Maintenance Technology May 2015 - (Page 28)

COVER STORY load-and-speed design limits in a 1. Lack of lubrication training clean operating environment, and 2. Lack of lubrication-application that an adequate lubricant film of engineering the correct viscosity is applied on a 3. Poor housekeeping (lack of order regular basis ("adequate" meanand cleanliness) ing a film equal to or greater than 4. Over-lubrication of bearings the composite roughness of the 5. Under-lubrication of bearings two mating surfaces). As a result, 6. Use of dirty or contaminated new reliability is the minimum percentlubricants age probability of 90% of a group 7. Infrequent oil/filter changes of identical bearings achieving their 8. Bearing lubricant contaminated L10 design life expectancy (operwith an incompatible lubricant ated under identical operating and 9. Bearing lubricated with the incorload conditions). With the advent of rect lubricant An over-greased bearing. Maintenance chose not to cleaner and degassed steels used in 10. Bearing mounted out of square or reset the auto lubricator but to put in place two greaserolling-bearing manufacturing, manmisaligned when set up catchment devices and a PM to empty the grease ufacturers are now able to upgrade 11. Note that nine out of 10 items on regularly. (Courtesy ENGTECH Industries, Inc.) the L10 rating to L10a designations this list are due directly or indirectly that promise even higher reliability to ineffective lubrication practices. percentages. The reality is, many bearings lead a less than ideal life, often TAKING THE PATH TO BEARING RELIABILITY subjected to the severest conditions and many forms of abuse The first step to reliability is to stop reacting to failure symptoms. within industrial-plant environments. Many maintenance and reliFor example, a simple oil leak is not always a failure if the type of ability departments don't take time to understand the root cause shaft seal used is designed to leak. If this is not the case, other of bearing failures, nor do they implement life-cycle management causes could include a cross-threaded drain plug, a drain plug strategies for these key components. refitted with no washer, a plugged breather, a damaged seal or even a porous casting. THE MANY CAUSES OF BEARING FAILURE By contrast, an oil leak in a hydraulic system can be caused If asked to project which bearing is most likely to achieve L10 life by dirt-contaminated hydraulic oil scoring lapped spools and nickstatus in the following scenarios, which would you choose? ing seals. Both show the same oil-leak symptom, but can have Scenario 1: A pillow-block bearing is placed in service in very different root causes. Implementing a root cause analysis of a HEPA-filtered clean-room manufacturing environment. The failure (RCAF) program to weed out the real reasons your bearbearing runs under light load conditions for eight hours per day, ings are failing, and using those findings to implement a strategic is set up using a laser-aligned and balanced drive shaft, and is lubrication management program will make an excellent first step. continually lubricated using an engineered automatic oil lubricaHere are other steps to take: tion-delivery system. Training Scenario 2: The same pillow-block bearing is placed in Use your RCAF findings as a kick-start to educate your service in a hot, dirty foundry operating two full shifts per day. maintenance staff on the value of good lubrication practices soon The machinery is set up using manual "eye-ball" alignment to be adopted. techniques, and is manually lubricated with a grease gun on a PM schedule with a subjective job task that states "lubricate as Lubricant choice required." Solicit the assistance of a reputable lubricant consultant and/ If you are like most, you will have voted scenario #1 as the or lubricant manufacturer/supplier to facilitate an engineered likely winner. In reality, both bearings are likely to prematurely lubricant-consolidation program. The purpose will be to determine fail if maintenance has not understood how failure can occur and the most suitable lubricant selection for all your bearings, and planned accordingly to prevent it! The top 10 causes of bearing picking the correct oil viscosity and additive package designed to failures-confirmed through this author's 40+ years of investigatwork in your ambient conditions that will reduce lubricant degraing real-world failures-are as follows: dation and the number of oil changes. 28 LUBRICATION TECHNOLOGY MAY 2015 LubricationTechnologyOnline.com Special Section http://www.LubricationTechnologyOnline.com

Maintenance Technology May 2015

Table of Contents for the Digital Edition of Maintenance Technology May 2015