Organisms that can adapt to changing conditions survive and those that cannot, die out. Mills in the papermaking industry have also been taking this fitness test, where those which can maintain demand…
Organisms that can adapt to changing conditions survive and those that cannot, die out. Mills in the papermaking industry have also been taking this fitness test, where those which can maintain demanding standards of quality, efficiency and cost control may survive and the rest must shut down.
Minas Basin Pulp & Power in Hantsport, NS, faced this reality and spent the last nine years developing, implementing and fine-tuning a preventative maintenance (PM) program that has reduced the materials and labour budget in its pulp preparation area by 35% since 2003.
“PM had to come. It wasn’t only maintenance costs, but machine unavailability, breakdowns and an increase in the level of off-spec paper, which we would have to sell for an off price,” says Terry Gerhardt, vice president of operations with the family-owned plant, tucked in a cove on the Bay of Fundy.
The company targeted pulp prep area for a new approach to maintenance in 1998. Pulp prep has the nasty task of processing as many as 275 tonnes of recycled paper furnish (otherwise known as OCC, or old corrugated containers) a day to make pulp for the mill’s paper machine, which has a production capacity of 80,000 metric tonnes per year.
At that time, the maintenance crews were replacing parts based on calendar and wear measurement, and breakdown maintenance was the norm. “We did not know how to spell PM and didn’t know what it meant,” Gerhardt acknowledges. He declines to make public the visible maintenance costs in 1998, but they were budget burners. The attendant production problems, he notes, “had enormous hidden costs.”
The switch to PM began with two years of work to develop a parts replacement schedule for the 400 pieces of equipment in pulp prep. The new schedule was based mainly on original equipment manufacturers’ recommendations, and the identification of all the critical equipment. “If you are starting a new PM program I think this is the only way to get started, unless you have a detailed history to reference,” says Chad MacDonald, the technical and process manager.
In 2000, the first version of the PM program was in place. In 2001 the results of the parts replacement program were measured and baselines and targets set. The maintenance staff was made accountable for the PM tasks and as the benefits of the new program became apparent, their doubts were replaced by greater interest in improving results; maintenance began presenting many new ideas to improve the program, according to MacDonald.
As maintenance gained experience with the PM program, certain repeated checks were identified as unnecessary and the saved time was invested in more detailed checks on other equipment. For example, the Number 3 decker, a thickener that takes water out of the pulp stock, used to be run to failure. Although the mill could be run without it until it the bearings were replaced, paper quality suffered. “Eliminating some tasks gave us the time to focus on high-risk equipment,” says MacDonald. “Now we grease the decker bearings every three months, instead of running the decker to failure.”
In 2000, Minas dedicated an employee to PM and lubricating on a lube schedule. He carries out three checks a week on all the equipment in the mill, which includes a visual and “feel” inspection on the equipment for abnormal temperatures, sounds, vibrations or seal leaks. The checks are logged, with results going back to the maintenance planner.
Although equipment problems were being identified, repair follow-through was just 40-50%. “Repairs were only being done on breakdowns or during our plant’s monthly shutdown. Due to limited resources during the shutdown, pulp prep would be neglected because its equipment could be bypassed even if it failed. Things were not getting done and the PM schedule was always behind. Also, the cost of repairing equipment run to failure was more expensive than equipment rebuilt on a PM,” MacDonald explains. “With a PM check, you have people on hand and the parts are ready. A failure can take out other equipment. PM is cheaper, and it is an easy thing to prove, because it is on the bottom line.”
Minas solved this problem by introducing a four-hour pulp prep shutdown every Friday morning for repairs; production makes and stores extra pulp so that the paper machine can continue to run at full speed through the shutdown. The result has been an increase in the repair completion rate to 90%. Importantly, notes MacDonald, this has reinforced the entire PM effort: “It has motivated people to complete their checks because they are seeing their issues being responded to.”
Minas brings in a contractor for a monthly vibration analysis (VA) of key equipment, but it learned it could remove some equipment from the VA checklist simply by following the recommendations of the lubricator and analysing process flow results. “You can gather too much information and pay for services that are not necessary,” MacDonald advises. Minas also introduced an annual thermographic survey of the electrical equipment; this work, currently contracted out, will be done in-house once the company purchases its own camera.
Minas complemented its PM program with numerous equipment modifications and outright replacement projects. Former pulp preparation manager Keith Hudgins was instrumental in defining the aspects of the operations that had to be replaced, and selling the ideas to management. “Every project we did had an ROI [which also took into account production downtime and equipment quality] of under a year, and many of them had an ROI of just a few months.”
For example, the bottom of the delta conveyor, which delivers the main feed of recycled paper furnish to pulp prep, used to be in the ground, where occasional high tides would flood it, ruining the conveyor slats, chain and bearings. Since rebuilding it in 2003 and raising it off the ground, at a cost of $120,000, the failure rate has dropped from twice a week to zero.
A small modification to the high-density cleaner, which removes metals from the recycled paper furnish, improved the swirl, which in turn removes more metal from the feed to the ADS. One of the most critical pieces of equipment in the pulp preparation area, the ADS is basically a huge basket with rotors that separates high-quality stock from stock that needs to be cleaned more, or rejected. The upstream equipment modification has decreased the wear on the ADS, extended its rebuild cycle from once every three months to once every six months.
Another example of an equipment improvement was the installation of a flinger a year ago in the CH7 screen cleaner to keep water from getting into the bearing. Maintenance used to replace that bearing once every three to six months, but since the greasing schedule was increased and the flinger was installed, the bearing has not needed replacing.
Maintenance examined the replacement schedule for disposable parts, and successfully extended the replacement schedule for many of them. Maintenance also changed the frequency of some equipment rebuilds, as some equipment had more life in them then previously thought. “Our ELP cleaners, which are used to remove fine grit from the system, were being changed every six months. We experimented with leaving them longer and found that their life was actually 12 months,” MacDonald says.
“We knew that [many] items were not only costing a lot of money to rebuild but we were spending too much time rebuilding them and neglecting other equipment. It all sounds easy, but in today’s manufacturing industry you have limited funds, so you must work hard to justify any changes, especially if they require high initial costs. You must work with production and sell your ideas to senior management.”
Minas created its own PM program, at a lower cost than commercial software. “A home-grown PM program takes longer to develop, but our people are experts in PM because they developed it and own it,” says Gerhardt.
MacDonald attributes the success of this nine-year project partly to management’s clo
seness to the equipment and to his maintenance team. Looking back, however, he notes, “I would suggest using a consultant, preferably one familiar with your industry, to help kick start a PM program. Someone familiar with your industry’s challenges can help you pick good PM tools. After the initial organizing, the consultant should no longer be needed, as you know your equipment better than anyone.
“The key to a successful PM program is creating a good equipment history so you can improve your program and justify changes. In the long term, spend time on the items with the biggest return but remember to resolve the simple issues first. They add up and offer quick returns.”
Carroll McCormick is a professional writer living in the Montreal area.
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