Bulk Solids Article

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Reprintfrom

Volume 18 Number 4OctoberIDecember 1998

Bulk Material Conveyor Belt InstallationVulcanizing and Maintenance

200 Paris AvenueNorthvale New Jersey 07647 USA

800-225-REMA

Belt Maintenance Group

240 Seneca StreetBuffalo New York 14204 USA

800-588-1 283


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Conveyor Belt Technology Volume 8 Number 4 October/December 998

ulk Matefial Conveyor eN Installatlan Vulcanhinmand Maintenance

This article provides an overview of con-veyor belt installations, vulcanizing, andpreventive maintenance. Installation ac-tivities covered include installation pointdetermination, pulling methods, beltbraking, and positioning for splicing. Vul-canizing activities covered include gen-eral splicing considerations for fabric car-cass and steel cable belts. Maintenanceactivities covered focus on the impor-tance of inspections and provide guide-lines on repair methods.

Once the belt has been specified and .purchased for the bulk material convey-ors, three activities must take place to ensure that the system delivers the de-signed output and that the belt meets, orexceeds, its expected service life. Thebelt must be installed on the system; itmust be spliced; and the system musthave regular maintenance.Belt installation, by its simplest definition,is the placing of the new belt on the con-veyor system. In those cases where the

new belt is replacing a worn or damagedone, the old belt is normally used as aguide to ensure that the new belt followsthe correct belt path around pulleys andon idlers. When a belt is being installed ona new system, or when the old belt hasbeen removed, a cable is strung on thesystem to perform this task. Proper in-stallation techniques allow the new belt tobe put in place without damage to thebelt or the system.Splicing is the activity of joining the twobelt ends together to form one continu-ous belt that is capable of carrying thebulk material. Although there are essen-tially three methods of splicing conveyorbelts, this article will focus on the vulcan-ization method only, as this is the onlymethod which can be used for both fab-ric carcass belts and steel cable belts.The vulcanized splice is also recognizedas the splice method which provides thegreatest strength and longevity. Propervulcanizing techniques ensure optimumtotal belt strength.Maintenance of the conveyor system isthe single most important activity that aconveyor system operator can perform topromote continuous, trouble-free move-ment of the bulk material being carried.This activity, which is the identificationand correction of problem areas as they

occur, helps to avoid untimely and costly stallation point, the belt roll handlingshutdowns or catastrophic belt failures. method, the means of pulling the newIn this article, general methods for com- belt on, and the preferred splicing point.pleting all three of the above activities are 0 systems here a significant change inpresented with the intent of providing an elevation is Present, consideration mustoverview for the reader. In practice, the also be given to a braking device to Pre-best methods for installing, splicing, and vent unexpected runaway of the newmaintaining any given conveyor belt are belt. All aspects of the installation shouldsystem specific. The conveyor operator be considered before starting.should confer with the belt manufact~rer, The new roll, 4r rolls, of belt must besystem designer, installation/splicing placed where there is adequate spacecompany ifused), and conveyor industry available for them and for a winder, orassociation to determine which meth- other belt-pulling device. hi^ space re-0ds are best suited to the System in quirement is the prime factor in determin-question. ing the new belt installation point. Other

important factors include worker safety,Belt Itmtahths accessibility, utility hook-up points, andheavy equipment needs. The Belt Mainte-Before installing a new conveyor belt on a nance Group attempts to have the newsystem, a number of factors must be belt installation point at the tail pulley.taken into consideration. Important deci- However, too many systems have wallssions have to be made concerning the in- or other conveyors at this point. When

sing the belt to feed the new one ensures proper placement


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~Qr dg: Volume 18 .Number 4 .October December 1998 conveyor elt Technology

this occurs, the installation point mayhave to be either under or over the sys-tem. In some installations, part of theconveyor system, building, or other struc-ture may have to be dismantled to allowaccess.If the new belt is a replacement for onethat is on the system, the old belt is com-

monly used to pull the new belt intoplace. This has the added advantage ofhelping to ensure that the new belt is in-stalled right side up as the top covercan be matched with that of the old belt.The new belt is generally attached to theold belt by means of mechanical fasten-ers for fabric carcass belts or by means ofa joiner plate or a partial splice for steelcable belts. If the belt is being installed ona system that does not have an existingbelt, the general practice is to run a cablealong the intended belt path and use it topull the belt into position. The fasteningmethod between the new belt and the oldbelt, or cable, must be strong enough toovercome all frictional forces of the beltagainst the idlers and pulleys, the gravita-tional forces of any changes in elevation,and the inertia forces involved with thestart of the pull.Depending on the length and weight ofthe belting being installed, the most com-mon method of pulling the belt on is touse a winder. The winder reels the cableor old belt at a controlled speed. In doingso, the new belt is fed on to the conveyor.In some cases, a winder is not sufficientlystrong enough to pull the belting into po-sition. Heavy motorized equipment, suchas earth movers or trains, have beenused to provide the necessary pullingforce. Specialized methods are requiredwhen a straight pulling force is not practi-cal. In some cases, the use of a crane tosupport a diverting roller will facilitatepulling by a winder or by a piece of heavyequipment. A belt winder is the preferredmethod for pulling a belt on the system asthe old belt or the cable is convenientlywound during the installation process.This saves time and expense, as extrasteps to handle the old belt or cable arenot required.

One special installation criteria needs tobe considered whenever a belt is beinginstalled on a system that has a signifi-cant change in elevation a braking sys-tem must be used for the roll of new belt-ing. This is to prevent the belt fromunrolling~by tself. If this happens, severedamage could occur to anything or any-one n its path. An efficient installation sdone at controlled speeds where spot-ters follow the leading end of the newbelting as it is being pulled. A brake onthe new belt roll will protect these walk-ers from injury.Other considerations with belt installation

include the positioning of the take-up andspotting the belt ends at the desired

Vulcanizing th splice

splice station. The take-up positioning isimportant whenever belt stretch must beconsidered, as with fabric carcass belts.The take-up should be positioned toallow for the anticipated stretch of thebelt. Ideally, it can be placed so that anadditional splice is not required.If the optimum splice station is differentthan the installation point, a means ofmoving the two ends of the belt to thesplicing area must be used. Frequently,this is accomplished by temporarily join-ing the belt ends together and using thesystem drive to move the belt. Alterna-tively, pulling one end of the belt with awinch or air-tugger can move the beltends to the desired position.Once the new belt is installed and prop-erly positioned, it can be vulcanized andput into service.

The vulcanized splice is widely acceptedas the preferred means of joining two beltends together to form one continuous

belt on the conveyor system. The mostcommonly used belts for bulk materialhandling are fabric carcass and steelcable. There are many variations in thecomposition of fabric carcass belts andthere are variations in steel cable beltstructure resulting from the tensilestrength requirements. In addition tothese variations, there are special vulcan-ization techniques required for the differ-ent rubber materials used by the beltmanufacturers. Also, there are a numberof specialty belts and specialty systemswhich demand specific splicing configu-rations. To a large extent, almost every

belt installation must be evaluated to de-termine which vulcanization method is

most suitable. Due to the multitude of vul-canization methods used, this article willbe restricted to very general considera-tions.The first factor to be considered for thevulcanization process is the belt itself. Thiswill determine the minimum splice require-ment. Once the belt specifications areknown, the proper cements, rubber, andbreaker fabric can be determined. The ac-tual splice layout should be determined byfollowing the belt manufacturer's and sys-tem designer's recommendations. t is im-portant to remember that the system de-sign may require a more involved splicethan that generally required by the beltmanufacturer. An example of this is withsteeply inclined systems with a sharpbend at the upper elevation. Frequently,an extra-long step length for fabric belts ora longer splice length for steel cable beltsshould be used to counter the extraforces placed on the belt at this point.The main vulcanization techniques to beconsidered for multi-ply fabric carcassbelts include belt squaring to ensure astraight splice; material choice to ensurecompatibility and strength; and steplength to ensure proper splice strength.With some systems, the bias angle of thesplice is important. Some systems re-quire a 45 bias angle while others requireless of an angle or no bias at all. It ismandatory to determine the splice re-quirements for the belt before starting.Generally, the Belt Maintenance Grouphas found that the splice should be madewith materials produced by the belt man-ufacturer or with quality Rema Tip Topsplice materials. When this is not possi-ble, compatible materials must be used. Ifthe belt is properly squared; is properly

stripped without damage to the fabric;'has the correct step length; is built with


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Conveyor elt Technology Volume 18ulk

lumber 4 October/December 1998 kydvs

the right materials; and is vulcanized port bulk materials. The next stage of beltunder the proper temperature, pressure related care is the ongoing, or preventive,and time; the splice will be good. The maintenance of the conveyor system.squaring and stripping help to ensure thatthe splice is straight. All of the abovesteps help to ensure that the splice is Mah.1 m Gstrong.Single ply belts, such as solid woven car-

cass, straight warp carcass, and aramidcarcass belts have specific vulcanizedsplice patterns ranging from finger splicesto scab splices. As with the multi-plybelts, the important considerations arethe squaring, stripping, fabric cutting,material selection, vulcanization tempera-ture, vulcanization pressure, and vulcan-ization time.Steel cable or steel cord belts will havespecific splice layout patterns and splicelengths which are largely dependent onthe cable diameter size and spacing. Although the strength of the vulcanizedsplice is largely dependent on the splice

length, it is mandatory that good adhe-sion be achieved between the cables andthe rubber that is between them. This isone of the reasons why extra pressure isused on steel cord splices. It is also desir-able to strip the steel cords in such a

Preventive maintenance s by far the mostlabor-intensive activity related to the con-veyor belt, It, literally, never ends. How-ever, preventive maintenance is also themost cost-effective means of protectingthe operator s conveyor system invest-ment. It pays for itself through increasedconveyor productivity, optimized energyefficiency, and avoidance of unscheduledsystem downtime.

The key ingredient of an effective mainte-nance program is the inspection. Theconveyor system, including the belt,should be inspected before each use oron a frequent, regular basis. By conduct-ing inspections, faulty equipment can be

identified and repaired or replaced beforedamage is caused. The Belt MaintenanceGroup inspects all components of theconveyor system; including the pulleys,the idlers, the belt cleaners, skirting sys-tems, chute liners, impact pads, and the

Inspection and action of system faults can prevent costly wear the belt and idlws

manner as to avoid baring or nickingthem. A stronger bond is achieved whenvulcanizing fresh rubber to the rubberaround the steel cords, as opposed tothe metal itself.With all vulcanized splices, the pressureshould not be relieved until the press plat-tens have cooled to the temperature rec-ommended by the belt manufacturer.Normally, this is 70 C or 150°F

Upon the successful completion of thevulcanized splice and the re-assembly of

any conveyor system components dis-turbed, the system can be used to trans-

belt itself. In addition to these static in-spections, the system should be in-spected while running with a load. Thishelps to identify idlers that are starting tofail, improperly functioning belt cleanersor skirting, and mistraining points.

The inspections provide information onwhat maintenance work needs to edone to prevent a breakdown. Preventivemaintenance requires hat the informationgathered by the inspections be actedupon before there is a problem. There-

fore, any hardware component thatneeds replacement or adjustment, must

be done. A stalled idler can rapidly bestrapped by the belt to the point where itbecomes a double bladed knife that cancut the belt. A worn or poorly adjustedbelt cleaner or skirting can trap material,which can cause severe wear of the beltcover. Worn or poorly adjusted returncleaners can allow material to build-up

between the pulleys and the belt. Thiscan result in damage to both the bottomcover and carcass of the belt. Trappedmaterial can cut a belt in half. Taking ac-tion can be very important.

Damage can occur to the belt even whenall preventive maintenance stops aretaken. When this occurs certain actionsteps can be taken to prolong the servicelife of the belt.

If it is noted that the belt has a hole or ripin it, it should be repaired immediately. Although a temporary repair of fabric car-cass belts can be effected by using solidplate type mechanical fasteners, the beltshould have a vulcanized repair as soonas possible. Depending on the extent ofthe damage, a cold care repair may workwell.

Whenever damage to the belt is noted, adecision must be made as to which typeof repair, if any, is most suitable. Longterm repairs can be achieved by bothcold cure and hot vulcanization methods.A large variety of repair materials areavailable to help correct cover gouges,wear lines, and carcass damage. Gener-ally, cover gouges are repaired with coldcure materials and damage to the splice

or to the carcass results in hot vulcanizedrepairs. Whatever repair methods areused, it is important to make repairs be-fore the injury becomes major.

Repairs to steel cable conveyor belts aregenerally done by means of the hot vul-canization method.

Maintenance work will prolong the ser-vice life of the conveyor belt and the con-veyor providing the most cost-effectiveway of moving tons of material.

A conveyor belt is an important part of thebulk materials handling process. Properinstallation, vulcanization, and preventivemaintenance will help to provide the ex-pected capacity and service life of thebelt. The longer the belt lasts without anyunscheduled downtime, the more prof-itable the system is. Taking care can paydividends.

Maintenance Group, 240 Seneca Street, Buffdo,NY 14204 SA.Tel.: I 716852 0832; ax: 1 716852 4 98;E-mail: bmgbuffalMdnet.att.netwww:

beltmaintenance.com

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Bulk Solids Article