Total Productive Maintenance (TPM)

Lean concepts like Standard Work and Just In Time are predicated on dependability: dependability of materials, dependability of workers, and dependability of equipment.  It’s this latter subject that I want to address in this post.

A standard maintenance program uses maintenance personnel to perform routine functions like oiling and lubricating equipment.  When a machine fails, the maintenance department repairs it; yet, rarely brings it back to it’s original specs.

In a preventive maintenance program, machines are maintained prior to failure.  These programs are often like the 15,000 mile checkup on a car.  The mechanic performs all the routine functions specified by the checkup and then runs a diagnostic to give the owner advance warning about potential problems.

How does productive maintenance differ from these?  First, the goal of a productive maintenance program goes beyond merely keeping machines running.  In a TPM Kaizen event, machines are cleaned, restored to their original specifications and then minor changes made to improve both the functionality and longevity of the machine. 

In addition, the Kaizen event establishes areas that need to be attended to at least once a day.  These points are marked on the machine and on an operator’s dashboard (usually a laminated card with photos of the machine and the numbered locations of all inspection points matching those on the machine).  It then becomes the operator’s (not the maintenance department’s) responsibility to check these points, and perform any minor maintenance indicated, at least once a shift.

This means the operator oils and lubricates, looks for leaks, reads all gage values and calls maintenance immediately when anything is not what it should be.  The operator also keeps the machine wiped down and dusted as a way of ensuring that it's constantly being inspected for leaks, broken hoses, broken gages, broken sight glasses, etc.  In short, the operator is the first line of defense in maintenance of the machine.

A quick story:  A colleague of mine was touring a plant in Asia and found a bumper sticker on the side of a machine that had a red heart in it.  Since it was in Koren, he asked his guide what the sticker meant.  He was told that it translated “I love my machine.”

Seeing the quizzical look on my colleague’s face, the guide went on.  “This man’s livelihood is derived from that machine.  Not only his, but also his family’s and extended family’s; sometimes even others in his community."

When workers are able to make that connection between their equipment and their livelihood, it changes their perspective about preventive maintenance.  This relationship frequently leads Lean organizations to assign responsibility for each piece of equipment to a single operator.

Often as part of the TPM Kaizen event, the “capability” of a machine is determined.  The machine’s capability is a measure of it’s ability to reach and hold tolerances.  These capabilities are then used in the designing of new products and in choosing to which machine to assign new designs.

Now, the maintenance department is not off the hook.  First, it works with operations to monitor drift of the machine’s capability.  When the machine cannot hold tolerances, it is shut down or at least slated for PM.  Notice: the machine is still making good parts.  It's shut down because it can't hold tolerances.

Beyond that, the maintenance department establishes a program to perform critical maintenance functions for which the machine needs to be shut down; e.g. replacing hoses or gears.  These preventive maintenance events are placed on the operations and maintenance calendars.  Every effort is made to maintain the machines on those dates, but some organizations allow operations to shift the date, one time, to the right or left on the calendar.  TPM is taken so seriously that there is no additional shift allowed.

In summation, TPM is a critical part of Lean.  As I said at the beginning, an organization cannot really establish standard work, or meet Takt Time, until they have established a TPM program on their equipment.