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: Grinding process using superabrasive metal-bonded wheels is unavoidably linked to long and inefficient truing and dressing processes. This document presents the application of electro-discharge dressing process as an alternative to form wheels. The accuracy of the process and its efficiency has been analyzed on wheels of different grit size. To do so, complex geometry has been completely profiled to a 1A1 type wheels. Results show that the process can provide the desired geometry at the cost of a high processing time. The comparison between fine and large grit size grinding wheels shows that there is apparently no geometric limitation imposed by the grit size apart from that associated to grit diameter in corners and inner radii.
Abstract: The purpose of this paper is to evaluate the surface properties and corrosion behavior of Co-Cr alloys ground by employing Electrolytic In-process Dressing (ELID) grinding; this evaluation was carried out by abrading the alloy surfaces using ultra high molecular weight polyethylene (UHMWPE). The evaluation results showed that ELID grinding can be used to perform mirror finishing on Co-Cr alloys. ELID grinding also showed its ability to create a stable modified layer which improves corrosion wear characteristics on the workpiece surface.
Abstract: The dressing methods of monolayer diamond tool have recently been developed increasingly because a substantial improvement of the ground surface roughness could be achieved with the dressed monolayer diamond tools. In this paper, a new dressing method was proposed, namely chemical-mechanical dressing of the diamond grits. Dressing experiments were carried out on the monolayer brazed diamond grinding wheel. The grit-tip distances from the base of wheel substrate were measured before and after dressing. Grinding experiments were conducted on K9 optical glass after each dressing interval. The roughness parameters of the ground surfaces were measured. The outcome of this attempt appeared highly encouraging, and the dressing of monolayer brazed diamond grinding wheel is effective with the chemical-mechanical dressing.
Abstract: Water soluble coolant has been widely used as machining fluid owing to its environment- friendly characteristic, fine protection property and low price. However, as this type of coolant is perishable, a large amount of labor is required for its maintenance of the coolant. Moreover, in high precision machining, separation of minute machined chips generated during grinding and machine oil from the coolant is indispensable, and a special filtering-device and other equipments are necessary. In this paper, a method to purify water-soluble grinding fluid using PGA based flocculant was examined. As a result of experiments, it was clarified that the suspended matters such as grinding swarf or free abrasive grains in the fluid can be removed at the collection rate of more than 99%. A new filter-less coolant purification technology was established by combined use of micro bubble coolant.
Abstract: This paper proposes a new grinding-fluid-supply system for improving the grinding performance of a CBN wheel. The system generates cavitations in the fluid flow, which is expected to provide higher cooling and superior grinding-chip removal capability. The system is applied to one-pass surface grinding of steel plates, and residual stress and surface roughness are evaluated. The system has a major effect on improving surface roughness, but has a minor effect on reducing the residual stress under shallow-cut grinding conditions. The effects appear greater under the heavier grinding conditions.
Abstract: Fluids have an important role in grinding. Correct fluid application results in enhanced process stability, better work piece quality, and tool life. This paper shows that Computational Fluid Dynamics (CFD) models can be used to simulate the fluid flow and heat transfer in a grinding process, replacing numerous experiments that are expensive, time-consuming, and have limited capabilities. The most important properties of created 3-D model are described, along with results obtained. The results show very detailed distributions of temperatures, pressures, and flow rates in and around the grinding region. The data obtained is essential in studying the influence of the grinding fluid on the grinding process, as well as in determining the best fluid composition and supply parameters for a given application. The results agree well with experimental global flow rates and temperature values and show the feasibility of 3-D CFD-based simulations in grinding applications. The parametric studies of influence of several fluid physical properties on useful flow rates and temperatures were presented as well.
Abstract: In dry grinding, as there is no coolant lubricant to transfer the heat from the contact zone, generation of surface damages are not preventable. Promising alternatives to conventional flood coolant applications are also Minimum Quantity Lubricant (MQL) or Near Dry Machining (NDM) or Semi Dry Machining (SDM). This research has been conducted to study the influence of the abrasive and coolant-lubricant types on the minimum quantity lubrication (MQL) grinding performance. One type of CBN and three types of conventional wheels (corundum) were tested. The tests were carried out in presence of fluid, air jet and eleven types of coolant-lubricants, as well as in dry condition. The results indicate that the finest surface quality and the lowest grinding forces could be obtained when grinding with CBN wheels. In the case of conventional wheels, the coarser wheel induces much proper grinding results.
Abstract: Wire cutting, originally developed for the processing of natural stone, is increasingly used for the machining of reinforced concrete and metallic structures. In this field of application the diamond wire sawing tools are subjected to a higher-than-average wear. Furthermore the metallic bonding of the cutting beads is not suitable for machining metallic structures, because of a missing self-sharpening effect. Within this paper, conventional wire sawing tools are investigated in pure steel structures. These tools are supposed to be suitable for the cutting process in accordance to their tool concept. The manufacturing process and the grain sizes have an influence to the tool performance. From these investigations requirements for a new tool concept will be derived.
Abstract: The abrasive drilling achieves high hole qualities in processing carbon/epoxy (C/E) composites. In order to investigate the cutting force and the material removal mechanism for drilling C/E composites with abrasive drilling tool, this paper presented a mechanistic model to predict the cutting force of single grain. The model assumes fibers as a beam with two ends fixed. The beam is subjected to extrusion of diamond grain and mainly fractures by tensile damage. The failure mode is then validated by finite element simulation and scratching experiment. The cutting simulation of single grain using Abaqus showed fracture occurred in the points with maximum tensile stress. The tensile damage results in many claval chips. Local fiber tensile damage is the mainly failure mechanism for the fibers, accompanying the fiber compressive failure and shear failure.