Members of the International Magnesium Association (IMA) honored their peers with a series of awards, which were handed out at the 2017 World Magnesium Conference held May 23-25 in Singapore. A host of industry leaders attended the three-day conference and were on hand to congratulate award recipients. Honors annually bestowed by the IMA include four Awards of Excellence in the categories Automotive Cast Products, Commercial Cast Products, Wrought Products, and Process, as well as an Environmental Responsibility Award.
Automotive Cast Product Category
In the Automotive Cast Product Category, the Award of Excellence was presented to General Motors, Dongguan EONTEC Co., Ltd., EDAG Engineering, Wanfeng Meridian, and The Ohio State University for two magnesium die cast side-door inner panel designs for prototype automotive side-doors.
The applied-header door panel was designed by General Motors, Dongguan EONTEC Co., Ltd., and EDAG Engineering. This experimental automotive side-door inner panel was high-pressure die cast (HPDC) in magnesium alloy AM60B in order to reduce mass, consolidate five parts into one, and enable fine details that cannot be achieved in sheet stampings. Variable wall thickness and extensive use of ribbing were used in order to meet strength and stiffness requirements, while maintaining light weight. The dimensions of the inner door panel are 1202 x 843 x 170 mm with a typical wall thickness of 2 mm, and an overall weight of 2.7 kg. Innovative cast-in features include pockets for attaching the header portion of the door, which surrounds the window glass on three sides, and rivets for attaching a module panel which holds the speaker, window regulator and pull handle. After trimming and machining, the part was coated by micro-arc oxidation and polymer electrocoating to increase corrosion resistance.
A full-header door panel was developed by General Motors, Wanfeng Meridian, The Ohio State University, and EDAG Engineering. In comparison to a conventional steel stamping design, this experimental HPDC magnesium door inner panel design utilizes alloy AM60B and achieves a reduction in mass, reduction in part count, and addition of fine detail features. The mass is only 52% of that of the stamped steel version. Seven parts are consolidated into one casting. The innovative design uses variable wall thickness, ribbing, and an S-shaped cross section to achieve the required strength and stiffness. The dimensions of the inner door panel are 1209 x 1130 x 290 mm with a minimum wall thickness of 2 mm. Blind cored holes were cast in for later use with thread-forming screws to attach a stamped aluminum outer beltline reinforcement and a pull handle support. the design is surface treated with conversion coating plus powder coat. The fully assembled door-in-white includes a stamped aluminum outer panel, and weighs 9.5 kg, which is about half the weight of the steel counterpart. Advanced modeling and thermal management techniques were used in design of the die in order to achieve fully-filled high-quality castings.
Commercial Cast Product Category
The award in the Commercial Cast Product Category was presented to Yamaha Motor Company and the Japan Magnesium Association for the design of a front and rear die cast magnesium wheels for the mass-produced YZF-R1 2015 model super-sport motorcycle. The new model of YZF-R1 included front and rear wheels made from ASTM-AM60B magnesium die castings, providing a dramatic increase of magnesium usage exceeding 10 kg. Yamaha has been incorporating magnesium into its motorcycles since 1998, with almost all of magnesium parts adopted in the super-sport or sport categories. However, magnesium usage has spread year-over-year to other motorcycle categories. Since 2008, Yamaha has manufactured large structural magnesium parts in-house. The development of heat resistant alloys has expanded the use of magnesium, such as the use of magnesium wheels. This has not only resulted in a weight reduction of 870 g, but has also decreased inertia mass and improved the overall design to provide improved performance of the super-sport motorcycle.
Wrought Product Category
The Advanced Materials Institute of the Shandong Academy of Sciences and China Magnesium Association were presented the Award of Excellence in the Wrought Product Category for the design of a magnesium alloy electric buss skeleton. The Advanced Materials Institute developed the world’s first lightweight magnesium alloy electric bus, which is 8.3 m long and contains 24 seats. The bus body frame is comprised entirely of 226 kg magnesium alloys (ZTM630 and ZK61), which is 780/110 kg lighter than that of steel/aluminum alloys. A novel magnesium alloy of Mg-Zn-Sn-Mn was developed. The yield strength (YS) and ultimate strength (UTS) for the as-extruded Mg-6Zn-3Sn-0.5Mn (wt%) alloy reached 383 MPa and 412 MPa, respectively. The YS and UTS for the as-extruded ZK61 alloy could reached 285 MPa and 336 MPa, respectively. Nine kinds of magnesium alloy extruded profiles were used in the bus body frame. All of them were coated using F-free and Cr-free phosphating technology to improve the corrosion resistance. By adopting lightweight magnesium alloys, the electric bus achieved improved mileage, shorter braking distance, and noise reduction.
A biodegradable magnesium alloy for orthopedic application was developed by the University of Oxford in collaboration with U&I Corporation. The magnesium headless screws, cortex screws, and K-wires were developed for use in mending broken bones and fractures. The Mg-Ca-Zn alloy utilizes only materials that are biobompatible with the human body, so that the screws and wires will absorb into the body instead of requiring a second surgery for removal as with current titanium screws used.
“We have overcome the current limitations and created a road map to the next generation of metallic biodegradable implant materials with the addition of completely biocompatible elements,” noted the University of Oxford. “Along with the addition of Ca, which is a biocompatible element that plays major in bone formation and remodeling, excellent material properties were achieved through the in-house built special mechanical extrusion machine. The state-of-the-art method to synchronize the corrosion potentials of two constituent phases (Mg + Mg2Ca) with the selective doping of Zn into Mg2Ca was developed to control the corrosion rate. Furthermore, mechanical extrusion broke the connectivity of the Mg2Ca phases, which prevented continuous corrosion and the formation of a galvanic circuit that caused severe corrosion of the Mg-Ca alloy. Newly developed set of RESOMET implants have the mechanical strength, ability to stimulate bone growth and controlled slow degradation rate to be considered as an ideal candidate for biodegradable implant applications.”
Working closely with major hospitals in Korea, the University of Oxford has performed over 200 cases of small bone fixation screws so far and the screws were approved for sale in Korea by MFDS (Ministry of Food and Drug Safety). Results of clinical tests were published on PNAS. “With the completion of first clinical trial, we are still at the very early stage of biodegradable material development process,” said Chris Hyungseop Han, University of Oxford. “Current [magnesium] screws aren’t quite as strong as the traditional titanium ones but can be used for broken bones in fingers or fractures in the face. We are in the process of improving the mechanical properties and the application feasibilities are endless.”
Environmental Responsibility Award
The Environmental Responsibility Award was presented to Oskar Frech GmbH + Co. KG for the development of FGS technology for magnesium hot chamber die casting. The FGS technology development had the primary target of mostly eliminating the customary runners in a die using a hot runner technique and corresponding HPDC process control. The challenges in HPDC of casting non-ferrous metals are quite significant when developing a hot runner system. Using Mg alloys, which have rather high melting temperatures, requires a specific heating technology, equipped with very good temperature control. So the precondition in HPDC is to have a powerful close-loop temperature controlled casting unit.
Due to the metal casting process, the system has to be extremely robust and with excellent tightness, so it can function during operation as well as start-up procedures, when strong thermal expansion takes effect. In the HPDC process, it is not possible to put locking elements in the die, since during the die open period, magnesium oxides may possibly form, which interfere proper operations.
According to Oskar Frech, the FGS technology has a great number of advantages. Measurements have shown that the hot runner system significantly relieves the classical temperature control of the die and the casting system, which results in less overall energy consumption. The electrically heated casting system requires more than 50% less electricity than conventional heating, and the FGS system reduces the energy consumption for die temperature by 11%. This energy saving is associated with a corresponding reduction in CO2 emissions during die casting. Approximately, 38 t CO2 is thus avoided for casting a 320 g Mg part with an annual production of 660,000 pieces.