02-08-2014, 04:46 PM
CRYOGENIC GRINDING
Cryogenic grinding improves product quality by controlling thermal effects..pptx (Size: 310.86 KB / Downloads: 42)
INTRODUCTION
The word ‘cryogenics’ originates from Greek word ‘cryo’, which means cold.
Temperatures as low as -180ºC are attained in cryogenic systems.
The extremely low temperature are produced by using substances called ‘cryogens 'such as liquid nitrogen and liquid helium.
Cryogens are stored in vessels called as Dewar flask which provides good insulation.
CONT.
4. Cryogens are used in food industry for food handling and processing.
5. Cryogens are used in various machining operations such as cryogenic deburring, cryogenic deflashing, cryogenic tempering and cryogenic grinding.
6. Cryogens like liquid nitrogen are used in special chilling and
freezing applications.
CRYOGENIC GRINDING PROCESS
Cryogenic grinding , also known as freezer milling/
freezer grinding/ cryomilling is the act of cooling or
chilling a material and then reducing it to smaller
particle size.
2. Almost all materials embrittle when exposed to low
temperature. Cryogenic size reduction utilizes the
cooling effect of liquid nitrogen to embrittle materials
prior to and or during the grinding process.
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CRYOMILLING
Cryomilling is a variation of mechanical milling, in which metallic powders or other samples (e.g. temperature sensitive samples and samples with volatile components) are milled in a cryogen (usually liquid nitrogen or liquid argon) slurry or at a cryogenics temperature under processing parameters, so a nanostructured microstructure is attained.
ADVANTAGES
Higher material removal rate can be achieved.
Tool wear and tear is minimized to a great extent.
Grinding forces are reduced.
Cryogens act as coolant and hence the effects of
overheating of the tool and work piece are reduced.
Materials which are soft and elastic in nature such as rubber can be easily machined with this process.
Smaller particle size can be achieved.
Better surface finish and dimensional accuracy can be achieved.
CONCLUSION
Cryogenic grinding improves product quality by controlling thermal effects.
Oxidation and surface burning are eliminated.
Surface damage is eliminated.
Finer particle size is achieved.
Material removal rate is high.
The process is economical in the long run.