Equipment specification SectionRaw MillII Equipment NameRaw Mill Main

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

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: 30 PM 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.

Observation and Before stoppage analysis: 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

Vibration Trend (30. 10. 2013 to 22. 01. 2014) LINE-2 Equipment Vibration Report VRM LINE-2 Location MOTOR Direction Units After BD Value on Value on 30. 10. 2013 26. 11. 2013 26. 12. 2013 11. 1. 2014 17. 1. 2014 22. 1. 2014 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 GEAR BOX Vertical mm/sec 1. 89 2. 14 2. 11 1. 88 2. 5 1. 5 G. B. INPUT DEA 1 Axial mm/sec 3. 49 3. 14 2. 62 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 DEV 1 Vertical mm/sec 6. 34 6. 54 4. 63 5. 68 6. 06 4. 37 G. B. INPUT DEH 2 Horizontal mm/sec 5. 26 6. 91 5. 76 5. 7 4. 79 3. 63 G. B. INPUT DEV 2 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 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

Time Wave Form

Waterfall Diagram

Summary of the Gearbox Shaft Speeds Stage of Drive Motor Bevel stage Input Pinion Shaft ( RPM) 990 Helical Shaft (RPM) 217. 80 Planetary Stage Sun Gear (RPM) 217. 80 Related Planet Pinions (RPM) 78. 12 Planetary Carrier (RPM) 32. 27

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

Observation After Dismantling of GB

Damaged Planet Gears

Planet Gear Bearing BRG, ROLLER, 23244 CCW 33, SKF