25-07-2012, 11:32 AM
GRINDING OPERATION-TYPES AND APPLICATIONS
GRINDING OPERATION.pptx (Size: 562.17 KB / Downloads: 50)
INTRODUCTION
Grinding is an Abrasive Machining process for finishing operation where material removal process is accomplished by abrasive particles that are contained in a bonded grinding wheel rotating at very high surface speeds. To Grind means to abrade, to wear away by friction or ‘to sharpen’. Technically, grinding is a subset of cutting, as grinding is a true metal cutting process.
Analysis of Grinding Process
The cutting conditions in grinding are characterized by very high speeds and very small cut size, compared to milling and other traditional machining operations. Using surface grinding to illustrate, Figure :1 shows the principle features of the process.
The peripheral speed of the grinding wheel is determined by the rotational speed of the wheel: V=πDN
In grinding operation, the material removal
rate is, RMR=vwd
the number of chips formed per time nc
is given by, nc= VwC .Where,
V=wheel speed, mm/min(in/min);
w=crossfeed, mm(in); and
C=grits per area on the grinding wheel surface,
grits/mm2(grits/in2).
Surface Grinding
Surface grinding is normally used to grind plain flat surfaces of metallic or nonmetallic materials and one of the most common grinding operations. It is performed using either the periphery of the grinding wheel or the flat face of the wheel.
Applications:
Steel balls for ball bearings are grinded by surface grinding.
Flat metal plates are superfinished by surface grinding.
Cylindrical Grinding
As its names suggests, cylindrical grinding is used for rotational parts. In cylindrical grinding work can be done on a variety of shapes, however the object must have a central axis of rotation.
There are three different types of cylindrical grinding:
External Cylindrical Grinding,
Internal Cylindrical Grinding, and
Form Grinding.
Other Grinding Processes
Electrochemical grinding: Electrochemical grinding is an electrolytic material-removal process involving a negatively charged abrasive grinding wheel, a conductive fluid (electrolyte), and a positively charged workpiece. Workpiece material deplates in to the electrolyte solution.
Applications:
Production of tungsten carbide cutting tools.
Grinding of superalloy turbine blades.
Form grinding of aerospace honeycomb metals.
Applications of abrasive belt grinding
Finishing: surface roughness, removal of micro burrs, cosmetic finishes, polishing.
Deburring: radiusing, burr removal, edge breaking
Stock removal: high stock removal, cleaning (e.g. of corrosion), eliminating mill or tool marks, dimensioning.
Hydro-erosive Grinding:
Hydro-erosive grinding is a process for radiusing of orifice edges and bore hole intersections by flowing them with an abrasive fluid in order to pre-age the hole geometry and/or to calibrate the static flow to precise tolerances.