July 19, 2016
Today’s more evolved ultrasound data collectors present results that take reliability practitioners beyond the single decibel. Using only an overall dB value may indicate something inside the machine has changed since last readings were taken. But it provides no additional insight to determine what type of defect may be present.
Moreover, a single dB only provides a useful trend if the inspector has control of the acquisition time during data collection. Acquisition time needs to be adjusted in concert with the speed of the machine. More time for low speed applications and less for high. The aim should be to capture a minimum of 2-3 full shaft rotations.
The SDT270 takes inspectors beyond the single decibel by presenting ultrasound data in terms of machine condition. We call them Condition Indicators and there are four (RMS, Max RMS, Peak, and Crest Factor (CF)) and are abbreviated as 4CI. Ultrasound identifies defects in machines when those defects produce one or more of the following phenomena: FRICTION, IMPACTING, or TURBULENCE (FIT).
- A bearing that requires lubrication will present higher levels of friction. Therefore, an RMS danger alarm will be triggered at 8 dB and an RMS/CF alarm when severity increases.
- A bent shaft produces higher levels of friction and therefore present danger and alert warnings with the RMS condition indicator.
- Electrical defects such as arcing, tracking, and corona are first alarmed with the RMS condition indicator and severely alarmed with Max RMS and CF.
- A faulty steam trap is detected with an elevation in Temperature and Max RMS.
Traditional ultrasound is useful for trending decibel levels that alert us when machine condition changes. Evolved ultrasound goes beyond the single decibel to recruit Condition Indicators that help inspectors determine the type of defect that is creating the alarm. SDT’s Four Condition Indicators demonstrate how ultrasound must be used for both defect alarm and identification.
July 12, 2016
The maintenance and reliability world is filled with key performance indicators (KPIs). Properly tracking KPIs can be challenging due to difficulties in obtaining accurate data and the time required to obtain them. The key is to pick KPIs that will help you identify and drive the behavior that you need to change right now. As advances are made, additional KPIs can be added which help identify and drive additional behavior changes and improvements.
It is very important to understand that KPIs can lead to false positive indications and never actually result in value added or sustainable improvements within your organization. You must understand and address the true root causes behind a deficient KPI and eliminate them.
For example, mean time to repair (MTTR) can be a very good indicator leading to great improvements. Unfortunately, this indicator can also be harmful if misunderstood or given the wrong improvement focus. What if individuals decide to take deleterious short cuts to quickly get a machine operational again? MTTR may seem to improve on that machine, but did overall asset health and reliability really improve, in a meaningful way that provides real value back to your organization? These short cuts may actually lead to additional machinery failures and greater downtime.
MTTR could be an indication that maintenance staff requires training on how to properly repair the machine. Too short and perhaps unwanted short cuts are being taken. Too long may indicate that excessive time is being wasted hunting for tools or spare parts due to a lack of proper planning and/or kitting. Is a detailed and efficient work plan available, to guide your maintenance staff in correctly repairing the equipment? MTTR, if properly used and tracked can point you toward areas of substantial improvement.
Never forget to determine and address the root causes of equipment failure. Doing so may eliminate the need to work on the equipment in the first place. Prevention is always the best way to drive sustainable improvements in uptime and capacity.
Beware of driving improvements in KPIs for the wrong reasons. This can lead to a false sense of progress that never brings about real changes and advancements in reliability to your organization. Ensure that you understand the real variables driving the KPIs you have selected. Don’t let your chosen KPIs give you a false sense of improvement!
July 5, 2016
Problem: The machine shop of the engineering department of a prestigious Florida university wanted to identify the source of error in their tool room lathe. They had previously observed that when working pieces further away from the spindle chuck, there was an appreciable deviation in accuracy compared with close-to-the-spindle work. The machine shop instructor suspected the problem to lie somewhere in the tailstock and asked us to confirm or refute his suspicions.
Solution: The Easy-Laser E940 Machine Tool laser alignment system was used to perform three types of measurements:
- Z-axis straightness measurement
- A spindle direction measurement
- A spindle-to-tailstock alignment measurement
In addition, the Values program was used to check for play in the tailstock sub-spindle bearings. An additional check was performed to verify whether the tool support returned to its original position when it was unlocked, and then locked again.
After accomplishing the above measurements and checks, it was determined that the straightness of the Z-axis was within tolerance, the spindle direction was ascertained and the alignment between the spindle and tailstock at the furthest distance revealed a small angle. There was no significant play in the sub-spindle bearings and the tool support check was good.
This data allowed the instructor to narrow down the possible corrective actions to take in order to achieve a better alignment and return the lathe to an optimum performance condition.
The ability to perform all of these checks and measurements to a high degree of accuracy allowed the university to quickly and more certainly identify worn components, which will save them a great deal of money in spares costs, as well as ensure that parts and workpieces fabricated on this lathe will turn out as expected, on time and within design tolerances.
June 28, 2016
Going “green” and saving energy are two separate ideals that merge by circumstance, and focus on a campaign with huge potential wins. This battle starts in the air compressor room (supply side) and branches throughout the facility (distribution) to wherever air is needed (demand side). Along the way there are leaks, wasted dollars spent and energy consumed, all the while enlarging your carbon footprint. Take a look at these compelling reasons to tighten your compressed air system:
- Compressed air production is the 2nd or 3rd highest source of energy consumption in most companies.
- On average, air compressors account for 18% of all industrial electrical consumption in European manufacturing plants. Some suggest that compressed air costs account for as much as 30% of a manufacturing plant’s electricity bill.
- For every kWh spent on compressed air, an additional 0.8 kg of CO2 per month is spewed into our atmosphere.
- 75% of the total cost of your compressed air system goes to your electricity provider. The other 25% is accounted for by capital costs and ongoing maintenance.
- On average, only 43% of compressed air produced gets used to satisfy real demand.
- On average, 34% of compressed air produced is wasted to leaks.
- The remainder is consumed by wasteful applications and artificial demand.
Download and learn more about Sustainability through Ultrasonic Energy Conservation
June 21, 2016
How do you obtain the desired return on your assets? Availability, maintainability and reliability are foundational elements required for a proper return on your equipment. Condition Monitoring is a tool that can help you build these elements and obtain the desired returns. Condition Monitoring can be completed while equipment is running to maximize uptime and help provide better overall reliability. Conditional changes can be identified before functional failures that result in downtime occur, preventing other unwanted consequences. Unneeded work can be avoided (unnecessary PM’s, failures, etc.), and better planning and improved scheduling achieved through CM.
Use Condition Monitoring as a means to build a solid foundation for your facility!
June 14, 2016
Companies spend lots of money, time and effort on systems to document what needs to be done, should have been done, failures that occurred, etc. Unfortunately, these systems usually show and document the point of failure (F) and not the point of conception (P) for a problem. These are examples of downtime systems and are important for success.
Does your company invest in uptime systems and processes? What is an uptime system or process? These systems help your facility identify the point of conception (P) of a problem. This is very important, because it means your facility has more time to mitigate a problem before it results in unwanted consequences (injury, downtime, increased costs, poor quality, less maintprofit, etc.)
Condition monitoring (CM), reliability efforts, proper planning and scheduling, kitting, effective PM’s, reliability based engineering, etc., will reduce the amount of information that must be entered and tracked through the downtime systems that have been heavily invested in. The results can be extremely rewarding.
What uptime systems and processes does your facility utilize?