Dough mixers' aid dough consistency, become more energy efficient

Dough mixers have become steadily more adept at tasks such as self-diagnosis and energy management. In coming years, they will take on even more complex roles.

The world of the industrial dough mixer hasn't been stirred by new developments in quite awhile, although dough mixers have been getting steadily smarter and more automated through the years. Now, the mixers themselves lend a hand in ensuring dough consistency from batch to batch.

But even as mixers of all types have become more automated, safer and more energy efficient to meet the needs of today's wholesale bakers, many smarter mixer innovations are coming down the pike, says Tom Lehmann, director, bakery assistance, AIB International, Manhattan, Kan.

“Imagine a mixer that tells you if you forgot to add an ingredient,” Lehmann says. Such smart-mixers are on the immediate horizon, he adds.

Meanwhile, most of what's seen in dough mixers lately in terms of innovative introductions has been a move toward higher automation and energy efficiency, says Bruce Campbell, vice president, dough processing technologies, AMF Bakery Systems, Richmond Va.

Batch consistency

Automative advances, as well as any smart-mixer introduction, are vitally important in an industry in which the temperature of ingredients and energy required during dough mixing plays such a vital role in product consistency and quality, says Lehmann, who's known as the “dough doctor.”

Mixers' advances have a place in ensuring batch consistency, but will play an even greater part in the process as automation continues to advance, Campbell says.

“Every baker in North America is looking for a more repeatable process from batch to batch to reduce the waste and downstream difficulties that come when the dough is not the same density and mix quality,” Campbell adds.

Tracking improvements in precision

Campbell's company sells mainly horizontal mixers that offer the capability to monitor processing parameters during dough mixing, essentially allowing operators to peer inside the mixer.

The dough-mixer industry has offered this capability for several years, Campbell says.“ But the quality of the information we can transfer and the way we can transfer it to the end user is much better now and better integrated into machine controls,” he adds.

Information now is returned graphically via programmable logic controllers (PLC) for easy operator reference. Graphs depict the electrical power used by the mixer as compared to the energy specifications called for in the wholesale baker's formula. In this way, the operator can tell at a glance how close the mixer is operating, compared to the energy parameters called for in what Campbell calls the precise or master formula. If the graphs aren't following similar trends, an operator is alerted to a problem within the batch being mixed. Perhaps ingredient levels hadn't been added correctly or ingredients weren't at the proper temperature when they entered the mixer, he says.

“If the wrong type of flour was added to the batch, the operator could catch this right away because the mixer wouldn't be using the same amount of energy as it would when mixing the precise formula,” Campbell says.

Graphical info at a glance

Similarly, the PLC screens included with dough mixers now are easier to read and contain more information than in years past, says Alain Lemieux, dough systems manager, AMF Canada, Sherbrooke, Québec. The screens provided with AMF mixers feature a liquid crystal display (LCD) that can be read more easily than older models.

Information returned from the sensor and monitoring system also is displayed on one screen rather than on separate screens, Lemieux says. “Because they're now integrated, the operator can be constantly monitoring rather than toggling between screens and can take action more quickly to stop the mixer if need be,” Lemieux adds.

In keeping with trends in today's dough mixers, AMF, like other manufacturers, is adding more sensing equipment to its mixers. This gives mixers the capability to more closely measure mixing parameters. Parameters now monitored include temperatures of the water and flour as they're added to the mixer, as well as the operation of mixing sub-systems, such as the cooling system, he says.

“In this way, the operator knows why he's not getting the same dough quality as the day before. Maybe a valve is defective or someone changed a setting and the end operator can't figure it out,” Lemieux says. “Now they can receive messages on exactly what variables have changed.”

In addition, dough temperature must be regulated during mixing or the dough may become too hot or cold and thus unusable.

A matter of safety

The sensors also help with safety considerations, especially as safety standards in Europe and Canadian bakery systems are tightened, Lemieux says. Mixers are often part of an automated system in which the mixer and downstream processing equipment work together.

In this instance, sensors prevent operators from entering the mixing room during a part of the process that may be dangerous to them, Campbell notes. The sensors will literally lock the door to the room surrounding this equipment during specific dough mixing and dumping processes.

“Every customer has a special ingredient they want to add where the operator needs to come into this automation area. So the doors will lock at certain points,” Campbell says. “These machines are big and dangerous. Even when the door is unlocked and the operator opens it, the system isolates electrical power feeds and redundant systems to make sure there's no danger that by mistake or failure, the mixer would start again and endanger the operator.”

Mixers self diagnose

The Peerless Group, Sidney, Ohio, also is focusing its research and development efforts on making mixers smarter, says Matt Zielsdorf, vice president, sales and marketing, Peerless. Those efforts have paid off with the release of mixers that call upon sensors and controllers to, essentially, self-diagnose potential equipment problems, reducing maintenance.

“They're checking vibration in the shaft to give an early warning about a crack in a shaft or a failure,” Zielsdorf says. Also, motor sensors send temperature readings to the PLC. When a reading is too high, operators are alerted to potential motor overheating, he adds.

Today's Peerless mixers are designed to meet exacting sanitation standards, which means there are no areas where flour and water can collect on a mixer. In addition, maintenance doors on the machines are sealed to prevent flour and water from entering the internal workings, Zielsdorf notes.

About 18 months ago, Peerless began offering a maintenance-free trunnion bearing the agitator shaft rides through.

“You use to have to grease these bearings often or your bowl could seize on you,” Zielsdorf says. Now, the bearing is lubricated once in-house when the equipment is manufactured, lubricated one time at the bakery's site, and then never lubricated again.

Adding sustainability to the mix

Mixer upgrades not only reduce maintenance and attendant costs, they also play a role in sustainability, Zielsdorf notes. Bakers use fewer lubricants, which is helpful for their green efforts, he adds.

To that same effect, Boston Gear, Charlotte N.C., now is using a specialized lubricant that reduces friction and increases efficiency within the gear boxes it sells into the dough mixing industry, says Rick Wucherer, product manager, Altra Industrial Motion, Boston Gear Division.

“That lubricant doesn't break down like a conventional mineral oil and lasts forever,” he says. It also reduces heat generated within the gear box, cutting the heat the dough-mixer generates overall.

“Anything you can do to reduce heat helps with mixing,” Wucherer adds.

And, anytime mixers can be made smarter or more automated, the wholesale baker's bottom line benefits, note Lehmann and Campbell.