February 2023 Volume 5

MAINTENANCE

TPM– an Evolution We have come a long way since the 1940s when the standard practice was best described as ‘run to failure’. Preventive Maintenance techniques began being practiced in the 1950s in the U.S. As with other industrial management concepts, Japanese manufacturers took the concept of equipment reliability to another level in the 1960s and 1970s. Involving operators in the responsibility of maintaining equipment was a natural step in the evolution. After all, operators must run equipment in such a way that is not detrimental to its reliability. Equipment reliability becomes a shared objective between operators andmaintenance technicians with clearly defined responsibilities for both. This is referred to as Operator Assisted or Autonomous Maintenance . Operators are also in the best position to detect even subtle changes in the condition of the equipment that may be indicative of problems in the making. This led to Predictive Maintenance techniques - a significant step in the evolution. Don’t just do maintenance per a prescribed schedule as is often done with Preventive Maintenance, do it when machine conditions indicate that it is necessary. Whether it be operators or traditional maintenance technicians, the tasks required to maintain reliability must be made as easy to perform as possible. This usually involves the actual design of the equipment itself. Productive Maintenance concepts include providing techniques to easily detect changing conditions (think sensors), improving accessibility to perform maintenance tasks, and simplifying the methods and tools used. Total Productive Maintenance or TPM is composed of these four concepts: Preventive Maintenance, Autonomous Maintenance, Predictive Maintenance and Productive Maintenance. A real world example of an ‘evolution’ that you may or may not relate to (depending on your age) is the office copy machine. In the 1980s, a well-trained technician had to be called for nearly every problem. Frequent and lengthy downtime was the norm. Copy machines today are principally maintained by operators with less frequent technician involvement. Visual signals show operators where problems exist in the machine, and provide instructions on what steps to take, often with no tools required. While it is certain that problems still exist, uptime has vastly improved. Next, we’ll look at Most people will change their vehicle’s engine oil per the manufacturer’s recommended schedule. This is an example of Preventive Maintenance. Examples relevant to forging equipment provided in the November 2022 article include changing filters on press, shear and other equipment, draining water from the compressor system on a daily basis, just to name two. Pete Campbell, of Campbell Press Repair in Lansing MI, told me during an interview that each OEM provides a PM checklist for their equipment. Campbell Press Repair has been serving forging and stamping companies for 50 years. “Regular (quarterly, semi annual, annual) PM inspections by maintenance technicians are often lacking. The checklists exist, it’s putting aside the time to do the application of TPM to the forging industry. Applying TPM to Forging Equipment

them, and follow up on what has been uncovered. For example, keeping things square and true is one of the most important things to maintaining a high level of equipment reliability. Maintenance technicians should periodically check that running clearances are adjusted to proper levels, and check parallelism and total lift clearances that indicate the level of bearing wear.” Campbell continues, “for a hydraulic press, adjusting the packings and seals on rams and pull-backs need to be periodically done. The need to do this can be identified during a PM inspection.” Continuing with the motor vehicle example, owners will periodically wash the vehicle. This is an example of Autonomous or Operator Assisted Maintenance. Driving your vehicle, you notice the wheel pulling to one side, a slight noise when using the brakes, or one of many other conditions that can be detected best by the regular operator of the vehicle. Further, indicator lights on the dashboard make certain conditions visible to the driver. The necessary maintenance is planned and scheduled rather than waiting for a breakdown on the road to occur. These are examples of Predictive Maintenance, often in which the operator is directly involved. Most commonly, machine operators are responsible for maintaining cleanliness of the equipment, often its lubrication, and always monitoring for changes in condition. Campbell was clear that cleanliness was important for three reasons: to provide a positive working environment for operators, to spot problems early on, and for fire safety. I spoke with Jeff Fredline, President of Prestrade in Greeneville, TN. Jeff has 40 years of experience with forging equipment. Jeff emphasized the importance of involving the operators in the monitoring of the machine, as well as baselining certain conditions. “When cycling the machine, the operator should be looking for any movement of components that shouldn’t be moving. For example, operators should look for shifting of in-press tooling. Excessive play in the crank shaft and drive gears may indicate that major repairs can soon be expected. They should be checking for the presence of lubricant on running surfaces using a flashlight.” Fredline explained that the most important factors to the proper function of a press are repeatable tonnage and force, and squareness of the die space. He noted that when purchasing a new piece of machinery, a company will often not opt to pay extra for important features. “Tonnage monitoring can identify overloads or underloads. Lube fault indicators are also an option. Such monitoring capabilities are available on equipment, but many don’t purchase them.” Jeff says that such features can be retrofitted to existing equipment if necessary. Another example involves amperage meters on motors. Fredline explained that a ‘baseline’ can be established when the equipment is properly running. The operator can then monitor. “If the motor is drawing more current than the baseline, this would be an indication that the motor is working harder than it should. It might be issues with the drive train shaft, a lack of lubricant or bearing wear.” Again, such meters can be installed on existing machines if not presently in place. Campbell added that operators can also monitor lubricant quality by rubbing some between their fingers. Even brass dust can

FIA MAGAZINE | FEBRUARY 2023 22