Good food—by design

Steel drive 
tape in grill 
design provides 
user-friendly, consistent cooking

—By Tim Potrikus, 
Sales Manager, 
Belt Technologies, Inc.

The moment that specialized equipment began to replace short-order cooks signaled a major turning point in the fast-food industry. Over time, the list has come to include everything from grills, ovens and fryers, to soft-serve dispensers and drink makers. Not only is speed maintained throughout an entire shift, but also quality is consistent from burger to burger, French fry to French fry. As in industrial-scale food processing plants, these machines have to tolerate long periods at high or low temperatures, be easily and readily cleaned, and resist breakdowns.

Of course, nutritionists will be arguing a while longer on the effects of fast-food in an adult diet, but that’s a topic for another publication.

Grilled to taste

One of the major U.S. manufacturers of equipment for the fast-food industry was approached by one of their top customers with a design challenge. Their customer wanted to add automation to a cooking process that would achieve three objectives:

• Remove the manual decisions and opportunity for error regarding a critical function of the cooking process.
• Create a solution that would enable end users to set all cooking parameters with a “one touch” button.
• Maintain quality and consistency in the cooked product while reducing crew training, maintenance, and repair costs.

Achieving these goals meant the restaurant could expand menu items without adding unnecessary equipment, labor or maintenance costs, while improving the quality and appearance of their product.

In developing design options for the new commercial grill system, the equipment manufacturer employed an in-house multifunctional team consisting of design engineering, manufacturing engineering, field service and marketing. This “engineering cell” had the responsibility to engineer the grill, build the prototypes, modify the designs and write the performance reports. Part of the testing phase included setting up a simulated quick-service restaurant where product could be cooked as though it were in an actual customer kitchen.

A critical component of the design is in the positioning of two cooking platens, one on top of the other. By actuating a precise movement, a programmable, repeatable distance can be set between the two platens. Ideally, the end-user envisioned positioning the upper platen within 0.002 in. of a number of various “stop” positions above the lower platen. This would achieve the objective of setting a critical feature of the cooking process, without complex operator involvement, for a multitude of products. As the engineers looked at methods for automatic positioning of the upper platen, three alternative techniques were considered: cables, inclined planes and steel belts. 

Stainless tape, medium-well

In a food-processing environment, stainless steel offers cleanliness and exceptional performance in a hot environment. As an added benefit, the steel provides a low mass belt that performs well without any lubrication. For design assistance, the project engineer contacted Belt Technologies, Inc, Agawam, MA. 

A steel drive tape, a derivative of endless steel belts, was envisioned. Drive tapes are ideal in applications where rotary motion needs to be converted to linear motion. Similar drive tapes are used in robotic arm actuators, carriage positioning systems, or mirror positioning systems for military or satellite use. For durability, the drive tape most often is fitted with a reinforced end tab, to ensure a firm and secure contact is maintained where the tape is terminated. Specifically, the use of steel drive tapes in this application could provide near-zero backlash, no stretch, and the repeatability desired by the customer.

According to the vice president of engineering/technical services at the equipment manufacturer, the steel drive tapes were a “clear winner” early in the design phase. When compared to inclined planes, the drive tapes were less complex in design, and offered a significant advantage in space and weight. He further explains that the incorporation of the metal drive tape was a “very intuitive design,” offering the benefits over cable in manufacturing simplicity and field service. The non-stretch nature of the metal drive tape allowed the company to achieve consistent, predictable results in the performance of their grill. The final design incorporates the use of the steel drive tape, terminated to both the upper cooking platen and a drive pulley. Using a single button on the operator control panel, the drive assembly moves the upper platen to the precise position the customer requires.

Done to perfection

Implementation of the design was not without challenges, however. Although the engineers were encouraged with the initial performance of the prototype drive tapes, improvements to the design were needed to achieve optimum life-cycles. According to Rich Lunden, Belt Technologies’ manager of new product development, the change resulted in lower bending stress, with ample strength to carry the load of the cooking platen. Lunden states, “We like to see a significant ratio of pulley diameter to drive tape thickness. With the original design, we would have needed a pulley that exceeded the available space. By changing the belt thickness, we kept the pulley diameter within the customer’s design requirements, and achieved the life cycle we were all looking for.” A slight modification to the location of the pulleys in relation to the termination point of the drive tape was the final correction. The redesigned system was tested to three million cycles, after which a review by an independent metallurgist showed no signs of fatigue.

As for further testing, the grill’s manufacturer monitors a statistically meaningful number of the installed grills and inspects core components for wear. The stainless steel drive tapes have shown no measurable stretch after repeated use, and the metallurgical analysis shows no change in the structure of the belt from installation through usage.

The company considers the project an absolute success, with the grill achieving “approved and released” status from their customer. “The metal belts allowed us to achieve results that were not possible with other alternatives,” says the engineering/technical services vice president. Lunden agrees. “The opportunity for Belt Technologies to work with the engineers at our customer’s location early in the design phase was important to the success of the project.”

For more information:

Circle 340—Belt Technologies, Inc., or connect directly to their website via the Online Reader Service Program at www.rsleads.com/202df-340