Kiwamu Ashida

Microfactory—Concept, History, and Developments

This paper reviews the new concept microfactory and related developments. Machined parts are becoming progressively smaller, so production machinery that remains a conventional size is often inappropriate for such products. The term microfactory represents an entirely new approach to design and manufacture that minimizes production systems to match the size of the parts they produce. It leads to conservation of space and energy, and the reduction of investment and operational costs, as well as the reduction of emissions and the load on operators. Furthermore, it provides a system with dynamic reconfigurability, aiming at a light and agile manufacturing system optimized for current manufacturing needs in a borderless and highly competitive market. In Japan, research institutes, research consortia, and the private sector have carried out targeted research and development aimed at this concept for over a decade. Some systems are past the research stage and in daily use. Outside Japan, the philosophy and advantages of microfactory have reached an appreciative audience in the U.S., Europe, and Asia. Microfactory is at the cutting edge of competitive manufacturing in the 21st century, ushering in a multidimensional paradigm shift. Here we also briefly examine some future tasks.

Nanomachining of Silicon Surface Using Atomic Force Microscope With Diamond Tip

This paper investigates nanomachining of single-crystal silicon using an atomic force microscope with a diamond-tip cantilever. To enable nanomachining of silicon, a nanomachining cantilever with a pyramidal diamond tip was developed using a combination of photolithography and hot-filament chemical vapor deposition. Nanomachining experiments on silicon using the cantilever are demonstrated under various machining parameters. The silicon surface can be removed with a rate of several tens to hundreds of nanometers in ductile mode, and the cantilever shows superior wear resistance. The experiments demonstrate successful nanomachining of single-crystal silicon.

Design of a Microfactory

This paper describes the concept of a “microfactory” and design basics of its components. The microfactory is a super-miniature manufacturing system consists of miniature machine tools and manipulators. The authors proposed the concept and prototyped the first performable microfactory later in 1999. The former part of the paper introduces the basic concept and effort to systemize the factory. The concept was first proposed in 1990 and was expected to reduce energy consumption and space occupation of small parts fabrication. In 1996, the “micro-lathe” was developed and showed an unexpectedly good machining capability. The success of the micro-lathe was the driving force to systemize the rest of the microfactory. The newly prototyped microfactory was able to machine several small parts and assemble them into a miniature ball bearing to show its capability. The latter half of the paper describes design concepts, theories and tools that were used in designing the each component of the microfactory.Copyright

Rapid nanopatterning of a Zr-based metallic glass surface utilizing focused ion beam induced selective etching

A simple and rapid method is proposed for nanoscale patterning on a metallic glass surface using focused ion beam irradiation followed by wet etching. It was found that the etch rate of a metallic glass surface irradiated with Ga+ ions could be drastically changed, and rapid patterning was possible with this method. Cross-sectional transmission electron microscopy observation reveals that the metallic glass substrate maintains an amorphous phase following irradiation. Etching enhancement was not observed for irradiation with Ar+ ions. The results indicate that enhancement of etching results from the presence of implanted Ga+ ions rather than a change in crystallography.

Van der Pol-Type Self-Excited Microcantilever Probe for Atomic Force Microscopy

A control method is proposed in order to reduce the steady-state amplitude of a self-excited cantilever probe in atomic force microscopy. The control method induces van der Pol oscillation by applying both linear and nonlinear feedback. Oscillation of the controlled cantilever cannot easily be stopped, even with the modulation of the viscous damping effect in the measurement environment, because the self-excited oscillation is produced far from the Hopf bifurcation point by high-gain linear feedback. Also, high-gain nonlinear feedback realizes a low steady-state amplitude to enable noncontact measurement. Finally, the feasibility of the practical application of a van der Pol-type self-excited microcantilever probe to nanoscale imaging is examined.

Sub-micrometer-scale patterning on Zr-based metallic glass using focused ion beam irradiation and chemical etching

This report describes a method of sub-micrometer-scale rapid patterning on a Zr-based metallic glass surface using a combination of focused ion beam irradiation and wet chemical etching. We found that a Zr-based metallic glass surface irradiated with Ga+ ions could be selectively etched; a concave structure with a width and depth of several tens to hundreds of nanometers rapidly formed in the irradiated area. Moreover, we determined that the etching was enhanced by the presence of Ga+ ions rather than a change in the crystal structure, and the structure could be fabricated while the substrate remained amorphous. The shape of the structure was principally a function of the dose and the etch time.

Nanomachining Zr-based metallic glass surfaces using an atomic force microscope

This study investigated the nanomachining of metallic glass surfaces using an Atomic Force Microscope (AFM). To reveal the nanomachining characteristics of metallic glass, machining experiments were conducted under various machining parameters. The metallic glass was machined to fabricate an 8-nm-deep by 120-nm-wide groove pattern. It was found that metallic glass is a more challenging material to machine than single-crystal silicon. The tool life is significantly shorter, although it can be improved somewhat by machining in water. Observation of the machining residue revealed that continuous and shear cutting chips were generated that differed from those generated by machining amorphous silicon.

Micro-Groove Cutting for Different Materials Using an Elastic Leaf Spring Type Tool Holder

Micro-grooves fabrication is increasing due to its importance in different technology fields, as they are required for higher functional applications such as the development of optical lens or micro channels for heat exchangers. A novel method based on the technology developed for Atomic Force Microscopes (AFM) nano-cutting is proposed, where nano-scratches are made using a micro-cantilever with a sharp tip where a normal load sufficient to remove material is applied. Instead of a rigid system to control the relative position between the tool and the workpiece, AFM nano-cutting uses a force feedback control (FBC) of the normal load on the tool edge in order to maintain a constant cutting depth during the manufacture. Due to the limited scale range of AFM machining, a larger mechanism was developed and consists on a XYZ-stage system where an elastic leaf spring type tool holder is mounted with a diamond tool chip. FBC is not yet implemented on this system; however, basic experiments (micro-grooves cutting) were performed on different materials to verify the feasibility of this setup. With these results, it is possible to analyze the relationship between static indentation tests and the normal load required during the micro-grooves fabrication.

Torque Control Method of an Electromagnetic Spherical Motor Using Torque Map

This paper describes a new method for driving electromagnetic type spherical motors that has arranged permanent magnets on a rotor and arranged electromagnets on a stator. The most significant feature of this method is, in principle, applicable to any permanent magnets arrangement and electromagnets arrangement, and it can generate torque to any direction from any rotor attitude. In the spherical motor, cogging torque between permanent magnets and electromagnets causes not only instability of rotation but also causes rotor attitude error because the rotor has three degrees of freedom. The method of canceling the cogging torque is introduced. In the case of arranging four or more electromagnets, the combination of the electric current supply becomes infinite in number and generally not determined uniquely. However, we have developed a method for deciding the electric current distribution that generates maximum torque under the limited supply of each electromagnet. In the experiment of open-loop control, it was confirmed that the rotor was able to rotate about the axes that had been set by the calculation.

Miniature Modular Manufacturing Systems and Efficiency Analysis of the Systems

In recent world, there are many small mechanical parts and products are used for mobile phones, medical devices, home appliances, and so on. However, manufacturing systems for those devices are large and complex. Manufacturing systems are not goals. So, manufacturing systems should be small as possible within satisfying requirements in the production. In addition, every activity in manufacturing industry is required to be environmentally benign, these days. Being environmental consciousness a big trend in manufacturing technology, space occupied and energy used by conventional manufacturing systems became considered as big wastes. Among all the energy usage of a manufacturing system, just a small portion is used for cutting and the rest for moving heavy structures of machines or generating heat. So, a large machine represents considerable waste. As a countermeasure for the situation, AIST (National Institute of Advanced Industrial Science and Technology) proposed a concept of a microfactory that consists of tiny machine tools and robots. However, for the first decade, the concept had been only a figure indicating a future application after micro-machine technology has been developed. Miniaturization of machine tools to size compatible to the target products without compromising the machining tolerances leads to enormous savings in energy, space, and resources. It also makes it easy to change the production layout of the factory. In 1996, AIST developed the first prototype of the miniaturized machine tool; a micro-lathe [1], with considerable metal cut capability and substantial energy saving effects. The machining capability of the lathe was far better than we expected in advance. This success of the micro lathe was the driving force to prototype a whole factory that performs a series of fabrication and assembly on a desktop. In 1999, AIST designed and established a machining microfactory, which consisted of afore-mentioned micro-lathe, other small size machine tools and manipulators for parts handling and assembly. Ttest results showed that a downsized manufacturing system could be a feasible option for micro mechanical fabrication. Some other miniature manufacturing systems [4-6] have been proposed since then and the concept has now become quite common. 24