PM analysis is a problem-solving tool that is particularly used under the ” quality Maintenance” Pillar of the TPM approach.
The PM method was developed by the JIPM. This method helps to highlight the principles and “ natural laws ” that are causing a problem. Also called 2P5M analysis, it means:
- 2p for problem (quality, loss of performance…) and physical (principle or natural law).
- 5M For the mechanism causing the problem and the 4m (Machine, labor, material, methods).
Step 1: Clarify the phenomenon
This step is intended to describe through a simple observation, the physical phenomenon of the problem. For this, we use the 5W2H. A drawing is also welcome.
Below is an example of a soldering problem:
Step 2: Analyzing the physical principles of the phenomenon
It is a question of explaining the phenomenon according to the physical principles. Generally, this phenomenon is expressed in 4 phases as in the following example:
- Operational principle: describe the physical principle of the operation and decompose it into a subset.
- Operational Standard: find the standards that are known and used to date to operate the equipment.
- Interacting element: look for the different interactions between the subset or parts.
- Physical Analysis: look for the consequences of the variation of different interactions and quantify them.
Elements in Interactions
This process uses a metal electrode placed in the atmosphere of an inert gas. This gas protects the metal from oxidation. The heat of the arc formed between the electrode and the metal melts the edges of the metal.
Position DB and FB on the copper lath.
Check the alignment and the day.
Clean with air.
The preset of the instructions is given by the automation.
Adjusting the speed of the trolley using a potentiometer.
Height H between the slat and the nozzle.
The end of the wire and the contact tube.
The weld may break on the line. The lack of penetration of the welding cord decreases its resistance to mechanical and thermal stresses. The end of the weld does not reach the bottom of the tape.
Step 3: Study the first level of conditions likely to generate the phenomenon
It is a question of identifying all the potential ‘ first ‘ causes direct or indirect. In our example, we can cite 5 potential raw causes:
A. FB and DB Placement on the lath
B. Welding inerting
C. Welding seal Follow-up
D. Cleanliness of the tape
E. Welding parameters.
Step 4: Study the causes likely to generate the phenomenon
The PM analysis asks to identify the second level of causes causing the root causes according to the 4m (Machine, material, methods, labor). As before, it is necessary to be as exhaustive as possible in the enumeration of possible causes and to identify the causes of 1St, 2nd or even 3rd level (use the 5 why to go back to the root cause ).
First level 4M correlation
Second level 4M correlation
A. 1 End to end band edges with some game.
a. Play too big
b. Play too small
c. Different play on the width…
A. 1.1 Lack of lighting
A. 1.2 Recovery manually resumed
A. 1.3 Operating Procedure
A. 1.4 Training
A. 1.5 No downstream loop
4.1.6 Slipping in Combs
4.1.7 Not taken enough tape
4.1.8 slip in the BSP
4.1.9 play in chassis (rack, clevises, cylinder mounts, slide)
4.1.10: position of the Stop (set of wear)
4.1.11 foreign body between the strips
4.1.12 wrong Cut (burrs, flatness).
Step 5: Set the ideal state of operation
For each of the root causes identified, it is necessary to find the ideal state that allows not to reveal the problem. The ideal state is defined as a state where the operation is guaranteed and the occurrence of the chronic defect is non-existent.
Step 6: Define the points to analyze and measure
We validate the different points of measurement and their ideal value relative to the previous solutions. In fact, the values defined above may be too much or not accurate enough. This step allows to validate the measure in particular:
- Validate the measuring system.
- Define the measuring procedure.
- Validate the operational skills for the measurement.
Generally, a study of the Gage R & R is used.
Step 7: Identify gaps
Last step of validation, we apply the elements identified in step 6 and make sure that this makes it possible to make the difference of a normal state in relation to an abnormal state. This should be done in the actual production conditions. Generally, tests are done with several people to ensure that the system is reliable.
Step 8: Propose improvement solutions and build the action plan
Finally, the final stage of the PM analysis, the Working Group must identify all the solutions to meet the criteria identified above:
- Measuring tools.
- Poka Yoké.
- Redesign of the equipment.
Depending on the solutions, we will put in place a plan of improvement actions and make sure that it helps to remove the defect and avoid recurrence.
All the examples come from: M. Rajendran (2006)-Deployment of the quality maintenance plan on a galvanizing line
J. Buffer (2011) – The TPM guide
K. Shirose, Y. Kimura, M. Kaneda (1995) – PM analysis An advanced step in TPM implementation