Williams Sausage of West Tennessee installed a Texwrap Model 2202 CR continuous-motion side seal shrink wrapper to address its growing breakfast sandwich business.
Running at speeds to 28 cartons/min, it replaces an L-bar shrink-wrap sealer that maxed out at 14 cartons/min and that had to be stopped and changed over when a new carton size entered the picture.
The Texwrap Model 2202 CR continuous-motion wrapper does not stop while the end seal is being made, thereby increasing throughput speed. Its conveyors can move at 100 ft/min with versatile carton-handling flexibility. The system is all stainless steel for ease of washdown.
For this box-motion style wrapper, the device makes the end seal move horizontally with the product as the seal is being made. When the seal is complete, the head rises and the carriage returns to engage the next package and make the next seal. Box motion refers to the rectangular-shaped path of the sealing head.
The box seal requires a heavy carriage assembly to which the seal is mounted. The hardware has to execute rapid movements back and forth. It has to open up, come back across the package, seal, open again, and go back and grip the next package. This requires considerable motion for a large, heavy assembly. Instead of using just bottom bearings as is typical on most shrink wrappers using this method, this unit uses top rail bearings as well, double bearings. This takes the stress load off from the top and stabilizes the movements of the seal assembly. Without this feature, the carriage could not move as fast.
Also instead of using bumpers to provide hard stops for the seal carriage, as is the norm on typical shrink wrappers, a cam and spring assembly, assisted by compressed air, is used to rotate the carriage into a soft return. This eliminates the shaking that usually occurs on fast returns, forcing the system to pause while the photo eyes and sensors settle out. Since there is no bounce, the carriage can return up to 15% faster, increasing cycle times.
To further maximize throughput speed, the wrapper is equipped with Motion Trim™ technology, which electronically minimizes the motion of the end seal device. It also includes a Speed-Maximizer™ system that automatically brings the machine up to top speed for any given carton-size setup.
Auto-Spacing™ is used to separate randomly-spaced incoming cartons for wrapping. A photoeye is mounted above the infeed conveyor, which detects the front and rear edges of the incoming cartons and spaces them an exact distance apart for wrapping. With Auto-Spacing control, horizontal as well as vertical photoeyes, and the ability to precisely vary the conveyor speeds to relax the film between products, Williams Sausage’s new shrink wrapping system can accommodate randomly-fed cartons and accurately separate them for reliable, consistent packaging using the absolute minimum amount of film.
The cartons are manually placed on the conveyor and automatically indexed just before they enter the shrink wrapper. If the line is running boxes with ten different lengths, they can be put back-to-back on the conveyor without worrying about spacing. The wrapper spaces the variable-length cartons with automatic standard gapping.
To negate the problem of ice build-up and belt slippage, which can affect registration, Texwrap embossed some of the wrapper’s surfaces with little bumps to minimize the slick surface-effect. Also, special freeze-resistant valves were utilized on its air cylinders. The wrapper can run either flat or center-folded film, including a wide range of polyolefin, polyethylene, PVC and some polypropylene based films.
To support the shrink wrapper, a Texwrap Model 1432 CR shrink tunnel was added to the line. This single-chamber forced air convection tunnel uses large volumes of high velocity air to impart the necessary energy to the film for the best shrink package. The tunnel is equipped with digital temperature controls, high velocity fans, individual top and bottom controls for air direction, and variable-speed conveyors. These features control the right amount of heat to be put in the right places, over the correct amount of time to produce consistent shrink results.
Because the popularity of its breakfast sandwiches is continuing to grow, Williams Sausage is now planning another upgrade to its sandwich lines by again expanding its shrink packaging capability. “This new system will be equipped with servo-controls which will allow us an even higher level of line throughput and performance,” Ray says. “We are looking at another Texwrap, because our current shrink wrap system has proven to be such a good investment for us.” —Jim McMahon