After running 100 million units over a seven-year period through a dual machine line, Tri-Cities Block Plant Manager Bryan Hoilman welcomed a new challenge: How to broaden an already deep catalog of building and hardscape offerings without lowering productivity. He responded by placing the first order for a machine bearing the most radical change in equipment methodology Besser Company has adopted in a 104-year history underpinned by cam-actuated block-making.
The concrete division of the nation's leading clay masonry producer and distributor, General Shale Brick, Inc., Johnson City, Tenn., runs the inaugural Servopac machine at its Tri-Cities Block plant in nearby Piney Flats. The four-at-a-time model trades the cam shaft and mold-based vibrator design of the manufacturer's longtime machine blueprint for an open configuration with four slide shafts guiding a hydraulically activated stripper head and pallet receiver. Joining the Servopac's key distinctions are a handful of control, material feed belt, vibration, and automated pallet and mold handling features.
The Servopac integrates with Besser's standard rail-mounted kiln transfer rack system. At Piney Flats, where the new machine is placed in an existing production line, pallet and mold handling devices are contained in an approximately 20- _ 40-ft. area. Molds are changed, transferred and stored in a sequence much like product pallets travel from lowerator/elevator and kilns in a typical hardscape unit line. Pallets, on the other hand, are retrieved, stacked at a buffer point, and relayed to the machine by tandem servo-driven magnetic clamp devices. The Servopac and its quick mold transfer and clamping sustain optimal cycle times; augment product variety; and, offer the shortest mold and machine changeover times possible.
The Servopac has proved well suited to Tri-Cities Block and its market development goals. I am intrigued by challenges, and new things in the plant tend to trip my trigger, says Hoilman. This model is out of the box. Some machines make pavers better than block, and vice versa. This one gives you the best of both worlds. I can go from an 8_8_16 block to a 1_24-inch square unit in 15 minutes. That timeframe, he adds, includes changing the agitator grid and cut-off bar, and making necessary changes to the rest of the plant equipment.
Every block comes out of the first cycle at the right height. Product recipes contain all settings Û feed times, finish times, desired heights and movements Û so that the machine keeps up with the fast mold changes, Hoilman says. We are working on more half-high block, hardscape units and other new products. The new machine reduces mold change time by up to 90 percent. A mold change, without changing the agitator grid and cut-off bar, that used to take 20-30 minutes is now down to less than five. We can go from a 7?-in.-high product to 3?-in. product in three minutes.
This is a machine for a wide variety of production and plants that have to mold a lot of custom units. Our market place has gotten more diverse with masonry options and creativity. This machine makes it cost effective to deliver the greater product variety building designers and owners demand.
Fast mold change potential was not the first thing that came to his mind upon viewing the Servopac. I was initially concerned going from a machine with cams to one without them, he says. My first instinct was to ask the engineers if they thought the machine is going to be as durable and robust as their others.
In the development phase, Besser ran the Servopac approximately 500,000 cycles; through mid-year, Tri-Cities Block has nearly equaled that level. When you look at the Servopac, there is not much machine there, Hoilman explains. Because of the open design, there is no point you can't access. It's easier to work with the Servopac than we're accustomed to with a cam-type machine.
Consistent with General Shale Quality, a protocol requiring manual and automated equipment checks, Piney Flats staff worked with the Besser product development team to create a Servopac log book for operators to track machine progress and suggest improvements. In the first combination of its kind, Besser added a satellite link to monitor the Servopac and installed a webcam so engineering staff could observe machine operation from several locations.
Tri-Cities Block began Servopac production in early January, six days after the machine's arrival on two tractor trailers. The producer committed to a second model for its Knoxville satellite plant just over a month later. It is scheduled to be running this summer.
Both machines replace Besser Ultrapacs, one that had run in tandem at Piney Flats, the other with fewer than three years' service time at the greenfield site about 100 miles away. The Servopac fits the Ultrapac footprint; hence, the expense of new or modified foundations and changes to product handling lines are reduced. At Piney Flats and Knoxville, work on existing equipment has been limited to shortening the material feed belt, modifying the foundation, and removing the pallet return conveyor.
The upgrades spur expanded building and hardscape product development to coincide with distribution opportunities through existing and newly acquired General Shale Brick masonry yard properties in the South. Premium architectural block and hardscape products from Piney Flats can now reach such markets as Atlanta, Charlotte, Richmond, Va., and Chattanooga. The latter city is home to a distribution center and showroom General Shale opened in late 2006-the first of potentially two such properties the company is considering for the region.
The eastern Tennessee plant and yard investments follow two major acquisitions through which General Shale has expanded westward and rounded out product offerings for residential and low-rise buildings. In mid-2007, General Shale acquired Cambridge, Ontario-based Arriscraft, whose stone, brick and marble innovations join a clay and concrete masonry portfolio to create a full veneer catalog. Arriscraft, which fabricates natural stone and makes conventional cast stone and calcium silicate units, has plants at headquarters, St-Ötienne des GrÀs, Quebec, and Fort Valley, Ga., plus a dolomitic limestone quarry at Ontario's Bruce Peninsular region.
General Shale opened 2007 exercising an option to purchase Louisville, Ky.-based Modern Concrete, with one Indiana and four Kentucky masonry yards. In mid-2006, the company acquired Denver-based Robinson Brick, a family-owned operation providing a new platform spanning markets mostly west of the Mississippi. In addition to clay and concrete unit production, Robinson brought manufactured and natural stone veneer offerings on par with what Arriscraft has added to General Shale regions east of the Mississippi.
General Shale produces more than 1.6 billion brick annually, supplying residential, commercial and specialty architectural wall and paving units. Parent company Wienerberger AG, Vienna, is the world's largest brick producer.
SERVOPAC AT A GLANCE
The Servopac is Besser Company's answer for producers seeking more block and hardscape variety with limited downtime from frequent mold and height changes. Company engineers accustomed to cam-type machines such as the Ultrapac, Dynapac and Vibrapac, which remain workhorse models for higher output of narrower product lines, approached the Servopac development with a blank sheet.
The Servopac team consists of engineers from Alpena and Holland, Mich., and Sioux City, Iowa, plant locations. With the input of engineers from Germany's Omag AG, which Besser acquired in 2004, the team adopted vibration and mix feed technology in the Servopac design. Engineers aimed for a model that would fit in most existing customers' production lines and, with factory-supplied adaptors, accommodate most 1-in. to 12-in.-high product molds on hand.
The Servopac machine is shipped in two parts: 1) a main forming section comprising a bolted frame with rectangular footprint, stripper head, and pallet receiver bearing on four vertical slide shafts; plus, mold vibrating table flanked by twin servo motors; and, 2) material feed section; servo walking beam pallet delivery conveyor; and, pallet-placing system.
Borrowing Omag technology, Besser engineers incorporated servo technology in lieu of variable-speed AC motors on certain applications. Servo motors have good torque and speed characteristics. They are very accurate and precise, and allow complete control of amplitude and frequency of vibration, says Besser Director of Applications Engineering Duane Rondeau. Beyond the primary mold vibration role, he adds, servo motors control the pallet-delivery system, precisely positioning pallets and speeding production cycles.
Operators run the Servopac with a color graphics control station built around the Allen-Bradley ControlLogix 5000 platform. Replacing the SLC500, it provides more memory for recipe storage; precise metering of mixes conveyed directly from feed belt to feedbox; and, real-time machine monitoring and diagnostics.