INVESTIGATION ON TURNING OF STAINLESS STEEL(GRADE J4) USING CHILLED AIR

MACHINING TECHNIQUE

TEAM MEMBER PROJECT GUIDEAbhishek Kumar Mr. A.Tamilarasan ,M.Tech.Ajit Kumar Asst. Prof. / Mech. Engg.Ashish Kumar Deep narayan gautam Dinesh Kumar

OBJECTIVE

To get optimum surface roughness value for the turning of

Jindal stainless steel [Grade J4] in term of cutting speed, feed

rate and depth of cut assisted by chilled air cooling technique.

Machining work carried out using CVD Multi coated carbide

tool under different cutting conditions.

To indentify tool wear through SEM analysis.

WORK MATERIAL

Work material used was stainless steel [Grade J4], family of

stainless steel in the 200-series and these grades are austenitic,

they are not magnetic.

Good formability and weldablity.

Excellent toughness (impact resistance) even to very low

cryogenic temperatures – ferrite grades have poor low

temperature toughness.

The chemical composition of stainless steel Cr-Mn is C

0.115% , Cr 14.69%, Mn 7.97% ,Ni 0.263% etc.

The acidic nature of the sugar cane juice and toxicity associated

with gaseous product encountered in the manufacture of sugar,

pose a serious challenge to sugar industry.

Chrome-Manganese austenitic stainless steels are suggested to

keep the performance-cost ratio reasonably economic.

TOOL MATERIAL

We used TNMG multilayer coated insert. Inserts were coated with

TiN/Al2O3/TiC.

TiN offers low friction and improved resistance to built-up edge.

A TiC coating has high hardness and excellent wear resistance.

Al2O3 provides a heat barrier with low thermal conductivity

which protect the substrates.

Coating may be a single-layer or multi-layer and typically 5-20

microns in thickness.

TOOL INSERT & TOOL HOLDER

TNMG CQ 5525

Tool holder MTJNR 2525 M16

RECENT COOLING TECHNIQUE LUBRICATION

High pressure lubrication (HPL)

Minimum quantity lubricant (MQL)

Steam cooling

Solid coolant

Chilled Air Assisted machining technique

COLD AIR GUN

HOW VORTEX TUBE WORKS

Compressed air are injected tangentially into the vortex tube

through the nozzle.

Accelerated to a high rate of rotation of about 1,000,000 rpm.

Air stream moves towards the hot end where some air escapes

through the control valve.

Remaining air is forced backed through the centre of the vortex

tube losing their kinetic energy.

EXPERIMENTAL METHODOLOGY

An experimental of prior experimental studies, a methodology was

developed to study the surface roughness of the machined part in

turning.

CUTTING CONDITIONS

Cutting tests were carried out on the medium duty lathe machine

under chilled air assisted condition.

The tools were tested under a various spindle speed of 208, 310, 320

RPM.

The feed rate used was varied from 0.07mm/rev to 0.2mm/rev.

The depth of cut varies from 0.1mm to 0.5mm.

Sl. no. Cutting speed (Vs) m/min.

Feed rate (f) mm/rev.

Depth of cut (mm)

Ra (micron)

1. 20.91 0.07 0.1 1.00

2. 20.91 0.09 0.3 1.61

3. 20.91 0.2 0.5 3.46

4. 31.16 0.07 0.3 1.23

5. 31.16 0.09 0.5 1.91

6. 31.16 0.2 0.1 2.13

7. 32.16 0.07 0.5 1.37

8. 32.16 0.09 0.1 0.94

9. 32.16 0.2 0.3 2.14

EXPERIMENTAL DETAILS

EXP. NO: 01 EXP.NO: 02 EXP.NO: 03

EXP. NO: 07 EXP.NO: 08 EXP.NO: 09

EXP. NO: 04 EXP.NO: 05 EXP.NO: 06

RESULT AND DISCUSSION

The experimental results were analysed using analysis of

variance(ANOVA) for identifying the significant factors affecting the

performance measures.

Residual for Ra

Source DF Seq SS Adj SS Adj MS F P_______________________________________________________________________________

Vc 2 0.43742 0.43742 0.21871 6.45 0.134F 2 3.16549 3.16549 1.58274 46.67 0.021DOC 2 1.22829 1.22829 0.61414 18.11 0.052Error 2 0.06782 0.06782 0.03391

_______________________________________________________________________________Total 8 4.89902_______________________________________________________________________________

 S = 0.184150 R-Sq = 98.62% R-Sq(adj) = 94.46%

The total variation is the sum of variation due to various

controlled factors , their interactions and variation due to

experimental error.

Effect of feed is important as the statistical significant values less

than α (0.05)value at 98.62% confidence level.

R- sq represent the regression confidence larger values of R-sq is

always desirable.

The R –sq values are 98.62% which shows the high correlation

that exits between the experimental values and predicated values.

32.1631.1620.91

2.5

2.0

1.5

1.00.200.090.07

0.50.30.1

2.5

2.0

1.5

1.0

VC

Mea

n of

Mea

ns

F

DOC

Main Effects Plot for MeansData Means

Fig 2 main effect plot for means

LEVEL1 Vc F DOC

1 -4.973 -1.511 -2.010

2 -4.662 -3.073 -4.181

3 -2.935 -7.986 -6.379

DELTA 2.038 6.475 4.369

RANK 3 1 2

RESPONSE TABLE FOR SIGNAL TO NOISE RATIOS “SMALLER IS BETTER”

LEVEL1 Vc F DOC

1 2.023 1.200 1.357

2 1.757 1.487 1.660

3 1.483 2.577 2.247

DELTA 0.540 1.377 0.890

RANK 3 1 2

RESPONSE TABLE FOR MEANS

The response table show the average of response characteristic at

each level and factor.

Rank is based on delta statistics ,compare the relative magnitude

of effects.

The delta statistics is the highest minus the lowest average of

each factor.

From means the response ,cutting speed 32.16m/min,

0.07mm/rev

feed and 0.1mm depth of cut good for surface finish.

20 22 24 26 28 30 32 340.91

0.92

0.93

0.94

0.95

0.96

0.97

0.98

0.99

1

1.01

Cutting Speed Vs Surface Roughness

Ra (µm)

cutting speed in RPM

Surf

ace

roug

hnes

s inµ

m

EFFECT OF CUTTING SPEED DURING MACHINING

0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 0.220

0.2

0.4

0.6

0.8

1

1.2

1.4

Feed Rate Vs Surface Roughness

Ra (µm)

Feed Rate in (mm/rev.)

Surf

ace

Rou

ghne

ss in

µm

EFFECT OF FEED RATE DURING MACHINING

SEM ANALYSIS

Dominant wear was observed at early stage of cutting .

Discrete micro-chipping of the cutting edge is observed at low

cutting speed .

Flank wear occurs on the relief face of the cutting tool.

The flank wear is characterized by the abrasive grooves and

ridges on the flank face.

Crater wear occur on the rake face of the tool.

Crater Wear

Flank Wear

CONCLUSION

Feed rate provide the primary contribution on surface roughness.

Depth of cut is less significant.

Application of chilled cold air give the best result of surface finish.

At 32.16m/min spindle speed, 0.07 mm/rev feed rate and 0.1mm

depth of cut gives the best result of surface finish.

THANK YOU