This Small Business Innovation Research (SBIR) Phase II project is directed towards the development of an ultrahigh speed micro-spindle for micro-machining. The proposed spindle for micro-milling and micro-grinding at speeds near 500,000 rpm will be implemented with existing commercial micro-machining systems. Micro-manufacturing refers to the creation of high-precision three-dimensional (3D) products using a variety of materials and possessing features with sizes ranging from tens of micrometers to a few millimeters. While micro-scale technologies are well established in the semiconductor and microelectronics fields, the same cannot be said for manufacturing products involving complex 3D geometry and high accuracies in non-silicon materials. The trends in industrial and military products that demand miniaturization, design flexibility, reduced energy consumption, and high accuracy continue to accelerate -- especially in the medical, biotechnology, telecommunications, and energy fields. The principal advantages of the proposed micro-spindle include higher production rates and precision obtained through the implementation of ultrahigh speed machining that will decrease the cutting forces and tool vibrations. The prototype micro-spindle will be evaluated in a series of alpha and beta testing with commercial micro-machining systems. The objective of Phase II is to perform the necessary R&D to prepare the micro-spindle for marketing.
The broader impact/commercial potential of this project encompasses the following. The ultrahigh speed micro-spindle will enable the production of cost-effective micro-components and will positively impact the micro-fabrication industry. Since the underlying scientific principles of micromachining at such high speeds are not known, the availability of the proposed spindle will allow for basic studies to uncover the response of materials under these conditions. Such basic information could lead to new scientific discoveries and further extend the micromachining processes. The data and information generated will undoubtedly be used in future for training of graduate students. The broad impact of this research includes expansion of micromanufacturing research, and research opportunities for next-generation scientific researchers and technology developers to pursue micro machining and micro manufacturing related efforts in the broader fields of micro positioning devices, micro die-and-mold manufacturing, micro sensing and monitoring systems, and micro factory integrations and optimization. Commercialization of the proposed micro-milling spindle will be instrumental in the development of new businesses and industries, and high value added jobs.
Said Jahanmir, PhD, Principal Investigator Mohawk Innovative Technology, Inc. 1037 Watervliet-Shaker Rd. Albany, NY 12205 National Science Foundation, Phase II SBIR, Grant No. IIP-1127346 The demand for miniaturization of systems and/or their individual components has been on the rise for many years in several industries including, defense, medical devices, aerospace, energy, electronics, and others. These miniaturized systems provide for a faster response time, and more efficient performance, and occupy smaller footprints, resulting in smaller and lighter overall systems. The key to successful miniaturization lies in the fabrication methods used to manufacture such components for the micro-systems. While most present micro-systems are fabricated with silicon micro-machining technology, the mechanical micro-machining technology is rapidly evolving, thus enabling fabrication of micro-components from various engineering materials instead of silicon or glass. Mechanical micro-machining methods such as milling, drilling and grinding, enable fabrication of 3D free-form micro-scale components, e.g., ceramic micro-turbines for miniature UAVs and micro-power generators, class IV MEMS, molds for micro-injection molding of small polymer components, micro-fluidic devices, fuel micro-injection systems, circuit boards, and many others. However, current mechanical micro-machining technology is limited in dimensional precision, surface quality and fabrication rate due to the limitations of the rotational speed of the machining spindles. Insufficient linear surface speed at the cutting point of micro-tools (less than 100 μm diameter) not only results in inefficient cutting and tool wear, it excludes machining of hard materials such as ceramics. A substantial increase in the cutting speed will also enable an increase in the machining feed rate that will accordingly increase the material removal rate. This R&D effort supported by the NSF SBIR program led to the development and validation of a unique ultra high speed micro-spindle for micro-machining. The spindle was designed through a systematic design analysis including dynamic analysis to ensure rotational stability of the rotor system. An axial flow turbine concept was used to provide for a high power compact system. The spindle was fabricated and its performance was validated through a series of micromachining studies that included micro-milling, micro-drilling and micro-grinding. While the rotor system has the capability of operation up to 1,000,000 rpm, the micro-spindle can be used up to 500,000 rpm due to strength limitation of the rotor material. Micro-machining studies with the MiTi micro-spindle integrated with the Microlution Micro-Machining system confirmed that the new spindle can be used at high rotational speeds and allows for a substantial increase in machining feed rates, thus increasing the production rate of micro-fabricated components. The materials machined with the new spindle included aluminum alloy, stainless steel, fiberglass composites, single crystal silicon and silicon nitride. Micro-machining at such high speeds (approaching 500,000 revolutions per minute) has not been achieved before. Such a high rotational speed is transformative and the developed technology can be used in other applications besides machining. The new novel machining process for miniaturized components greatly enhances the US position in anufacturing and will create new value-added industrial jobs. The capability of mechanical micro-machining at ultra high speeds allows for fabrication of miniaturized components that have not been possible before. It also creates new research frontiers for fundamental studies of material behavior during small-scale micro- and nano-fabrication. The new micro-spindle will be commercialized and made available for manufacturing companies to be retrofitted with existing precision machine tools. This micromachining process can be used also for research at universities to uncover fundamental material behavior during micro-cutting.
