After experiencing a high failure rate in extremely dusty and abrasive material environments, we decided to look for solutions to high wear and scoring problems on our hydraulic cylinder shafts. These materials became embedded in the seals, and wore the shafts even though protective sleeves were installed. The answer was through ceramic coating the shafts. After undercutting the shaft surface a few thousands of an inch to support the coating, they were sent to a specialty coating manufacturer for the coating. The resulting MTTF was increased three-fold, but because of MTTR was long, the resulting morale increase in the maintenance staff was a pleasant by product of the new process.

Reader Tip submitted by Thomas Heiserman, Maintenance Solutions Group

Thanks Thomas - your Maintenance Tips hat is on the way!

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TIME WAVEFORM TIP

These days, Time Waveform Analysis is commonly used only as a method of providing confirming evidence of a machinery fault signature indicated in the vibration spectrum. Normal machinery trending will not require the measurement of a TWF unless that machine is a gearbox, or one that operates at relatively low speeds (less than 300 RPM or so). Analysis of broken tooth faults in gearbox applications are a must for TWF analysis. The frequency of the broken tooth occurs at 1x RPM and is usually masked by rotating speed response in the spectrum. Enhancement of bearing defects in low speed machines is provided in the TWF as well. In addition to the bearing fault impact rate, modulation of this fault (rotation through the load zone) can be can be detected effectively in the time domain.

Tip by Dan Ambre, P.E.
Full Spectrum Diagnostics, PLLC
Phone: 763-577-9959
http://www.fullspec.net

Vibration Fault Guide

Using the kVA/HP Code, A Voltmeter and Ammeter to Commission an Electric Motor

This process can be used with either new or repaired electric motors. Using the nameplate information of a three phase induction motor, you can obtain the current, horsepower and kVA/HP Code. These values can be used to calculate the inrush, or locked rotor, current of the motor. The ammeter and voltmeter must each have the ability to capture min/max readings. Connect the ammeter to Phase A and the voltmeter leads between Phase A and B with the ammeter set to capture max current and the voltmeter set to capture minimum voltage. Start the motor and obtain the results from both instruments.

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Consistency is key

When doing an alignment, along with a good procedure and alignment tool, it is very important to be consistent during the task. Always obey all safety regulations. Always turn shafts in the normal direction of rotation. Always check for repeatability of readings. Always use a torque wrench for consistency, so that all hold-down bolts are always tightened equally. This is especially important when working in pairs, where the tendency is for one craftsman to be on each side of the machine.

Tip provided by LUDECA, INC.
ALIGNMENT * VIBRATION * BALANCING
http://www.ludeca.com
Tel: 305-591-8935

Benefits of laser alignment

When starting a new oil analysis program the test results can reveal an overwhelming number of problems with the lubricants in your machinery. One key to making progress in correcting your lubrication troubles is to prioritize your remediation efforts.

Start slow and localize your early efforts to one area of your plant. If sample ports, breathers, filtering connections, and sight glass modifications are planned, then get those started before your sampling program begins and build your routes as the equipment is retrofitted.

If nearly all of your equipment seems to be in a critical state, according to your sample results, then prioritize your remediation efforts. Consider focusing on chemistry and wear problems first. Your initial work orders are written to change out the sour oil, oil with water contamination and filtering to reduce or eliminate wear debris before filtering just for contamination. Trend the wear debris data with data from other technologies, e.g. vibration, ultrasound, and thermography, to determine which equipment needs inspection, repair or replacement.

Lessons Learned: Build your program in stages, start with your highest priority area and systematically work your way through other areas. Early successes build confidence and enthusiasm.

Tip submitted by Clyde Hughes, CMRP, MLT II, MLA II, Lubrication Technician and Junior Instructor, Allied Reliability
http://www.alliedreliability.com

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