Bulk Container Start-up Optimizes with Plant Efficiency Solution

KEY WORDS

Machine control

Monitoring

Software for control

Manufacturing execution systems (MES)

Start-up manufacturing facilities have never had it easy, but these days the usual challenges, such as designing, implementing, and optimizing the production process, are compounded by the mounting pressure of increasing production goals, which can stop them from reaching profitability.

Plant managers at Weyerhaeuser were keenly aware of this requirement when they opened the company’s 110,000-ft2 SpaceKraft manufacturing facility in Salem, OR, in October 2000. To reach its profitability goals, SpaceKraft implemented an operational equipment efficiency (OEE) monitoring solution in its intermediate bulk container (IBC) manufacturing application.

Paper container beats drums

Developed so food, chemical and solid material manufacturers can replace bulky 55-gallon drums commonly used to ship goods, a typical SpaceKraft IBC is 40.5 inches tall and features an outer corrugated sleeve or shell; an inner film liner; and a corrugated top cap. The containers can withstand 30 tons of compression for better protection; are collapsible and reusable for convenient handling; and can be stacked six high for space savings of up to 80% compared to drums.

SpaceKraft produces its IBCs using a patented process involving four main machine centers: corrugator, winder, saw, and ”endclosure.” The corrugator transforms paper into ”singleface” prior to winding, and the winder then uses special glue to wrap six to ten plies of singleface into a seamless sleeve. To meet requested specifications, the saw slices the sleeve, and the endclosure applies container ends and drills an access hole.

The four machine centers require six operators and use a variety of Rockwell Automation’s (Milwaukee, WI) equipment to control, automate and monitor production. The operation relies on multiple programmable controllers and three communication networks (Data Highway Plus, DH-485 and Ethernet) to run the four machine centers, multiple conveyors and more than 100 motors.

An Allen-Bradley (A-B) ControlLogix 5500 controller runs the corrugator and winder, and operators use a PC running Rockwell Software’s RSView human-machine interface (HMI) software to monitor machine operations. Allen-Bradley PLC 5/20 controllers control the saw and endclosure. These stations also use three A-B PanelView operator terminals for monitoring.

Pinpointing problems

”We were successfully producing quality products, but we didn’t have a way to measure efficiency,” says Glen Lawson, SpaceKraft’s production manager. ”I knew we needed a tool that could collect, store, and analyze production data over time.”

Mr. Lawson’s search led him to Rockwell Software’s RSBizWare PlantMetrics software, which would allow SpaceKraft to find and minimize events that sap capacity and reduce OEE. The software captures and uses data from plant-floor control systems to help users pinpoint which machines, parts and shifts cause efficiency problems, as well as which three OEE components-availability, throughput, quality-they fall into.

For example, at SpaceKraft, the software collects event data, such as machine start and stop times and total part numbers, from the controllers, and stores them in Microsoft SQL Server database.

Setting controls

To help implement PlantMetrics, Mr. Lawson called in system integrator Concept Systems Inc. (Albany, OR) to make sure required data were in the PLCs; modify the process’ nine controllers to capture OEE and event data; and test and document each PLC and HMI register to cut implementation time.

”We worked with the SpaceKraft team to clearly define and develop a vision of what was wanted,” says Michael Gurney, Concept’s co-owner and principal engineer. ”The usability and canned functions in PlantMetrics help cut our configuration time in half.”

Mr. Lawson also used consultants from Rockwell’s Global Manufacturing Solutions (GMS) to ensure proper configuration of the software’s data collection and reporting system. From planning to implementation, the PlantMetrics installation was completed in less than three months. And the GMS consultants brought PlantMetrics online within a week.

Mastering throughput

Because the SpaceKraft plant operates as a single line, output is limited by the slowest machine center. Mr. Lawson says PlantMetrics’ real value comes from its ability to collect data on a bottleneck, and address specific processes in that machine center. Using starve/block analysis, managers can then make incremental improvements to each step to remove that bottleneck.

The system also evaluates production patterns over several months to note throughput trends. For example, managers recently discovered that the winder was highly productive in the morning, but slowed down in the afternoon. ”Once we spotted the trend using PlantMetrics, we looked deeper into the operation to determine the root cause of the slow down,” says Mr. Lawson. ”After consulting with the winder and maintenance teams, we decided to add a third operator to the machine center. This increased productivity throughout the shift.”

Managing maintenance

PlantMetrics’ ability to capture and report on factory-floor events was also used at SpaceKraft to record the running hours for each of the plant’s 102 motors. ”Initially, maintenance intervals were based on estimated motor running hours,” says Rodney Hansen, SpaceKraft’s maintenance supervisor. ”Based on this, we might service a particular machine center every three months. However, even with regular maintenance, we still had puzzling breakdowns, especially with a few critical machine centers. Each breakdown would cost us valuable production time.”

Once PlantMetrics began collecting motor start and running time data together, the problem became evident. ”PlantMetrics treats every motor start as an event, allowing us to capture the number of starts for each motor,” says Mr. Hansen. ”After reviewing these data, we were surprised to learn that some of the motors were cycling beyond their specifications. This meant the problem wasn’t excessive run time hours, but motor starts. Now we take the PlantMetrics data and import it directly into our Computerized Maintenance Management System to generate maintenance orders based on concrete data, rather than guesswork.”

Increasing quality

The quality of corrugated board in SpaceKraft’s IBCs can be affected by many factors, including faulty equipment, inferior raw materials, such as paper and starch, and unstable process conditions. However, the most critical factors involve the pressure at which the corrugated sheets are applied to the IBC mandrel and the viscosity of the glue that seals each sheet.

As each IBC is produced, pressure and glue viscosity data are sent from the ControlLogix controller to the PlantMetrics system. This shows when a sleeve is within tolerance, assigns a date and time stamp for each, and stores these data in an accessible database.

”PlantMetrics allows us to identify the right production parameters to manufacture to the specifications we desire,” adds Mr. Lawson. ”The quality report helps quickly identify when a sleeve goes out of tolerance, and then we can scrap it if necessary.”

In the future, Mr. Lawson hopes to expand these quality reports by adding a temperature sensor to the winder to measure paper temperature because heat inconsistency can have a negative impact on sleeve quality.

”Our plant now has the capability of producing considerably more on a per shift basis than in the past,” says Mr. Lawson. ”With PlantMetrics, we’ve been able to boost total output by 30% without additional capital expenditures or increases in labor.”

In addition, SpaceKraft’s ability to pinpoint problem areas in each work cell and make improvements to machine availability, throughput, and quality has led to a more than 23% increase in machine efficiency in less than a year. In addition, it has led to a 17% reduction in the endclosure’s cycle time.

”PlantMetrics has become more than just an OEE solution,” concludes Mr. Lawson. ”We don’t just use it for efficiency monitoring purposes, but also as a tool to determine how we run our entire plant everyday.”

For more information, visit the Rockwell Automation website.

—Comments? E-mail jmontague@reedbusiness.com

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