A group of students of the Master in Design and Engineering for Additive Manufacturing of the UPC School of Barcelona (A. Miró, A. Sanchis and T. S. Tello), have developed as a final master project of the current edition a real case of development of a high added value product to be manufactured by metal 3D prineting.
The DEFAM master is carried out at the CIM Foundation, a technology center in Barcelona dedicated to Digital Manufacturing with a triple training, research and transfer to industry, leader in 3D printing, and attached to the Universitat Politècnica de Catalunya. Both this master’s degree and the rest of the training carried out at the CIM UPC Foundation have a strong industrial and practical character, and includes a final project based on a real case of industrial interest. According to its academic director, F. Fenollosa, “Additive manufacturing is a disruptive technology for which the quality training offer from an industrial point of view is very limited today, when it is already an urgency to open lines of business based on customization or the ability to materialize ultra-optimized geometries, as has been the case here”.
ADDA is a Barcelona-based digital design company dedicated to providing innovative solutions in product, interior and architecture. The project tutor and member of ADDA, J. Ardanuy, is, at the same time, professor of Topological Optimization at DEFAM Master. Thus, ADDA proposed a project related to a scaling product called active wedge or “Friend”. This product is used in unequipped sport climbing, in those routes where there is a crack and there is no other option but to anchor in case of a fall. This device is manufactured in many models and brands, but we focused on a product of a particular brand: the cam TOTEM CAM 1.80 orange. TOTEM is a prestigious cooperative company from the Basque Country, which has positioned itself as one of the international leaders in this type of climbing aid products thanks to its concepts and technology.
Left: Carries TOTEM CAM
Right: anchoring in fissure
The climber, to complete a route of ascent, can carry more than twenty of these elements hanging from the harness. Therefore, the weight reduction in this product is an important value proposition that results in less climbing effort.
This was the first goal throughout the project: to take advantage of additive manufacturing to propose a new design in which a significant reduction in the weight of the element is obtained, improving its functionality if possible.
HOW HAS IT DEVELOPED?
The first stage of the project focused on understanding the product, how it works and what the most important parts are. Then the focus was on the cam, the part in charge of anchoring to the wall, and therefore the most vital and yet heavy part of the product. The next step was to study its geometry: it is a metallic element, currently produced through machining, with two outer curves that follow the shape of a logarithmic spiral providing optimal functionality for its use.
Esquerra: logarithmic spiral on which the cams are based, given its characteristic of maintaining constant tangency at any angle.
Right: positioning of the cam according to the crack width
Once this was understood, the study of the forces acting on the cam was carried out, introducing these data into the virtual finite element testing program (CAE) to carry out the necessary simulations. Design and engineering programs oriented to additive manufacturing of the latest level (Fusion360, Ntopology, Solidworks, Altair…) were used, which are the same as those applied during the master’s degree in the framework of different projects. After several design iterations through topological optimization, and validating the prototypes, a final design was achieved that improved the current values of strength and stiffness of the cams.
CAD/CAE topological optimization process for cams
Since the ultimate goal was to be able to obtain this product through additive manufacturing, an analysis of the possible compatible materials and technology that could make it happen was carried out. TOTEM currently manufactures the cam by CNC machining from a 6061 T6 aluminum bar.
First, we analyzed the materials available on the market that were more similar in mechanical properties or even surpassed them, prescribing the use of AISi19Mg, an aluminum alloy that gives very good results in metal 3D printing. Once the design was finalized and the material selected, it was time to study the different technologies that could make 3D printing feasible.
It was concluded to use 3D printing based on Pulse Bed Metal Fusion (PBLF), also known as Selective Laser Melting (SLM), specifically the machines manufactured by RENISHAW, model Ren500M or Ren500Q. Selective layer-by-layer laser powder melting today offers a very wide production level and repeatability, which results in an acceptable price/part ratio. Moreover, it is the most accepted technology by the market today (aeronautical and medical industry), and is giving very good results with high reliability and mechanical strength.
A first prototype was then printed thanks to MADIT, a company based in Bizkaia that uses SLM technology to carry out projects and productions of other companies seeking to incorporate Additive Metal Manufacturing in one around Industry 4.0. This prototype allowed to confirm the feasibility of the production process, and, in the future, it is the basis to be able to perform comparative functional tests with current models.
Until a few years ago, the use of SLM technology could only be allowed in high value-added sectors such as aerospace. Even so, MADIT’s business strategy, with a high focus on productivity, has allowed the introduction of this technology in the general metal-mechanical industry, being able to service the production of parts in most sectors (automotive, consumer goods, etc. ).
This technology is still unknown by the industry, and that is why MADIT offers its support to those initiatives that demonstrate the disruptiveness of Additive Manufacturing to the current industry: the industry needs to see to believe, even if the climbers do not need to see the summit to start climbing.
Top corner: Prototype of the cam realized at MADIT with RENISHAW SLM technology.
Center: the final SLM prototype together with a pre-SLS prototype made at the CIM UPC
Right: Presentation of the DEFAM Master’s project
The end result was a cam with 38,5% less weight than the original model, resulting in a total product reduction of 20 grams, 2 grams lighter than the lightest competitor’s model. In this case, only one part of the product has been optimized, but it is fair to say that it could be extrapolated to other parts, positioning the brand in a new ultra light model that will hardly be surpassed by the competition that has not yet made the leap to 3D printing. At the cost level, and in the face of the great competitiveness of CNC-based digital technology, 3D printing technology still has to lower barriers to respect so that the value/cost ratio facilitates the leap to 3D printing. Another conclusion is the excellent exercise of professional preparation carried out by the students, who face their incorporation into a labor market in need of really differential technological profiles for a growing industry.