Wheel and Axle plant

Pride of Durgapur steel plant.Major supplier of wheels to Indian railways.Commissioned in 1962.Wheels and axles manufactured by forging

followed by machining.

Wheel plant

• Raw materials :

o 12 sided flutted bottom poured steel ingots with diameter of 16” or 14”.

oChemical composition :

C = 0.62 to 0.68 % , Mn = 0.70 to 0.85% Si = 0.24 to 0.28 % , P =0.045 and S = .04 %

Rough shaping of wheel

Flutted ingots sliced into 4 blocks of which 3 used.

Ingot blocks (cheese) free fromo circular crackso Bottom crackso Cold shunts Heated in rotatory hearth (A) furnace of 1220 C for 6Hrs.

63 / 12 Mn. Forging and Punching combination press.

Heated to 1200 C in batch type holding furnace B.

Computerised wheel rolling One thread roll – shape n thread profile Two web roll – shapes the web portion Two edge roll – rim thickness

• 20Mn. DISHING PRESSoWeb form changed from flat ring to truncated

cone slopping from boss to rim.• Serial no. , year and cast numbers stamped in

HEAT TREATMENT :• Spraying is done depending on C equivalent.>78 - heat to 860 C and cool to room temp.=78 - spraying time 50seconds.<78 - 15seconds more per point

TESTING :

• Drop Testo 100 mm. wheels, height – 10 ‘ , no. of falls – 3

• 5 wheels sent to Ultrasonic test

MACHINING : Rough boring , finished machining of rim width,

web thickness, boss length and threads on wheel.CNC vertical lathes 15 in no. are used

• Final inspection for dimensions and any other metallurgical defects.

• Some of the defects :

DEFECT CAUSER

MATERIAL1) INCLUSION2) CRACK3) LAB

Poor quality of refractories during teeming, improper heating, crack in forging dye etc.

MILL

UNDER / OVER DIMENSIONS

SCALE FITTED

Wheel not rolled properly, descaling not properly done, weight may not be proper.

MACHINE

1) MERCHINING IMPROPER

2) WEB CURVATURE WRONG

Operators negligence or tool not proper, improper distribution of metal during rolling

Axle Plant

• Raw materials : Squared bloom rolled in Blooming mill

C = .33-.37 Mn=.65-.80 Si=.12-.17 S=.040 P=.040 Al=.01-.025

• Shaping of axle : Heated in a continuous pusher type furnace for 8 hrs. at 1220

C. Forged in axle forging hammer for about 9-10min Final temp being 850 C

• Heat treatment : Walking beam type furnace Discharged into quenching tank of oil Straightening in 150 Tons horizantal hydraulic

straightening press.

• Machining : Sawed for required length Drilling and tapping of 3 holes at the ends.

• Inspection for dimensional accuracy. Assembly of wheel and axle.

o Inspected by Railway Inspecting Agency (RITES)o All sets are painted to avoid seasonal corrosion.