2.2.1 Chemistry, Types and Characteristics of Silicon Carbide Silicon carbide, also known as carborundum and SiC, is used as abrasive material in its hexagonal form, a-SiC (Fig. 2.10) [MALK08, p. 24]. It is composed of 70.05 wt % Si and 29.95 wt% C [LIET08]. Each C atom is surrounded by four Si atoms and vice […]
Рубрика: Life Cycle and Sustainability of Abrasive Tools
Purpose of Coatings
Grit coatings are applied for various reasons, such as grit retention in the bonding, grit protection, grit alignment, or heat transfer during the tool manufacturing process or tool use. One coating can have several useful purposes, which are described in the following. 2.7.1.2 Grit Retention in the Bond Grit morphology and grit surface define grit […]
Sustainability Dimensions to Abrasive Grits
2.10.1 Technological Dimension Table 2.7 summarizes the most important grit characteristics in grinding technology. In general, the grit type is chosen with regard to the machined material and the grit size is defined by the desired workpiece quality. The individual performance profiles of the grit types can be visualized in radar charts [HELL11]. The abrasive […]
Sintering Process
In the sintering process, the bond components melt and flow around the abrasive grits. Bonds with a large amount of clay melt at higher temperatures; bonds with more frit content melt at lower temperatures [MALK08, p. 27]. The mechanisms of melting, wetting, resolidification, and forming of bonding bridges between grits are highly complex [BOTS05, MOSE80]. […]
Shapes
Tools are characterized by tool shape and abrasive layer composition. The tool shape specification follows DIN ISO 525 and DIN ISO 603, FEPA standards, ANSI B74.2 (conventional tools), or ANSI B74.3 (superabrasive tools) [DIN00a, DIN00b]. In addition, the wheel specification often includes company specific terms as well as the used standard. Table 4.1 shows typical […]
Tool End of Life
Product life is defined by several causes, such as physical life (break-down beyond repair), functional life (need for the product ceases), economic life (new products offer the same functionality at lower operating costs), legal life (regulations make the product illegal) [ASHB09, p. 66]. The most important causes for end of grinding tool life are tool […]
Balancing of Stationary Wheels
Stationary wheels can be balanced with one or more counter-weights, whose positions are determined when the grinding tool hangs freely on a cylinder rod through its inner hole [DIN05, KLOC09, p. 284]. Wheels with flanges have a notch on the circumference to hold two or three sliding blocks [WECK05, p. 245 f.]. 5.2.2.1 Balancing of […]
Other Methods
The dynamical cutting edge number results from the process kinematics and can be obtained with a thermo-element inside the machined workpiece. Each impulse during grinding should indicate a grit-workpiece contact [PEKL57, DAUD60]. The smaller the contact area of the thermo-element is, the more reliably the temperature peaks can be related to grits. Luminescence offers another […]
Dressing of Superabrasive Tools
The high wear resistance of superabrasive grits provides challenges to dressing procedures. CBN grinding wheels are commonly dressed with rotating diamond tools because of the lower toughness and hardness of CBN compared to diamond [MARI07]. However, the dressing forces for CBN are higher than for conventional wheels, which needs to be considered for the dressing […]
Reducing Heat by Convection and Conduction
Heat removal includes all aspects of cooling and lubrication and has been researched a lot [HEIN09b]. The basic principles for heat removal are heat convection Fig. 7.26 Few interactions per time and short interaction time (diagram follows Fig. 7.23) and heat conduction (Figs. 7.23, 7.27 and 7.28). It is commonly assumed, that all process energy […]