Some 55 miles north of Toronto, Ont., robotic assemblies are turning out all varieties of concrete pipe and culverts in one of the most modern plants in North America. Following years of investigation and tens of thousands of miles logged to meet equipment manufacturers all over the globe, a single plant established by Munro Concrete Products Ltd. in Barrie, Ont., will serve the sprawling northward movement of Metropolitan Toronto for years to come.

Conceived by company president John Munro and operations manager John Mokrzycki, P.E., plant layout and design were formulated on the basis of extensive research devoted to machinery selection and the synergy of those machines working together productively and profitably. Underlying the entire scheme is Munro's conviction that thorough plant automation will help the concrete pipe industry protect or boost its market share by helping producers fabricate more units, with more consistent quality, at a lower cost.

“It's one of the most modern concrete pipe plant in North America,” Munro contends. “Productivity has increased dramatically, and material costs have decreased as well.”

Comprising the heart of the facility's completely automated production process are two powerhouses: a Schlusselbauer GmbH Exact 2500 concrete pipe and manhole plant, and a twin-station Hawkeye Group Vibration-Under-Pressure (VUP) pipe and culvert fabricator adapted by the manufacturer to provide simultaneous casting of two products at once. These machines replace a Hawkeye Pipe Plus plant that is being decommissioned.

The plant is capable of producing a range of dry cast pipe and manhole product from 12 in. to 144 in. and box culverts in sizes up to 144 in. ∞ 120 in. Excluding the old Pipe Plus machine, the plant can output three different products simultaneously.

REINVESTMENT SPURS PRODUCTIVITY

“Producers lowering their costs by reinvestment are the ones who will advance the product, and advance market share,” Munro tells Concrete Products. “Productivity is a big issue,” he emphasizes. “With high productivity comes lower unit costs, because you can repeat the unit endlessly.”

In addition to launching the new plant, Munro serves as 2003 chairman of the American Concrete Pipe Association (see companion report, pages 24-26). His company's roots are deep in Ontario. Munro Concrete Products Ltd. was originally founded by Munro's father, J.W. Munro, in 1957. As Precast Tank and Vault Company, it supplied Ontario with maintenance holes, catch basins and other products. In 1985, John Munro became president.

The existing plant has grown from an operation opened on the 80-acre Barrie property in 1989. Originally a 14,000-sq.-ft. facility, the plant reached 166,000 sq. ft. by 2002, with plans for future expansion to 250,000 sq. ft. in 2003. While Munro Concrete has spanned many varieties of precast product, it now specializes entirely in underground pipe and manholes for southern Ontario. It employs 55 production and adminstrative staff.

Having learned from Southwest Airlines that standardized equipment reduces effort and saves time for employees, Munro employs that philosophy throughout the new plant. “You'll see a fleet of 11 Caterpillar fork lift trucks, all from the same series,” Munro says. “Ergonomically, a driver can go from one to the other effortlessly. Replacement parts are standardized. These management techniques work in every industry, and they work in this one as well.”

The new plant is the culmination of extensive travel through Germany, Austria, elsewhere in Europe, and beyond. Although he began his research in Ontario, Munro had to see production equipment in person before making a purchasing decision. The research and planning was a five- to six-year process, he recalls.

“Initial investigations for our plant expansion began in 1996,” Munro reports. “You read magazines, then listen to everyone who comes into your office, although some you don't listen to for long,” he confides. “And, you travel and look at equipment in place.”

Munro spared no pains in his travels. “The level of automation in Europe is much higher than it is in North America,” Munro explains. “Is it a tax issue, a labor issue, or is the cost of materials higher? The answer is that it's a little bit of all of the above.”

At various locations throughout his travels, if equipment did not appear to be working correctly, Munro says that before ruling out a piece of machinery he would determine if the fault lay with the machinery or the mode of operation or installation. “It might not have been the equipment's fault; it might have been the people who were running it,” he notes. “If I put you in a 900-hp Formula One car, you're not going to go anywhere if you don't have the skill to operate it.”

While the plant was designed by Munro and his staff, manufacturers provided valuable input regarding the integration of the equipment. “We presented equipment manufacturers with our process and where they had to put the equipment,” Munro tells Concrete Products. “Of course, there's always feedback saying a space is or isn't big enough. But we have Danish, Austrian, German and U.S. equipment in this plant, and we went through nearly 30 layouts before we established the final plan.”

MILESTONES

The Barrie plant boasts a number of firsts, including the world's largest pipe tipper, Munro asserts. “We can tip and depalletize 120-in. pipe. We have the largest MBK wire-making machine in North America. We are the largest Canadian pipe plant under one roof. And, we have the highest output batch plant among precast facilities in Canada.”

Ted Handy and Associates Inc. of Barrie provided advanced architectural design for the plant office and company headquarters building, with handsome interior touches and individual offices for all engineers. Naturally, it's constructed of architectural precast panels fabricated by Munro Concrete plant crews.

An addition to the manufacturing plant to accommodate a large employee lunchroom and kitchen as well as a training room was in progress when Concrete Products visited in August. “We demand a lot of our employees, and we want them to be comfortable when they're at work,” Munro emphasizes.

Also, Munro points out that his plant — encompassing 25 acres of storage area — is one of the few completely paved yards in North America. “The advantage is less damage to equipment because potholes are eliminated,” observes Operations Manager John Mokrzycki, “If you have a forklift carrying pipe weighing seven tons, uneven terrain is hard on the bushings, bearings, forks and the pipe itself. Forklifts can become unbalanced. With paved surfaces, the operator can travel faster, increasing productivity.”

CONTINUOUS CASTING

Though in August the plant was operating with one shift, the new robotic Schlusselbauer Exact 2500 offers continuous 24-hour casting year-round, with a unique curing system that can fully cycle pipe to inventory in five to eight hours. “The plant can operate continuously; we don't have to stop,” Munro tells Concrete Products. “If a pipe is made at 8 a.m., it may be inventoried in the yard at 1:00 or 2:00 in the afternoon.”

The Exact equipment features complete robotic automation, including all-robotic cranes handling headers and pallets; robotic depalletizing; and, robotic manipulators (grippers) turning pipe, testing it, taking it to kilns and removing kilns roofs, as well as removing and storing product.

With the exception of the Exact 2500 plant, all overhead cranes are Demag models. Some drives on the end trucks were purposely oversized to reduce the number in the plant.

Pallet and header cleaning is automated in the Exact plant and semiautomated in the Hawkeye VUP plant. Depalletization is automated in both Exact and VUP plants for up to 120-in. pipe.

Concrete is mixed in three Haarup mixers, each producing 3.5 metric tonnes per batch. They're served by four cement silos. Inside the plant, all material and concrete handling equipment was supplied by Haarup.

Every piece of pipe and manhole from 12 in. to 60 in. is gauge-tested, both bell and spigot; and, each piece is vacuum-tested. “The measurements of the bell and spigot are recorded for each piece of pipe. Every piece is serial-numbered, and all data is compiled in a database,” Munro reports.

Facilitating parts interchangeability, all three wire cage machines — one larger and two medium-sized — were provided by a single manufacturer, MBK. The largest machine makes a 4.2-meter maximum diameter cage. A Hawkeye robotic cage removal arm serves the two medium-sized machines.

Two 3-tonne Demag cranes serve the wire room, and two 10-tonne cranes are stationed in the old plant where the Pipe Plus is located. A 10-tonne model included with the Exact 2500 is used for maintenance purposes, and another stands behind the Hawkeye VUP machine. Additionally, a 10-tonne overhead crane is located at the maintenance shop, and a 40-tonne crane at the VUP machine.

SITE-SPECIFIC UNLOADING

While the old plant used outdoor aggregate storage, raw material is now stored under cover, with the dump hopper sized to accept a full 40-tonne truck load. A truck driver dumps its full load, selects the destination bin and hits the actuating button. As the driver departs, the aggregate is conveyed to the right enclosed storage bin.

Heat is available at the truck dump hopper. “Because we want to get rid of most of the water before it enters the plant, we can heat aggregate in winter, not to raise the temperature of the aggregate, but to drive off moisture and melt frozen chunks,” Mokrzycki explains.

From the dump hopper, aggregate is conveyed to one of six 120-metric tonne storage bins inside the plant, which also are heated. Even in August, the inside heaters were active to melt potentially frozen material unearthed from inside stockpiles. Storage bins and the raw material incline conveyor were made by a local manufacturer, Vandergeest Inc., of Shanty Bay, Ont.

“We have a lot of storage to get aggregate to a constant state,” Mokrzycki says. “Even though we have all the automation, if something goes wrong, we can set our parameters manually so it will be consistent throughout the day.”

CEMENT STORAGE

The plant has four cement silos, each storing two tankers of cement, about 80 metric tonnes each. In August, the plant was using U.S. Type I (Canada Type X) normal portland; 100 percent ground granulated blast furnace slag, blended at the plant; and, a silica fume cement comprising 9 percent silica fume and 91 percent normal cement. Munro uses an air-entraining agents and superplasticizers for both dry- and wet-cast concrete. These are stored in plastic tanks adjacent to the cement silos. Process water from a well is stored in a 15,000-gal. tank.

From the aggregate bins, transfer belts beneath the hoppers transport material to one of two weigh belts, and thence into one of three Haarup skip hoists serving the mixers. “Because of the way we designed the plant, the skip hoist is in a position where we can store a batch of concrete,” Mokrzycki notes. “We can have a batch weighed and waiting on the weigh belt, a batch in the skip hoist, a batch in the mixer, and a batch in the traveling bucket on the way to a production machine. If you wanted to make a lot of concrete really fast, that's a good way to do it.”

Screws bring cement from the four silos to the three mixers. “Because we want the option of getting any cement into any mixer, we have a total of 12 screws,” Mokrzycki says. “It was a lot of fun getting all of that to fit!”

In practice, admixtures are weighed before entry into the mixer. “Most people use a volumetric method,” Mokrzycki asserts. “The problem therein is that potential volume changes due to temperature fluctuations. The volume can change, but the weight never does.”

With the exception of the raw incline conveyor and storage bins, all belts, skip hoists, mixers, traveling buckets and rails, cement screws, and weigh hoppers are from Haarup of Denmark. The robotic traveling bucket system carries fresh concrete mix to one of three fabrication areas, although the plant is designed for four buckets. Each bucket holds 3.6 metric tonnes, or nearly 4 short tons, of concrete. The line will also be expanded to seven discharge points.

CAGE FABRICATION

Wire cages are fabricated at the MBK machines. For two machines, a Hawkeye robotic cage lifter — a cradle with fingers — grasps and removes the cage, turns it vertically, and sets it upright on the floor. For manhole and pipe products, circular or oval reinforcing cages are made on the MBK machines; for square products like box culverts and rectangular catch basins, mats of prewelded steel are cut to size and corners shaped on a wire bender. For flat tops and base slabs, Munro's rebar welding shop will cut and weld the rebar manually. Hoop steel reinforcing is purchased premade.

If the reinforcing cage is going to the Exact 2500, it's either placed by hand or overhead crane on a floor conveyor to travel from the wire room to the Exact header and pallet storage area. At the end of the conveyor, a robot picks up the cage and places it on a pallet, which is shuttled over to the Exact machine.

If reinforcing cages are needed at the old Pipe Plus plant or the VUP machine, a propane-powered forklift carries the pallet with cage, placing it in front of the machine. “We don't have reinforcing cages all over the floor,” Mokrzycki observes.

EXACTING WORK

In August, the Exact 2500 was producing completely finished manhole taper tops at a rate of one every four minutes. The product is cast and vibrated below grade, then lifted to grade and moved outward. One by one, the product moves forward to an overhead robotic manipulator, which gently grasps it for conveyance to one of 14 12- ∫ 35-ft. moist-cure kilns adjacent to the Exact 2500.

“The Exact's vibration system is different from most manufacturers,” Mokrzycki reports. “Molds are core-vibrated with no vibrators mounted on the jacket. Varying the speed of the vibrator offers the potential for better consolidation of concrete. If I can get a denser mix with less cement because my vibration is better, I can save money on materials and run a drier mix as well.

The size of the kiln cells is suited perfectly for maximum production. “The plant is designed to run continuously, and if the plant had a large kiln, it would take too long to fill before I could turn the heat on,” Mokrzycki says. “Smaller compartments let me turn the heat on as soon as I fill the cell.”

Maximum cure temperature is 135°F (57°C), and the rate of increase is 10°F every 20 minutes. “A lot of people in the industry don't understand the hydration process in the curing cycle of concrete products,” Mokrzycki contends. “People want maximum heat as soon as they can in order to remove the pipe from the kiln. The problem is they're not getting the full potential strength of the concrete. We carefully control the rate of increase.”

Manufactured by Schlusselbauer, the kilns employ radiant heat via circulation of boiler-generated hot water through plastic capillary tubes, part of a heating system provided by IFS Systembau of Berlin, Germany. Water misters, also supplied by IFS, add humidity to the kilns.

Concurrent with the production cycle, as the robotic manipulator takes fresh product to the kiln, it transports cured product on the return trip to the depalletizing plant. “It operates in a circle,” Mokrzycki explains, “but it's smart enough to know whether it's getting ahead of itself.”

At the depalletizing plant, the header and pallet are removed by two manipulators (one, if no header is involved, as with the taper tops). If a header sticks, hammers powered by an air cylinder will gently rap the header until it comes loose. The header is placed on a shuttle cart and cleaned automatically; the header spins as brushes spin, and the clean header is then indexed to another station where it is oiled for the next product. In similar fashion, the pallet is handled with its own manipulator and air hammer in advance of cleaning, indexing and oiling treatments.

The system detects whether or not depalletizing is keeping pace with production. If not, it will bring additional pallets and headers out of storage. Depalletizing is followed by tipping, deburring, and the bell and spigot testing station.

ADAPTING THE VUP

On the other side of the operation, the new Hawkeye VUP machine has been configured to work as two separate machines, comprising two weigh systems, independent filling systems, and two hoppers for two mixes. “If you look at anyone else's twin-station VUP machine, you'll see one concrete hopper and one belt feeding concrete,” Mokrzycki says. “You can only fill one station at a time.”

With Munro's custom-configured VUP machine, each of two stations is filled independently, using two different mixes from two different hoppers and belts, if so desired. And, Munro can fill two molds at the same time, as its VUP works like two single-station machines.

“It's our twist on Hawkeye's concept of the VUP machine,” Mokrzycki affirms. “It never made sense when I'd go into plants with the two-station VUP machine: everyone was standing around waiting for something to happen because they're only filling one station. On our particular machine, the heaviest pipe we can make is 27 metric tonnes, a 144-in.-diameter pipe. That will take half an hour to fill, and during that time, the other mold stands empty. Why wouldn't you want to fill both stations at once?”

Each station operates independently with a computer that monitors both operations. Unlike the Exact 2500, both the kilns and heating system for the VUP plant were manufactured by IFS. Hawkeye Group supplied the depalletizing system.

A brand new machine, the system is dubbed VROC for “vertical, remove, oil, and clean.” Accordingly, Munro's VROC will depalletize and tip up to 120-in.-diameter pipe with an outside diameter of 12 ft. and maximum weight of 17 tons.

“No one felt comfortable squeezing it and flipping such a pipe over in the air, so we put it on the VROC, with L-shaped cart and hydraulic cylinders,” Mokrzycki relates. “The cylinders take the pipe from a vertical position with the spigot at the top and tip the “L” so it's horizontal, at which time a fork lift can remove the pipe.” Testing of product is done manually at the VUP production line.

MEETING STANDARDS

Only a few months after startup, the plant met prequalification standards of the Ontario Concrete Pipe Association and the Municipal Engineers Association. Full certification is forthcoming, Munro asserts.

Even as the plant became fully commissioned this summer, more changes were coming for Munro Concrete Products. A concrete pressure pipe plant currently under construction will manufacture embedded and lined cylinder, 400 mm to 3,600 mm in diameter and up to 7.315 meters in length. Housing three 50-tonne cranes, three 80-tonne cranes, a 10-tonne crane, and two spiral welders for steel cylinder production, the plant will provide 90,000 sq. ft. of completely enclosed work space with a clear interior height of 72 ft. Production will begin in January 2004.