Maintenance Resources

Wednesday, November 25, 2009

MiaOsk - Our maintenance KIOSK created

Dear Friends,
Our maintenance Kiosk as I described in my earlier post is just created. Now it is us, who have to participate promptly to rip gain of it.
It's a general forum to discuss our problems for solutions, new information on just achieved improvements and A lot.

Initially  data Kiosk (Manuals, training presentations discussion and other form of datawill be available to group generally.
 All data and other benefits will be strictly restricted to members only.
Group Link:

Please Join and improve our MaiOsk - Our own Maintenance KIOSK 


Thursday, November 19, 2009

Why to analyze breakdown and which format to follow?

Once upon a time, there was a king in Mathura , named Kansa. He was the most outrageous king .every body was too ungratified to stay in his kingdom. Once a voice from heaven foretell that the eighth son of sister Devaki & Basudeva will kill him & save mathura. …………………………………

Horrified Kansa arrested them & kept them in jail .He brutally murdered their seven children but the eighth son, lord Krishna escaped from there with divine help. Later lord Krishna killed Kansa & brought peace in Mathura.
Teacher stopped and asked the students, have you any question about it?
One of them raised his hand. Teacher thought what question can arise within this traditional saga.
He asked “if kansa knew the fact then why he kept Devaki and Basudeva in one cell?”

(Please, I have no intention to heart anybodies believe but it’s a nice story to understand the need of root cause analysis I have ever heard)

Moral of the story is without digging the root cause if anybody wants to take an immediate action, then the killer cause may got escaped .
Rather than taking actions that are merely band-aids, a why-why helps you identify how to really prevent the issue from happening again.

I have seen that without looking for expected outcome almost all are following a common format blindly. Either of WHY-WHY or 5W2H.

5W2H is one of the best format to communicate the problem to management but daily breakdowns should be discussed and analyzed in WHY-WHY format and outcome should be a kaizen or final countermeasure ( Change in JH maintenance sheet or preventive maintenance sheet) to stop it

Just compare the both

1. 5W2H

a) What (Happened) ?
b) Where (Happened) ?
c) Who (Identified /Responsible)
d) Which (Part)
e) Why (It Happened OR Why it is a problem)?
f) How much (Quantify to understand the severity )
g) How to do (Action plan to stop)
h) When (Time line to execute the action plan )

It's a complete informative sheet to communicate to the management but searching for root cause is absent. So, By 5W2H the objective of breakdown analysis is not getting satisfied and Management hopefully  have interest only in actions to stop breakdowns rather than in detail of each breakdown until unless management involvement is require for some particular major breakdowns.   Out from TPM, Just see the classic example bellow, It's a mail communication what I got from (easily communicated the subject matter in 5W)

So, the solution is

1. Why-Why

a) Why
b) Why
c) Why

…Still a actionable root cause found.
It is a method of questioning that leads to the identification of the root cause(s) of a problem and So, To find root cause and take permanent corrective action, WHY-WHY is best brain storming method. Others are FTA analysis, MFMEA (Before machine design), Parato (for priority setting).

How to conduct WHY-WHY analysis?

I usually follow the format I learnt from Yamaguchi San where to ask to final action and I feel it is easy to go down logically rather than to describe B/D phenomena and ask why it happed.
a) Conduct analysis season imitate after the breakdown got over ( memory will be fresh and so it is easy and less time consuming)
b) Ask why to the final action after which machine gets started (Generally we have several actions in way to make the machine up)
c) Then WHY WHY WHY….

Expected Outcomes:

Generally causes of breakdown fall in following five categories and expected final action is-
1. Poor Basic condition – Final action on preventive Maintenance to restore and honor basic condition (JH and Or PM).
2. Poor Operating condition - Final action on Maintenance (JH and Or PM)
3. Deterioration – PM check sheet or frequency is expected to be modify
4. Week Design – Cry for a Kaizen (Brain storming) to rectify the same
5. Skill – Training to enhance skill in same area.

Why why Format and example is available in TPM club India web site and you can download it here.
You will get more other Doc.s to download in there download section.

Thursday, November 5, 2009

Energy and Cost Savings in Air Compressor

Air is free but compressed air is too costly. And by its operation, We have a lot scope to save Energy and money from their operation. Common methods are

1. Arresting air leakage
2. Air inlet system should be cool and dirt
3. Pressure setting and compressor modulation
4. Installing VSD (variable speed drive) to optimized it’s power consumption on load and no load
5. Optimizing Air line to reduce pressure drop

But before to discuss its saving aspects, let’s see how costly it is

Cost of Compressed air = {(BHP) x (0.746) x (# of operating hours) x ($/kWh) x (% time) x (% full load BHP)}/Motor Efficiency

1. Where BHP—Compressor shaft horsepower (frequently higher than the motor nameplate
Horsepower—check equipment specification)
2. Percent time—percentage of time running at this operating level i.e full load % and no load %
3. Percent full-load BHP—BHP as percentage of full-load BHP at this operating Level
4. Motor efficiency—motor efficiency at this operating level

5. And Total cost = Full load cost + No load cost

A typical manufacturing facility has a 33.5 hp compressor (which requires 45.56 BHP)
That operates for 6800 hours annually (Assume compressor operated 2 shifts a day, 5 days a week) . It is fully loaded 85% of the time (motor
Efficiency = 95%) and unloaded the rest of the time (25% full-load BHP and motor efficiency = 90%). The aggregate electric rate is Rs. 7/kWh.

Cost when fully loaded =

{45.56 BHP) x (0.746) x (6800 hrs) x (Rs. 7/kWh) x(0.85) x(1.0)}/0.95

= Rs. 1447520

Cost when partially loaded =

{45.56 BHP)x(0.746) x(6800 hrs)x Rs. 7/kWh)x 0.15) x (0.25)}/0.90

= Rs. 60668

Yearly cost of Air generation
(Except Timely maintenance cost ) = Rs. 1447520 + Rs. 60668 = Rs. 1508188. + Std. Maintenance cost.

Now see bellow example for leakage cost
Stop all loads and check for load and unload pattern for 8 to ten cycles and take average for accuracy. at compressor end. Assume leakage test yields flowing results
Compressor capacity (m3/min) = 35
Cut in pressure = 6.8 KG/ cm2
Cut out pressure = 7.5 kg/cm2
Load KW drawn = 188 kw
Unload Kw drawn = 54 kw
Average load time = 1.5 min
Average unload time = 10.5 min

So, Leakage qty. = (1.5 / (1.5+10.5)) X 35 = 4.375 m3/min
Leakage per day = 6300 m3 / day
Power require for air generation = 188 kw /(35 m3/minX60) = 0.0895
Energy loss due to Leakage / day = 0.0895 X 6300 m3/day = 564 kwh
Assuming Rs. 7 /KWH in average cost of air leakage = Rs. 3948 / day , Rs 98700/ month.

SO..STOP Leakage!

2. Air Inlet System – Compressor room need to be well ventilated and need separate exhaust for hot air

3. Compressor modulation = Optimize sizing and scheduling of compressor
4. Installing VSD = A very sensible issue but before to install we need to check our requirement or else it will not give saving as desired fashion and still for many cases, motor with soft started and Pressure on/off control is cheap and efficient option. Flowing are hints
a) Due to efficiency factor of VSD, at full load, compressor with VSD drive takes more current then general compressor.
b) A compressor controlled by a variable speed drive draws power in almost direct proportion to the load, with energy consumption dropping to near zero at no-load. In contrast, conventional compressors are less efficient because at no-load they consume between 13 and 85 per cent of their full-load consumption, depending on the manufacturer and operating mode.
c) VSD system will give significant savings 0f 10 % to 30% of operating cost if and only if compressor is running with fluctuating load between 40 to 80 % and install with pressure sensor to modulate VSD outputs. Because No load loss will be almost near to zero and may run with friction of efficiency as per load demand.