International Journal of Abrasive Technology (7 papers in press)
An Experimental Study on the Prediction of Grinding Wheel Dressing Intervals by Relating Wheel Loading and Surface Roughness
by VIPIN GOPAN, Leo Dev Wins K, Arun Surendran
Abstract: Grinding being the most commonly performed finishing process and requires frequent dressing operation to restore the original cutting capability of the abrasive wheel. Predicting the time to carry out the dressing operation is very significant in grinding process. The present work focuses on predicting the dressing intervals based on the final surface finish. The surface finish was primarily affected by the wheel parameters, grinding parameters and wheel loading. Wheel parameters were kept constant in this research work and grinding parameters were optimized using Artificial Neural Network-Particle Swarm Optimization (ANN-PSO) approach. Since the grinding parameters were optimized, now the surface roughness depends primarily on wheel loading. Experiments were conducted on cylindrical grinding machine with AISI D2 steel as the work specimen. Wheel loading is quantitatively evaluated by machine vision and image processing technique and surface roughness was monitored during the grinding process. Artificial neural network was used for developing the computational model for correlating the wheel loading and surface roughness data. This developed predictive model was used for determining the dressing intervals based on the surface finish requirement for different applications. Experimental results show that a strong correlation exists between wheel loading and surface roughness which determines the dressing intervals and this correlation can be used an explicit criterion in determining the dressing intervals.
Keywords: Wheel loading; Artificial neural network; Particle swarm optimization; Image processing; Wheel dressing; Optimization; Condition Monitoring; Machine vision; image segmentation; thresolding; abrasive grains; chip removal.
Investigation on Magnetic Polishing Characteristics of Metal Additive Manufactured Ti-6Al-4V
by Tatsuya Furuki, Takamasa Hirano, Hiroyuki Kousaka
Abstract: The metal additive manufacturing (AM) of Ti6Al4V is expected to fabricate artificial replacement products with high efficiency. A hybrid additive manufacturing machine that combines with a machining center was developed in the recent years. A desired shape can be obtained, but generating a high-accuracy surface roughness is difficult. However, these products need a high surface quality. These products are generally polished by hand work, resulting in the deterioration of the shape accuracy or increase in the non-machining time. Therefore, this study develops a magnetic polishing method that can polish Ti alloy on a hybrid metal AM machine. A workpiece made of Ti6Al4V is fabricated in the metal AM machine, and is ball end-milled to a flat shape. The workpiece is then magnetically polished on the machining center. The pressing force, polished amount, and surface roughness are measured. Moreover, the Preston constant of the additive manufactured Ti6Al4V is calculated. A typical Ti6Al4V is also magnetically polished, with its Preston constant calculated. In summary, the Preston constant of the additive manufactured Ti6Al4V was approximately 0.78 times smaller than that of the typical Ti6Al4V.
Keywords: magnetic polishing; metal additive manufacturing; machining center; Ti-6Al-4V; Preston constant.
Experimental Study on Abrasive Water-jet Polishing of Cemented Carbide and
Polycrystalline Diamond (PCD) Tools
by Julius Caesar Puoza
Abstract: This research paper studies the material removal mechanism, influence of water jet pressure and jet impact angle on the polishing effect of cemented carbide and polycrystalline diamond cutting tool surfaces and edges. A high-pressure nanodiamond abrasive water jet polishing system was built for this experiment to polish the edge of super-hard cutting tools. The results showed that the water jet pressure and jet impact angle have little influence on the surface roughness, but have a great influence on the materials removal efficiency. The jet angle of 15
Keywords: Polycrystalline diamond tool; cemented carbide tool; water jet polishing; edge strengthening; processing parameters.
Research on scan polishing flat surfaces with a small diameter tool
by He Wang, Weimin Lin
Abstract: High profile accuracy and high surface quality, which are achieved by stable polishing velocity, are needed in the machining of NiP neutron reflection mirror along with suitable machining tools. To respond to the growing demands for high quality reflection mirrors, in this study, a small diameter polishing tool was used on a three-axis CNC ultra-precise polishing machine. Mathematical models of polished profiles based on the Preston equation were built and discussed along with the simulation results of the polished profiles. These models of polished profiles were proved to be effective by numerous experiments under diverse conditions. The polishing characteristics of electro-less plated NiP surface were reviewed, and smooth surfaces could be achieved by scan-type polishing.
Keywords: NiP; Finishing; Material removal velocity; Polishing models.
A Study of methods for the magnetorheological finishing of glass panels for the inner screen of mobile phones
by Bin Luo, Qiusheng Yan, Jisheng Pan, Jiabin Lu
Abstract: In order to solve the problem that there are many scratches on the glass panels of the inner screen of mobile phones after chemical mechanical polishing (CMP), three different magnetorheological finishing (MRF) methods were investigated to polish the surface: (1) single-point MRF with static magnetic field, (2) cluster MRF with static magnetic fields, and (3) cluster MRF with dynamic magnetic fields, which turned out to be the most suitable one of the three. The rotation of a permanent magnet relative to the polishing disc generates dynamic magnetic fields, which have a positive effect on the polishing process and thus enable an ultra-smooth, scratch-free, high-quality surface on the glass panels required for the inner screen of mobile phones. Single-factor experiments were carried out to further adjust the key process parameters, such as machining time, machining gap, magnetic-pole speed, polishing-disc speed, and workpiece speed. An optimised parameter set of 20 min machining time, 1.0 mm machining gap, 120 r/min magnetic-pole speed, 60 r/min polishing-disc speed, and 400 r/min workpiece speed led to an improvement of the original surface roughness of a glass panel with scratches and pits from Ra 1.15 nm to Ra 0.45 nm, that is tantamount to an ultra-smooth surface.
Keywords: Magnetorheological finishing; MRF; single-point MRF; cluster MRF; static magnetic field; dynamic magnetic field; glass panel; mobile phone; surface roughness.
Polishing investigation on zirconia ceramics using magnetic compound fluid (MCF) slurry
by Feng Ming, Wang Youliang, Bitou Teruo, Nomura Mitsuyoshi, Fujii Tatsuya, Wu Yongbo
Abstract: Zirconia ceramics have wide applications in the fields of aerospace, defense industry, new energy, automotive, electronics and biomedical. Although the conventional methods can fabricate zirconia ceramics products efficiently, the induced scratches, micro-cracks and sub-damage are inevitable. Therefore, the post-polishing processing should be employed. The magnetic-assisted polishing with MCF slurry is considered as a friendly polishing method which can not only achieve smooth surface but also reduce the defects remained at the work-piece surface. However, the investigations on the high precision polishing of zirconia ceramics by using the MCF slurry were not conducted so far. In this work, the polishing method by using magnetic compound fluid (MCF) slurry under the rotary magnetic field was proposed for the zirconia ceramics polishing. The principle and the constructed experimental setup were presented at first. Then, the spot polishing was conducted. Finally, the effect of parameters, including working gap h, MCF carrier revolution speed nc, abrasive particles (APs) size, the concentration of carbon iron particles (CIP) and concentration of ?-cellulose on the finishing of work surface was investigated. The polishing results show that surface roughness Ra 5 nm was obtained at the surface of zirconia ceramics with 0.5 mm of h, 400 rpm of nc, ?1.25 ?m of abrasive particle, 45 wt.% of CIP concentration and 3 wt.% of ?-cellulose concentration.
Keywords: MCF slurry; Rotary magnetic field; Zirconia ceramics; Polishing; Precision.
A New Method of Real Time Monitoring of Cutting Tool Status bases on HHT
by Qzheng Liu, Guoqiang Guo, Zichao Lin
Abstract: The machine tool is the main execution unit in the Cyber-Physical system (CPS system), which can improve the product quality by dynamic monitoring and real-time perception of its wear status. In order to realize the on-line signal acquisition and monitoring of tool wear status, the spindle power signal acquisition system was implemented. The cutting force signal is used as contrast analysis. The HHT method and wavelet transform method are introduced to construct the tool wear coefficients, which are corresponding to the tool wear status. Compared with the wavelet transform, it is proved that Hilbert-Huang transform can restrain the noise signal effectively and improve the accuracy of the monitoring. Finally, the new tool wear monitoring method is applied to drilling 45# steel and titanium alloy TC4 to catch the tool wear state, and the power signal is used to carry out comprehensive online tool state monitoring. It is accurate and practical in the drilling test, which shows prospective usage in the near future.
Keywords: Cyber-Physical System; Power Signal; Hilbert-Huang Transform; Tool Wear Coefficient; Wavelet Transform.