Maintenance Technology August 2016 - (Page 6)

UPTIME Don't Overlook Spare-Parts Reliability Bob Williamson Contributing Editor M aintenance management covers a variety of functions, including the managing of spare parts. We know that the quality of those parts has a direct impact on the reliability and maintainability of equipment, machinery, and facilities. There's more to it, though, than simply managing a storeroom. How spare parts are specified, purchased, shipped, stored, dispersed, and installed reflects critical elements in physical-asset performance and operating cost. Unfortunately, the parts are often overlooked in ways that compromise equipment reliability. Real-world impact Even the most reliable equipment can fail if the right spare parts-fit for service and mission ready-aren't installed properly. While a maintenance staff 's skill and knowledge is an important reliability factor, the inherent reliability of spare parts at the time of installation is even more so. Consider these examples of how spare parts can contribute to machine failures, excessive downtime, higher costs, and financial losses. Transportation damage. Several catastrophic failures of the fan in a plant's heat-treatment carburizing furnace led to enormous production and financial losses, not to mention a disruptive domino effect on production schedules. Removing and replacing the fan is difficult and time consuming, given its location in the bottom of the furnace. A failure analysis determined that cracks in the fan cooling jacket led to bearing failures. These events continued even after months of discussing fan construction with the OEM, changing welding methods, and carefully installing new fans. Eventually a root-cause analysis session was held with operators, maintainers, supervisors, area managers, plant engineers, and the fan company's owner. All potential failure causes were quickly ruled out based on prior actions. The facilitator then asked the group to take a hard look at the fan currently installed in the furnace and a new spare in the storeroom. 6| MAINTENANCE TECHNOLOGY As participants checked out the new spare firmly strapped to a wooden pallet with its shaft in a horizontal orientation, the fan manufacturer asked a question that ultimately unraveled the mystery of repeated failures: "Is that how we ship these fans to you?" At this point, a mechanic interjected that when a fan is installed, its shaft is vertical. "That could cause bearing problems," he said. Others weren't so sure. The OEM began speculating: "These fans are shipped more than 800 miles to your plant by truck," he said. "Imagine the bumping and jarring with the weight of the fan and shaft supported by the bearings on the cooling jacket. The cracks in the failed units seem to start around the upper side of the shaft-bearing mounts. Shipping them flat, in the same orientation as they are installed in the furnace, may prevent the cracking." Was he on to something? Once the manner of shipping was changed, i.e., with the fans strapped to pallets in the same orientation as they were to be installed, the failures ceased. The maintenance group also found that the fan bearings lasted longer. In-plant moving methods. "It's a big electric motor. How did you expect me to move it?" The speaker was a forklift operator who found it easier to pick up large motors by the shafts located at each end of the units. After all, they fit nicely between the forks, with minimal adjustment, and would roll to the back of the forks when they were tilted back slightly. Great move for the forklift driver. As for the motors, their shafts were becoming hammered, especially at the keyway. Maintenance techs thought the units sometimes seemed to be out of balance. Taking note of the forklift operator's preferred methods, they finally realized the cause of the problems: improper handling of electric motors from the receiving dock to the storeroom and from the storeroom to the job site. Behind-the-scenes. One of the most frequent and penalizing mechanical failures on a brewery's packaging lines was attributed to conveyor-belt AUGUST 2016

Table of Contents for the Digital Edition of Maintenance Technology August 2016

On The Floor
Accepting The Challenge
Advanced Software In The Jungle
Put Efficiency in MRO Storerooms
Rethink Overall Vibration Monitoring
Reliable Pumping Supplement
Practical Oil Analysis: Why and What For?
SAP Tips and Tricks
Maximize Ethernet
Compressed Air Care
Nurture STEM Learning
Heed Drive-Belt Temps
Internet of Things
ISO 55000
Ad Index
Final Thought

Maintenance Technology August 2016