Baked goods can travel a long way before ever leaving the factory: from the mixer to the oven or fryer through the freezer and onto packaging, with other stops along the way, depending on the product. Snaking through oven heat and subzero freezers, conveyors keep products moving through all kinds of conditions. 

“Extreme temperatures, whether hot or cold, pose risks to any machinery,” said Kyle Schultz, engineer, Eaglestone Equipment. “Extreme temperatures will cause commonly used materials, such as metals and plastics, to lose structural integrity leading to failure or accelerated wear. It can also cause some materials to grow or shrink significantly, leading to components seizing or becoming loose. Last, especially for plastics and polymers, extreme heat can create toxic conditions near food or even a fire hazard. This can stop production in its tracks.”

Keeping these critical workhorses running through the extremes takes careful treatment of the equipment and good planning.

“Without appropriate accommodations or designs, the belting can mis-track, jump sprocket teeth and ultimately crash, causing significant damage and product loss,” said Barry Voshell, strategic account manager at Regal Rexnord. “Conveyor belting designed to allow for thermal expansion or contraction is the key to a successful outcome.”

The heat of ovens and the cold of freezers present different challenges to the efficient running of conveyors. Understanding how the various equipment will react under these conditions helps manage problems.

“Expansion and contraction, that’s the thing you’ve got to be careful about, especially if you’re going into ovens, out of ovens, into freezers, out of freezers,” said Jonathan Lasecki, director of engineering, Ashworth Bros. Inc. “You have to know, is it going to grow or is it going to shrink? And then build up your take-ups accordingly and also framework clearances. You need to have all that in place.”

Take-ups are the extra slack built into conveyors because they expand and contract in the heat and cold, so this allows the equipment to adjust as needed.

“Metal expands both in length and width,” Lasecki explained. “Whatever framework is there, which are the side guides, if the belt expands too far it’s going to rub, and of course rubbing adds friction, adds tension, adds to wear debris and all those things that affect the operation, not only in the system but also affects the life of the belt. You need to make sure if the belt’s going to expand say an inch, you’ve got to have an inch and a half available so they will ride through there and not bind up and get caught.”

High temperatures can induce structural damage and material fatigue while the cold can cause materials to become brittle and increase friction, said Frank Achterberg, president, CBF Bakery Systems.

“Motors are susceptible to overheating or increased friction in extreme temperatures, and low temperatures can cause increased friction and viscosity in lubricants,” he said. “Some solutions include selecting motors with a broad temperature operating range, implementing cooling systems and ensuring proper lubrication. Conveyor belting faces issues such as loss of flexibility, fatigue or deformation.”

Bryan Hobbs, director of factory service, Ashworth Bros. Inc., said getting the proper lubrication is vital because freezers see a lot of moisture buildup in bearings where it becomes ice particles and can damage the rollers in a bearing or damage gear boxes if it does.

“Oftentimes customers aren’t aware when they buy a bearing or a gear box from a local distributor, and it comes equipped with a grease or oil that is general duty oil, general duty application, and not necessarily for extreme temperatures be it cold or warm,” he said. “It’s important to make sure you’re buying the components with the appropriate greases and oils.”

He said that the bearings are generally located outside ovens, so they can be greased while the oven is being used.

“Likewise with freezers oftentimes the drive might be located just outside the edge of a freezer in order to maintain it,” Hobbs pointed out. “It reduces exposure to the temperature cycles.”

Other equipment is specially designed to handle temperatures, including nitrile seals in gear boxes that work in extremely cold temperatures. He added that conveyors that come into and out of ovens and freezers may require increased energy use or could cause moisture buildup in the freezer.

“The longer an infeed to an oven is, the more you have to reheat the oven bands because of the time it spends out of that heated chamber,” Hobbs said. “And the longer the conveyor sticks out of the freezer, the more opportunity for it to collect moisture because moisture is going to collect on the coldest component in the room. You’re just introducing that moisture back into the freezer where you’re going to build up frost on your coils.”

The challenges associated with maintaining freezer belts are similar to ovens, but more options are available to use in freezers because plastic belting can be used, said Dan Regan, president, Custom Cut Metals.

“We’ve gone into freeze tunnels where it will be -400˚F going onto our belting, and it means we just have to adjust which of the plastic belting we are using because if you’re using the wrong one, it will start cracking and breaking because it’s frozen,” he said. “As long as we can anticipate that, and we have the right belting on there, we’re fine.”

Plastic conveyors and components are susceptible to blackening and deformation in high temperatures, pointed out Will Rollins, technical service engineer, Wire Belt Co. of America.

“Some good practices when moving out of an oven is having a system that can support the repeated temperature changes,” he said. “No matter what material is chosen, you will always find that the heat cycling will take its toll.”

This article is an excerpt from the April 2024 issue of Baking & Snack. To read the entire feature on Conveyors, click here.