It seemed like an exciting product development opportunity. Building material suppliers in cold climates were moving packaging operations outdoors. They needed equipment that could operate in an open shed or shelter to bundle their bricks, blocks and masonry products. In addition, ice cream and frozen-food producers wanted to bulk package their products in below-zero warehouse environments for better quality and productivity. But these applications required stretch-wrapping equipment that could withstand frigid conditions.

Wulftec, a leading provider of robust packaging solutions, recognized that these market trends were creating an attractive business opportunity. But developing a stretch-wrapping system that could operate efficiently from -30˚C in the winter to 70˚C in the summer would bring new technical challenges.

Based in Ayer’s Cliff, Quebec, Canada, Wulftec has built a reputation for offering rugged equipment with heavy-duty structural steel construction. These systems are customized for specific customer requirements across a wide range of food, beverage, printing, building products and metal coil applications. The company uses non-proprietary components to make it easy for end users to maintain their equipment.

We Fear No Packaging Challenge

Driven by its motto, “We Fear No Packaging Challenge,” Wulftec decided to explore this interesting new market niche. As company engineers assessed the rigors of cold-weather operation, several product design issues emerged.

The most critical problems involved the machine’s pneumatic components. In frigid temperatures, any humidity in the compressed air supply rapidly turns to ice. This condition can damage the pneumatic valves and cylinders and shut down the machine’s operation. Understanding the end users’ air supply quality would be essential to determining the machine’s air-drying requirements.

In addition, pneumatic components would have to be sourced that could withstand -30˚C temperatures. The seals, O-rings and solenoids incorporated in standard pneumatic products were not designed to operate in low-temperature conditions.

The third problem involved the machine’s bearings and gear boxes. When a machine is powered up after several hours of cold-weather downtime, the frigid components will not perform correctly. In some cases, these products would require reengineering, modification or heating, particularly at the lubrication level, to withstand a frozen environment.

Solving these issues would be essential to developing a reliable, low-temperature stretch-wrapping system.

Engineering the Solution

Wulftec turned to a key supplier, Emerson, to help solve the cold weather’s impact on the machine’s pneumatic components. Wulftec has incorporated Emerson’s ASCO Numatics products in its equipment for over 29 years, and the companies have held a close relationship.

With Emerson’s support, Wulftec queried end users to define the air quality standards required for its new stretch-wrapping machine. Customers confirmed that humidity in the compressed air entering the pneumatic system could be an issue. Emerson technical support helped solve the problem by recommending the appropriate air drying equipment, and in some cases, suggesting more robust components that could withstand less than ideal environments.

Another challenge was identifying the pneumatic products that could operate reliably in extreme conditions. The pneumatic system for the new stretch-wrapping machine required directional control valves and manifolds, aluminum-body cylinders, bellows, slides and air preparation equipment with dump valves. The Wulftec design team collaborated with Emerson to select components that would meet the application’s requirements.

Wulftec’s equipment design was based on NFPA standards. Emerson’s ASCO Numatics product line had a complete pneumatic offering that met this standard. This simplified product application to the new stretch-wrapping machine and also made installation and assembly easier.

The ASCO Numatics brand also encompassed the industry’s broadest range of components rated at -35˚C. But it was evident that additional engineering work would be required to certify the entire pneumatic solution for low-temperature operation.

For position sensing and spool detection, the Wulftec-Emerson team already had identified switches that were rated for low temperatures. They added an ASCO Numatics pilot valve that was ATEX-rated to -40˚C. The assembly was tested at -30˚C and the team was satisfied with its performance.

The initial design also called for a filter, regulator and lubricator (FRL) with two dump valves that were rated at -40˚C. Plus, the dump valves were specified with quick-exhaust, soft-start capabilities. This solution was deemed too expensive and would not have the desired air flow. Emerson suggested a higher-flow FlexiBlok FRL with a single, dual-redundancy dump valve to reduce the cost. However, the standard FlexiBlok components were not all certified to -30˚C. To solve the problem, a FlexiBlok slow-start assembly with a -40˚C-rated regulator, plus another component rated at -32˚C, were connected with a ring seal and tested together to prove they could operate at low temperature.

The dump valve also required engineering work. The dump valve’s body was rated at -40˚C, but the solenoid was not. Emerson located an ASCO Numatics solenoid in Europe that fit the specifications and installed it on the valve body with cold-weather O-rings. Testing proved the modified dump valve would reliably operate in frozen climates. In addition, the ASCO Numatics cylinders were fitted with low-temperature seals to enhance cold-weather operation.

Wulftec and Emerson then conducted rigorous testing in frigid environments and became confident that the entire pneumatic system would operate reliably at -40˚C.

The machine’s bearings and gearboxes were the other components most vulnerable to below-zero conditions. Wulftec found that many of these products could be sourced with low-temperature ratings. In some cases, the addition of heating elements was required to warm up the lubrication and permit normal performance at start-up.

Wulftec became the first company in its industry to introduce a line of stretch-wrapping systems for low-temperature operation. Now, building material producers can package their products in outdoor locations. And frozen-food makers can stretch-wrap their goods in their freezers, reducing the potential for spoilage. 

The Journey Continues

Wulftec’s low-temperature stretch-wrapping equipment continues to evolve with the market. Stretch film is becoming thinner, more specialized and higher performing. But at -30˚C, the film becomes very brittle. Wulftec is adapting the low-temperature machines to effectively manage these newer and thinner materials.

Emerson continues to support Wulftec with pneumatic system enhancements. The companies are discussing the application of the new ASCO Numatics Series 652 FRL to the stretch-wrapping machine. With its modular construction, higher flow and low-temperature dump valve, the FRL will help reduce operating and maintenance costs while improving system flexibility.

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