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Interview MAPAL: Additive hybrid design is convincing

Keeping stress states in the components under control​

Optimization of additive hybrid components

Over 90 percent of the additively manufactured tools from MAPAL are based on a hybrid design. It makes it possible to produce a component from a conventionally and cost-effectively manufactured base and the attachment of an additively manufactured complex part with targeted functional integration.

The weight of the tools is significantly reduced

The combination of additive and conventional manufacturing facilitates the achievement of economic and functional goals. In order to be able to ensure the high quality of the tools manufactured in this way, MAPAL uses the Ansys Additive Suite simulation software offered by CADFEM. With additive manufacturing, tools can be designed and manufactured with significantly less weight. In addition, the coolant flow can be optimally designed. The serious weight savings enable higher cutting data and thus reduced machining times. The areas of application for hybrid production range from reamers to boring and milling tools to hydraulic chucks and combinations of these tool types. For example, MAPAL has optimized an existing conventionally manufactured bell tool. The interior of the tool was changed using the selective laser melting process - instead of solid material there is now a specially designed honeycomb structure. As a result, the tool is 30 percent lighter, and the damping effect increases tool life by around 40 percent. This allows faster machining, while the quality remains unchanged at a high level. CADFEM Journal spoke with Dipl.-Ing. Matthias Schneider, Team Leader - Product Development Team at MAPAL, about the advantages of the hybrid design and the use of Ansys software, as well as the insights and benefits gained through simulations.

MAPAL Corporate Group

The headquarters of the MAPAL group of companies and the seat of the management is MAPAL Dr. Kress KG in Aalen. Key competencies are concentrated here, the areas of research and development, controlling, marketing and corporate communications, training and further education and the area of services. Aalen is also the largest production location of the MAPAL Group and is substantially responsible for the product areas of fine boring tools, indexable inserts, fixed multi-blade reamers, clamping tools and adapters, ISO tools, mechatronic systems, setting devices and tool output systems.

  • More than 5,500 employees worldwide, of which approx. 3,600 are in Germany
  • Sales 2018: 640 million euros

Mr. Schneider, can you briefly summarize the decisive advantages of hybrid production for MAPAL?

Matthias Schneider: We see the most important advantages of hybrid 3D printing in the fact that, on the one hand, we can use the extraordinary shaping possibilities of additive manufacturing while, on the other hand, also using the cost-effective traditional manufacturing methods of turning and milling. This leads to a significant reduction in pure printing costs compared to a tool that we would execute entirely as 3D printing.

Are hybrid-made tools as easy to use as traditional tools?

Matthias Schneider: Our standardized machine interfaces serve as the basis for further machining of the components, so that a very high changeover accuracy and reproducibility can be ensured. We are more or less building on our own zero-point clamping system. With the fixture, which we developed specifically for the hybrid design, we save time when setting up the machine. However, the difficulty we have is that there are many different machine interfaces in different sizes. This requires a large number of fixtures in order to be able to work very accurately and also as effectively as possible.

What problems can arise with hybrid manufacturing?

Matthias Schneider: Due to the bi-metal effect - hot metal is welded onto a “cool” lower part - stresses occur at the interface with larger cross sections. These can lead to the mechanical failure of a partner, either the conventional lower part or also the additively manufactured upper part. When we discovered defects such as stress cracks on components, we wanted to use simulations to analyze how these defects could occur. The stress cracks occurred on a tool used to machine components in the internal combustion engine. An additional hydraulic clamping bushing for a second, smaller tool allows simultaneous machining of a large and a small diameter with good coaxiality. We hoped the simulations would provide a relatively accurate representation of the stress states in the components during the build process and also in the finished state. Likewise, we hoped to gain insights into which design and process engineering changes we could use to minimize the stress states that occur.

How did you go about simulating the tool?

Matthias Schneider: First, as with most simulations, we had to build a simulation model that would provide us with the most accurate and reliable answers to our questions. At the same time, however, the required computing times had to remain within limits. Another challenge was the material parameters required for a realistic simulation. For the material used, 1.2709, no corresponding material model was available within the simulation solution at the time, but now with the new version this would have been the case. Therefore, we first had to determine the necessary characteristic values from data sheets and our own material investigations. Finally, various simulation models were compared with each other in terms of calculation speed and accuracy of the values determined. The calculations were carried out with highly simplified geometries. Only after the decision for the most reasonable simulation approach was made, the calculations were carried out with the detailed tool geometries.

Did the results meet your expectations?

Matthias Schneider: On the one hand, the results confirmed that our previously elaborated optimization proposals were heading in the right direction and encouraged us to consistently follow this path. On the other hand, the simulation showed us for a concrete problem case how the planned change could be further optimized and refined. We were then able to start a field test with the appropriately modified tool. Without appropriate simulation software, we would have had to continue with the “trial and error” procedure. It is true that we also used the simulation to calculate different variants in order to compare and evaluate them - but this enabled us to reach our goal very quickly. Without simulation - with trials only - the road would have been much longer and rockier. We would have had to go through many more iteration loops, which means developing and implementing new design ideas, producing real prototypes, and carrying out elaborate and comprehensive test phases. That would have cost a lot of money and, above all, a lot of time. With simulations, and the knowledge gained from them, we were able to optimize the tool in question to such an extent that only two iteration loops with real prototypes were required.

What benefits do you see from the use of simulation?

Matthias Schneider: The knowledge we gained from the simulations confirmed our assumptions about the stress problem and provided us with sound knowledge about the component behavior. At the same time, we were able to further expand our know-how regarding process control. With regard to quality, we hope to take a big step towards “zero defects” with the simulation. In addition, the simulation helps us to secure the competitive advantage we have gained in recent years in the field of hybrid production of cutting tools.

Thank you very much, Mr Schneider. We wish you continued success with hybrid additive manufacturing.

MAPAL Dr. Kress KG
Matthias Schneider

Author: Gerhard Friederici (CADFEM GmbH)
© Images: MAPAL Dr. Kress KG

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