ControlLogix Boosts Agility for 3M, Frito–Lay

Nov. 19, 2008
One 'Plug-and Play’ Solution Fits All

At the Consumer Packaged Goods Industry Forum held at this week’s Automation Fair event, two manufacturing companies explained the role that ControlLogix solutions played in helping them upgrade key operations and as a result become more flexible and agile.

Tracy Harvey is an engineering specialist for 3M Canada in the company’s tape-converting operations, which take large-format jumbo rolls of stock and slit them to become the various roll tapes that 3M provides.

He discussed the controls upgrade of a semi-manual tape slitter, in which operators load a jumbo roll in the unwind station, where it’s pulled through dancer tension controls to be cut into ribbons, which then are rewound and packed accordingly.

“We had thirty plants of differing ages, but needed one ‘plug-and play’ solution that fit all of them.” Frito-Lay’s Mike Walker detailed his company’s successful, multi-plant roll-out of a ControlLogix-based inline blending system.

“The critical control variables obviously are length and width,” said Harvey, “but winding tension plays a major role in product quality.”

With a machine such as this slitter, which has many potential hazard points, Harvey discussed the upgrade process. “Risk assessment is the first step in determining the required upgrades and includes a mandated internal pre-start review team with representatives from production, safety and maintenance to determine risk…and ultimately design a system appropriate to the risk,” he said. “Then based on the new controls contemplated, we reassess.”

Once that’s done, Harvey said the assessment must be approved in writing by a registered professional engineer, who lists additional measures that need to be done to comply with all applicable regulations.

“Slitter 3 loading and packaging operations are manual,” Harvey said. “The unit is 30 years old, so we needed to do this before it broke down.” The old controls also made it harder to comply with new safety codes, namely the Canadian Standards Association (CSA) Z432, a standard that provides criteria for the selection and application of guards and safety devices on machines to protect personnel.

The upgrade involved controls, not mechanical issues. The controller was a PLC-2, the screen a T30, he said to appreciative laughter regarding the age of the components.

Light curtains “guarded” the front, “but if machine was running slowly, Harvey said, “operators could walk right in. In addition, some of the operations were awkward, and we had some lost-time accidents.”

Harvey discussed how GuardLogix was necessary to bring the machine guarding up to code, since the machine had to be in operation for loading of the jumbos.

Two-handed “hold-to-run” controls and limited operator-movement constraints supplemented the control of the machine to below 10 m/min. Zones of control are required since the operators need access to various parts of the system, and two-man independent control is required.

“Without GuardLogix, safety becomes a difficult, hard-wired task, with jumpers and bypasses necessary to operate during the feed process,” Harvey stated.

Later in the morning session, Mike Walker, vice president of engineering technical services for Frito-Lay, discussed a project that addressed cost, response time and consumer expectations regarding the blended oils used for their unseasoned products. The blends typically are made from corn, soybean and sunflower oils.

“Before the project, each oil was put in its own separate storage tank connected via a site-specific piping header to feed to the required production line,” said Walker. “If you wanted a blend, you needed to get it from one of the oil-processing plants and have it shipped in. Pre-blending required double-handling of at least one of the oils, shipping it to a second processing site, doing the blending and then shipping to our plant.”

Costs were higher and delivery times were extended because of this, added Walker. Frito-Lay realized it needed the means to do its own blending. The solution had to be done with absolute minimum production disruption, minimal capital and still produce blends that maintained the quality and flavor expectations of the consumer.

The project proposed by Rockwell Automation examined three possible solutions. “We could do ratio-lending, batch-blending, or inline blending,” said Walker. “Each had pros and cons regarding accuracy, lead times, capital cost and cycle times, but our evaluation pointed us to inline blending.”

The project had further requirements as well. “We had thirty plants of differing ages,” said Walker. “We needed one ‘plug-and play’ solution that fit all of them, that didn’t raise flavor issues with the consumer and was self-monitoring.”

To meet the plug-and-play goal, the components were assembled on a pre-fabricated skid that held two mass flowmeters, two low-shear pumps and the control and operator interface panel. The units were checked out and approved for operation prior to shipment. The design leveraged Logix features such as DriveExecutive, Phase Manager and modular code.

The results have been very good, said Harvey of the project for which Rockwell Automation took engineering, procurement and construction (EPC) responsibility. The company can now manage the availability of the oils on a site-specific, sometimes on a line-specific, basis based on price and availability of the various oils.

So how did that work out? “I’m pleased to say that all 18 sites in the original project scope are installed, operating and meeting or exceeding our original economic expectations,” reported Walker. “Even before we completed this project, we extended the scope to include even more sites. Today we have 27 sites operating with the new blending system. Rockwell delivered exactly what they’d promised.”