PM Advances Conveyor Reliability

An effective predictive-maintenance plan for conveyor systems will account for all components, not just those that are easily evaluated.

As with all plant assets, scheduled preventive maintenance is the key to avoiding expensive component failure.

By Jason Crain, Motion

Breakdowns are a common occurrence in conveyor systems and, when they happen, immediate part replacement is critical. A broken conveyor translates to high production costs every minute. In many scenarios, this issue is alleviated by having spare components in stock ready for installation, but that takes investment. Not only is there overhead for storing components on a shelf, there’s extra maintenance time and cost to replace something that wasn’t on the schedule.

Many customers do not have the capital to invest in a full second system of parts, or the experienced manpower to promptly fix a problem. How many people have a spare vehicle in their driveway to use for parts if something breaks down during their daily drive?

When your car is being serviced, the servicing shop runs through a full list of checks. This process helps the mechanic ensure, to the best of his/her ability, that you will not have a catastrophic failure. This example is analogous to conveyor systems. You have bearings that need consistent greasing and motors that need their oil serviced and checked. Shafts, scrapers, and pulleys need to be cleared of buildup. Additionally, conveyor belting and skirting needs to be adjusted or observed for damage.

Maintaining easily overlooked components, such as scrapers, can prevent extensive downtime and expense. Proper scraper maintenance has been performed on the system on the right. Photo: Motion

In optimum cases, a preventive-maintenance (PM) plan is created. This is perfect for a consistent maintenance review and keeping components healthy. It also helps you get full life out of each component. But is it an efficient plan? Consistently monitoring key components might take a lot of time and manpower in a world that needs to run with full efficiency.

Thus, we look at what can be monitored with little effort. There are always items that take priority and will pull maintenance crews away from PM tasks. When “firefighting” is required, the PM schedule will tend to be overlooked, often for long periods of time, because there is no perceived urgency attached to preventive functions. This is where catastrophic failure happens.

The following series of events is from an actual occurrence: Maintenance personnel evaluated a belt and motor, as well as the easy-access components, and decided that there were no issues. They checked the main conveyor components, and everything seemed fine. Some time later a bearing failed on an idler because of buildup or it had not been greased. This caused the belt to track off the system. After hours of trying to track the belt, it was determined to be faulty and a rush order placed for a new belt.

When the belt arrived, it was only then that the source problem, the bearing, was discovered, or they ran into the same issue by trying to track the belt, which could potentially cause a camber in the new belt. As a result, a small component, that was not easily seen, consumed hours of maintenance time and the cost of a rush order.

Another example is from a facility that had recently installed several types of scrapers. All of them had the same issue. The scrapers were doing their job—reducing fines and material buildup on the underside of the conveyor which, in turn, significantly reduced labor hours and cleanup. The customer was happy, and all seemed right. But, like many components in a system, the scrapers were not checked and maintained.

Removing buildup of material on a scraper, as part of regular inspection, would avoid this situation. Photo: Motion

A period of time after the installation, a nail or hard piece of material became lodged in a straight, spring-actuated scraper, lifting the blade on half the belt and causing a cut the length of the belt. This cut took weeks to produce. It was so deep into the belt that it caused the belt to split in half in some spots, requiring expensive replacement.

On another system at the same location, a finger-style scraper was installed, resulting in a significant improvement in material drop. But no one checked or adjusted the scraper for at least three months. Because of this, material built up on the scraper and hardened to the point that it was damaging the scraper and digging into the belt.

In these scenarios, maintenance and cleaning crews were cleaning all around these scrapers, but ignoring the actual scraper because, up to that point, it wasn’t broken, so why fix it? In these cases, it took the cost of replacing the blades and the belting for maintenance to realize these items needed to be checked regularly.

After hours of maintenance to remove the buildup and properly adjust the scrapers, personnel developed a schedule that included clearing the scrapers. Time allotted was approximately two minutes per scraper per month. When looking at the initial numbers, the facility was nervous about the added time. “We don’t have time to cover this.” However, when factoring the breakdown time to get the systems back to working order, more labor hours were spent bouncing between priority projects and fixing broken components than when a solid PM plan was implemented. Additional savings were realized because the  belt and other components would not have needed to be replaced.

Another consideration is to use technology. There are wired and wireless units that monitor noise and vibration, along with oil and grease levels. These units can be monitored from one location with actuating preemptive signals to alert personnel that service should be performed. This technology can detect issues, stresses, and potential breakdowns even before there are visible signs.

Today’s technology provides several devices and systems that can help maintenance focus on what is important. Some of these devices and changes involve a significant up-front cost, but the true ROI—the true savings from preventing failure—more than justifies the investment. EP

Jason Crain is Business Development Manager Heavy-Duty (HD) Fabricated at Motion Conveyance Solutions Group, Birmingham, AL, (motion.com). He has been in the conveyor belt/systems industry for more than 24 years. In his current role, Crain helps customers find solutions to their conveying problems.