Grinding Wheel and Other Abrasive Materials Review Questions Flashcards
Why are abrasive processes technologically and commercially important?
- Can be used on all types of materials ranging from soft metal to hardened steels and hard nonmetallic materials such as ceramics and silicon
- sOME OF THE PROCESSES CAN PRODUCE EXTREMELY FINE SURFACE FINISH (TO O.O25 MICRO METER OR 1 MICRO INCH)
- For certain abrasive processes, dimensions can be held to extremely close tolerances
What are the five basic parameters of a grinding wheel?
- aBRASIVE MATERIAL
- GRAIN SIZE
- BONDING MATERIAL
- WHEEL GRADE
- WHEEL STRUCTURE
What are some of the principal abrasive materials used in grinding wheels?
- Aluminum oxide
- silicon carbide
- cubic boron nitride
- diamond
What is wheel structure?
Relative spacing of the abrasive grains in the wheel
What is a wheel grade
Indicates the grinding wheel’s bond strength in retaining the abrasive grits during cutting
Why are specific energy values si much higher in grinding than in traditional machining processes?
Not all of the individual grits are engaged in actual cutting
Beacuase of random positioning in the wheel some grains do not project out far enough into the work surface to accomplish cutting
Grinding creates high temperatures. How is temperature harmful in grinding?
- surface burns, surface cracks
- burn marks show themselves as discoloration on surface caused by oxidation
- metallurgical damage beneath the surface
- softening of work
- cause residual stresses in the work surface, decreasing fatigue strength of part
What are the three mechanisms of grinding wheel wear?
- grain fracture
- attritious wear
- bond fracture
What is dressing, in reference to grinding wheel wear?
Consists of breaking off dulled grits on the outside periphery of the grinding wheel in order to expose fresh sharp grains and removing chips that have been clogged in the wheel
WHat is truing, in reference to grinding wheels?
alternate procedure that not only sharpend the wheel being dressed as it rotates but also restores its cylindrical shape
What abrasive material would one select for grinding cemented carbide cutting tool?
diamond
What are the functions of a grinding fluid
Reducing thermal effects and high work surface temperatures
What is centerless grinding
Alternate process for grinding external and internal cylindrical surfaces
Work piece not held between centers
Reduction in work handling time, used often for high-production work
How does creep feed grinding differ from conventional grinding
Performed at relatively high depth of cut and very low feed rates
Material removal rate and productivity increased because wheel is continously cutting
How does abrasive belt grinding differ from conventional grinding
uses abrasive particles bonded to a flexible cloth belt
SUpport of belt is required when work is pressed against it and support provided by a roll or platen located behind the belt
