When a bearing is in a lack of lubrication state, there is an increase in both friction and noise. When using the ultrasonic instrument, the inspector listens to the bearing and watches the decibel level on the instrument. As grease is applied, there is less friction and less noise.
Once a proper lubrication level is reached, the dB level will remain steady and constant. If grease continues to be applied, the dB level will gradually start to increase. At this point, lubrication would need to cease because the threshold for over-lubrication has been reached. An over-lubrication condition also increases both pressure and friction inside the housing, thus creating more noise.
This is the time series view from a recorded ultrasound of a bearing in the process of being lubricated. The sound file was approximately 13 seconds in length. Notice the levels before lubrication on the far left, compared to the levels after lubrication on the far right.
How Much Does a Slipping Belt Cost?
It is common to ignore belt squealing and slipping. Belts are often running to break-down, with the argument that they are cheap to replace. So, is it worth considering Reliable Manufacturing techniques for belts?
What we know:
• There are many causes of belt problems such as tension, pulley /sheave, wear, overload, contamination, or overheating.
• A properly adjusted V belt slips between 2-5 percent.
• The slip is simply the difference between the RPM of the sheaves and the RPM of the belt, expressed as a percentage. We can use a stroboscope to get the data.
Now for the cool part (or hot, actually!):
1. A 100 hp motor that has a 10 percent slipping belt is losing 10 hp! About 5-8 hp of this loss can be avoided, since the normal belt slip is 2-5 percent.
2. Based on latest government data (June 2013), industry pays between US$0.0416 /kwr (LA) and UW$0.1347/kwhr (MA). So, depending on where you are in the country and what you pay for power, the cost is between US$469/hp per year and US$1,408/hp/year.
Which means that additional 5-8 percent slip on a single 100 hp motor is costing you between US$2,345 – US$11,264 every year, depending on where you are in the country.
Now ask yourself:
• How many belt drives do you have?
• Do any of them squeal?
• Could your belts cause a breakdown, incurring additional cost?
Contributed by Reliability Solutions Training LP, www.reliabilitysolutions.net.
Greasing Unsealed Applications
When greasing an application where there is no seal, such as heavily loaded chassis shackle pins or pins and bushings on blades or buckets, two or three shots of grease should be applied at the beginning of every shift.
In wet or humid environments, such as pulp and paper, marine, and road construction applications, it may be necessary to relubricate more frequently to purge contaminants. The same is true for dusty and dirty conditions associated with agriculture, mining, or quarry applications.
Contributed by Noria Corp., www.noria.com.