One of the most important expectations of asset managers is to minimize equipment downtime. For many years I have heard operations personnel complain that:
- the equipment is always down;
- it takes forever for maintenance to respond to and fix the problems; and
- operations is not notified as soon as the job is completed.
On the other hand, maintenance claims that downtime could be reduced dramatically if:
- operators were better trained on the equipment;
- operations would alert maintenance faster and more accurately as to the nature of the downtime; and
- operations were to resume immediately following a repair job instead of waiting hours or even days.
In my opinion, we do have a serious downtime problem in North America. The average company wastes hundreds of thousands of dollars in equipment downtime. No doubt both operations and maintenance can make improvements.
The classic arguments above have been bantered about ever since maintenance departments became separate entities. Unfortunately, top management does tend to side with operations because it is revenue-generating, while maintenance is viewed as an expense generator. Thus, when operating budgets are cut, maintenance expenses are the first on the chopping block.
Sometimes, in the name of lower costs and decreased downtime, the maintenance/operations power struggle has resulted in assigning resident mechanics with direct responsibility for servicing equipment for a given area of operations. The mechanics report directly to the area operations supervisor and indirectly, if at all, to the maintenance supervisor. Establishing a resident mechanics program can pay dividends in reduced downtime, but it should be instituted based on economics, not politics.
So how do we repair this potential breakdown in communications? First, let’s examine some definitions.
Production vs. machine downtime. Production downtime refers to the amount of time a machine is not processing a given product, when it was scheduled to do so, (for example, when there is a material shortage). Machine downtime is the amount of time equipment is incapable of processing product or out of service.
Thus, production downtime is product-oriented and is primarily the responsibility of the operations supervisor. Machine downtime is equipment-oriented and is primarily the responsibility of the maintenance supervisor.
Downtime reporting. The operations supervisor should be tracking deviations from planned production, and in particular, production downtime. This can be incorporated into existing data collection systems such as time reporting, ERP system, PLCs, or tracking systems built right into the equipment.
Reasons for downtime should be identified using coded fields for easy trend analysis (for example, preventive maintenance; machine breakdown; lack of materials; unscheduled set-up, changeover, or clean-up; testing; insufficient labor; or awaiting instructions). However, only the first two, preventive maintenance and machine breakdown, constitute machine downtime.
The maintenance supervisor should track machine downtime, identifying the length of and reasons for the interrupted service. This data can be collected using time reporting and fault codes via the work order system and equipment history file of a CMMS.
In theory, companies should not focus on who is at fault; the emphasis should be on how everyone can best minimize downtime. In practice, however, it is important to keep accurate records. In the event of a large unplanned loss of production, the production and machine downtime records provide a tracing mechanism for identifying the root cause of the problem.
Computerized downtime recording. For more accurate and timely sourcing of problems, both production and machine downtime can be collected automatically. This is accomplished by attaching the necessary sensory devices to the production equipment, and then connecting these sensors to a programmable controller. In turn, the programmable controller feeds downtime information to software that tracks the downtime such as provided by vendors of condition monitoring systems, CMMS, shop-floor monitoring systems, and so on. Workstations or terminals can be provided to key plant personnel in production and maintenance with online monitoring capability. Output screens list the production equipment, and display the following information:
- up-to-the-minute standard versus actual production
- classification of downtime (e.g., set-up, clean-up, breakdown, no material)
- number and duration of occurrences.
Upon detecting downtime, a sensor would immediately trigger some sort of alarm to identify the failed piece of equipment. An example would be flashing the equipment listing on each monitor. The alarm would prompt a mechanic to investigate.
Still further sophistication and automation would require the mechanic to key or wand in a personal badge number into the nearest key station. The mechanic has now logged on. The computer screens will show that the downtime problem is being serviced (by replacing the flashing with, say, an asterisk), and the computer has recorded the response time.
When the maintenance work is completed, the resident mechanic communicates this to the system by logging off, that is, by re-entering his badge into the key station. The mechanic then uses the keyboard to enter the downtime classification and/or a reference work order number, and any comments.
Some CMMS packages can be integrated directly with a downtime recording system to provide condition monitoring, alarming, and downtime trends and statistics. Most CMMS packages are at least moving in this direction. Given that our production equipment has become smarter and more interconnected over the years via the Industrial Internet of Things (IIoT), this factory automation process has been accelerating.
Major benefits include the following:
Improve communications and highlight problem areas – Proper downtime management systems will improve communications between the maintenance and operations departments. Accurate downtime recording highlights problem areas, and promotes timely and effective solutions by quickly revealing the true sources of problems. Thus, if the number or duration of material shortages, changeovers, machine breakdowns on certain pieces of equipment, and other problems is excessive, it can be rectified by those responsible as efficiently and effectively as possible. This reduces downtime and therefore lowers production and maintenance costs.
Cost-justify machine replacement – Downtime information is also utilized in the cost justification of equipment replacement. If records reveal downtime caused by machine breakdown is such that the cost of repairs and lost production exceeds the machine replacement cost, money can be saved by purchasing new equipment.
Assess maintenance department performance – Downtime information is useful in assessing the performance of the maintenance department. Reductions in labor and material dollars spent divided by dollars spent on capital equipment, mean improved productivity and therefore lower costs.
Reduce the cost of operations and improve capacity utilization – The biggest winner is operations, especially if the plant is at capacity. That is, the lower the downtime, the more product is made and sold at a profit. Less downtime can also yield labor savings by avoiding production workers sitting idle, assuming there is nothing else for them to do.
This article is part of our monthly Asset Manager column. Read more from David Berger.