There are three major contributors that can affect overall performance of tires and trunnions on kilns, and each of these factors taken alone can cause significant damage when operating incorrectly. They are: contact mechanics, material makeup, and friction management.

Any work that can be done to improve any one of these items automatically improves the performance of the other critical areas even though nothing may have been done directly to improve the non-performing areas.

The cause and effect among these three areas is not a simple science and requires experienced technicians or maintenance staff to personally visit the sites and customize solutions to ensure that an ideal operating environment is achieved.

There are products, such as those developed by Kelsan, that are said to increase traction or reduce friction and drag with components that improve the lasting qualities of steel. These products are said to impregnate the steel surfaces as opposed to sitting on the surface. The products also do not migrate like grease. Instead, they will transfer only when there is direct pressure.

Contact mechanics This area relates to the alignment of the tire to the trunnion through the complete cycle of the kiln process. The load and directional thrust of the forces on the tire and trunnion change considerably as the load moves through the kiln.

For years, the industry has developed some highly technical engineering solutions to alignment challenges. The field operators also have developed some innovative approaches that improve the results in the short term. However, the OEM engineers would not approve of some of these approaches because the evidence of long-term cost benefits exceeds the short-term savings. The cost of achieving an improvement in contact mechanics involving the operating dynamics is quite expensive.

Material makeup Material makeup includes hardness, cleanliness of environment, and fracture toughness. Extensive research has been carried out to determine the best approach for least cost operations over the life of the kiln. Field engineers have developed their own views regarding the best approach and metal toughness, with many advances being made over the years.

The cost of achieving an improvement in material makeup involving the operating components of the plant is expensive and not a real option until replacement comes around. Even at replacement, the tire and the trunnion, for example, do no necessarily get replaced at the same time. If you change the material makeup of one without changing the other, then you can lose far more than you gain.

Friction management Friction management includes the full range of ideal friction operating levels, from extremely low to very high. Until now, the only real focus of friction management was to use lubrication to reduce friction. However, Kelsan has developed products that will lubricate in the roll and grip in the slip.

Friction management is the least expensive factor to change. The synthetic improvement in performance in the other two areas just from the application of friction management products is generally sufficient to increase the overall operating performance of a kiln.

The Kelsan friction management approach comes from a different focus and uses a barrier approach that ensures that no masking occurs. The fundamentals of the operating system are improved, giving a sustainable improved operating environment that increases the life of the interfacing working steel components, thus reducing maintenance and replacement costs.

While the Kelsan products are a synergistic contribution to the operation of a kiln system and can contribute to the effectiveness of contact mechanics, kiln tire material, and operating dynamics, they will not overcome significant misalignment or problems with the system on their own. The better aligned a kiln is and the smoother the tire and trunnion surfaces are prior to the application of any product, the better the results will be.

In the cement industry, the following applications have proven the most popular:

* Thrust buttons/rollers The area where the largest savings have resulted is thethrust rollers with solid friction modifier (SFM) sticks. In one case, the drum walking was so significant that the thrust rollers were coming under extreme pressure and the surface of the roller was covered with flat spots where the side of the tire was contacting the thrust roller and grinding it. The bearings on the thrust roller were not coping with the pressure, and the whole roller was getting red hot as the result of the pressure. SFM sticks were applied, and the flat spots have gone, while the surface of the thrust bottom is smooth and shiny.

* Kiln-to-tire lubrication One of the most common problems is excessive tire pad wear. These pads sit between the tire and the shell and can be costly to repair or replace. Solid flex lubricant (SFL) sticks and GritGuard lubricant have been successful in this area.

* Tire to trunnion Another application is the tires and trunnions, which have common problems such as scalloping, pitting, flaking, and flat spots. These problems are costly to repair in terms of labor. It can be expensive to replace the tires and trunnions when downtime is added, which often runs in excess of $100,000 per day. The solid lubricant (SL) sticks have been effective in this area.

Information for this article was supplied by Kelsan, 1-800-7KELSAN. All views expressed in this article are those of the Kelsan and are not necessarily those of the editors.