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The cutting performance of indexable insert drill that has non-axisymmetrical geometry for drilling of difficult-to-cut materials is investigated. A twisted drill is also used to compare the cutting performance. The cutting characteristics are evaluated by tool flank temperature at peripheral corner edge θα, thrust force Ft, chip geometry and surface roughness Ra. The temperature of cutting tool is measured using a two-color pyrometer with an optical fiber. As work materials, the carbon steel, stainless steel, titanium alloy and nickel-base alloy are used. The θα and Ft of indexable insert drill are lower than that of solid drill in cutting of titanium alloy and nickel-base alloy. In the case of titanium alloy, the Ft of indexable insert drill is only 40% in the case of solid drill. On the other hand, this tendency reversed for stainless steel, and θα and Ft of indexable insert drill become higher than that of solid drill. The chip geometry by indexable insert drill is divided into parts in fragments so that there is chip breaker on the rake face of insert while the chip geometry by solid drill is continuous and long. The difference of surface roughness by the indexable insert drill and solid drill is negligible in the cutting of difficult-to-cut materials.

In roughing of large module gears, high efficient gear cutting with a formed milling cutter is noticed. In this case, the milling cutter is an insert type with both negative top rake and side rake angles. It is well known that negative rake angles increase cutting force and produce undesirable cutting surfaces. In this paper, a design method of insert-type gear formed milling cutters with both positive top rake and side rake angles is proposed. Firstly, the profile of cutting edge is calculated from the axial profile of the cutter by giving the design parameters such as the top rake angle, side rake angle and cutting edge angle, and the shape of insert pocket for the cutter body is designed by giving the thickness, length and width of the insert. However, these obtained design parameters are not always available because interference between the flank face and the work may occur. Therefore, a simulator that can interactively decide these design parameters was developed. Finally, the formed milling cutter were designed and made using the proposed method. Cutting tests using the trial-made milling cutter were carried out. As the results, the sufficient accuracy as the cutter in roughing of large module gears was obtained.

The cutting performance of indexable insert drill that has non-axisymmetrical geometry is investigated. A solid drill that has axisymmetrical and twisted geometry is also used to compare the cutting characteristics. The diameter of drills is 16mm and carbon steel is used as work material. The application effects of MQL that oil mist is supplied from oil holes in the tool are also examined. The temperature of peripheral corner edge of outer insert is measured using a two-color pyrometer with an optical fiber. The tool temperature of indexable insert drill is higher than that of solid drill and it reaches approximately 525°C at highest. On the other hand, the thrust force of indexable insert drill is lower than that of solid drill and it do not change so much with cutting speed. The surface roughness of indexable insert drill is approximately 1.15-5.4μm and this is higher than that of solid drill in each cutting speed. However, it is improved by supplying the oil mist.

The bolted joint is a common assembling method for carbon fiber reinforced plastic (CFRP) members. However, cracks or plastic deformation can occur around bolt holes of CFRP members even when employing low fastening forces. As a result, CFRP failure occurs around bolt holes because of bearing forces, and the strength of a CFRP joint is reduced. To address this problem, we change the configurations of washers and insert a thin sheet having a high friction coefficient between CFRP members. In friction coefficient measurements, the insertion of sandpaper was found to be the most suitable method for increasing friction forces at the interface between CFRP members. Three-dimensional finite element method analyses were conducted to investigate the effect of washer configurations in terms of the maximum allowable fastening force and the joint strength. From these analyses, the cone washer was found to be the most effective design for increasing the joint strength. In the full model analyses, the failure strengths of proposed CFRP bolted joints were higher than those of normal CFRP bolted joints. The verification tests for the proposed joint were conducted according to ASTM D5961. It was observed that the load at failure for the proposed bolted joint was about 45 % greater than that for the conventional joint.

The outstanding performance of Al2O3-TiC ceramic cutting tools in term of high cutting speed can lead to economies in the metal machining. However, there is limited use of this ceramic because of its expensive price. In this work, the microwave combustion synthesis method was applied to produce Al2O3-TiC powder from low cost precursors. The microwave combustion synthesis of Al2O3-TiC can be achieved in a very short time. As a consequence, Al2O3-TiC cutting tools were produced by pressureless sintering. The performance of microwave combustion synthesized Al2O3-TiC cutting tools was investigated and compared to that of commercial insert. The flank wear of Al2O3-TiC insert was increased with cutting time and cutting speed. Although the cutting time of microwave combustion synthesized insert was shorter than that of the commercial one, its cutting performance demonstrated that the microwave combustion synthesized Al2O3-TiC powder showed some potentials to be developed as a cutting tools insert by proper control of composition and sintering temperature of combusted powders.

The modeling of face milling operations has been traditionally focused on using flat faced tools with an assumption of perfectly straight chip formation. However, curled chip formation is a common phenomenon in practical milling operations, and it has a profound effect on machining performances. A new analytical model that takes into account the chip curling effect in milling operations is proposed in this paper. It is shown that chip morphology and machining parameters, such as the chip up-curl radius, the chip thickness, and the tool-chip contact length, simultaneously change with varying undeformed chip thickness during each tooth cycle. The proposed model is validated through milling tests. Good agreement between theory and experiments has been reached. A comparison of the average resultant force among three types of commercially available tool inserts is made to demonstrate the effect of tool insert chip-groove geometry on milling performances.

In order to simulate the wear of the valves and valve seat inserts of automotive engines, impact wear tests were conducted using rings made of a JIS SUH 3 steel valve material and disks made of a sintered alloy valve seat insert material. Test conditions were as follows : impact energy of 0.588 J ; normal air atmosphere ; ambient temperatures of room temperature, 200°C and 400°C ; and sliding speeds of 0 to 0.8 m/sec. Under these conditions, very low wear was observed for both materials subjected to impact without sliding. For impact with sliding speeds over 0.4 m/sec, a bright worn surface was observed and the wear rate was severe at room temperature and 200°C. However, at 400°C, oxidation occurred and no acceleration of the wear rate was observed at any sliding speed. These results can be explained in terms of the occurrence of oxidation and the mechanical properties of the test materials.

Experimental data of liquid and vapor flows of R113 for Re = 5,000--400,000 were obtained for both a plain tube and tube with snugly fitted twisted-tape inserts. No evidence of tape fin effects was found in the heat-transfer characteristics of a stainless-steel tape insert when compared to a Teflon-tape insert. For twist ratios {gamma} = 5.9, 10.0, and 16.0, improvements in heat transfer of up to 35 percent were observed. Based on a simple consideration of the heat-transfer enhancement mechanisms of twisted-tape inserts, a Dittus-Boelter-type correlation for a plain tube was modified to include twisted-tape effects. For such a case, use of available plain-tube data were recommended to maximize the accuracy of the proposed correlation. The trade-off between pressure loss and heat-transfer enhancement was considered to determine the overall desirability of twisted-tape inserts.