Con­di­tion-based main­te­nance ( CBM) by ifm


The more a plant runs, the more ef­fi­cient it is. That is, of course, un­til it breaks down.

Dif­fer­ent op­er­at­ing philoso­phies can be ap­plied to r un­ning any op­er­a­tion. Tra­di­tion­ally i t was com­mon to take the ma­chine out of ser­vice on a reg­u­lar ba­sis, ser­vice i t, and then put i t back i nto op­er­a­tion but more re­cently that has been seen as po­ten­tially waste­ful, be­cause there might not ac­tu­ally be any­thing that needs do­ing, yet the pro­duc­tion time will never be re­gained.

The tech­nol­ogy to pre­dict what could go wrong has never been bet­ter than it is to­day, so there is ev­ery rea­son to run ma­chines as much as pos­si­ble and only stop to main­tain them based on the con­di­tion they find them­selves in.

Es­ti­mates vary, but it gen­er­ally ac­cepted that at least 70 per­cent of all hy­draulic fail­ures and up to 45 per­cent

of all bear­ing fail­ures are caused by oil con­tam­i­na­tion. So, it cer­tainly makes sense to mon­i­tor the con­di­tion of the oil in any sys­tem.

Two ma­jor fac­tors de­ter­mine the con­di­tion of the oil; how much wa­ter it con­tains and the ex­tent of solid par­ti­cle con­tam­i­na­tion.

What are the con­se­quences of wa­ter in oil? Once any wa­ter mol­e­cules dis­solved in oil ex­ceed sat­u­ra­tion of the oil, the wa­ter will ex­ist as droplets in emul­sion, then even­tu­ally free wa­ter. It is these lat­ter two stages that can cause the most harm through cor­ro­sion, and the in­com­press­ibil­ity of wa­ter which leads to wear. Wa­ter will cause the vis­cos­ity of the oil to de­te­ri­o­rate and will re­act chem­i­cally with the oil thereby hav­ing a detri­men­tal im­pact on its lu­bri­cat­ing prop­er­ties. In ad­di­tion, wa­ter will lead to age­ing (ox­i­da­tion) of the oil. The end re­sult will be cav­i­ta­tion of pumps, and poor fil­ter­abil­ity, lead­ing to a re­duc­tion in fil­ter ser­vice in­ter­vals, and over­all a re­duc­tion in ma­chine avail­abil­ity.

When it comes to de­tect­ing the amount of wa­ter in the oil, ifm elec­tronic Ltd of­fers and ideal so­lu­tions with their LDH. The LDH is a sen­sor de­signed to mea­sure the rel­a­tive wa­ter con­tent in the oil in the range of 0 to 100 per­cent by means of a ca­pac­i­tive mea­sur­ing el­e­ment and to pro­vide this as a pro­por­tional 4 to 20mA sig­nal.

To break that down a bit: At 0 per­cent the oil is ab­so­lutely “dry”, and the out­put sig­nal level oud be 4mA. At 100 per­cent the medium is com­pletely sat­u­rated, and this would be sig­nalled by 20mA. No more wa­ter can then be dis­solved so it is present as free wa­ter, which causes a cloudy ap­pear­ance. The wa­ter mol­e­cules are no longer in the gas phase but they are present in the oil in liq­uid form. The LDH100 sen­sor mea­sures in the gas molecule phase.

The great ad­van­tage of this is that coun­ter­mea­sures can be taken long be­fore free wa­ter is formed.

Be­sides the rel­a­tive wa­ter con­tent the sen­sor also mea­sures the oil tem­per­a­ture as a 4 to 20mA sig­nal be­tween -20°C and +120°C, and it will op­er­ate up to a sys­tem pres­sure of 50 bar.

So, that is the wa­ter prob­lems solved, but what about solid par­ti­cles?

The pres­ence of solid con­tam­i­nant par­ti­cles in the oil in­ter­feres with the abil­ity of the fluid to lu­bri­cate and causes wear to the com­po­nents. The ex­tent of con­tam­i­na­tion in the fluid has a di­rect bear­ing on the per­for­mance and re­li­a­bil­ity of the sys­tem and it is nec­es­sary to con­trol solid con­tam­i­nant par­ti­cles to lev­els that are con­sid­ered ap­pro­pri­ate for the sys­tem con­cerned. Heav­ily con­tam­i­nated oil can re­duce the power by as much as 15-20 per­cent, slow­ing ma­chine re­sponse and tak­ing longer to per­form an op­er­a­tion.

Re­mem­ber­ing that at least 70 per­cent of all hy­draulic fail­ures are caused by oil con­tam­i­na­tion, what is the cure? Fil­ters can be used, and they are valu­able, but the sys­tem needs to be turned off to check or change them. Again, the so­lu­tion can be found in the prod­uct range of ifm elec­tronic Ltd with the LDP par­ti­cle count mon­i­tor.

Oil clean­li­ness i s stan­dard­ised un­der ISO 4406, and the LDP mon­i­tors to this this stan­dard, mean­ing that par­ti­cle sizes of 4 ‘ m, 6 ‘ m, 14 ‘ m & 21 ‘ m are de­tected and re­ported. The op­ti­cal tech­nol­ogy deep with the LDP de­tects any par­ti­cles and pro­vides the in­for­ma­tion in the form of ana­logue, dig­i­tal or CAN out­puts.

The LDP is de­signed to take the pres­sure, too, with a dy­namic rat­ing of 420 bar and a static rat­ing up to 600 bar.

So, keep­ing plant run­ning at its most ef­fi­cient is a wor­thy aim, but only pos­si­ble with the right equip­ment. The right equip­ment, and ad­vice, comes from the right sup­plier: ifm elec­tronic Ltd, says the com­pany. ifm elec­tronic is com­mit­ted to work­ing closely with its cus­tomers and de­vel­ops prod­ucts which pre­cisely match their needs, it prom­ises. The com­pany pro­vides ex­pert, read­ily ac­ces­si­ble tech­ni­cal sup­port to help users max­imise the ben­e­fits they gain from ifm elec­tronic prod­ucts.

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