned.
What is an example of a recent project where a mold has led to advantages for the client?
Philips Plastics and GPI collaborated in a case study on the benefits of using conformal cooling for injection molding. It is a good example of what can be done with conformal cooling and using additive for tooling for injection molding. Some of the accuracies that were accomplished, the stresses, the shrinkage and having an accurate part almost first shot in a tool are all definite benefits when trying to get parts completed on a production line.
The time that is involved in perfecting the temperatures, the flow pressures and the flow rate that go on to make a part in a tool is often a drawn-out process. But the use of conformal cooling and even temperatures across those tools make that process rather streamlined—compelling the production of more accurate parts out of the tool at almost first shot.
How could a traditional tool builder start using metal additive manufacturing? Do they need machines? Can they partner with Incodema?
Many companies have purchased equipment of their own. A good example is HARBEC – an upstate New York injection molding company that produces tools in house as well as for others. HARBEC brought in its first EOS machine several years ago. Now with three machines, the company has learned how to use them well. It’s expensive, but it’s an easy technology to utilize once it’s embraced.
Partnering with another company to build tools also is an option if a company prefers not to buy equipment. The company will know how to labor through the intricacies of building parts, finishing them, getting tools out, how to treat them and use them.
How does the cost of the raw materials compare between traditional mold building and additive manufacturing?
Raw material costs are a bit higher than what a traditional machinist would see for stock materials. For instance, people expect parts to be extremely cheap because they have looked up their stock market price. But the driving cost factor within our technology is the time on the machines. When looking at costs and the benefits of additive, the advantage isn’t what additive does in the machine that creates the part; the advantage is the time savings that it brings to the table for all the other processes after that.
The tooling process is expensive and time consuming. For instance, rough electrodes are going in and roughing out the pockets that can’t be machined, and then a finish electrode must be made. But there are only a few other ways to create that detail within tooling. It is hard work, but we certainly don’t eliminate traditional mold building.
Should a traditional moldmaker feel threatened by metal additive manufacturing?
There still is going to be a need for the post-finishing of tools. Currently, the technology for additive is not at all in one process. Experienced, knowledgeable machinists are still needed to work on the tools. Additive may be a quick way to create a blank, or the tool itself, with added value of that conformal cooling – and in some cases special design – however, a slide might be built in a different way.
When looking at how to build a part with additive, new base designs will eventually be created. Additionally, new ways to hold tools and load slides also will be needed. But injection molding technology and the knowledge that goes into preparing a tool for injection molding is still needed. The experience and background that goes into creating those tools is still imperative. Additive doesn’t replace traditional, but additive is a component within the process.
The American Mold Builder would like to thank Scott Volk, director of additive manufacturing at Incodema3D for his assistance with this article. The Freeville, New York, company features state-of-the-art facilities that were set up to meet any level of manufacturing needs – from prototype to production. “We don’t just print parts…We manufacture parts to print.” For more information, visit www.incodema3d.com.