Company: Rosswag GmbH
End Use Sector: Power Engineering
Product Density: 7.8-8.2g/cm³
Tensile Strength: 1520 GPa
Yield Strength: 1290 GPa
By combining the two production processes of open die forging and selective laser melting, the disadvantages of each process can be circumvented. For this purpose, the respective method is only used in the segment of the part for which it is suitable. A basic body is conventionally forged and subsequently machined to produce a plane surface. On this surface, the functionally optimized contour is added by selective laser melting.
With this innovative production chain, for which Rosswag GmbH was awarded the German Resource Efficiency Award (Deutscher Rohstoffeffizienz-Preis 2016), a component is created which consists of one identically material charge and has been produced in a resource-saving manner. The loss of material is reduced, since the complex geometries aren’t produced with high costs and expenditure of time by machining. This also reduces the consumption of coolants and lubricants.
The remnants produced during sawing and forging can be used for the additive manufacturing process. For this purpose, they are converted into a fine-grained metal powder in an atomizing process. The so-called Atomizer has a melting crucible in which the metal scrap is heated above the melting point. The molten material is atomized from the crucible via a nozzle by means of an inert gas stream to a spray. Subsequently, the spray particles solidify in the drop tower. In a downstream process step, the particles are fractionated for a stable SLM process between 10 μm and 60 μm.
The forging-SLM-Hybrid produced in this way offers a possibility to equip even large-volume parts with features which can only be realized by the additive manufacturing process. Due to the optimum grain structure profile, the forged component area has excellent mechanical-technological properties, especially with regard to the fatigue strength. The complex segments of the part are then manufactured in such a way that an added value results which could not be achieved by conventional production processes.
The hybrid production process is therefore the ideal approach to meet safety requirements and still achieve a functional optimization of the component. Lightweight components in particular must be designed in such a way that the requirements can be met by the use of additive manufacturing technology.
NNS Reactor Coolant Pump Impeller HIP
Company: Framatome / Aubert & Duval
End Use Sector: Energy (Nuclear Power Plant)
Product Density: 7.96g/cm³
Tensile Strength: 580 MPa
Yield Strength: 290 MPa
Product Hardness: 220 HV
Framatome, fabricates and supplies reactor coolant pump (RCP) sets covering the worldwide nuclear market. In this RCP, a component with large-dimension and complex geometry puts real production difficulties. Moreover, the manufacturer aims at improving its mechanical performances in connection with the nuclear power plants lifetime extension politics.
Large components with complex shapes, such as impellers, were traditionally manufactured by casting but the lifetime of these products was limited by the ageing of the material due to the presence of ferrite years, alternative approaches consisting of machining impellers from a forged ingot have appeared in the market place. Of course, this solution offers an improvement of the mechanical characteristics but, in the case of a RCP impeller, it implies to start with a 4000kg ingot to finish with a 600kg impeller, resulting in the scrapping of 85% of the material. This observation is also valid in the field of aeronautics where impellers for gas turbines are elaborated by a forging/machining process with a mass ratio of 10 to 100 between the starting ingot and the final part. On the basis of this analysis, a consortium composed of Framatome, Aubert & Duval, Ventana Group, Metalscan and institutional laboratories (Université de Bourgogne, ARTS and CEA) established the manufacturing sequence of a large-dimension impeller in 316L austenitic stainless steel by means of PMHIP processes with a Near Net Shape (NNS) approach.
The tooling of the impeller has been designed by 2D/3D simulation and then machined in low carbon steel elements. Once assembled and welded, the low-carbon steel container is filled with 316L powder and prepared according to classical HIP capsule preparation procedures. After the HIP cycle, a rough machining was performed to open hydraulic channels and then facilitate the chemical pickling. This approach aims at reducing as much as possible the machining and finishing operations after HIP, in particular on the blades of the impeller, to limit the final cost of the part and reduce the fabrication times.
Finally the part produced exhibited the expected geometric features (+/- 2mm), fine grain size (around 50µm) and isotropic microstructure and excellent mechanical properties (Rp0.2=290MPa, Rm=580MPa, A%=57) thus validating the global NNS fabrication approach of a large and complex part by PM+HIP. At the end of the project, Framatome considers the PM+HIP NNS impeller as a technical solution, promising an extended lifetime, that could be quoted at the next calls to tender.
One Piece Nozzle MIM
Company: AMT PTE Ltd
End Use Sector: Automotive
Product Density: >7.60g/cm³
Tensile Strength: >600 GPa
Yield Strength: >350 GPa
Product Hardness: >93 HRB
Elongation: 10% max
The metal injection molded One Piece Nozzle has pushed this technology to greater heights. It is an impossible task to produce this product near net shape using other conventional methods. Possible methods will be brazing of multiple machined components, which will end up with high material wastage and high cost. The MIM One Piece Nozzle produced good finish with complex internal channel in a sustainable and economical way. This product has open up an entirely new application for MIM process capability, and definitely the most complex part that we have ever produced.
Development efforts were focus on controlling the distortion of the plastic inserts during metal injection molding, as high injection pressure and temperature will greatly affect the insert integrity. On the contrary, we need to maintain high packing pressure in the inner core channel, as any loss in pressure will encourage weakness resulting in cracks. Finding the ideal injection parameters that resulted in overall good part were highly challenging during development phase. The other critical feature is the tip of the nozzle, the diameter of the hole and gap surrounding it are controlled in micron range which are MIM without secondary operations. Looking at the cross-section you will understand the critical features were achieved with great definition.
The One Piece Nozzle is applied in a Selective Catalytic Reduction (SCR) system for commercial vehicles in Europe to comply with the Euro 5 and Euro 6 standards. Urea is connected to the center through hole, and compressed air is connected to the other channel. The compressed air is pumped into the nozzle exiting though the "ring" at the nozzle tip, this generates a low pressure region at the tip producing a venturi effect. This will draw out the urea from the middle channel and spray onto the SCR system, which will reduce the exhaust NOx to N2 and H2O.
The special feature is the undercut internal channel, which can only be produced using our patented In-Coring™ technology. No other metal forming process can produce this near net shape with minimal secondary finishing operations. Hence, it is specially designed for MIM process. The cost savings would probably be more than 200% if ever similar quality and finished part were produced by conventional machining + brazing.
Driving Flange PMSP
Company: GEVORKYAN, s.r.o.
Product Density: 6.9g/cm³
Tensile Strength: 460 MPa
Yield Strength: 330 MPa
Product Hardness: 42 HRC
The Driving Flange was designed in cooperation with one of the leading power tools producers. The part is absolutely brand-new. It has never been produced before by any other technology. The original conception, including prototypes, was designed for CNC machining from conventional bars. Yet, the adaptation to PM technology provided a huge price reduction in comparison to traditional technology.
The serial scale production provides a cost effective solution to the customer. The new design of the driving flange represents a truly new approach in cutting and brushing disc clamping action. We expect to spread this concept worldwide during next few years, including complete replacement of old generation of a flange, which uses an internal thread to create a clamping force. From an end user point of view, the main contribution is the reduction of the time which is needed to replace an already worn disc – within a few seconds instead of one minute. The Driving Flange is compacted on a CNC hydraulic press using all three upper axes and all four lower axes. To ensure a higher hardness of the surface layer and tough core of the part, case hardening is used. CNC turning is used to ensure a precise internal diameter, and CNC milling is used to create four counter bars for screws.
KRAKEN - Special Light Milling Head
University of West Bohemia, Regional Technological Institute
Schunk Sintermetalltechnik GmbH
ASCO Sintering Co
More information about these, and all entries to the 2018 competition can be found in the pdf EPMA PM Component Awards 2018 Booklet (8.65 MB)