Leaves its Mark. The New Speed Benchmark for Precision Drills.
Lichtenfels, Germany, July 20, 2015 – The days when precision tools and additive manufacturing strategies could not co-exist are history. The new Mapal QTD-series insert drill prove this again. For the first time, the precision tool specialists from Aalen are manufacturing drills additively, with amazing results. Dr. Dirk Sellmer, Head of Research and Development at Mapal, explained the reasons behind this new development and the new geometric freedom for designing complex parts.
Once again, Mapal has emphasized its role as a think tank for high-tech drilling solutions. While searching for new, innovative metalworking solutions, the company has re-invented itself again and again in the 65 years since it was founded in 1950. In this pioneering role, Mapal now relies on additive tool solutions with LaserCUSING systems by Concept Laser.
Requirements in practice
High performance, long service lives and rapid tool changes are the central requirements for modern tool concepts. The QTD insert drill excels with good chip deformation and reliable chip removal thanks to its geometry. The insert is held in a stable prism connection. These precision features make high cutting specifications and drill quality possible. Mapal offers four types of the inserts for steel, stainless steel, cast iron and aluminum.
New QTD insert drill developed with diameters from 8 to 32.75 mm
The new Mapal QTD insert drill is certain to impress users. The drills have a lot to offer in detail. Additive manufacturing from metal powder using laser melting systems by Concept Laser makes entirely new design approaches possible. The QTD insert drill was previously available in diameters of 13 mm and greater. One reason for this is the coolant supply in the tool body. The smaller the tool body, the greater the adverse effect the standard central coolant supply on the tool’s performance. Central coolant supply weakens the core of the drill and makes it unstable. In addition to this, the cooling channels must be ever smaller. That reduces the flow of coolant to the insert. The new steel tool body design with spiral cooling channels is not usually used for small diameters. The new design now allows even solid drills to be produced in the 8 to 12 mm diameter range.
New, spiral cooling concept
The new QTD-series insert drill are manufactured using additive laser melting. These are hybrid manufactured parts: The tool shank is machined conventionally and the drill is laser melted with additive methods. This approach makes the manufacturing process significantly more economical. Dr. Dirk Sellmer: “Hybrid strategies are the ideal method of choice: Simple component parts are machined and more complex areas are then built up additively.” Unmanned manufacturing and a reduction of tooling-up times and reworking in the digital laser melting approach are other aspects which improve the economy. However, the greatest advantage of transitioning from a conventional manufacturing strategy to additive manufacturing was that it facilitated an entirely new geometry, increasing the performance of the tools. Dr. Dirk Sellmer: “The additively manufactured insert drill has a cooling concept with spiral ducts, which improves the cooling performance. Compared with the previous central coolant supply with y diversion, a spiral coolant routing increases the coolant flow by 100%.” It also increases the core stability with coolant ducts which run parallel to the flute. The cooling is also improved by the new coolant duct profiles which deviate from the usual circular form with a slightly triangular shape. That optimizes the geometrical moment of inertia and the flow rate. Tests found that choosing a cross section of this type increases the flow quantity by 30%. Coolant profiles like this cannot be produced conventionally. The coolant flows at a pressure of 1.6 to 3 bar.
Overall, the new cooling concept means that better cooled drills are available for longer drilling tasks. It also allows to expand the range with smaller drill diameters. Stainless steel 1.2709 is used. According to Dr. Sellmer, the powder requirement is calculated from the effective construction weights plus 10%, and the scrap material is easy to recycle. Internal tension in parts is critical for rotating tool solutions by Mapal. Tension must be removed from conventionally manufactured parts after machining due to the immense forces to which they are subjected. That is not the case for LaserCUSING. The constantly changing exposure locations in the geometry mean that the tension is removed from the part internally during the build process.
Two Concept Laser M1 cusing systems with a central material supply container are used. The systems, from the medium performance range, have a build envelope of 250 x 250 x 250 mm. The QTD insert drills are created as 10×10 or 11×11 unit solution in this build envelope. 100 to 121 drills are produced in one set-up. The build rates of the 400 W lasers are between 6 and 18 cm³/h. In order to avoid contamination, the M1 cusing operates under a nitrogen protection gas atmosphere as usual. During processing, the laser heats the powder material to 60-70°C for fusing. The thermal expansion in the build process has to be taken into consideration in the design. However, after initial successes with series products, the demand for internal capacities is also growing, even though clever organization results in production availability of 24 hours, seven days a week with unmanned production. According to Dr. Dirk Sellmer, options include using multiple lasers in a system and/or a general expansion of capacity. In 2014, Dr. Kress, owner of Mapal, mentioned a need for at least 5 systems in the medium term.
Why Concept Laser?
If you ask Matthias Schneider, an employee from the Dr. Sellmer’s R&D department, the reasons for choosing Concept Laser are handling, accessibility and user-friendliness. Matthias Schneider also mentions open variation of parameters for process design as strengths of Concept Laser. Variable parameters are particularly interesting for tests and new products to define an optional process. If we take a closer look, some things Schneider mentions make it clear that he knows what he is talking about: The topology options for LaserCUSING are among them. Concept Laser systems stand out due to their stochastic control of the slice segments (also referred to as “islands”), which are processed successively. This exposure strategy induces the lowest tension in the component.
What’s inside counts: Geometry and lightweight construction for balancing
The changes in the design are also apparent in other areas at Mapal. The Aalen-based company’s weight-optimized, laser-melted external reamers are new. The lighter the external reamers are, the better they work. That is particularly true for machining small-diameter shafts. Conventionally manufactured 8.5 mm steel external reamers already weigh 400 grams. This weight and the resulting mass inertia severely restrict the maximum step speeds. Additive manufacturing allows lightweight external reamers to be built with integrated balancing potential. Dr. Dirk Sellmer: “The mass distribution of the honeycomb structure of the external reamers is like balancing wheels. We call the internal cavities balancing profiles. The balancing profiles enable us to achieve virtually perfect concentricity of the rotating tools.” A rib structure, specially designed for the application, which has been registered for a patent, reduces the “new” 8.5 mm external reamer’s weight to 172 grams. That is a weight saving of 57%, which results in a better performance for this rotating component: Machining is faster and precision is greater.
New products on the horizon
Additive manufacturing strategies have been shown to boost competitiveness, economy and value added. “In a broadest sense, we can say that the parts of the future are more intelligent or complex, and also offer better performance,” continues Dr. Dirk Sellmer, and adds: “They also give us new design options. And that will result in new geometries with new performance features. In general, additive manufacturing facilitates new product solutions, which would be inconceivable with conventional methods. Every project implemented is a learning experience. This knowledge is then used in new, future projects. “Besides optimizing the quality, Mapal prioritizes process management, to manufacture additively with better surfaces closer to the precision component. Both cryogenic chip removal and the requests for closed cooling circuits and chambers make new requirements of the technology.
Interview with Dr. Dirk Sellmer, Head of Testing and Development at Mapal:
Editorial team: You call the new QTD insert drill a world’s first. What makes it so innovative?
Dr. Dirk Sellmer: The innovation is based on two aspects: On one hand, the use of additive manufacturing technology for high-precision drills, and on the other an innovative cooling concept.
Editorial team: What does that mean specifically?
Dr. Dirk Sellmer: We can use a spiral cooling system with laser-melted insert drill. That improves the cooling performance thanks to the higher coolant flow. And we succeeded in offering smaller drills, i.e. expanding the product range downwards.
Editorial team: Please describe this cooling concept.
Dr. Dirk Sellmer: The changed cooling concept improves the cooling performance. Compared with the previous central coolant supply with a Y diversion, a spiral coolant supply increases coolant flow by 100%. This also increases the core stability via coolant channels which run parallel to the chip flutes. As part of the development, we designed new coolant channel profiles. They deviate from the usual circular form with a slightly triangular shape. In tests, we found that choosing a cross section of this size increases the flow quantity by 30%. The volume flow in the drill is 1.6 to 2 times greater than conventionally manufactured tools. The ability to offer drills with smaller diameters was almost a side effect.
Editorial team: What are the main requirements for a precision drill?
Dr. Dirk Sellmer: The ideal drill is very hard outside and somewhat flexible inside. Laser melting makes it possible to generate selective thicknesses and then harden the surface with heat treatment and to create a cellular or honeycomb structure inside if necessary. That makes ductile lightweight solutions and e-modules possible, which we cannot produce conventionally. In detail, manufacturing based on the hull/core principle is immensely important for us. First, the core of an insert drill is built with the cooling system, which is added to the conventional shaft. In a second additive run, the outer hull is built up with higher densities. This is almost the perfect drill – hard on the outside and soft on the inside. We combine ductility with high tensile strength and hardness. Of course, the finished component is then hardened, i.e. heat-treated. We use a vacuum hardening process for this.
Editorial team: Mapal uses additive construction for external reamers. What advantages does that have in practice?
Dr. Dirk Sellmer: For these rotating tools, the weight and imbalances determine the performance characteristics due to the mass inertia. External reamers manufactured additively can be roughly 50% or more lighter. In particular, they can be made with cavities, which we call balancing profiles. That permits lower imbalances, higher speeds, higher precision and greater economy. This is based on a honeycomb structure which facilitates lightweight construction and balancing potential. In general, we assume that we can also optimize the honeycomb structure bionically. FEM analyses allow us to optimize these honeycomb structures to increase the rotating potentials. Our patent for solutions like this gave us the foundation we needed. But that is not the end of the story. Process-appropriate design allows us to implement new ideas constantly as a “work-in-progress”.
Editorial team: When did you start using additive manufacturing?
Dr. Dirk Sellmer: First, we explored the market on the supply side and evaluated the different system concepts for our applications. We soon found that all of the concepts would enable us to change our previous machining environment. Just 12 months after choosing the Concept Laser technology, we put the first series-ready products on the table, in spring 2014. Our boss, Dr. Dieter Kress, is so impressed that he often carries an additive part to show visitors these minor miracles.
Editorial team: Why Concept Laser?
Dr. Dirk Sellmer: When making decisions like this, there is a lot to think about as, fundamentally, all three main providers offer good solutions on the hardware side. However, there are certain nuances in the details which can be important. We soon found that Concept Laser has a special approach to topology. In the exploratory negotiations, Concept Laser also focused on our applications and showed us how additive manufacturing is currently used by other processing companies. That meant that we soon knew everything a user needs to know. Concept Laser offers open parameter intervention. That was also an important point for us in the R&D department, enabling us to make specific developments. In my opinion, the M1 cusing system is designed very customer-specifically and easy to operate. It’s not an “off the rack” system, it’s highly customized with a few soft factors. Our cooperation is one between equal partners.
Editorial team: Was the investment a difficult decision for Mapal in terms of profitability?
Dr. Dirk Sellmer: Of course it was the subject of debate. And it did involve a certain amount of risk initially. Dr. Kress, an owner highly interested in technology, also realized that something special happens when geometries are created from powder, as if by magic. The process has a special charm, even in unmanned manufacturing. Manufacturing: 24 hours a day, seven days a week. He also knew that we in the Development department would support an entrepreneurial decision like this with a great deal of commitment. That meant 15 engineers and technicians, along with 10 technical assistants, who were convinced they should break new ground. We defined specific goals and were given a lot of freedom when we went to work. Looking back, the owner’s decision was spot-on and points the way to the future. I am very happy that we took this step as early as possible. The experience we are collecting gives us some competitive advantages, where others are still plucking up their courage. The initial investment decision should not be left up to the Controlling department alone. The production solutions possible, unmanned manufacturing and many other factors of an additive strategy really characterize competitiveness, economy and value added immensely.
Editorial team: Do you think this will be a trend?
Dr. Dirk Sellmer: The industry is highly conservative overall, which means that innovations take a long time to catch on. But as you can see here, additive strategies shift the design principles towards product solutions which would have been inconceivable previously. The products offer obvious positives for us and our customers. There is no other way if you want to be successful in future. Both for us, in our manufacturing costs and range of performance for our products, and for our customers when it comes to quality, availability and unit prices.
Editorial team: Wouldn’t titanium as material for the external reamer have been an alternative with a classic strategy?
Dr. Dirk Sellmer: Traditionally, that would be the right solution. Just use titanium instead of steel. That reduces the weight by approx. 35%. But the material is expensive. It is also difficult and expensive to machine. Instead of titanium, we get by with stainless steel 1.2709. Besides, the density would be evenly distributed in an external reamer. Figuratively speaking, we would stop thinking innovatively halfway to the goal. From a certain point, it makes no sense to optimize old strategies to the max. You have to try something new.
Editorial team: Which other approaches do you take with an additive manufacturing strategy?
Dr. Dirk Sellmer: New products and new options: Take retrofitting, for example. An ISO tool has a certain number of lifecycles based on the workload in the user’s processes. This wear is normal. However, today, taking sustainability and resource saving into account, we have discovered that ISO tools do not have to be discarded, as they still have potential for retrofitting. In short, additive structures offer many ways to restore the ISO tool surface to an as-new condition. Of course, now that the technology is available, we are checking all of our products to assess the viability of design adjustments. There will be a range of new products and features.
Editorial team: What developments do you expect in the future?
Dr. Dirk Sellmer: We can assume that the build rates of laser melting systems will increase significantly. Stronger lasers are not necessarily at the top of our wish list, as our parts are generally relatively delicate. But I believe multi-laser technology would increase the performance. That would allow either faster or more selective processing, i.e. varying the layer thickness. The quality level will also increase. Together, this increases the economy and the performance parameters of parts. I also expect the range of materials available to grow, which will allow us to adapt components even better to their tasks in terms of performance or service life. Fundamentally, I could envision designing powder materials to suit the process and application optimally. Our design options will also change. And that will result in new geometries with new performance features. In general, additive manufacturing facilitates new product solutions, which would be inconceivable with conventional methods. The process is doubtlessly ideally suited to increasing the imagination and creativity.
Editorial office. Thank you for the interview.