KMP 440RM MAIN DRIVE GB

RAW MILL GEAR BOX FAILURE 19.01.14 : 7.30 PM (68 HRS)

prepared by: Lokesh Jain

Make FLENDER

Model KMP-440

Main Gear Box Type PLANETARY GEAR BOX

Serial Number 181.304.008.2.1

Rating 1,700.00 KW

Main Gear Box Ratio 30.6

Input RPM 994.00 RPM

Output RPM 32.40 RPM

Oil Quantity 5200.00 Ltr

Lubrication System FORCED

Equipment specification:Section-Raw Mill-IIEquipment Name-Raw Mill Main Drive Gear BoxGear box details-SAP equipment no. 10010729

Problem Statement

On dated 19/1/2014 at 7.30 PM, Raw Mill-2 tripped due motor high current, on diagnosis reason of motor high current was mechanical locking / main drive GB internals damage. Tripping of RM-2 Main drive & sudden abnormal sound from RM-2 main dive GB at 07:30PM stopped mill operation

Observation and Before stoppage analysis:-

• Problem started few day before with a cyclic abnormal noise, near VRM body.

• Source of noise was suspected either gearbox or some other source from mill inside body.

To Identify the problem detail observations and vibration analysis done. Following observations noted.

Gear Box oil temperature (65-68°C) & bearing Temperatures

at Gear Box input (66-69°C), which was in permissible limit.

Oil analysis & WDA Report were normal tested on 16/1/2014.

Vibrations at Gear Box 5.5 to 7.0 mm/s, which was in

permissible limit.

Grinding Pressure changes (80-95 bars) have not significant

effect in pattern as well as amplitude.

Motor vibration level 1.0 to 2.0 mm/s, which was in

permissible limit.

The Gear mesh frequency has no signification side band.

No bearing fault frequency observed in vibration signature.

Noise level was slightly high.

Observation and Before stoppage analysis:-

•Lube Oil :-Last WDA and Oil Analysis reports are normal attach as below

Observation and Before stoppage analysis:-

LINE-2 Equipment Vibration ReportVRM LINE-2

Location Direction UnitsValue on 30.10.2013

Value on 26.11.2013

Value on 26.12.2013

Value on 11.1.2014

Value on 17.1.2014

After BD Value on 22.1.2014

MOTOR

MOTOR NDEA Axial mm/sec 1.32 1.85 1.39 1.7 1.25 1.29

MOTOR NDEH Horizontal mm/sec 0.75 1.1 0.77 0.98 1.2 0.84

MOTOR NDEV Vertical mm/sec 1.5 0.91 0.94 0.82 0.84 0.86

MOTOR DEA Axial mm/sec 1.5 1.8 2.1 2.3 2.7 1.5

MOTOR DEH Horizontal mm/sec 2.24 2.39 1.84 2.03 2.11 0.89

MOTOR DEV Vertical mm/sec 1.89 2.14 2.11 1.88 2.5 1.5GEAR BOX

G.B. INPUT DEA1 Axial mm/sec 3.49 3.14 2.62 3.02 3.06 1.97

G.B. INPUT DEH 1 Horizontal mm/sec 5.78 6.64 6.14 5.35 6.42 5.64

G.B. INPUT DEV1 Vertical mm/sec 6.34 6.54 4.63 5.68 6.06 4.37

G.B. INPUT DEH2 Horizontal mm/sec 5.26 6.91 5.76 5.7 4.79 3.63

G.B. INPUT DEV2 Vertical mm/sec 4.8 4.92 5 5.77 4.68 3.61

G.B. BODY DEH 3 Horizontal mm/sec 6.26 4.07 6.06 5.25 5.64 3.02

G.B. BODY DEH 4 Horizontal mm/sec 4.58 3.9 4.78 5.48 4.82 4.17

G.B. BODY DEH 5 Horizontal mm/sec 4.22 3.68 4.2 4.93 3.14 2.31

Vibration Trend (30.10.2013 to 22.01.2014)

VIBRATION SIGNATURE ANALYSIS

Key in

The Source of problem identification

Planet pinion gear rotational frequency 78 CPM observed dominating in vibration spectrum and time waveform analysis

Related Planet Pinions (RPM)

78.12

RM2 GB.wav

Time Wave Form

Normal sound.wav

Waterfall Diagram

Stage of Drive Motor Bevel stage Planetary Stage

Input Pinion Shaft ( RPM)

990 990

Helical Shaft (RPM) 217.80

Sun Gear (RPM) 217.80

Related Planet Pinions (RPM)

78.12

Planetary Carrier (RPM)

32.27

Summary of the Gearbox Shaft Speeds

• Breakage in teeth of planet gear, result in abnormal noise when hitting with its meshing gear.

Dominating peaks in vibration spectrum and time wave at planet pinion frequency 78 CPM was clearly suggesting that abnormal noise must coming from planet gear and its bearing assembly. Possible abnormalities could be

• Increased Bearing clearances of planet gear, result in planet gear teeth hitting to root of its meshing gear and generating abnormal noise

Vibration Analysis Outcomes

Observation After Dismantling of GB

Damaged Planet Gears

Planet Gear Bearing BRG,ROLLER,23244-CCW33,SKF