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Mexico SAN ISIDRO MAZATEPEC, Mexico — Desert Glory Ltd. is the largest producer of cherry tomatoes in North America. This 400-acre operation controls the entire production starting from seed. They are grown in four-acre greenhouses At one time, workers packed the tomatoes in mesh bags and placed the bags on a conveyor. At the end of the line, samples of the 12-ounce bags were weighed on a Rice Lake SURVIVOR® CW-80 Checkweigher, and tomatoes were added or removed as needed, which took extra time. Gustavo Vera, director of total quality management, asked Gerardo Yañez of Basculas Yañez Rios to help streamline the Desert Glory process. Gerardo, who had been providing scale calibration service to Desert Glory, recommended the incorporation of a 920i® HMI programmable indicator/controller into the production line. He developed a system that not only increases through-put, but is also easy for operators to use. It provides real time production and traceability information that Desert Glory needs. Basically, the 920i system controls 24 checkweighing scales. Each production line has an enclosure with two 920i panel mount indicators. Inside the enclosure, each 920i uses two six-slot expansion boards to accommodate six dualA/D boards and three 24-DIO boards. A single 1 MB memory board is plugged into a slot on the CPU board, and In the morning, a supervisor initializes the system, selecting a product from a database and the names of the operators who will be working on the line. Operators put an empty mesh bag on each scale and the supervisor zeroes all the scales. The blue light signals operators that the scale is in zero range and ready to be filled. The yellow light signals when the weight is at a low range but approaching the desired weight. The white light signals slight over-weight. The red light signals high over-weight. Both the yellow and white lights go on when the desired weight range is reached, but the system has not yet recorded the information in its database. The green light signals when the 920i has read and stored the weight, and notifies the operator to move the tomato-filled bag to the conveyor belt. All lights remain off until a new empty bag is placed on the cone-scale. When the scale recognizes zero, the blue light signals to begin the new filling process. During the day, supervisors can monitor the process on a PC screen. They can see how many bags each operator has filled, and how many bags were filled over and under the desired range. They also monitor a screen totaling the same information for all 12 operators on the packing line. At the end of the day, the packing manager connects to the network using an Excel® file with macros that send commands to all five packing line controllers. All data recorded during the day is downloaded to the packing manager’s computer. The manager then generates reports used to pay bonuses and incentives to operators depending on their individual performance. Gustavo reports, “The 920i provides us with the accuracy of measurement we need for our customers and our employees. We are confident that our product is going out at the correct weight—not underweight and not overweight. It has also allowed us to increase the speed of our production line.” With the 920i system, Desert Glory is packing 100 percent more than they were before, with the same number of operators. And those very pleased operators finish their workday two hours earlier than before the 920i system was in place. Instead of a daily production of eight metric tons, Desert Glory is now packing 16 metric tons of cherry tomatoes a day. That’s a 100 percent increase thanks to Rice Lake’s 920i controlled system. Holy tomatoes!
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