With tens of thousands of buns racing along at breakneck speeds, a slight uncoupling, a worn-out drive or a malfunctioning motor on a conveyor will derail a smooth, high-volume operation.
In the midst of peak summer barbecue season, overlooked belt-tracking issues that create unnecessary vibrations can quickly ratchet up waste and drive down efficiencies, especially as bakers push production to the limits to meet seasonal demands for their products.
“You need to look and listen to the system to make sure it is running right,” observed Jonathan Lasecki, director of engineering, Ashworth Bros. “Is it running right? Is it hitting something, or do you hear sounds that are not normal? When you start your car in the morning and you hear it grinding, you do not ignore it. Something is wrong. Let us fix it before something gets worse. You can touch the framework and feel vibrations that weren’t there on the previous day or during the previous examination of the system.”
A trainload of factors can hinder on-time performance and potentially compromise quality control when it comes to conveying. However, sometimes the solution could be harsher than the problem in the long run.
“Leaving a sidetracked belt running without fixing the tracking results in belt crumble and possible product contamination as bacteria can easily build up on the damaged belt,” noted Bobby Martin, executive product manager, AMF Bakery Systems. “Maintaining proper tracking requires constant resources and sometimes leads to adding tension to belts and consequently damaging them or adding too much load on the bearings.”
Preventive maintenance can be challenging, but Adam Erickson, project manager, Axis Automation, suggested that a simple visual check of the belt position usually will suffice for identifying tracking issues.
“This can and should be done while the belt is running,” he pointed out. “While the machine is off, it is also a good idea to check the belt itself. If there is uneven wear across the underside of the belt, there is an issue that needs to be addressed. Tracking issues do not fix themselves or go away on their own.”
For some conveyors, a weekly inspection will do, suggested Billy Rinks, national sales account manager, North America, for Stewart Systems, a Middleby Bakery company.
“For others, the belting may need to be undone to see what is going on with the wear strip,” he said. “Also, some conveyors wear faster than others, so those need to be identified for more frequent inspections. Some examples would be conveyors with curves, accumulation conveyors or friction-topped, incline conveyors.”
Depending on the bakery, the issues differ in various parts of the operation. In mixing, for instance, fewer belts mean minimal concerns.
“When you go to processing, belts can be placed under stress due to buildup of dough on the conveyors and pulleys, which tend to effect the tracking and life of the belt,” said Mike Galvanauskas, dry food area sales manager, Habasit.
These conveyors typically have very small pulleys for the belt to navigate or dead-plate nose bars, which stress the belts’ flexibility along with the life of the joining splice.
After the oven, he added, the stress level tends to decompress as the baked goods travel along typically long and wide belts in cooling or upon fabric, plastic modular and tabletop chains in packaging.
Short and high-speed conveyors should garner the greatest attention from maintenance and operators to keep the proverbial railway of the bakery running on time.
“When you have a short conveyor and you speed it up, the belt now is going round and round more often,” explained Frank Birkhoff, technical support group specialist, Intralox. “The belt is having a higher frequency of modules going around the sprockets and conveyor frame. When you combine this with high speed and the product that is being conveyed, short conveyors need more maintenance. Radius curve belts also need more attention. Belts that go around corners and then straighten out need to be guided carefully or else the belt edges can catch and break.”
Frank Achterberg, president, CBF Bakery Systems, suggested that the dimensions along with belt selection greatly influence tracking.
“A conveyor that is shorter in length than width can be a challenge and needs to be designed accordingly,” he said.
Incorrect locked sprocket location and unlevel shafts pose problems as well.
“You’ll also start to see worn sprocket teeth, causing the belt to jump,” said Mike LaValle, corporate account manager on the bakery and snack team, Intralox.
Ricky Milner, product line support leader, Wire Belt Co. of America, emphasized that all conveyors must be square and all shafts set so they’re perpendicular to the conveyor frame, regardless of the type of system. Because spiral conveyors have an outfeed motor, he added, they also need a proper tensioning device.
Mr. Birkhoff added that correct sprocket placement is also critical. With its low-tension belts, Intralox only locks the center sprocket on the drive shaft so that the belt will follow a straight path. Think of it working like a bicycle chain that must follow a straight line. Unlevel drive or idle shafts can also cause the belt to walk to one side.
“If you combine the uneven drive shaft, center sprocket not locked, and worn teeth, you have a recipe for disaster,” he said.
When the belt tracks in one direction, Mr. Erickson noted, the uneven distribution of tension may cause premature failure of the belt or damage other parts of the conveyor.
“I have heard of plastic belts tracking against stainless steel and cutting a groove right through it,” he said.
Bakers can take several steps to prevent such issues. On belts with drive sprockets, Mr. Erickson said, Axis Automation puts locking collars on both sides of the belt to make sure it doesn’t “walk on the shaft.” Tapered drive rollers also may keep the belt on track.
“We have also used a V-guide belt where there is a groove cut into the shaft and a ‘V’ that protrudes from the underside of the belt,” Mr. Erickson said. “This ‘V’ rides in the groove in the shaft and prevents it from tracking in any direction.”
On cooling tunnels where belts may be up to 48-inches wide and 400-feet long, Mr. Galvanauskas suggested using take-ups that maintain belt tension, prevent slippage and allow for adjustment when a belt stretches over time.
Often, however, tracking starts with installation.
“You want to make sure the belt is installed properly, and that involves a lot more than just putting the belt on,” Mr. Lasecki said. “It’s really an analysis of how the belt you’re taking off is operating. If it’s not operating straight or it’s not tracking, you have to figure this out and resolve those issues first before putting the belt on because the new one is going to take the same path as the old one.”
Focus on the basics, he added, including a flat and perpendicular proper alignment.
“Once you get that baseline, you can put in the belt, and it will track,” he said.
This article is an excerpt from the July 2020 issue of Baking & Snack. To read the entire feature on conveying, click here.