Takafumi Komatsu

Deburring of Micro-Scale Structures Machined in Milling

Recently micro cutting has been applied to manufacturing of micro devices. Burr formation is a troublesome problem in micro cutting. From the point of view of the required accuracy, burr removal in the micro manufacturing cannot be performed by the manual operations or the additional cuttings. The paper presents a deburring process to remove the burrs on the micro-scale structured surfaces, which are machined in micro milling. In order to remove the burrs on the pillars in the structures, the study examines burr removal milling, polishing and water jet finishing. Burr removal milling leaves the cutter traces with adhesion of the chips on the pillars. Polishing finishes the surfaces with removing the burrs on the top of the pillars. A supporting device is used for protecting the edge shapes of the pillars in polishing. Then, the burrs on the side of the pillars can be removed in water jet finishing. A water jet machine driven by a low pressure pump is developed to remove the burrs without losing their shapes. The process sequence of polishing and water jet finishing is effective in removing the burrs in micro milling. The presented process is discussed to manufacture the micro-scale structures in mechanical manner based on the axiomatic design.Copyright

Micro Hole Piercing for Ultra Fine Grained Steel

Ultra fine grained steels have been developed by many researchers. However, the study of influence on processes and product functions from different grain size are limited because the size of bulk material was small for these products. Authors have developed the production process of thin ultra fine grained stainless steel coil, and the effects are able to be clarified. This paper will firstly report the influence on micro hole piercing by comparing different grain size materials. Secondly, orifices are produced from these materials, and the liquid flow volume is measured as the functional effect of different grain size. The effects of grain size differences were discussed with observing the hole conditions and measuring flow volume. The effects of reduction of the grain size were summarized as follows: (1) Accurate small hole is produced when ultra fine grained stainless steel is employed. (2) Product functional improvement is possible, and the phenomena are useful for liquid control devices.

Micro Cutting Process of Ultra Fine Grain Steels

The paper discusses the effect of the crystal grain size of materials on the micro cutting processes. The cutting process of ultra fine grain carbon steel, which consists of 0.5 μm sized grains, is compared with those of the larger grain steels. The micro cutting tests were performed to measure the cutting force with changing the cutting thickness. The cutting force of the ultra fine grain steel is larger than that of the large grain steel corresponding to the hardness change of materials. The specific cutting forces remarkably increase when the cutting thickness becomes less than 10 μm. The shear angle of the ultra fine grain steel is larger than that of larger grain steels in small cutting thickness. The uniform chip formation is also observed with fine surfaces in cutting of the ultra fine grain steel.