Bear­ings

DEMM Engineering & Manufacturing - - CONTENTS -

Bear­ing reli­a­bil­ity is a cru­cial com­po­nent of pro­duc­tiv­ity and up­time in ex­pen­sive ma­chin­ery and plant through­out in­dus­tries such as min­ing, man­u­fac­tur­ing, bulk han­dling and pri­mary pro­duc­tion. If a bear­ing fails, pro­duc­tion can grind to a halt.

Bear­ing fail­ures can be caused by a num­ber of fac­tors, in­clud­ing:

1. Fa­tigue, which can oc­cur nat­u­rally over time, but also oc­curs pre­ma­turely if the in­cor­rect bear­ing is cho­sen for the task.

2. In­cor­rect in­stal­la­tion or mount­ing, which can lead to sig­nif­i­cantly higher wear and tear and ul­ti­mately pre­ma­ture fail­ure. Ex­am­ples in­clude mis­align­ment, in­cor­rect fits – too loose or too tight, out- of- round­ness in shafts or hous­ings. About 25 per­cent of bear­ing fail­ures oc­cur be­cause of in­cor­rect mount­ing.

3. Lu­bri­ca­tion prob­lems, which can oc­cur if too lit­tle, too much or in­cor­rect lu­bri­ca­tion is ap­plied to the bear­ing. In­cor­rect or in­suf­fi­cient lu­bri­ca­tion is the sin­gle big­gest cause of bear­ing fail­ure, ac­count­ing for more than 45 per­cent of prob­lems.

4. Poor main­te­nance or mon­i­tor­ing, be­cause even the best pre­ci­sion bear­ings are not ‘set-and­for­get’ tech­nolo­gies. Their main­te­nance needs change with ser­vice and lo­cal con­di­tions, so good mon­i­tor­ing and suit­able main­te­nance is vi­tal. (See con­clu­sion for fur­ther de­tails.)

5. Con­tam­i­na­tion, which can oc­cur when for­eign sub­stances en­ter the bear­ing. It is of­ten con­sid­ered to be the ma­jor com­po­nent of lu­bri­ca­tion prob­lems. Con­tam­i­na­tion is par­tic­u­larly preva­lent in ag­gres­sive process and man­u­fac­tur­ing en­vi­ron­ments, such as min­ing, pri­mary pro­duc­tion and bulk han­dling.

BEAR­ING CON­TAM­I­NA­TION CHAL­LENGES

“De­spite it be­ing an em­i­nently pre­ventable prob­lem, a stag­ger­ing 25 per­cent of all bear­ing fail­ures are caused by con­tam­i­na­tion,” says Martin Grosvenor, In­dus­trial Sec­tor Man­ager, Scha­ef­fler Aus­tralia.

“Con­tam­i­nants can in­clude air­borne dust, dirt or any abra­sive sub­stance that finds its way into the bear­ing. The main sources of these con­tam­i­nants are dirty tools, con­tam­i­nated work ar­eas, dirty hands and for­eign mat­ter in lu­bri­cants or clean­ing so­lu­tions,” ex­plains Grosvenor.

Symp­toms of a con­tam­i­nated bear­ing in­clude ex­ces­sive vi­bra­tion and wear, which is best de­tected be­fore it be­comes ex­pen­sively ob­vi­ous in the form of un­sched­uled main­te­nance, or worse, pro­duc­tion break­down.

SCHA­EF­FLER SO­LU­TION

In chal­leng­ing en­vi­ron­ments or op­er­a­tions where the risk of con­tam­i­na­tion is high, such as con­tin­u­ous cast­ing plant, con­veyor belts, el­e­va­tor plant or food in­dus­try ap­pli­ca­tions, Scha­ef­fler’s FAG Sealed Spher­i­cal Roller Bear­ing (SRB) is ide­ally suited to the task.

FAG SRBs are a spe­cial rolling bear­ing de­sign where the in­ner ring runs in­side the outer ring on two rows of rollers. The bear­ings have an an­gu­lar ad­just­ment of up to 2° and are not only de­signed for high load car­ry­ing ca­pac­ity but can also com­pen­sate mis­align­ments, due to the fact that the sym­met­ri­cal bar­rel rollers ori­ent them­selves freely on the con­cave outer ring race­way.

FAG Sealed SRBs of­fer the same ben­e­fits as open SRBs, but with seals typ­i­cally con­sist­ing of nitrile rub­ber or, high per­for­mance flu­oro rub­ber* de­pend­ing on the ap­pli­ca­tion and op­er­at­ing con­di­tions.

FAG Sealed SRB’s are avail­able to suit a wide range of com­mon ap­pli­ca­tions in Heavy In­dus­tries such as Pulp & Pa­per, Min­ing, Min­er­als Pro­cess­ing, Wood Prod­ucts, Power Gen­er­a­tion. (For more in­for­ma­tion on the com­plete range, please re­fer to the prod­uct cat­a­logue.)

“The seals ef­fec­tively close off the bear­ings, giv­ing them an in­creased op­er­at­ing life com­pared with open bear­ings, be­cause they are pro­tected from con­tam­i­nants.

“Ad­di­tion­ally, they re­quire sig­nif­i­cantly lower quan­ti­ties of grease to keep them lubri­cated (up to 80 per­cent less in some ap­pli­ca­tions1), which means they can as­sist in re­duc­ing en­vi­ron­men­tal im­pacts too,” said Grosvenor.

OTHER FEA­TURES OF SEALED SRBS IN­CLUDE:

• Very high ba­sic dy­namic and static load rat­ings.

• En­vi­ron­men­tally friendly char­ac­ter­is­tics.

• Lower grease con­sump­tion and dis­posal costs.

• No re­quire­ment for ex­pen­sive re­lu­bri­ca­tion sys­tems.

• Re­duced main­te­nance out­lay.

• Sim­ple re­con­di­tion­ing.

X- LIFE SEALED SRBS

Scha­ef­fler’s FAG Sealed SRBs are also avail­able in X- life ranges (marked by the suf­fix E1), which have im­proved kine­mat­ics, op­ti­mised sur­faces, are made from higher per­for­mance ma­te­ri­als and do not have a rigid cen­tral rib.

These en­hanced char­ac­ter­is­tics of the premium X-life range mean that un­der iden­ti­cal op­er­at­ing con­di­tions, ba­sic dy­namic and static load rat­ings as well as the ba­sic rat­ing life of the bear­ing is sig­nif­i­cantly im­proved. In cer­tain ap­pli­ca­tions, this means that a smaller bear­ing ar­range­ment can be de­signed.

SCHA­EF­FLER IN­TRO­DUCES LARGEST EVER SEALED SRB

De­signed to help in­dus­try re­duce costs and boost ef­fi­ciency, Scha­ef­fler has de­vel­oped the world’s first sealed 241/1250 spher­i­cal roller bear­ing for high- pres­sure grind­ing roll crusher ap­pli­ca­tions.

In an en­gi­neer­ing mile­stone that is ex­pected to of­fer sig­nif­i­cant cost sav­ings to min­ing and bulk ma­te­ri­als han­dling com­pa­nies through­out the world, Scha­ef­fler has de­vel­oped the world’s first sealed 241/1250 spher­i­cal roller bear­ing.

Fea­tur­ing an out­side di­am­e­ter of nearly two me­ters, the ul­tra-large 241/1250 bear­ing was

specif­i­cally de­signed for the high­est- ca­pac­ity High Pres­sure Grind­ing Roll Crush­ers (HPGRs) used by the min­ing in­dus­try. Pre­vi­ously only avail­able in an open con­fig­u­ra­tion (i.e., with­out seals), Scha­ef­fler’s new sealed ver­sion of this mas­sive roll sup­port bear­ing is de­signed to prevent the crush­ing ma­te­ri­als from con­tam­i­nat­ing its in­ter­nal com­po­nents.

Scha­ef­fler de­vel­oped the sealed 241/1250 bear­ing to help the min­ing in­dus­try cut costs and boost ef­fi­ciency. Un­til now, min­ers have typ­i­cally been forced to in­ject high quan­ti­ties of grease into the bear­ings to prevent con­tam­i­na­tion. While nec­es­sary, this prac­tice wastes re­sources and sig­nif­i­cantly in­creases a mine’s pre­ven­tive main­te­nance ex­pen­di­tures. By in­tro­duc­ing a sealed bear­ing for this chal­leng­ing ap­pli­ca­tion, Scha­ef­fler’s in­no­va­tion prom­ises to also in­crease min­ing pro­duc­tiv­ity.

The bear­ing’s sheer mass – as ev­i­denced by a to­tal weight of ap­prox­i­mately eight met­ric tons, in­clud­ing rolling el­e­ments that weigh 60 kg each – pre­sented an en­gi­neer­ing chal­lenge that very few com­pa­nies are able to mas­ter, even be­fore the com­plex seal­ing ar­range­ment is fac­tored in. The out­side di­am­e­ter of the moulded seal, which fea­tures unique de­sign el­e­ments that were first de­vel­oped for ma­rine ap­pli­ca­tions, mea­sures ap­prox­i­mately 1.4 me­ters.

The state- of-the-art seal­ing prop­er­ties are pro­vided by metal shields in­stalled on both of the bear­ing’s side faces, each of which fea­tures an op­ti­mised poly­mer seal that pre­vents the ingress of crush­ing ma­te­rial. Ac­cord­ing to Scha­ef­fler In­dus­try Man­ager for Raw Ma­te­ri­als, Mike White, “The new sealed ver­sion of our high per­for­mance 241/1250 bear­ing is ex­pected to of­fer sig­nif­i­cantly longer op­er­at­ing life, while sub­stan­tially re­duc­ing the cost of pre­ven­ta­tive main­te­nance to the end user. Scha­ef­fler is com­mit­ted to help­ing our min­ing part­ners pro­duce more while con­sum­ing fewer re­sources. We are very proud to be the first bear­ing man­u­fac­turer to of­fer this de­sign im­prove­ment to the min­ing in­dus­try.”

CON­CLU­SION – THE IM­POR­TANCE OF MAIN­TE­NANCE AND MON­I­TOR­ING

High qual­ity bear­ings are a worth­while in­vest­ment be­cause they will op­er­ate re­li­ably for longer. In or­der to op­ti­mise the per­for­mance and op­er­at­ing life of such a valu­able in­vest­ment, proper main­te­nance and mon­i­tor­ing is es­sen­tial. In some cases, it can as much as dou­ble the op­er­at­ing life of the bear­ing.

One method is to in­stall mon­i­tor­ing tech­nol­ogy such as Scha­ef­fler’s FAG SmartQB (in­cor­po­rat­ing SmartCheck tech­nol­ogy) ready-to- use mon­i­tor­ing so­lu­tion for elec­tric mo­tors, pumps, and fans. It is easy to in­stall and does not re­quire any spe­cific knowl­edge about vi­bra­tion di­ag­no­sis, in­clud­ing for com­mon in­stal­la­tions such as vi­bra­tory, grind­ing and rolling pro­cesses.

An­other in­no­va­tive new method is to use the bear­ing as the mon­i­tor­ing de­vice. Scha­ef­fler has re­cently in­tro­duced to Aus­trala­sia it’s new and rad­i­cally ad­vanced Var­i­oSense roller bear­ings that re­port on their own con­di­tion and load through built- in sen­sor clus­ters.

Scha­ef­fler’s new FAG Var­i­oSense bear­ings are con­fig­urable sen­sor bear­ings for mon­i­tor­ing machines, pro­cesses, bear­ing con­di­tion and load across di­verse in­dus­tries where down­time is costly and main­te­nance is ex­pen­sive.

To com­ple­ment ad­vanced bear­ing tech­nolo­gies and mon­i­tor­ing so­lu­tions, a main­te­nance pro­gramme tai­lored to each in­di­vid­ual ap­pli­ca­tion is ideal. In ad­di­tion to check­ing that the bear­ing is op­er­at­ing prop­erly and with­out con­tam­i­nants, this should in­clude re­lu­bri­ca­tion to en­sure the bear­ing does not suf­fer any pre­ma­ture dam­age.

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