Lean, Mean: Processing machines

October 1, 1997

10 Min Read
Lean, Mean: Processing machines

Michael Fickes

When RRT Design and Construction, Melville, N.Y., was hired to audit the operation of 50 processing plants owned by Waste Management Inc. (WMI), Oak Brook, Ill., it sought a way to save money that did not require expensive capital improvements.

The answer? Maintenance.

Inadequate staffing lowered performance at a majority of the plants audited, reports Nat Egosi, president of the independent design/build contractor that formerly was owned by WMI.

"The theory is that you save money by not having an extra mechanic," Egosi says. "But it doesn't work that way. In fact, you lose a lot more money when the plant is down."

Some facilities have downtimes as high as 20 percent, according to Egosi. "This doesn't mean the plant is down one day a week; it's down 15 minutes here and 30 minutes there. Unless you stand beside the line and use a stop watch, you don't realize how all those little periods of downtime can add up."

While facilities employ various maintenance approaches, one thing is certain: If maintenance is not performed regularly and correctly, the plant won't produce optimally.

Egosi views maintenance as three jobs: scheduled preventive maintenance, scheduled/unscheduled repairs and planned retrofit work. He recommends a staff size of one to seven employees, depending upon the plant size and number of shifts.

Additionally, maintenance mechanics should offer a range of skills and should understand hydraulics, electrical work, operations and safety, including fire prevention.

Preventive maintenance includes regular lubrication of tracks and belts, checking oil levels, checking operating temperatures, and clearing and cleaning the lines.

Repair work might be planned or unplanned. Unplanned repairs fall to the maintenance staff, but planned repair work can be performed in-house or can be outsourced. For example, he notes, "it's probably faster and easier to hire someone to reline a baler." For retrofit work, he recommends outsourcing. "We don't recommend plant staffing based on retrofitting needs, since retrofitting is an infrequent, planned event."

Egosi sets up systems to track material costs and labor through work orders, which allows managers to determine which pieces of equipment need to be replaced.

"We train plant managers to do a simple financial analysis which considers the labor and parts required to keep the equipment working, the equipment's trade-in or salvage value and the cost of new equipment," he says.

After the analysis, comes the determining factor: Can new equipment offer technology to lower operating costs? For example, a new, larger baler can operate at lower horsepower than an older baler because of a more efficient design, Egosi says. Such a machine will consume less electricity, require less maintenance and repair, and provide more throughput.

"You need to do a financial analysis to see what the extra capacity and electricity savings will mean," he says. "Don't forget the cost of removing the old [equipment] and be sure to check any electrical system changes the new [equipment] may require."

Extending Equipment Life Boston-based USA CRINC Inc. uses maintenance to extend the life of its equipment at the three plants it operates for municipalities in Poughkeepsie, N.Y., Milwaukee and Waukesha, Wis.

The equipment and capacity varies from plant to plant: Poughkeepsie handles 30 tons per day (tpd) in bottles and cans using a Bezner sorting system; Milwaukee pushes 170 tpd of bottles, cans and paper through lines with a Bezner sorting line and Bollegraaf balers; and Waukesha, the smallest of the three plants, uses a Bollegraaf baler and sorting system provided by a local contractor.

USA CRINC develops maintenance manuals for managers in each plant based on recommendations made by the equipment manufacturers, according to vice president Bob Torriere.

"We go through the manufacturer's maintenance manuals and synopsize the information by hours and equipment type," Torriere says. "For example, the book will have checklists for maintenance work to be done every eight hours, 40 hours, 80 hours and 2,000 hours. A second section will list maintenance requirements under each piece of equipment. The manager can decide which approach is best for the particular operation."

As the maintenance work is completed, managers submit equipment reports which cover status, failures, parts requisitions and maintenance to Torriere.

USA CRINC also takes advantage of manufacturer maintenance contracts. For example, Torriere says that one baler manufacturer sends "a technician into our plants every six months and go over their equipment for a predetermined fee, plus parts. Then, the technician gives us a detailed report on the baler's condition.

"In my mind, it's an insurance policy," he adds, noting that during a recent inspection, a technician found that a bolt on the main ram was ready to fall off - a situation which could have caused $10,000 worth of damage.

The records developed by the plant's preventive maintenance programs and the manufacturer's preventive maintenance inspections document the equipment's condition which becomes important at the end of a contract. USA CRINC uses the logs to prove to the municipalities that the equipment is in good shape.

Indeed, USA CRINC equipment often lasts longer than expected. "We had a baler in a Rhode Island plant that had 30,000 hours on it after five years," Torriere reports. "If you figure 2,000 hours per shift per year, that baler was still working after the equivalent of 15 years of service. Properly maintained, this kind of equipment will last 15 to 20 years."

Organizing By Checklist Maintenance planning is a necessary first step. But the real test, of course, comes on the plant floor, especially a busy plant floor. In Palm Beach County, Fla., the Solid Waste Authority runs an unusually busy material recovery facility (MRF): The 38,000-square-foot plant handles 100,000 tons per year (tpy).

The plant is busiest during the winter, as 2 million seasonal residents add to the county's full-time population of 1 million - an increase that triples business at the MRF, which expands to three shifts.

The plant is split down the middle, with half handling paper and fiber and half handling commingled containers. The paper line sorts primarily by hand, with conveyors and a 25-tons-per-hour (tph) Bollegraaf baler providing automation. The container line uses an air classifier, two eddy current separators, a 12-tph Mosely baler and numerous conveyors. Overall, this small plant runs about 40 conveyor lines.

Assistant director Patrick Carroll organizes maintenance under four headings: preventive maintenance, health/safety repairs, routine repairs and capital/major maintenance.

Preventive maintenance includes daily and weekly checklists that require:

* checking the head and tail pulleys on all the conveyors and cleaning debris;

* cleaning debris caught in the balers;

* adjusting the tracking of all belts;

* inspecting spillage points on the glass and air conveyor lines;

* adjusting the eddy currents and

* topping off oil levels.

In addition, the weekly checklist demands grease on all the fittings for each of the plant's 40 conveyors as well as the processing equipment.

During daily and weekly inspections, mechanics note repair needs which guide health and safety, general repair and capital maintenance work. Health and safety items, such as repairing guard rails and emergency stops on conveyers, receive top priority.

Routine maintenance covers work under $2,500, such as repairs to belts, minor welding and general repairs. Mechanics correct these problems as soon as reasonably possible.

Capital maintenance covers work that will cost more than $2,500. "Our preventive maintenance checks determine the need for major repairs and develop a schedule for handling them," Carroll says. This category includes replacing conveyor belts, chains, idlers, head and tail pulleys, as well as baler overhauls.

"During the daily and weekly preventive maintenance checks, for example, the mechanics may find that a conveyor needs replacing," he notes. "If it has broken, obviously it needs replacing right away. But we try to schedule this just before it happens."

Predictive Maintenance In Chesapeake, Va., the maintenance stakes are high for the Southeastern Public Service Authority which operates a 460,000-tpy plant that converts 81 percent of the tonnage into refuse-derived fuel (RDF). The Authority burns the RDF in an adjacent power plant, which provides steam and electricity under contract for a neighboring naval shipyard. If this facility goes down, the power plant is forced to purchase coal to continue operations - a costly alternative.

Refuse arrives at the facility from local transfer stations and begins its processing journey on the 1.3-acre tipping floor. Large objects that can't be processed are cut from the pile, and the remaining material moves onto two of three identical processing lines. The plant runs three shifts, with two of the processing lines in constant use. On a rotating basis, one line is always down for maintenance.

Preventive maintenance is ongoing at the plant during the daily processing operations. For example, when incoming refuse falls through a hole in the tipping floor, cranes remove rope, metal canisters and other material that can jam the lines.

From the second hand-sorting conveyor, material goes into a primary trommel where spikes open plastic bags. Small items fall through the screen to a conveyor below while larger items cross another conveyer into a shredder with 250-pound hammers.

The small items move through a magnet separator, and each line includes three magnets. Non-ferrous material flows into a secondary trommel which filters out fine bits of dirt, grass and glass. What's left travels to the main feed line for RDF production.

In August, plant manager Louie Jordan and plant superintendent John Hayes directed the installation of a new, automated maintenance management system (AMMS), which runs on an AS-400 computer. "We've always had strong preventive maintenance and repair maintenance programs," Hays says.

"AMMS will help us establish a predictive maintenance plan by tracking the frequency and types of breakages that occur," he continues. "At the moment, we do preventive maintenance on calendar time. As we gain experience with AMMS, we'll be able to develop a predictive maintenance program based on actual running times."

Hayes' predictive maintenance system currently employs infrared scanning and vibration analysis, combined with past trends based on notes and what's in his head. AMMS will replace his head with a computer.

According to Jordan, setting up the AMMS system involves logging more than 50 large equipment items and 1,600 parts into the computer. "The entries include the part name and number, the equipment it belongs to and what line it is for," he explains. "To go along with this information, we've begun bar coding our inventory."

So far, this system has reduced inventory costs by giving management a better running balance and eliminating the need to count parts. Hayes has begun using the system to stop stocking inventory that can be obtained overnight. "We keep spare parts for everything on the common line, the final line carrying product to the power plant," he says. "We can't afford to wait for those parts."

Capital items such as the conveyor belts that carry RDF to the power plant can cost up to $100,000, and of course, can't be stocked. The AMMS system adds to the knowledge base about such items so they can be ordered and installed in a timely fashion.

The new system also allows Jordan and Hayes to price labor and parts by the job. "We think this will direct us to problem areas, and in the long run help us to predict equipment replacement requirements more accurately," says Hayes.

So, what's it all worth? The maintenance line of the plant's $5 million annual budget tops out at $700,000, and Hayes estimates that his maintenance plans have saved the facility as much as $500,000 over the past three years in terms of reduced downtime.

The bottom line is if you can predict the right time to maintain your equipment, you'll never have to fix it.

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