The strength of the grain wear process is related to the magnitude of the stress impulses of the abrasive interactions. As an example, Figure 9.4 shows the abrasive grains of a D126 St50 grinding wheel with a concentration of C90 during grinding silicon carbide. In the left part of the image, the wear is typified […]
Рубрика: Handbook of Machining with Grinding Wheels
Influence of the grinding fluid in grinding
10.10.1 Conventional Grinding In comparison to dry grinding and grinding with emulsions, lower temperatures were measured in grinding with oil [Dederichs 1972]. The capacity of the cooling lubricant to discharge heat from the contact zone can be affected by the occurrence of film boiling of the fluid in the contact zone, leading to an abrupt […]
Sensors for Coolant Supply Monitoring
In almost all grinding processes, coolants are used to reduce heat and to provide sufficient lubrication. These are the main functions of any coolant supply. Furthermore, the removal of chips and process residues from the workspace of the machine tool, the protection of surfaces, and human compatibility should be provided. Modern coolant compositions also try […]
BACKGROUND ON CERAMIC MATERIALS
14.2.1 History The word ceramic can be traced back to the Greek term keramos, meaning “a potter” or “pottery.” Keramos, in turn, is related to an older Sanskrit root meaning “to burn.” Thus, the early Greeks used the term to mean, “burned stuff” or “burned earth” when referring to products obtained through the action of […]
Plain Slideway Materials
Slideways are traditionally made of cast-iron sliding on cast iron making use of the graphite present as lubricant or on porous brass, especially where gibs are applied. The brass is designed to wear preferentially while providing good lubrication. The major limitation of these combinations is static friction or stick-slip that can create drive problems with […]
Adjustment of Bearing Preload for High-Speed Spindles
Bearing preload needs to be carefully controlled and understood. Insufficient preload leads to low stiffness while excessive preload leads to higher temperature rise and even seizure. As rotational speed increases several factors cause an increase in preload: [4] Schematic drawing showing general arrangement of lubrication system 3/8 Steel tubing External by-pass line added to all […]
BASICS OF RECIPROCATING GRINDING
According to DIN 8589-11, reciprocating grinding is a peripheral longitudinal grinding process with a back-and-forth feed motion, in which the feed motion takes place gradually in small steps with a relatively high feedrate [DIN 8589]. 16.2.1 Process Characterization Reciprocating grinding is used for generating plain surfaces of usually large lateral dimensions. The grinding spindle is […]
Electroplated CBN
Electroplated CBN wheels consist of a single layer of CBN crystals on a profiled metal hub. As discussed in Chapter 4, this leads to limits on finish and profile tolerances unless the surface is conditioned after plating which adds significantly to the cost. Therefore, the wheels are used more typically in roughing operations and under […]
Wheel Speeds
The vast majority of standard grinders still use conventional abrasives at wheel speeds of 43 m/s or less. The wheel life is relatively long so any benefits from upgrading to CBN have to come from improved cycle time or quality. However, an analysis of about 30 different cylindrical grinders currently on the market reveals the […]
Quill Designs for CBN
The preferred approach is to ensure that the quill design has been optimized for use with vitrified CBN as illustrated in the Figure 18.6. The quill length should be reduced to a minimum and the Wheel screw Conventional quill mounting diameter increased. The standard wheel screw used for conventional wheels should be eliminated and the […]