Yuichi Okazaki

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.

In-process measurement and a workpiece-referred form accuracy control system (WORFAC): concept of the method and preliminary experiment

Abstract Precision machining can achieve high levels of accuracy through the use of a highly accurate spindle, straight feed mechanisms, a rigid base and a single-point diamond tool. Research is underway aimed at achieving even higher levels of accuracy by adding computers, interferometers or encoders for practical control. In this report, a control system (workpiece-referred form accuracy control system) is proposed in which the control is based on the workpiece, instead of the conventional approach which achieves the accuracy by increasing that of each mechanical element. This system performs inprocess measurement of the workpiece and uses this information to execute direct control over the machining.

On-machine shape measurement of workpiece surface with Fizeau interferometer

Abstract The Fizeau interferometer has been generally thought to be inappropriate for measurements during a machining operation because of relatively large vibrations of the machine and air turbulence in the optical paths. Experimental results presented in this paper, however, show that the Fizeau interferometer can be used on the machine at the manufacturing site when the machine is stationary and the air turbulence is eliminated. Interference fringes obtained with the interferometer have radial patterns due to machine vibrations. A dominant cause of the radial pattern of the interferogram is the vibrations of the main spindle. A newly developed machine with reduced vibrations has no radial patterns.

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.

Development of Pipe Structure Frame for CNC Lathe – Adaptation of Thermal Displacement Control

The miniaturization of many machine parts for machine tools is desired for the purpose of effective utilization of space, energy saving, and realization of desktop factory. To develop a compact and miniaturized NC machine tool, new downsized small parts such as hydraulic parts, pneumatic parts, electric parts and mechanical parts must be developed. These parts are not always satisfied for the practical usage in the present industrial level. Therefore, in spite of many requirements toward the miniaturization of the machine tool from the market, the miniaturized NC machine tool has not been put to practical use. The old-style structure of machine tools is one of the reasons of obstacle to solve this problem. We have proposed a newly developed ultra small size CNC lathe by using the pipe frame structure. The heat transfer between pipe elements and connecting block is affected strongly to the axial displacement. Therefore, the heat transfer between pipes can be insulated by the heat control on the connecting block. The thermal displacement control is realized by using the Peltier devices set on the connecting block. The results on the thermal displacement control of this structure and the effects on the cutting results are reported.

Newly Formed Bone around Implanted New Titanium Alloy: Ti-15%Zr-4%Nb-4%Ta

We have developed a new Ti alloy, Ti-15%Zr-4%Nb-4%Ta alloy (Ti-15-4-4) that showed higher biological safety and mechanical properties than the currently used Ti-6%Al-4%V alloy. The purpose of this study is to determine the biological performance of the new alloy. Ti-15-4-4 implants (machined or blasted) were placed in surgically created defects in rabbit femurs. The rabbits were sacrificed after 4, 8, 16, 24 and 48 weeks. Bone mineral density (BMD) and area of newly formed bone around the implants were measured using micro-CT. Results showed that the Ti-15-4-4 alloy is biocompatible and forms new bone around the Ti-15-4-4 implant, regardless of the surface treatment. The BMD and area of newly formed bone around the blasted implant surfaces were significantly greater than those around the machined surfaces. These results indicate that the new Ti-15-4-4 alloy has a potential for use as implants and has the advantage of improved mechanical properties described in earlier studies.