Papers by Keyword: Super Abrasive

Abstract: In order to cope with high demanded industry requirements. The super-hard alloys such as Tungsten Carbide have been widely used in aerospace and defense industries. So far, the grinding operation is still the most popular machining process being used to cut these materials in shape. But, owing to the nature of these materials mechanical properties, always made it very difficult to grind as well as to cut. Nevertheless, the allowable grinding parameters are resisted to very limited range and always require use very expensive super abrasive grinding wheel. Recently, study by many researchers show that the ultrasonic assist grinding had the advantage of higher material removal rate, less cutting force and lower cutting temperature. In the mean time, the tool life had been improved greatly. In this study, the conventional GC grinding wheel was used in the experiments to study the material removal rate; grinding force; surface roughness as well as specific grinding energy with and without the ultrasonic assist. The results show that these difficult-to-cut materials can be ground easier with proper ultrasonic assist and low-priced grinding wheel.

Abstract: Touch dressing of electroplated diamond wheels is a challenging technique used for precision form grinding. This paper presents an investigation to explore the capabilities of modern laser technology for touch dressing. A pulsed picosecond laser (ps-laser) beam (Yb:YAG) is used to cut diamond grains within a definite grain protrusion without noticeable thermal damage neither on the nickel bond material nor the diamond itself. A systematic study on laser irradiation parameters on cutting quality is presented. Series of experiments by dressing of SiC wheels using an ultrashort pulsed laser source as well as conventional touch dressed diamond wheel are carried out and both methods are compared. Significant advantages of the novel laser method are presented.

Abstract: Harder workpiece materials and increased efficiency requirements for grinding processes make the use of super abrasive grinding wheels indispensable. This paper presents newly developed processes for the dressing of super abrasive grinding wheels. The different bond systems of grinding wheels require distinct dressing process. In this paper, dressing processes for metal and vitrified bonded grinding wheels are investigated. It introduces the method of electro contact discharge dressing for the conditioning of metal-bonded, fine-grained multilayer grinding wheels. A description of the essential correlation between dressing parameters and the material removal rate of the bond material is presented. The considered parameters are the dressing voltage, the limitation of the dressing current and the feed as well as the infeed of the electrode. For the grinding of functional microgroove structures, multiroof profiles with microscopic tip geometries are dressed onto the grinding wheel. For this, a profile roller in combination with a special shifting strategy is applied on finegrained vitrified bonded grinding wheels.

Abstract: This paper provides a novel process that can readily make abrasive tools bonded ultraviolet-curing resin. Excellent characteristics of ultraviolet-curing resin make it possible for bonding abrasive tools. Moreover, more applications demonstrate that ultraviolet-curing abrasive tools possess excellent properties without the shortcomings that are encountered in the case of the conventional resin bonded abrasive tools. Furthermore, various factors influencing the qualities of ultraviolet-curing abrasive tools are discussed.

Abstract: A Nd:YAG crystal having a special structure achieved laser operation with an extinction ratio of over 20 dB, a CW (continuous wave) average power of 6 W, a pulse width of 50 ns, and repetition rates in the range 1 kHz – 10 kHz for an output wavelength of 1064 nm for effectively cooling the crystal for the case of laser dressing. The birefringence induced by the stress applied to the crystal results in the production of elliptical polarization before the Brewster-window and thus decreases the laser efficiency. In this paper, we analyzed the relationship between the distortion and the birefringence in a Nd:YAG crystal and the resulting effect on the laser power.

Abstract: A completely new diamond wheel, named the 3R wheel, has been developed. The 3R wheel has three unprecedented functions, reconfiguration, restoration and recyclability, and is molded from a mixture of special thermoplastic resin filler and diamond powder. The concept of the 3R wheel is to control the quantity and the position of abrasive material by actively using heat. In this study, tungsten carbide (WC) was ground using a thermoplastic resin bonded diamond wheels (radius 1.4 mm) with three different concentrations of 1500 grain size abrasive. As a result, a grinding ratio of over 200 and 18 nmRa roughness was achieved without dressing. In addition, a large quantity of abrasives was confirmed on the wheel surface by observation.