Masatoshi Fujino

Micro-EDM for Three-Dimensional Cavities - Development of Uniform Wear Method -

Abstract In this paper, we present a new method, called uniform wear method, for 3D micro-EDM. Simple electrodes such as with round or rectangular section are used. Uniform wear at the end of the electrode was realized by layer-by-layer machining. This maintains the original electrode shape and converts the three dimensional electrode wear to a linear one. By compensating the linear electrode wear, complicated three dimensional cavities were successfully machined. This technique was developed for micromolds, but the applicability for normal size molds was also confirmed.

Drilling of Deep Microholes by EDM

Summary The paper deals with an experimental study on the machining of deep microholes by EDM. The system proposed is based on a horizontal EDM using water as the dielectric, the electrode being formed by the WEDG method. The result shows the applicability of this technique to the industrial production of microholes with the depth ten times the diameter which ranges down to 50μm.

A Combined Electrical Machining Process for Micronozzle Fabrication

Abstract Smaller diameters are required for various types of precision nozzles. However, the accuracy of nozzle holes is a problem in mechanical machining processes and the choice of inner shapes is limited. A combined process with EDM, ECM and electroforming is proposed for the production of nozzles with small diameters and various inner shapes. Nozzle holes with the diameters of 6-100 micrometers were successfully produced with good concentricity to the outer profile. Some technical characteristics of the process were also investigated.

Vibroscanning Method for Nondestructive Measurement of Small Holes

Summary A new method for measuring inner dimensions of small holes was developed. The electrical contact between a vibrating feeler and the inner surface of a hole is detected, and the duty cycle of the contact is measured. Through a controlled scan by a feeler with a constant duty cycle, data on the ups and downs of the surface profile are obtained. Through the application of this principle, a φ 200μm hole with the depth of 700μm was successfully measured, and geometrical data such as straightness, declination and taper were obtained.

EDM-Lathe for Micromachining

Abstract In this paper a new type of micro-EDM machine is proposed. The machine operates similarly to a turning lathe. An electrode fabrication system is installed which makes it possible to fabricate on-the-machine complex microelectrodes with sharp edges and corners. A prototype set of equipment was realized and test machining proved that a machine of this type can produce microcylindrical, overhung cavities, or cylindrical microholes with larger internal diameters than the entrance diameter. This result reveals the possibility of fabrication of various microparts such as microball bearings.

Surface finishing of micropins produced by WEDG

Abstract This paper presents a new method of surface finishing for micropin products. Precision micropins thinner than o100 urn can be produced by WEDG (wire electrodischarge grinding). However, the surface quality of the products is not sufficient for applications that require mirrorlike surface and/or a surface without a heat-affected zone. A succession of two processes, WEDG and lapping, is proposed and tested for its feasibility. In order to ensure the control of the lapping conditions, micropins were WEDGed and lapped on the same machine. The wire electrode for WEDG was used as the lapping tool. A smooth, craterless surface with Ra=18 nm was achieved.

Application of USM to micromachining by on-the-machine tool fabrication

Most machining methods have difficulties in machining hard, brittle materials such as glass, ceramics, and silicon. Ultrasonic machining(USM) is a unique method from this point of view, because it easily machines these materials. However, USM has limitation in its application to micromachining because them are problems in fixing microtools to the machine and maintaining high precision. In this paper we propose a technique of micro-USM by applying on-the-machine tool. fabrication by wire electrodischarge grinding (WEDG). As a result, we were able to make microholes as small as 20pm in diameter on a silicon plate. Additional experiments revealed the possibility of wide application.