In any industrial setting, it is essential to prevent errors from occurring during the maintenance and operation of the assets. After all, even a tiny mistake can have serious consequences, ranging from production downtime to safety hazards depending on your processes and products. In his work at DuPont and other activities, Winston Ledet determined that 84% of failures originate from careless work habits. Contrast that to the typical myth that equipment is more likely to fail as equipment gets older. Winston found that 4% of failures could be attributed to equipment aging, and 12% to basic wear and tear. With reliability-centered maintenance (RCM II), John Moubray found that more than 70% of failures are self-induced, with 40% of that number being human error. To that end, we are our own worst enemies in ensuring equipment availability. If the numbers are that bad, don’t you think we should do something about it?
From the Plant Floor is a new monthly column that explores reliability challenges faced by organizations and solutions to overcome them.
To start, envision a simple conveyor, gearbox, and motor system on your plant floor. With an Avengers or Hunger Games movie approach, surround that system with a force field where no errors penetrate the shield. Any error that attempts to reach the system ricochets off the shield back to the sender. Taking this mindset, it becomes easy to see how the focus is not about finding more issues with inspections and then planning and scheduling more work. It is about eliminating the introduction of new errors into the system, errors that create failures, and eliminating the need to plan and schedule corrective work.
Sure, maintenance planning and scheduling do play a role. Standardized work is critical in both maintenance and operations. The maintenance planner should create reusable job plans that detail the task steps using a level of specification, i.e., gaps, fits, fastener torque, belt and chain tension. Using the motor in our system, the job plan should specify the grease, the quantity required, removal of the purge plugs while greasing, and so on. Using ultrasound would provide a better precision approach for greasing activities to ensure the right amount of grease is used. No doubt over-greasing is a more significant issue than under-greasing for many organizations. On the gearbox, provide the right oil, and fill level. Use desiccant breathers if needed.
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For PM inspections and adjustments, standard procedures should include cleaning rollers to reduce product buildup and belt stretch, ensuring belt alignment and the proper belt tension. Tighten fasteners and remove loose materials that may create a belt tear or jam. In my previous column, I shared ways to develop PM tasks that identify equipment in the act of failing. Leverage those concepts to prevent additional secondary damage. Ensure the inspection procedures detail any steps needed to return the equipment to an operational level, i.e., replacement of chutes, motor disconnects on, and sanitation of the belt.
On the operations side, procedures and training are necessary to ensure the proper operation of the assets. Items include not overloading the conveyor belt, clearing jams to prevent stretching and tracking issues, cleaning the belt and rollers, appropriate changeover setups, and much more.
As you consider other plant equipment, it is easy to identify many more ways to introduce errors to your assets. With more complex assets such as a cartoner, incorrectly made (out of specification) packaging materials can cause excessive machine adjustments, downtime, and significant waste. Yet, the operator still attempts to run it rather than rejecting the packaging material and running a different lot with the correct specifications. Continuing with the cartoner example, simply resetting the machine to its “home” timing position weekly can prevent excessive adjustments and downtime. Machine changeovers are another event that can trigger the introduction of errors. Ensure that standard work adequately documents the actions needed. Use fixed adjustments (pinning) over infinitely adjustable slots and color-coding to eliminate human error—coach and train personnel on the correct adjustments.
Again, the goal is to prevent introducing new errors into the equipment and identify and correct mistakes before they occur. Implement quality control procedures like audits. Use the force field concept and consider how errors are introduced. Use critical events (downtime of two hours or more) and review the potential root causes. Teach plant personnel to constantly ask, “How can we prevent introducing new defects or faults in the asset?” Taking steps to ensure they don’t occur using a combination of procedures and training can significantly impact plant reliability and reduce your frustrations.
This story originally appeared in the July 2022 issue of Plant Services. Subscribe to Plant Services here.
