Product spillage caused by material sticking to conveyor belts and discharging after passing hopper openings is a significant maintenance and safety concern in the aggregate industry (see "Belt Cleaners Aid Production and Cut Cost," page 32). This spillage, resulting in a pile of fine aggregate waste material under the belt, can be eliminated by applying the proper belt cleaner or cleaners.

Belt cleaners are available in many forms from several manufacturers. Each cleaner functions differently to remove the product from the belt. Though nearly all cleaners can be effective for a short time, enduring effectiveness varies based on the composition of the cleaner's surface.

Three other variables also must be considered when evaluating belt cleaner performance:

* constant tension between the cleaner and the conveyor belt;

* condition of the conveyor belt; and

* type of material sticking to the belt.

Belt-cleaning tips Position the cleaner or cleaners so that the cleaning surface or blade is in contact only with the portion of the belt actually carrying aggregate material. If the cleaner blade extends onto parts of the belt that are not carrying material, the blade will wear unevenly, reducing its effectiveness and allowing material to bypass the cleaner.

Use caution when applying any type of metal cleaner to a conveyor belt, particularly when the belt is mechanically spliced. A bent or broken fastener can adhere to a metal cleaning blade and tear the conveyor belt.

When mechanically splicing a conveyor belt, skive out part of the top cover, being careful not to skive into the fabric. Countersink the fasteners, covering them with a urethane or belt repair compound to create a smooth contact surface for the belt cleaner blade.

For most effective cleaning, always use primary cleaners-cleaners mounted just under the three o'clock position on the conveyor's head pulley. Cleaners that mount underneath the conveyor behind the snub pulley will be considerably less effective.

When selecting a belt cleaner, do not use strips of conveyor belt material as the cleaning blade. These belting strips are fabric-reinforced and are the same durometer as the conveyor belt they are cleaning. Using them could cause excessive wear on the conveyor belt, resulting in shortened belt life.

Perhaps the most important component in a belt-cleaner system is the tensioning device. There are as many tensioning devices as there are cleaners. Regardless of which is chosen, adjust the tensioning device so that excessive pressure does not force the cleaner blade too hard against the belt.

Many aggregate facilities use a makeshift approach to cleaning their conveyor belts, such as an old piece of rubber fastened under the discharge section of the conveyor belt. As many maintenance personnel know, that will not work for very long. The best approach is to consult your distributor or supplier to help select the proper cleaner for your application.

Properly applied belt cleaners will save money spent on unnecessary clean up of product spilled under the belt, as well as increase safety. Remember, always disconnect power when working on any piece of equipment and observe all the plant's safety policies and practices.

Lafarge Corp. recently signed an agreement with PSDI to implement an Internet-based procurement process for obtaining maintenance, repair and operations materials. Lafarge will use PSDI's Maximo software in conjunction with its MRO.com services (www.mro.com) to manage materials for 15 cement plants and 25 corporate, regional and branch sales offices in North America. In addition, Lafarge will use a standardized catalog on its company network, linking more than 1,000 users.

"As the cement industry becomes more competitive, managing our assets and having access to the materials needed to run our company becomes an important aspect of our business strategy," said James Vreugdenhil, director of purchasing for Lafarge.

Other online MRO procurement services include Applied Industrial Technologies (www.applied-access.com) and VendQuest (www.vendquest.com). Both sites are accessed from any Internet service and browser but require registration before purchasing replacement parts and maintenance supplies from a range of manufacturers.