Loss-in-Weight Feeders Produce Only Gains - Schenck AccuRate

cause manually weighing the ingredientswas not 100 percent accurate.This sometimes led to an ingredient’sweighment being outside the acceptableaccuracy range. Also, manuallyopening and emptying ingredientbags and dumping the ingredientsinto the small containers and hopperscreated fugitive dust that decreasedthe plant’s cleanliness. And manuallyhandling the bags and small containerscreated ergonomic issues for theoperators. Additionally, the companyexperienced inefficient productionrates because the dry ingredients inthe hopper couldn’t be discharged tothe mixer until the mixer had completelydischarged the molten materialto the extruder.To maintain its market competitiveness,the company decided to redesignand upgrade the Vonoreplant’s processing lines by eliminatingthe batch mixers and single-screwextruders and installing several continuoustwin-screw extruders, whichmix, melt, and extrude the ingredientsin one continuous process. As part ofthe plant upgrade, the company alsodecided to fully automate the ingredient-feedingprocess to eliminate theproblems caused by manually handlingthe ingredients.During its search for automated feedingequipment, the company contactedseveral feeder suppliers andtraveled to three suppliers’ test labsfor material tests. “We gave each supplierour toughest-flowing materialsfor use in feeder tests that focused ona feeder’s feeding accuracy overtime,” says Dennis Donalson, plantengineer at the Vonore plant. “To helpus nail down the accuracy of eachfeeder, the tests were computerized,and all of the test data was collectedso we could do statistical process controltesting and charting.”Of the three suppliers, two manufacturedfeeders that were able to feedthe material at the accuracies the companyrequired. Because of this, Donalsonsays, “We decided to evaluatethe feeders on other issues, such as thefeeder’s overall design and how theoperators and maintenance crewwould interface with them. We alsolooked at the components of eachTo prepare a batch for one mixer,an operator had to manually openthe bags and preweigh and premixthe ingredients in small containers,using a scale on the ground level.The feeder is connected to a graphical interface and recipe managementsystem that allows an operator to set the feeder parameters and monitorits operation from one central location.