Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1206285
monitoring done in near real time by imbedded sensors, a la the industrial internet of things (IIoT), can deliver an equal or superior advantage. As you might expect, location has to do with the optimum inspec- tion or data collection point. For example, in oil analysis, where is the optimum location to pull a sample? Likewise, what are the critical examination points when performing inspections? W hat about location as it relates to the use of heat guns and infrared thermography? A long P-F interval is obviously desired, which depends heavily on frequency. is helps close the gap between the point of detection relative to the failure inception point. Using condition monitoring to detect and eradicate failure root causes produces a negative P-F interval. What could be more ideal? Hence, condition monitoring performed at a high frequency will be more effective and far more proactive (root-cause oriented). is is the strategic foundation of proactive maintenance. Detection Zone Definitions e four zones in the DZT are color coded as follows: Green Zone (Proactive): Early root cause detection in this zone is related to frequent inspection in the right places using the right tools and methods as well as expert skills. Yel low Z one (Pred ic t ive): This zone may miss some root causes, but when well-executed, it can detect faults and incipient failure issues early (near to the time of inception). It will depend on frequent inspection coupled w it h sk i l l f u l tech nique s a nd effective tools. A mber Zone (Protective): Condition monitoring in this zone catches faults before catastrophic failure and collateral damage can occur. Some may call this just-in- time condition monitoring, but for many reasons, it is a slippery slope at best. Although a pre-failure detec- tion may be possible, in other cases the failure development period may be too narrow for a practical fore- warning to be achieved. Of course, there are also those pesky sudden- death failures. Red Zone (Breakdown): is is the complete operational failure. Detection Zone Coding Next, assign failure modes to the optimum, best-f it detection www . machinerylubrication.com | January - February 2020 | 5 RELIABILITY ZONES TIMING (Based on the P-F Interval) PRECISION/SKILLS/TOOLS (Knowing what to do and how to do it) AMBER YELLOW GREEN RED High Cost of Unreliability Low Cost of Reliability 1. Proactive (root-cause oriented) A. High (Skillful) Knowledge-based, quality tools and methods B. Moderate C. Low (Wild Guess) Trial-and-error based 2. Predictive (early fault detection oriented) 3. Protective (damage control) 1A 2A 3A 1B 3B 2B 1C 2C 3C Figure 3. A detection zone table used to illustrate how condition monitoring can detect and respond to failure in different ways • Inspection finds sludge and heavy surface varnish • Aeration problem detected and corrected • Oil analysis performed • De-varnishing measures performed • Bearing failure occurred due to lubricant starvation from oil-way sludge • Gross sludge on oil filter found. Filter was in bypass • Defective oil believed to be the cause. Oil type and supplier changed. No machine flush was performed • Aeration problem detected • Oil and filter changed with hope of remedying problem • High VP detected • Repeated oil and filter changes attempted to solve the problem. • Surface varnish and oil-way sludge accumulate • Inspection finds sludge and surface varnish • Oil and filter changed • Precision flush applied • Aerated oil quickly detected & recognized • Air ingression source found and corrected • Varnish potential (VP) detected by routine inspection and oil analysis • Troubleshooting finds and corrects aeration problem • Aeration problem detected • Root cause not resolved • Degas technology applied to remove entrained air • High VP detected • De-varnish technology used to restore health of oil • Cause of varnish was not found