Automating dough handling
Dec. 1, 2012
by Shane Whitaker
Automation often results in greater consistency of baked foods and can eliminate many headaches for bakers. Besides saving on labor costs, automating the dough handling process removes potentially dangerous activities of manually moving dough troughs through bakeries and having workers wielding knives to cut these large masses into smaller pieces.
When mechanically transferring dough, adding heat represents a primary challenge. Bakeries also don’t want to overwork it, which could make the dough denser or tougher.
Automated dough handling systems have been around for many decades, yet manufacturers continue to improve this equipment to overcome these challenges and more. Pumps, chunkers, conveyors and piping represent some of the most common equipment to transfer dough from mixing to makeup systems. Bakers can select automated trough handling systems and spiral flow feeders to streamline the front end of the production process.
Customizing equipment layouts
Using a trough to transfer dough from the mixer to a makeup hopper puts the least amount of stress on yeast-raised batches, but it also is the most labor-intensive.
Today’s high-speed bread and bun bakeries prefer to transfer dough without any human intervention, according to Larry Gore, director of sales and marketing at AMF Bakery Systems, Richmond, VA. In fact, AMF often integrates its automated dough handling equipment with its horizontal mixers and makeup systems to build entirely automated systems that are custom-configured to a bakery’s particular products.
With an integrated system, the dough hopper senses the level of dough and is able to shut off the pump or chunker. However, AMF has taken that one step further, using analog ultra-sensors that control the speeds of the pump and conveyors so that dough is fed at a continuous speed to makeup equipment.
“That way the hopper level is maintained, and the dough chunker and conveyor never stop, but you feed at a constant rate, so they maintain the speed at the throughput of the makeup line,” he explained. “A lot of electronic controls are involved in the newer systems that make this whole dough process possible.”
By feeding dough as hoppers need it, the dough is fresher. “Your end product looks better and is more uniform and machines better through the makeup equipment all because of the minutes of difference,” Mr. Gore observed.
When done manually, operators often will feed too much dough into the hopper, and this leads to inconsistencies in the final products, noted John Eshelman, director, pretzel and snack machinery sales, Reading Bakery Systems, Robesonia, PA.
Reading’s mixer discharge conveyor transfers batches to its Loafmaker to form blocks that weigh between 5 and 15 lb. Next, these pieces travel to the incline lift conveyor that feeds its shuttle, which deposits the portions into a segmented hopper.
While this system is often used to transfer doughs on its lines for snack production including pretzels, the equipment also can be combined with its Exact continuous mixers. However, because the dough is automatically cut into pieces at the end of the continuous mixer, the sandwich-style lift conveyor is generally the first piece of handling equipment employed on these lines.
When a pump is used with piping, the dough temperature increases and that can cause problems with downstream processing equipment, noted Terry Bartsch, vice-president of sales, Shaffer Mixers and Processing Equipment, a Bundy Baking Solutions company, Urbana, OH. “To decrease the amount of work put into the dough, the pipe can be replaced with a vertical sandwich-style conveyor,” he added, noting that Shaffer offers chunkers, pumps and conveyors for automating handling.
Ensuring proper belt tracking can be a constant maintenance task, and Mr. Bartsch noted Shaffer uses positively driven conveyors with self-tracking characteristics.
Also, keeping dough handling conveyors clean can be a challenge. “Shaffer sourced a special conveyor material that has excellent dough-release characteristics,” he added. “For any remaining dough residue, our belt scrapers — made of flexible material and strategically located — help keep the belt running clean.”
Previously, vertical conveyors were thought to not be as clean as an enclosed piping system for dough transfers. To make it a more sanitary process, AMF widened belts and redesigned how it feeds dough to the conveyors. “Today’s vertical conveyors are much better designed and cleaner for dough transfer, plus you get a better dough quality during the transfer process,” said Mr. Gore, adding that conveyors are much more common than piping nowadays.
The company offers Volta conveyor belts that feature guides underneath them to eliminate tracking issues that previously were common with dough conveyors, he said. The conveyor pulleys taper so that the belt runs centered and doesn’t track to the left or right.
AMF also manufactures single- and twin-auger dough pumps as well as dough chunkers. Whether a bakery chooses a single- or twin-auger pump often depends on the type of product being made, Mr. Gore explained. The twin-auger is open at in the hopper so the dough is immediately applied to the auger for transfer; whereas, the single-auger process uses a vacuum-assist to pull in tdough in for pumping.
The twin-auger system pumps 100% of the dough, Mr. Gore said, adding that sometimes the vacuum-assist system will require human intervention to scrape the sides of the hopper.
AMF’s pumps increase dough temperature 1°F at most. “We have also redesigned the augers so that they are open-flighted, which carries the dough more than squeezes it during the transferring process,” he explained.
Pumping systems are generally used with bun doughs that have higher moisture contents than their bread counterparts. While on the bread production side, dough chunkers are more often used because of the gentle transfer design.
Reducing dough stress
For soft, sticky doughs, Topos Mondial’s slide-gate chunkers portion pieces most effectively, according to Damian Morabito, president of the Pottstown, PA-based equipment manufacturer. These chunkers use either a dough position sensor under the gate or a timed open-close relay on the gate to properly size chunks using a pneumatically actuated stainless steel guillotine blade.
For stiffer formulas, Topos Mondial’s rotary chunkers use two adjacent, nonstick-coated 3-blade starwheel assemblies. As the blades rotate 120° at a time, they pull the dough from the hopper. The blades on the counter-rotating wheels converge to cut the dough into pillow-sized pieces, releasing them to a conveyor below.
“These chunkers don’t put any stress on the dough,” Mr. Morabito said. “You’re not degassing the dough, which helps maintain a desirable open cell structure in your product.”
When selecting dough handling equipment, Wally Mullvain, regional sales manager, Peerless Food Equipment, Sidney, OH, said several factors must be considered that could impact the next process and the final product. A baker should contemplate possible increases in dough temperature, as well as time and distance it must travel between the mixer and the next process.
Peerless offers two different handling methods and several conveying systems for transferring dough. Its spiral flow dough feeder uses a screw that feeds a continuous supply to a divider or forming equipment without changing the dough condition or temperature, he said. It works well with soft bread and bun doughs. Designed for either soft of stiff doughs, its rotary feeders cut dough into logs that travel to makeup equipment.
Recently, Peerless added a tubular design to the rotary feeder’s support frame to eliminate flat surfaces for improved sanitation and washdown access. “Designing a piece of equipment to be total washdown appears to be a simple solution to meet most new sanitary requirements,” Mr. Mullvain said. “Unfortunately, there’s nothing simple when it comes to designing a total washdown piece of equipment. Flour and old dough have an ingenious ways of hiding in corners, under clamps, and behind rollers and electrical cabinets.”
Peerless also redesigned its hopper/cutter oil assembly to provide a better spraying system to keep dough from sticking during the process. “Controls have been developed to allow bakery personnel to customize oil application settings,” he noted.
Automated dough handling systems offer solutions as high-speed bakeries look to improve the consistency and quality of baked foods. In short, automation advances quality and safety.