CRYOGENIC

GRINDINGBY- HIMANSHU TIWARI B. TECH 3RD YEAR

IntroductionProblems faced in Conventional GrindingCryogenic Grinding TechnologyWorking Principle of CryoGrinderPerformance Data &Technical DataField of applicationsSuperiority of cryogenic grinder over

conventional grinderMerits & DemeritsConclusion

CONTENTS:

The term “CRYOGENICS” originates from Greek word which means creation {or} production by means of cold.

Cryogenics is the study of very low temperature {or} the production of the same, Liquid nitrogen is the most commonly used element in Cryogenics & is legally purchasable around the world.

Cryogenic Grinding technology can efficiently grind most tough materials & can also facilitate Cryogenic recycling of tough composite materials & multi component scrap.

The Cryogenic process also has a unique capability for recycling difficult to separate composite materials.

INTRODUCTION:

High heat generation. Introduction of tensile residual stress.Less tool life.Clogging and Gumming of the mill.Oxidation.Loss of Enteric oil in Spice grinding.

PROBLEMS FACED IN CONVENTIONAL GRINDING PROCESS:

HOW..???

Now….elimination of all these problems are

required……..But……….

Here comes the necessity of

CRYOGENIC GRINDING

…..also known as Freeze Grinding

CRYOGENIC GRINDING TECHNOLOGY:

For pulverizing many materials, Cryogenic Grinding Technology increases productivity & lower power cost.

Many elastic {or} “soft” materials are very difficult to pulverize(crush to fine particle),requiring long cycle times & high power/energy consumption.

Cryogenic grinding involves cooling a material below its embrittlement temperature with a cryogenic fluid, typically liquid nitrogen.

After cooling, the material is fed into an impact mill where it is reduced in size primarily by brittle fracture.

WORKING OF CRYO-GRINDER: Material is to be ground is cleaned manually & fed into

the hopper.

From the exit of the hopper the material enters into the vibratory feeder, which is positioned with a small inclination towards the entry of the helical screw conveyor, It has ability to control the fed rate.

Liquid nitrogen from the storage container is sprayer into the screw conveyer, The time of stay of material in the conveyer can be maintained by varying the speed of the drive i.e., conveyer drive.

working representation of Cryo-Grinder

WORKING OF CRYO-GRINDER: The sensors monitors material’s temperature in the

conveyer.

When the mill is running, the material gets crushed between the studs & comes out through an optional sieve as a ground product.

To the bottom of the mill a collecting bin is housed where the ground product gets collected.

The vaporized nitrogen from the mill is sucked by a centrifugal blower & through the filter assembly is fed back to the mill, And the cyclic process is continued.

fig.- Schematic representation of CryoGrinder

Performance Data Cryo-MillField Of Application* Size reduction, Homogenation

Feed Material* Hard, Brittle, Soft, elastic & Fibrous

Feed size* Up to 8 mmFinal Fineness* Approx. 5micro-mmBatch/Sample Volume* Max.20mlTypical Mean Grinding Time* Pre-cooling:10 mins

grinding 1 minuteMemory for Parameter Combination* 1 nos

Technical Data ParametersPower Consumption 160 WattsW*H*D 385*370*570 mmNet Weight Approx. 46 Kg

*depending on feed material & instrument configuration/setting.

CryoGrinding of Steel;The large amount of Heat is generated during

machining/grinding at high speed & feed rate raises the temperature at the cutting zones excessively.

To overcome this problem liquid Nitrogen is fed to the grinding spot.

Thermoplastics & Thermo sets;To which Nylon, PVC, Polyethylene, synthetic rubber

are commonly used in powder form, but not limited to, a variety of applications such as adhesives, powdered coatings, fillers & plastic sintering & molding.

FIELDS OF APPLICATION:

Adhesives & waxes;To avoid pliable & sticky of certain materials

which is unable in conventional grinding.Explosives;

To grind the explosive materials(TNT) below their Ignition Temperature.

Spices;To overcome the volatility of Etheric Oils (gives

the taste & smell of spices).

FIELDS OF APPLICATION:

MERITS:1 .Increased throughput & power saving.

2 .Finer particle size.

3 .More uniform particle distribution.

4 .Lower grinding cost.

5 .No heat generation.

6 .Prevent oxidation.

.

MERITS & DE-MERITS:

1 .High operation cost.

2 .Maintenance cost is above the range.

3 .Filtering of Screw Conveyer is Difficult.

4 .High power consumption.

DE-MERITS:

Hence We CAN CONCLUDE THAT....

THANK YOU