To PM or Not to PM ?

It is a business decision that must be based on the benefits, and not viewed as “the necessary evil”.

PM and PdM arguments

• “Pm’s are costly, they spend a lot of money on parts”

• “We must have the production this week we cant turn the machine off.”

• “If it will run let it run, we will shut it down when it fails”

• “We need the PM crew to help on the floor, we have other issues right now.”

Vicious Cycle

• Look Familiar?Cant do the Pm because inventory is

low

Equipment downtime was due to not doing

the PM

Since equipment was down , inventory is

low

Sustainability and Lean

• A good PM and PdM program is necessary for sustainability, repeatable quality, reliable delivery of goods and lower overall cost in any process.

• A good PM and PdM program helps a manufacturer to be lean and green.– Example: Forgoing a PM on a conveyor with a bad

bearing.

Equipment Status

Mining Conveyor moves product from mine pit to loader.Inspection was done, and a bearing needs to be replace on the PM.Bearing cost is $400.00PM was scheduled for today, but “ We need to hit 1 million lbs today to make our target”.PM was deferred until a time when production demand was lower, as “it is running”.Bad Bearing Identified

Equipment is Down MondayBearing lasted 2 more weeks, but it finally tripped the motor.

Upon many motor trips the maintenance team found the shaft worn.

Downtime 2 hours, to remove belt, guards, chain drive, and old bearing.

No shaft on hand, as it is part of the roller assembly. It has a 4 week lead-time.

“We don’t have time to repair the shaft. Can’t we just put the new bearing on, and order the shaft?”

Down 2 hours to install new bearing and reassemble.

Waiting for new shaft and drum?

• “Hey we got drawings?” Let’s get a local shop to make us a shaft and roller.”

• “We can get it sooner and when the other comes in we will have a spare.”

• The cost to rush this is $2800.00.and 3 days to deliver. (Shop started work on Wednesday)

Meanwhile we wait.

• Motor trips became more frequent, at a rate of 2 times an hour.

• Each time the mechanic would spray some graphite on the shaft and reset the overloads.

• “ Boy will I be glad when the shaft and roller get here!”

• “Man this stopping and starting is killing our production!”

It has Arrived

• Shaft and Roller are delivered late Friday afternoon.

• “ We need three guys from the PM crew to stay over and install this shaft and roller.”

• “Don’t worry about the overtime, it is approved.”

• “How long do you think it will take?”

Job completed

• New shaft, roller, and bearing installed.

• Record time of 4 hours.

• “Thanks for staying over and helping out, guys. We really appreciate it.”

Cost Comparison -PM

• New Bearing $400.00

• PM for 8 Hours to complete 24 jobs- 8 hours downtime.

• Missed production for the day of the PM.

Cost Comparison-No PM

• 2 New Bearings- $800.00• Shaft and Roller- $2,800.00• Downtime- 8 -10 hours with the motor resets.• Only one job completed

• “We made production on the PM day.”

Other Waste due to no PM• Energy Consumption of the motor due to excessive friction and

load.• Maintenance focus on the resets, time taken from air and oil leak

repairs.• Efficiency of operators low due to frustration with equipment

performance.• Welding shop consumed $180 of electricity during peak demand

time.• Maintenance worked overtime to make repair.• Maintenance planner could not plan other task, as he/she was

focus on this one “major” repair.

To PM or Not to PM?

• Was the 8 hour PM and $400.00 bearing worth it ?

• Which cost more in the long term?

• Oh yea! The motor that was reset 2 x an hour for 3 days must be replaced on the next PM, it is showing signs of insulation failure from overheating.

Questions