Hiroshi Fujii

Nanoscale friction reduction and fatigue monitoring due to ultrasonic excitation

Abstract DLC film interfacial fatigue and changes in friction coefficient phenomena were investigated during quasi-static nanoindentation/scratch while the sample surface was excited ultrasonically. An original experimental setup combines nanoindenter, SPM scanner and ultrasonic transducer operating in an elastic standing wave mode. Nanoindentation loading–unloading curves revealed delamination induced excursions after a certain number of ultrasonic loading cycles. Drastic changes in quasi-statically monitored friction coefficient during nanoscratch were correlated with sample vibration amplitude and loading force. Resulting indentation/scratch film delamination effects and surface wear patterns were examined by an in situ SPM technique. Ultrasonically excited nanoindentation and nanoscratch techniques can be considered as fast and qualitative methods to characterize critical tribo surfaces for data storage devices.

Labour stability and flexibility – conditions to reach just‐in‐time

Describes labour stability and flexibility in Japanese versus Swedish manufacturing industries. Presents a theoretical framework where a number of fields which other researchers have regarded as influencing labour stability and flexibility are analysed. Also presents some of the findings of an empirical study of 17 Japanese and four Swedish companies measuring labour stability and describing similarities and differences in the companies′ condition and working methods to reach a stable and flexible labour situation. The results indicate a considerably more stable and flexible labour situation in Japanese companies when compared with Swedish companies.

Cutting performance of drills with three cutting edges (effects of chisel edge shapes on the cutting performance)

Abstract In this paper an investigation of the cutting performance of drills with three cutting edges is reported. Six drills having different chisel edge shapes were used and drilling tests were performed in which the accuracy of machined holes, surface roughness and cutting force were measured. The cutting performance of the drills was assessed using variance analysis. The investigation showed that drills with small inclination angles of thinned chisel edges are generally more effective than conventional drills. The effect of corner radius of thinned chisel edges is insignificant.

Piezo ceramic based locomotive drive

A milli size piezo ceramic based locomotive drive has been developed. The principle of locomotion is based on the execution of resonance vibrations in a set of induced strain actuators-transducers which ends with the end effectors. Motion is transferred from the induced strain actuators to the end effectors by increasing the amplitude of the vibrations. Control is performed by switching the different active zones at the piezo active induced strain actuators. A modelling in FEs is performed in order to obtain resonance frequencies, modal shapes and deflections of the end effectors.

Smart audiosonic contact impedance sensor for NDT of elastic polymers

A nondestructive identification system for diagnostics of rubberlike materials has been developed. The system is based on the simultaneous contact impedance and compliance test conducted at two different sampling frequencies which correspond to the dynamic and quasistatic loadings, respectively. Measurements are taken by a piezoactive contact impedance tester which is a standing wave device registering the leakage of acoustic flow from the actuator via indenter into loaded specimens. Lames elastic constants, density and rheological parameters of specimen are well correlated with a change in the output signal obtained from the sensor. Experimental data are processed by means of digital filtering, autoscaling and polynomial fitting. The LP filtered data, which correspond to the transient period of loading, are fitted with the dynamic model consisting of several Voigts elements connected in series. Furthermore, the non-filtered data sampled at high frequency, which correspond to the quasistatic loading, are compared with the database.

Characteristics of Cutting Force in Plain Milling Operation Using a Helical Cutter

A unique optical method is developed in order to measure the cutting force. The variation of the horizontal component of cutting force in the direction of feed, the vertical component which acts vertically to the arbor and the axial component are precisely measured corresponding to a variation of the undeformed chip thickness. Characteristics of the cutting force and influences of the helix angle are compared and discussed both for up and down milling, and also on the basis of the force variation ratio proposed. The cutting force component and the thrust force component are derived, and the normal and frictional force on tool rake face, the apparent friction angle and the chip flow direction are also obtained. The mechanics of the milling process is discussed basing upon the experimental results. The role of the helix angle is experimentally clarified and the concept of the effective rake angle is criticized.