Quick Changeover Strategies: Pigs Squeal, Change Happens

March 28, 2003
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Whether it’s color-coded changeover parts or automatic pigging systems, food processors are tapping a wide array of tools to improve plant flexibility.

An operator changes over a leak detector to accommodate a bottle-size change, using a modular system of quick-change parts. Source: Morrison Timing Screw


Time is money, and the meter is running faster in food and beverage plants. Optimizing up time while coping with a broader range of products has put a premium on quick changeover strategies. Fortunately for production managers, the tools available and the level of sophistication keep expanding.

“There are a lot of ways to look at changeover, but it all comes down to getting more out of existing assets,” says Rick Tkaczyk, vice president of business development for APV Solutions and Services in Schiller Park, Ill. “The need for flexibility has put a premium on strategies to keep costs in line and equipment running. Processing equipment doesn’t do anybody any good if it’s just sitting there.”

Color-coded change parts, threadless attachments and other tactics to speed changeover are all well and good, but they stop short of a system-wide approach. Production managers are considering both technical solutions and business drivers to model their facilities and make them more flexible without compromising efficiency. Tool-less changeovers, automatic pigging systems and applications software that can optimize scheduling are among the options available.



Packaging change agent

Packaging bears the brunt of changeover demands, which is one of the reasons this is often the most chaotic area in plants. High-speed filling magnifies any imprecision in the changeover process, and laser measurement tools and digital devices often are advocated to ensure precise settings to get lines running at optimum speed as quickly as possible.

Unfortunately, sophisticated tools require skilled mechanics and engineers, a vanishing breed in many plants. Goof-proof changeover systems are becoming a necessity as management relies on less-skilled workers to execute the change.

“Companies are pushing responsibility to the lowest level,” points out Nick Wilson, president of Morrison Timing Screw Co. “The goal is to design changeover systems so that there is only one way to install the parts.” Color-coded parts and location pins that allow only one installation option—the right one—help take the art out of changeovers and turn them into science.

Wilson’s firm specializes in food and beverage applications, with beverage companies constituting the bulk of the Glenwood, Ill., firm’s client base. Form-fitting, precisely machined screws control dividing, accelerating, discharging and other movements on rotary filling lines to tolerances within 0.002 inches over 10 feet, making line speeds of up to 2,000 units per minute possible. Much of Morrison Timing Screw’s work involves adapting OEM machines to fit today’s operating environment.

A quick-change system for a typical filling and capping machine might include 15 to 20 parts, Wilson says. That’s probably more than the OEM unit required. However, small change parts that fit together snuggly like pieces of a puzzle are more in line with today’s work force.

Star wheels on older fillers often require considerable strength to be changed. By breaking it down into multiple parts, “you don’t have to be Mike Tyson to make a change,” Wilson says. Drive hubs, mounting plates and other components remain on the machine with a quick-change system, eliminating the need to readjust core components with each changeover. Instead of spending an hour or longer changing over and debugging the line, the unit is ready to return to optimum operating speed in 10 to 15 minutes. Fewer worker injuries are likely with smaller components, and replacement parts can be produced faster and cheaper.

“For a contract packager who is changing over lines daily or even several times a day, the payback can be very fast,” he adds. With pressure building to increase throughput of shorter production runs, “most plants can get a payback in one to six months, and the six-month people are becoming rare,” says Wilson.



This little piggy

Shorter CIP circuits are one way to reduce downtime between production runs. Another option to clean out line residues like sauces, jams and cake batter is an automatic pigging system.

Pigging has been used for decades, beginning in the petrochemical industry where rubber missiles called pigs made squealing sounds as they traveled through pipelines. Early designs were manual, and the pigs had a tendency to get stuck if turns in the pipe were too sharp. System refinements have resolved many of those problems, and the advent of automated systems has increased pigging’s utility as both a time-saver and material-recovery tool in food plants.

“Manual pigging takes time, and returning the pig from the end of the line means opening up the system,” points out Ira Nadel, manager of food technology at APV Solutions and Service. By retrofitting a line with an automatic pigging system, processors can clean out the line in a controlled, enclosed environment, saving time and reducing waste simultaneously.

Automatic systems use pressurized water or gas to propel the pig from its launch station to a catcher at the other end. Residue in the line is pushed ahead of the pig and into a recovery tank, where a nonintrusive sensor can signal the PLC to shut off propellant and de-pressurize the pipeline when the tank is full. Another sensor detects the pig when it reaches the catcher, signaling the PLC to open the return-propellant valve to send the pig back to its housing. A three-way valve diverts the pig into a storage housing, removing it from the product path and storing it for the next use.

A magnet in the pig reacts with sensors in the line to let the operator view the pig’s location via the control panel HMI. Today’s pigs can negotiate turns with a radius of 1.5 times the diameter of the pipe, eliminating the need for costly retrofits involving long-radius bends, Nadel says.

Process pigging can’t replace CIP if allergens are an issue, and applications in dairy are somewhat limited. But for viscous pumpable products, pigging can produce faster changeovers, reduce CIP chemical and effluent costs and increase production yields. “Every food plant tracks its waste, and some are very aggressive in trying to recover materials in the line at the end of a production run,” says Nadel. Depending on the value of those materials, the savings from automated pigging “could be millions of dollars a year,” he says.



The mix of green and orange change parts on this filler is a sure sign that production won’t run smoothly after this changeover. Source: Morrison Timing Screw

Systematic scheduling

Better scheduling can short circuit the need for some changeovers altogether, but it requires forecasting and planning expertise beyond the control of production managers. Ill-fated ERP implementations of the past convinced some managers that no relief was in sight on this front. That’s beginning to change, however, as cookie and muffin baker Otis Spunkmeyer is demonstrating.

The West Columbia, S.C., processor produces almost 300 SKUs at four plants, including two copackers. Keying in sales and inventory data from distribution centers on Excel spreadsheets was a tedious, three-day project that only yielded a three-week production plan, recalls Kevin Tyschper, manager of production and demand planning. Last year Spunkmeyer implemented Strategic Network Optimization, a stand-alone production planning module from J.D. Edwards World Solutions Co.; in June, a sales forecasting component was added. Most of Spunkmeyer’s scheduling data is automatically downloaded from a legacy ERP system called BPCS, slashing data entry time to 35 minutes. More significantly production needs are projected 12 weeks out, allowing Tyschper to analyze sales trends and conduct contingency planning before placing production orders.

“I used to have to order multiple schedule changes each day during our peak periods, which made me a real popular guy with production,” he says. “Now we’re down to perhaps one schedule change a week.” Automatic scheduling also has reduced the number of changeovers system wide by two per week, despite the addition of 40 new SKUs. “In a sense, we saved 40 changeovers with the application,” he says. Six more items were added in August, and they were quickly integrated into the schedule.

Plant-specific considerations such as scheduling nonallergen products before allergens and beginning with light colored batters before dark are built into the program, just as they would be considered if plant personnel were scheduling production. But automated scheduling can “optimize the network” by factoring in system-wide considerations such as line costs, capacity costs and holding costs, Tyschper says.

The system has proven its worth in finished goods planning, boosting order fill rates to 99.5 percent from about 96 percent. The next step is to put it to work in projecting raw material needs and “provide buyers with the data to make educated decisions on when to lock in commodity contracts,” says Tyschper.

Work teams and mechanical changes remain an integral part of quick changeover strategies, but there is more to the issue than the physical act. Whether its surge systems or software solutions, there are many ways to skin the changeover cat and reconcile flexibility and efficiency. When considering the issue of quick changeover, production managers can focus on machine-specific changes or take a process-change tack to reduce downtime.

For more information:

Rick Tkaczyk
APV Solutions and Service
847-678-4300
rick.tkaczyk@invensys.com

Andrew Carlson
J.D. Edwards World Solutions Co.
800-727-5333
andrew_carlson@jdedwards.com

Nick Wilson
Morrison Timing Screw Co
708-756-6660

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