Maintenance: If it ain't broke, keep it from breaking!
Preventive maintenance, long an overlooked budget item, is gaining new respectability through profit potential.
In many foundries, maintenance is an area in which sound management principles are still largely ignored. Indeed, routine, or preventive maintenance, is often considered a necessary evil that handicaps production time. Millwrights work long hours, even weekends, to keep machinery in production, but little is understood about the how and why of total maintenance programs.
It is safe to say that most members of foundry top managements lack the means to measure either the efficiency or the effectiveness of their average maintenance workers. Their ability to return equipment to operating condition is generally the only criteria upon which they are judged. On average, "bailing wire" repairs are the rule, and many times are not followed by more permanent repairs. No breakdown analysis is done, nor are investigations undertaken to optimize repair times or methods. The master mechanic is happy and his efforts adjudged successful when all is quiet--when "all the boys are sitting around."
This is not intended to downgrade maintenance organizations or their personnel for without their willingness to work long hours under difficult circumstances, it is quite possible that many foundries would be shut down.
I recently saw a brochure which proclaimed that, "The Grease Monkey Is Dead." The obvious reference is to the mechanic who was said to fix equipment by one of three methods: hit it with a hammer, tighten it with a monkey wrench or grease it as heavily as possible.
For the last 40 years, the American form of preventive maintenance has been practiced by many foundries with limited to outstanding success. Preventive maintenance, American style, means an elaborate system of periodic equipment inspections that are performed so as to prevent the occurrence of breakdowns. This type of maintenance, if followed religiously using the best possible craftsmen, can be successful.
These programs, however, are subject to the development of inspection back-logs and scheduling problems that generate administrative nightmares. In time, many of these programs fall behind quickly and eventually grind to a halt. New equipment often is not entered into the maintenance program, and, over time, craftsmen begin to give lip service to what might once have been a good maintenance program.
With the recession of the '80s behind us, many foundries that survived have learned that they must automate or mechanize if they are to remain competitive. Rising costs, foreign competition, the demand for higher quality, continued environmental and governmental pressures and the new requirement to operate on the "just-in-time" production philosophy, all are demanding that foundries be more productive and more flexible.
The foundry of the future will require new manufacturing techniques and systems controlled by equally new and complicated technologies. Computers, robotics and programmable controllers will be the means of control, operation and information gathering.
If the grease monkey is indeed dead, he must be replaced by trained, skilled technicians and craftsmen able to keep operational the newest machines and processes and minimize downtime. Eighty percent production uptime won't be good enough to remain viable. Instead, 95% will be the norm required to capture our share of the casting business.
With these thoughts in mind, preventive maintenance, or PM, must be improved by using better controls and working closer with other maintenance techniques and procedures.
Preventive maintenance consists of the periodic inspection of existing facilities and equipment to uncover conditions that may lead to equipment breakdown, as well as to correct these conditions while they are still minor. PM inspections should be performed on those equipment items the failure of which could cause a production loss, a safety hazard, an unfavorable environmental condition, a decrease in product quality or a premature equipment replacement.
By definition, PM should go beyond periodic equipment inspections. It should encompass all of the recognized practices of an organized maintenance program, one that should start with the commitment of top management to a definitive policy that provides for: * organization; * supervisor and craftsmen training; * work order system; * planning and scheduling; * job priority system; * equipment history records; * spare parts inventory control; * lubrication system; * preventive maintenance inspections; * corrective maintenance analysis; * accounting and auditing.
The above programs are time-consuming and demanding from an administrative standpoint, but computerization can relieve that burden by reducing clerical labor, speeding up responses to planning, scheduling and emergencies, and organizing inventory, inspection and reporting functions.
Of course, your computerized maintenance program should be tailored to specific foundry requirements. It should be user-friendly and flexible and diversified enough to have the capability to identify excessive equipment downtime and/or repair costs, track work orders and set maintenance priorities.
The software should be capable of maintaining: * equipment inventories by age, repair costs, book value, unit numbers and aquisition costs; * work order planning/scheduling/status of work in progress; * job priority determination; * spare parts inventory and reorder system; * lubrication program and routing with equipment diagrams; * PM inspection scheduling and back-log; * corrective maintenance and life of repair analyses; * labor availability by trade or craft.
The typical equipment PM program with inspections based on hours or calendar days to use can be supplemented with Predictive Maintenance whereby the actual conditions of equipment items are measured as a guide to schedule maintenance repairs. Unlike run-to-failure and preventive maintenance, predictive maintenance is an active, rather than reactive, approach to maintenance.
Predictive maintenance is a maintenance philosophy, or method, which uses direct monitoring techniques to determine when and what type of maintenance is required. Repairs then are based on actual need rather than elapsed time. However, even the best predictive maintenance program will not eliminate all unexpected failures. Predictive maintenance monitoring must be combined with the preventive maintenance procedures described above to provide a cost-effective maintenance program.
Predictive maintenance is widely used in factory operations, and its techniques include: * vibration monitoring of rotation or mechanical equipment; * thermography, including infrared temperature monitoring and thermal imaging, to determine hot spots, heat loss, buildup or transfer, and loose electrical connections; * tribology, including lubricating oil analysis, wear particle analysis and other techniques to determine lubricating oil condition, generally on mechanical equipment.
Total Productive Maintenance
The Japanese introduced Total Productive Maintenance (TPM) as a means of improving upon other maintenance programs. TPM can be defined as productive maintenance with all employees participating through small group activities. It is different from American-style PM where operators are concerned with machinery production and maintenance departments are responsible for machinery repairs, with little or no interchangeability between the two.
Before TPM, the jobs of machine operators and maintenance men were kept separate by the ingrained "them vs. us" distinction of job responsibility. Changing this pervasive attitude so that the operator maintains his equipment (autonomous maintenance) is the first and major step in TPM. The key to its success rests on properly training operators in equipment maintenance.
Some successes typically claimed by TPM users are: * corrected 95.3% of minor defects in first three months; * reduced downtime by 70%; * improved equipment efficiency 20-50%; * reduced equipment breakdowns 80%; * reduced maintenance personnel 12.5%; * reduced maintenance man-hours 20%; * return on investment over three years, 262%; * operators spend 3% of their time (15 minutes/day) on TPM.
It is estimated that 75% of maintenance problems can be prevented by machine operators, since most PM inspections are visual. Operator training by maintenance craftsmen, however, is essential. Keeping machine checklist records, making PM inspections according to predetermined schedules and reporting more serious machine problems should become routine for operators. Doing this significantly eases the maintenance crew workload, and the craftsmen can then be used on major rebuilds and repairs, installations and other assignments that in the past may have been contracted out.
PM performed by operators is virtually free because the operator is already at the machine. It has been noted that operators who work at TPM with enthusiasm often use free periods to perform minor maintenance. TPM creates a pride of ownership and better-trained employees, and the spirit of cooperation between operators and maintenance crews is enhanced.
In the past, American unions have objected to assigning TPM to production employees, but that view is changing. They now offer little opposition to operating and maintenance practices that improve productivity, accepting the need for U.S. plants to be productive and competitive.
Examples include Harley-Davidson and Detroit Diesel, both of which found their union representatives and maintenance craftsmen quite willing to support operator involvement in preventive maintenance. Both operators and craftsmen, however, must be trained to see that TPM can contribute to a total plant commitment to reduced costs and improved profitability.
The maintenance performed by machine operators is not only beneficial to the maintenance of equipment and improved uptime, but it is a motivational factor for most operators. Training for operators must consist of both mechanical and attitude training. With management now stressing cooperation between production and maintenance (a factor that is usually absent), the operator must be convinced that his new maintenance duties are going to contribute to total plant productivity and profitability.
As foundries become more automated and more accustomed to operating in a "just-in-time" mode, preventive maintenance becomes even more advantageous in its contribution to profits. It has been documented in some industries that a one dollar saving in maintenance is equivalent to an increase in sales of $18. If this is reasonably correct, then maintenance savings are a key consideration for any operation.
Simply paying attention to preventive maintenance can pay off quickly. Early on, Black & Decker emphasized PM on key machines. Operators recorded problems on cards kept at each machine, and maintenance craftsmen referred to these cards on regular shop rounds. Problems were quickly corrected and equipment availability increased by 10% within a few months.
While TPM refers to operators becoming involved in machine maintenance throughout the total plant, perhaps we should consider it in another way. "Total Productive Maintenance" must include all of the recognized good practices of a total maintenance management program. The principles of preventive and predictive maintenance must be joined by that of TPM (operator maintenance). The use of operators to perform minor repairs and PM inspections, freeing craftsmen for other maintenance, can add substantially to machine readiness. The machine uptime objective of a company should be 95% or more.
Jonh W. Wasem American Steel Foundries East Chicago, IN
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|Author:||Wasem, John W.|
|Date:||Oct 1, 1989|
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