CRYOGENIC GRINDING

CONTENTS :

1. INTRODUCTION2. GRINDING

3. PROBLEMS IN CONVENTIONAL GRINDING 4. CRYOGENIC GRINDING

5 . WORKING OF CRYOGENIC PLANT

6. APPLICATIONS 7 . PROS AND CONS

8. CONCLUSION 9. BIBILOGRAPHY

GRINDING :

PROBLEMS DUE TO CONVENTIONAL GRINDING

INTRODUCTION

EXPERIMENTAL SET-UP

CRYOGENIC SYSTEM

Freezer milling is a type of cryogenic milling that uses a solenoid to mill samples.

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 nano structured microstructure is attained.

Cryomilling takes advantage of both the cryogenic temperatures and conventional mechanical milling.

FREEZER MILLING AND CRYO MILLING

SOLENOID- BASED CRYOGENIC GRINDER

STEELS OF DIFFERENT MICROSTRUCTURES WHICH ARE GROUND

Ice bath for cryogenic grinding

For heat sensitive materials such as plastics and rubber it is possible to embrittle the material with liquid nitrogen and  Perform an additional external freezing of the fast clamping jars. Those jars are either made from Teflon or from stainless steel and are suitable for cryogenic grinding applications. 

The cryogenic grinding lowers the thermal related problems

Reduced grinding forces

High M.R.R. can be achieved

Minimizing residual stress and micro-cracks

Retention of wheel grit sharpness (i.e. low rate of grit wear)

Surface finish, dimensional accuracy and tool life improved

Difficult-to-machine materials can also be machined

Moreover, use of liquid nitrogen as a grinding fluid

facilitates clean and pollution free working environment

The application of cryogen in moist atmosphere may cause formation of ice around the delivery nozzle and the piping system carrying the cryogen .

This may cause a possible blockage in the delivery system of liquid nitrogen .

Economic considerations should be solved .

Cryo-grinding improves product quality by controlling thermal effects.

Oxidation and surface burning are eliminated .

Surface damage is absent.

The surface roughness in cryo grinding is found to be greater than in conventional grinding .

Reduction in forces and specific energy.

The benefits of cryo-grinding are greater for harder materials and higher infeeds.

CONCLUSION :

BIBLIOGRAPHY

1. A short term QIP course on cryogenic technology (Center for continuing education IIS Bangalore)

2. AICTE-ISTE Short-term programme on contribution to technology development from space research

3. Mc Graw Hill Encyclopedia of science & technology: 7th Edition VOL-4

4.Proceeding of the 18th International Cryogenic Engineering Conference (Edited by K.G. Narayankhedhar, Narosa Publishing House)

5.http://www.csa.fnal.gov Cold Facts (The quarterly magazine of the Cryogenic Society of America).