Just about everybody agrees that effective maintenance can minimize the need for capital investment, boost plant capacity, extend equipment life, reduce repair costs and downtime, prevent lost profits and prevent the erosion of product quality. In short, good maintenance protects company assets.
But management commitment to maintenance is critical, and "this is where -- in my opinion -- more than half of preventive maintenance programs fail," observed Pete Carrino, chief engineer/manufacturing for Giant Food, Inc., at Food Engineering's PlantTech '99 Conference May 23 in Oak Brook, IL. Giant, based in Landover, MD, operates six plants manufacturing bakery, dairy, ice cream, ice and beverage products.
The initial costs of establishing a preventive maintenance program are high, Carrino continued, and include replacing worn equipment, which drains maintenance resources. Implementing a preventive maintenance program is in fact a rebuilding process and may not generate a return on the investment (ROI) for nine months to two years, depending on the size of the facility.
Since implementing a PM (preventive maintenance) program at a Giant Foods dairy plant in 1994, Carrino reported, annual equipment breakdowns declined from 397 to 130, and plant productivity rose from 175 to 250 gpm (gallons per minute) while the plant's maintenance staff was reduced from 22 to 12. "We now produce more volume in four days than we previously produced in six days," he added.
Networked PLCs incorporating diagnostic capabilities, which indicate when a machine should be serviced, allow shifting from preventive maintenance to predictive maintenance "which is where you want to be," said Carrino. "We hope to be in a fully predictive maintenance mode by the end of this year, and are currently about 30 percent there."
Predictive paybacksRalph Lostracco, president of the consulting firm Predict Monitoring Systems (Fenwick, ON), discussed at PlantTech '99, the dramatic payback which can be achieved through investment in advanced maintenance. Lostracco cited a survey of more than 1,000 industrial plant managers who have installed predictive maintenance systems. As shown on the table on page 58, returns ranged from four to 30 times investment, with a median of 11 times investment. Substantial reductions in breakdowns, unscheduled downtime and maintenance costs were also reported, resulting in productivity gains averaging 21 percent.
But few industrial plants are realizing the full potential of advanced maintenance, Lostracco continued. Fifteen percent of industrial plants claim to be using advanced maintenance strategies, but only 5 percent are "really into it." Continuous process plants, mainly in the petrochemical industries, are leading the way.
Lostracco defined predictive maintenance as "the technology of determining the condition of a machine without disrupting normal operations." By contrast, some preventive maintenance operations require taking a machine out of service. Predictive maintenance includes collecting, analyzing and trending machine data, then servicing the machine and replacing parts before they wear out. The condition of the machine is always known. Objective: to eliminate breakdowns.
Most ailing components will give warning, Lostracco continued. Warnings include vibration, heat, noise, thickness decrease and oil-wear particles. Recommended predictive technologies are listed below. Some pertinent facts:
- According to industry surveys, vibration analysis -- "the cornerstone of predictive maintenance" -- can payback 10 to 50 times the total cost of the program in the first year.
- Rotating-shaft unbalance has several causes, but the most common is material buildup on fan blades and impellers.
- More than 40 percent of machinery breakdowns can be attributed to improper lubrication.
- Infrared thermography, which remotely measures heat generated by electrical systems or within mechanical systems, is the most popular predictive technology because of requirements to reduce fire hazards.
- Non-destructive tests, to monitor reduced thickness of pipe and vessel walls due to corrosion and erosion, include several methods: visual; liquid penetrant; magnetic particle; ultrasonic; radiographic; eddy current; and acoustic.
Trending is the key element of a successful predictive maintenance program, Lostracco concluded. He recommended creating a maintenance-improvement plan with specific goals, then selecting the technologies which will generate the quickest results.
Predictive technologies"One big score" can provide the payback for a predictive maintenance system, said William E. Lundgren, engineering manager at the Chicago Bakery of Nabisco Biscuit Co. He outlined major predictive technologies applied at his plant.
Vibration-signature analysis detects faults such as eccentric or bent shafts, mass unbalance, misalignment, and bearing wear in rotating equipment by providing instant waveform readouts for trend analysis. Capital cost for an IRD (Columbus, OH) dataPAC 1500 portable data collector at Nabisco was $35,000; training costs were $6,000 each for certification of three hourly employees. "You must dedicate motivated people to learn these technical skills, and you must have upper management support," Lundgren added.
Infrared (thermographic) imaging is especially useful in detecting electrical faults and excessive or insufficient heat in machine components, Lundgren continued. Equipment costs vary widely based on thermal sensitivity. Nabisco opted for a "high-end" system consisting of an Inframetrics (North Billerica, NY) ThermaCAM radiometer with processing software, plus a Sony video recorder and color monitors, for a total cost of about $50,000.
According to Lundgren, ultrasonic testing offers "by far the biggest bang for the buck" with a $2,000 UE Systems (Elmsford, NY) Ultraprobe, which can detect problems ranging from worn bearings and gears to pump cavitation and under-lubrication at distances up to 100 ft. With ultrasound, electrical switchgear can be checked for arcing and corona before opening the panel.
Motion analysis, for troubleshooting and testing mechanical timing and contacts on equipment such as closure machines and product accumulators, is accomplished with a portable Kodak (San Diego, CA) MotionCorder. The unit costs about $25,000.
Precise shaft alignment using a Ludeca (Miami, FL) Optalign laser aligner, extends the life of couplings, bearings and equipment by reducing vibration and also reduces energy consumption. "Eighty percent of all mechanical problems have a root cause of misalignment or unbalance," Lundgren pointed out.
Oil analysis complements vibration analysis by pinpointing, for example, what component of a gearbox is failing. It also reduces lubrication costs by indicating when an oil change is actually needed, Lundgren added.
Outsourced maintenanceAccording to Gary Brown, packaging line manager at the Miller brewery in Albany, GA, production volume at his plant has increased over the past decade but some maintenance skills were lost as the work force was downsized from 1,400 to 550. Preventive maintenance conducted on the plant's Riverwood Twinstack multiple packaging machine resulted in reasonably acceptable and predictable machine performance, but maintenance-resource and spare-part costs were considered excessive.
In March 1998, the plant shifted to a 100 percent predictive maintenance program in partnership with machine supplier Riverwood International (Marietta, GA). The objective was to utilize each machine part as long as possible and replace it before failure during a production run. Key elements of the project included an expected service life for each machine component and sub-component; a service schedule based on machine production hours rather than calendar days; and division of the machine into nine basic systems (lubrication, pneumatic, infeed, etc.), which creates the basis for a maintenance checklist. "Utilizing this checklist, we are either checking, adjusting or replacing all major components," said Brown. Based on current production, these activities are scheduled about every four months.
The fixed-price maintenance contract with Riverwood includes the cost of all spare parts, delivered just prior to the scheduled service and guaranteed for one complete maintenance cycle (1,400 hours). It also includes the cost of a Riverwood engineer at each scheduled service who works with and trains craft people, then inspects machine adjustments and parts installation to validate the warranty. The predictive-maintenance program was expected to reduce maintenance costs by more than 50 percent ($85,000) during the first year but has exceeded that goal, Brown reported.
Organizing for maintenanceFood plants organize for maintenance in different ways, depending on whether they have traditional departmental structures or team structures, and varying with specific plant needs and company culture.
In some plants, operators are trained in troubleshooting, routine maintenance and preventive-maintenance tasks, leaving only heavier maintenance work such as breakdown repairs and machine overhauls to skilled craftsmen in the maintenance department. At the new Hunt-Wesson aseptic pudding plant in Waterloo, IA, for example, operators double as maintenance technicians and are responsible for operation and preventive maintenance of all line equipment in their assigned areas (see Food Engineering's "New Plant of the Year," June 1999). A small team of facility technicians, composed of skilled tradespeople such as machinists, welders, electricians and PLC programmers, maintains plant utilities and HVAC systems, and handles the heavier maintenance and repair jobs requiring its skills. Plant Engineer Tim Yost refers to this type of organization as "participative maintenance."
Some plants incorporate skilled maintenance people into production teams. At the Sara Lee frozen baked goods plant in Tarboro, NC, operations, maintenance and sanitation people are all included in manufacturing teams organized by production line, said Peter Kratz, vice president/manufacturing for Sara Lee Bakery, at PlantTech '99.
Bridging 'the skill gap'Technology is outpacing training in maintenance and engineering, and "maintenance skill gaps" will not be closed as long as "seniority, not skill, is valued in our current compensation system," said Dan Babin, vice president/manufacturing for Stroehmann Bakeries (Horsham, PA), at the 75th annual meeting of the American Society of Baking (ASB) March 2 in Chicago.
To bridge the skill gaps, Babin recommended:
- Pay-for-skill compensation systems, based on demonstrated mastery of various skill sets, as incentives for developing the required skills.
- Graduate-school partnerships with colleges and universities to access professional engineering talent. For example: Four master of engineering candidates from Cornell University last year applied simulation modeling to redesign the preventive maintenance program at a Stroehmann bakery. Such partnerships also provide a recruiting opportunity. Partnerships with professional organizations such as the American Institute of Baking (AIB) can also provide engineering expertise.
- "True, interest-based partnerships" with equipment vendors.
- Flexible work schedules to address quality-of-life issues. Stroehmann maintenance departments offer scheduling alternatives such as: four 10-hour days with three consecutive days off; three 12-hour days plus a four-hour training or preventive-maintenance task; a schedule based on equipment responsibilities; part-time down-day specialists.
- Transferring lower-skill maintenance work to production and/or sanitation employees, which allows maintenance to focus on higher-skilled tasks, allows greater scheduling flexibility, and can help cover the costs of a "pay-for-skills" compensation program.
Maintenance toolsComputerized Maintenance Management Systems (CMMS) are helping food manufacturers better organize and execute their maintenance programs.
Several food plants recently visited by Food Engineering use Datastream's (Greenville, SC) MP2 maintenance management software which tracks equipment history, schedules preventive-maintenance tasks, generates work orders, requisitions and purchases spare parts, maintains spare-parts inventories, allocates and records maintenance resources, and projects equipment failures for predictive maintenance. The open system integrates with other software packages.
At the new Dole Value Added Products plant in Springfield, OH (Food Engineering, April 1999), for example, MP2 manages spare-parts purchasing and inventory, preventive maintenance and asset history, says Maintenance Manager Bill Vith. At the Hunt-Wesson aseptic pudding plant in Iowa, maintenance and repair activities are managed by an MP2 program with database identifying every piece of equipment in the plant. For an MP2 application in a seagoing seafood plant, see page 14 in this issue.
Datastream MP2 was even encountered by FE in the deserts of Saudi Arabia at the new Almarai dairy plant near Al Kharj (Food Engineering, June 1998). According to Plant Manager Abdulrahman Al-Fadley, MP2 integrates with the plant's APV ACCOS process-control system to schedule preventive-maintenance work, generate work orders, inventory and order spare parts, and record work completed.
You Can Bank on itEmergency repairs cost 10 times more than planned repairs, yet reactive maintenance -- "don't fix it 'til it breaks" -- is still the mindset in many food plants. Proactive maintenance can dramatically cut costs and boost productivity.
--Charles E. Morris, Midwest Editor
The Ultraprobe 2000 ultrasonic detection system is used for a wide range of predictive maintenance applications by detecting: worn bearings and gears; under lubrication of bearings (as shown above); gas, liquid and vacuum leaks; pump cavitation; arcing or corona problems in enclosed electrical switchgear, before opening the panel. (Source: UE Systems, Inc,)
Recommended Predictive Technologies
Vibration Analysis All rotating equipment
Alignment & Balancing All rotating equipment
Oil Analysis Critical or low-speed and hydraulic equipment; large gear boxes
Infrared Thermography Electrical components; roofs; insulation; steam traps
Motor Analysis Motor stator, insulation breakdown and rotor bars
Airborne Ultrasonics Compressed air, steam and vacuum leaks; steam traps
Non-destructive Testing Pipe & vessel thickness
Process Parameters Process or mechanical degradation tracking (temperature, pressure, etc.)
Benefits Of Predictive MaintenanceShort Term:
- Identify and troubleshoot problems easier and faster
- Save money on maintenance overtime
- Detect problems when less critical and expensive to repair
- Prevent unplanned downtime
- Repairs can be planned in advance
- Easy to quantify costs to repair
- Cost savings justify investment
- Payback periods often less than one year
- Improvements in maintenance and operations
- Longer equipment life
- Less capital cost to replace
- Avoid redundant equipment purchases
- Identify equipment exceeding design specs
- Identify parts deficient in design or quality
- Set acceptance criteria for new or rebuilt equipment
- Improvement in maintenance standards
Predictive Maintenance Survey Results1Benefits Range Median
Return on investment (ROI) 4 to 30 times 11 times
Reduction in maintenance costs 7 to 60 percent 27 percent
Productivity gains 2 to 40 percent 21 percent
Breakdowns eliminated 50 to 98 percent 74 percent
Reduction in unscheduled downtime 33 to 45 percent 40 percent