8.1 INTRODUCTION 8.1.1 Loss of Accuracy and Productivity Vibrations can cause serious problems in grinding processes leading to loss of machining accuracy and loss of productivity. Of the various types of vibration, chatter vibration is one of the most crucial ones because it reduces form accuracy as well as increasing surface roughness of the ground […]
Рубрика: Handbook of Machining with Grinding Wheels
Handbook of Machining with Grinding Wheels
Grinding, once considered primarily a finishing operation involving low rates of removal, has evolved as a major competitor to cutting, as the term “abrasive machining” suggests. This is what Milton Shaw, the man who is considered the great pioneer and father of American grinding, said about 10 years ago. Shaw led the development of grinding […]
2.2.25 Decay Constant t
When the infeed reaches its final feed point, the grinding force F will change with time t as the system relaxes according to the equation Ft and power are directly related; therefore t can be determined from a log plot of the decay in power during spark-out. After 3t virtually all grinding has ceased, preventing […]
Fine-Grained Materials
When a scratching tool enters a fine-grained material, an entry section is formed by pure plastic deformation. The length of the entry section strongly depends on the corner radius of the diamond. If the material-specific shear stress is exceeded due to increasing scratching depth, a permanent deformation occurs thrusting aside the material and causing bulgings […]
Clamping Force to Compensate for the Weight of the Wheel
Fm = Ms g/ 4.6.3.1 Clamping Force for Unbalance of the Wheel Fu = 8 Vs2 /rs2 Vb where 8 = unbalance (force. distance) vs = wheel speed rs = wheel radius 4.6.3.2 Clamping Force for Motor Power Surge It is assumed that electric motors can develop a surge torque of 2.5 times their rated […]
Comparison of SG and Cubitron Abrasives
Direct comparison of the performance of SG and Cubitron is difficult because the grain is merely one component of the grinding wheel. SG is harder (21 GPa) than Cubitron (19 GPa). Anecdotal evidence in the field suggests that wheels made from SG give longer life but Cubitron is freer — cutting. This can make Cubitron […]
Hardness of CBN
The hardness of CBN at room temperature is approximately 4,500 kg/mm2. This is about half as hard as diamond and twice as hard as conventional abrasives. 5.7.7 Wear Resistance of CBN The differences in abrasion resistance are much more extreme. A hardness factor of 2 can translate into a factor of 100 > 1,000 in […]
Vitrified bonds for cbn
6.7.1 Introduction When CBN was introduced into the market in 1969, its cost naturally lent itself to being processed by wheel makers that knew how to handle expensive abrasive — namely, diamond wheel makers — using the dense hot-pressed vitrified systems described above. Unfortunately, these had none of the properties, such as chip clearance and […]
UNIAXIAL TRAVERSE DRESSING OF CONVENTIONAL WHEELS WITH ROTARY DIAMOND TOOLS
7.4.1 Introduction Rotary diamond tools were the industry’s answer to life issues with stationary tools and are in many ways the rotary equivalents to single points, blades, grit tools, and form blocks. A rotary diamond tool (also called “truer,” “dresser,” or “roll”) consists of a disc with diamond in some form held on the periphery […]
Forced Vibration
Out-of-balance and eccentricity of the grinding wheel are the main causes of forced vibrations [Inasaki and Yonetsu 1969, Gawlak 1984]. The wheel, as a source of vibration, can be relatively easily identified through frequency measurement. The main concern with wheel-induced vibration is how to eliminate out-of-balance and wheel runout. There are a number of other […]