Deep hole drilling

About: Deep hole drilling is a research topic. Over the lifetime, 1366 publications have been published within this topic receiving 14123 citations.

Some experimental investigations in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates

Abstract: In this paper, a concept of delamination factor F d (i.e. the ratio of the maximum diameter D max in the damage zone to the hole diameter D ) is proposed to analyze and compare easily the delamination degree in the drilling of carbon fiber-reinforced plastic (CFRP) composite laminates. Experiments were performed to investigate the variations of cutting forces with or without onset of delamination during the drilling operations. The effects of tool geometry and drilling parameters on cutting force variations in CFRP composite materials drilling were also experimentally examined. The experimental results show that the delamination-free drilling processes may be obtained by the proper selections of tool geometry and drilling parameters. The effects of drilling parameters and tool wear on delamination factor are also presented and discussed. Cutting temperature has long been recognized as an important factor influencing the tool wear rate and tool life. An experimental investigation of flank surface temperatures is also presented in this paper. Experimental results indicated that the flank surface temperatures increase with increasing cutting speed but decreasing feed rate. Optimal cutting conditions are proposed to avoid damage from burning during the drilling processes.

Hole-drilling strain-gage method of measuring residual stresses

Abstract: The hole-drilling strain-gage method of measuring residual stresses in elastic materials can be termed semidestructive if holes of very small diameters are used. The method permits the magnitudes and principal directions of residual stresses at the hole location to be determined. This is accomplished by means of an emirpically determined relation between the magnitudes and directions of the principal stresses and the strain relaxation about the hole as the hole is drilled. This relation was obtained for a nondimensional model of the hole-gage assembly in order to make the results independent of hole size. A generalization was postulated to extend the use of this calibrated solution to the measurement of residual stresses in all elastic, isotropic materials.

Influence of EDM process parameters in deep hole drilling of Inconel 718

Abstract: This paper reports on an experimental investigation of small deep hole drilling of Inconel 718 using the EDM process. The parameters such as peak current, pulse on-time, duty factor and electrode speed were chosen to study the machining characteristics. An electrolytic copper tube of 3 mm diameter was selected as a tool electrode. The experiments were planned using central composite design (CCD) procedure. The output responses measured were material removal rate (MRR) and depth averaged surface roughness (DASR). Mathematical models were derived for the above responses using response surface methodology (RSM). The results revealed that MRR is more influenced by peak current, duty factor and electrode rotation, whereas DASR is strongly influenced by peak current and pulse on-time. Finally, the parameters were optimized for maximum MRR with the desired surface roughness value using desirability function approach.

Machining of NiTi based shape memory alloys

Abstract: The machinability of NiTi based shape memory alloys has been examined. Starting with turning experiments, cutting parameters were varied within a wide range. In addition, the influence of the cooling lubricant concept was investigated. After reaching acceptable results for turning, the field of investigation was extended to the drilling process. Furthermore, first examinations regarding deep hole drilling of tubes from NiTi shape memory alloy were carried out. The machining process was optimised with respect to environmental and commercial aspects with minimal influence on the characteristics of the shape memory alloys. The machining process was evaluated in terms of tool wear, cutting forces and machining quality. The tool wear was analysed with a scanning electron microscope and the influence of the machining on the subsurface zone was investigated by micro hardness measurements.