Mounted bearing installation and best practices for the grain industry

Transcription

1 CONVEY 18 / Mounted bearing installation and best practices for the grain industry Marc Mondi, Territory Manager ABB/Dodge

2 Agenda OSHA standards related to grain handling bearings Bearing myths Mounted bearings what are they? Mounted bearings where are they? Types of mounted bearings / characteristics Bearing installation best practices Alignment Shaft tolerance Torque specs Lubrication of mounted bearings Seals Mounted bearing long-term storage 2 Baldor Electric Company

3 OSHA standards related to bearing maintenance Standard (m) Preventative maintenance (1) (m )(1)The employer shall implement preventive maintenance procedures consisting of: (m )(1)( i) Regularly scheduled inspections of at least the mechanical and safety control equipment associated with dryers, grain stream processing equipment, dust collection equipment including filter collectors, and bucket elevators (m )(1)(ii ) Lubrication and other appropriate maintenance in accordance with manufacturers' recommendations, or as determined necessary by prior operating records Appendix A (2) Equipment such as critical bearings, belts, buckets, pulleys, and milling machinery are potential ignition sources, and periodic inspection and lubrication of such equipment through a scheduled preventive maintenance program is an effective method for keeping equipment functioning properly and safely. The standard does not require a specific frequency for preventive maintenance. References 1. / pls/ oshaweb/ owadisp.show_document?p_table=standards&p_id= / pls/ oshaweb/ owadisp.show_document?p_table=standards&p_id= Baldor Electric Company

4 Mounted bearing myths 1. If lubricant is visible easing out around the shaft and seal, the bearing has too much lubricant and the seal has been broken 2. Bearings should not be hot to the touch 3. It's fine to hand-tighten setscrews one at a time 4. If a shaft spins inside a bearing race, simply tighten the setscrews more 5. Sealed/ lubed-for-life bearings will las t forever 6. Re-lubrication once a year is sufficient 7. Any greas e will do 8. Just shoot grease through the fitting 9. If a bearing makes noise, grease should be added References 1. / Departments/ Feed-Operations/ 2015/ 5/ Replacing-bearings-and-motors.aspx?cck=1 2-3, / single-article/ debunking-the-myths-around-bearings.html?print=1 4 Baldor Electric Company

5 Mounted bearings: what are they? Mounted Ball Bearing Standard Naked Ball Bearing A self-contained system with it s own sealing package, lubrication system, & misalignment capability Housing Spherical outer ring Wide inner ring Mechanical shaft attachment Sealing system A component part of a larger piece of equipment, like a motor, pump, reducer / conveyor roller Cylindrical outer ring Narrow inner ring Limited sealing system (shielded) Loose or press fit shaft attachment

6 Mounted bearings: where are they? Pit conveyors

7 Mounted bearings: where are they? Bucket elevators - head section

8 Mounted bearings: where are they? Bucket elevators - head section

9 Mounted bearings: where are they? Reclaim conveyors

10 Mounted bearings: where are they? Reclaim conveyors

11 Mounted bearings: where are they? Reclaim conveyors - incline

12 Mounted bearings: where are they? Distribution conveyor - belt conveyor

13 Mounted bearings: where are they? Distribution conveyors

14 Ball bearing characteristics Used for light to medium loads, and low to high speeds. Radial Load Can handle pure radial load, pure thrust load, or combination of both No minimum loading requirement to prevent skidding damage Thrust Load Capable of static misalignment Point Contact D-Lok

15 Ball bearing construction Outer Ring Flinger Seal Cage Inner Ring SC/SCM

16 Tapered bearing characteristics Used for medium to heavy loads, and low to high speeds Pure radial load, pure thrust load, or any combination of both No minimum loading requirement to prevent skidding damage Many are capable of static misalignment Great for augers/screw conveyors Thrust Load Radial Load Full contact Type EXL

17 Tapered bearing construction Cup Setscrew collar Cage Seal Type EXL Cone

18 Spherical bearing characteristics Used for medium to heavy loads, and low to high speeds Require one pound of radial load for each pound of thrust load Minimum load (> % of cataloged C) Capable of both static and dynamic misalignment Not recommended for augers/screw conveyors S-2000 Curved contact Imperial

19 Spherical bearing construction Outer Race Inner Race Seal Adjusting nut Roller Imperial Adapter Sleeve

20 Alignment Almost all mounted bearings are self -aligning Misalignment is usually caused by improper installation and can lead to premature bearing failure due to: Excessive loading High bearing temperatures Vibration Consult manufacturer s literature to identify the acceptable degree of misalignment

21 Alignment, cont. Forms of misalignment: 1. Static Conditions bearing and shaft axis not co -linear before operation Most mounted bearings have the ability to statically misalign Bearing supports not on same plane vertical axis, horizontal axis Deflection misalignment shaft bending in a fixed direction due to load 2. Dynamic misalignment conditions bent shaft; unbalanced rotating load Only spherical roller bearings and double row ball bearings can dynamically misalign Static Dyanmic

22 Shaft tolerance Most mounted bearings are slip locking device Provides easy installation Excessively undersized shafting may result in: -fit over the shaft, and secured with a Increased vibration, increased temperature, reduced locking ability If a bearing is not secured to a shaft, or loses lock to shaft, the shaft can rotate in the bearing bore causing damage to both bearing and shafting Shaft size Recommended Setscrew, Eccentric/Concentric Collar Mounted Bearing Recommended Tapered Adapter Sleeve Mounted Bearing Commercial Shafting Over Incl Min Max Min Max Min Max 0 1.1/ /2 2.1/ /

23 Torque specs setscrews & bolts All setscrews and bolts (cap/base) have a torque spec Not specific to manufacturer, but rather standard for fastener size Refer to instruction manual for proper spec Under-torqued fasteners can cause bearing failures (slipping/ spinning) Over-torqued setscrews can cause cracking of raceways

24 Usage of anti -seize caution Fretting corrosion While OK to use with setscrew mounted bearings, adapter mounted/tapered bearing surfaces never use anti -seize on These bearings rely on metal -metal contact for proper installation Use of anti -seize can cause false tightening, causing bearing sleeve to spin on shaft Light lubricant on sleeve threads is generally OK

25 Grease lubrication 90% of all bearings manufactured today are grease lubricated Advantages to grease lubrication include: Simple design Action of the grease as a sealing agent Long Service Life Simple lubricating equipment Greased for life bearings can be used on less strenuous equipment If high stresses are involved (speed, temperature, loads) re -lubrication at appropriate levels must be planned.

26 Re-lubrication Intervals General re-lubrication intervals are listed in Dodge instruction manuals. Utilize these intervals as a starting point and increase or decrease frequency depending on temperature, contamination, loads, speed.

27 Re-lubrication quantities and type Begin with general recommendation in respective installation manual Ensure grease gun and zerk are free of contaminants At the prescribed re -lube interval, re -lubricate the bearing while it is rotating, if safe to do so, until fresh clean grease is seen purging at the seals. If purged grease is clean after a small quantity of lubricant is used, then increase the time interval between re -lubrication Rule of Thumb: 3 shots grease / inch of shaft size Less grease, more often > more grease, less often Lithium -based greases only standard bearings (NLGI #2) Dodge Roller Bearings use Mobilgrease XHP222 (Dark Blue) Dodge Ball Bearings use Mobil Unirex N2 (green in color ) Washdown bearings use Mobil FM222 Aluminum complex Recommend not mixing greases bases

28 Grease base compatibility AL COMPLEX BARIUM COMPLEX CALCIUM CALCIUM COMPLEX LITHIUM LITHIUM COMPLEX POLYUREA AL COMPLEX BARIUM COMPLEX CALCIUM CALCIUM COMPLEX CLAY LITHIUM LITHIUM COMPLEX POLYUREA SODIUM NOT COMPATIBLE COMPATIBLE BORDERLINE 28

29 What is grease? G R E A S E Additives 0-10% Types: EP additives, corrosion preventatives, AW agents Base oil 75-95% Main characteristics: oil type, viscosity (most important characteristic) Thickener 5-20% Main characteristics: consistency

30 Purging grease Re-lubricating Replaces and pushes old grease out Pushes contaminants out and/or away from the bearing Provides fresh grease to rollers and raceways Recharges grease dams Seal crimped in outer ring / housing

31 Lubrication Ideal bearing Grease barrier: contamination out

32 Lubrication Visual: no signs of grease When was bearing lubricated?

33 Lubrication Lubricate during rotation (safely) Grease purging in one area: temperature at start up (100% fill)

34 Bearing lubrication purging contaminated grease

35 Bearing temperature High Temperature Description Normal Operating Temp below 212 F (100 C) Causes Insufficient/Excessive Aged lubricant Poor Installation Extremely small bearing clearance Improper / Ineffective Lubricant Temperature rise expected during start up and when bearing is Pain Threshold 130 F Water Evaporation 220 F re-lubricated

36 Seals Different types Contact Labyrinth Other (aux., end caps, cast closed) Seal that is best for each application varies with environment and application

37 Sealing System 4 grease dams

38 Sealing Systems End covers: Safety / contamination out

39 Bearing failures (80% of all premature bearing failures are lubricant related) Wrong Bearing 9% Installation 10% Mfg Defects 1% Wrong Lubricant 20% Lubrication 80% Aged Lubricant 20% Solid Contamination 20% Insufficient Lubricant 15% Liquid Contamination 5%

40 Bearing storage guidelines All bearings should be stored in a cool, dry area Keep unused bearings in manufacturer s packaging An additional light coating of oil or rust preventative can help extend storage life Apply bead of #3 or #4 grease at seal, housing and shaft junctures Rotate inner ring minimum of revolutions every 2-6 months Standard long -term shelf life approx. 3-5 years

41 In summary Ball bearings lighter loads, higher speeds Tapered bearings high loads, slow speeds Spherical bearings high loads, medium speeds (preferred bearing except for augers) Check shafts for tolerance and properly torque bearing fasteners Be cautious when using anti -seize, especially with adapter mount bearings Good maintenance and lubrication is critical to long bearing life Lithium -based greases / NLGI #2 Choose the correct grease Re-lubricate when running Purge bearings of old grease until fresh grease develops at seal area Maintain critical spare bearings 41

42 Questions? Thank you for your time! Marc Mondi Territory Manager ABB/Dodge West Des Moines, IA