The ribbon blade element consists of a central shaft that rotates two spiral or helical ribbons, inner and outer, with reversed pitches that force material in opposing directions (Figure 4). For optimum results, the blade’s geometry is customized for specific feed properties, making testing critical to the engineering process. The agitator element is easy to remove, designed in an assembly that may be lifted out if necessary for cleaning or maintenance, although ribbon blenders are well known as tough designs that rarely need maintenance.
Figure 4. Use now has been extended to 10 different products.
Since many of DCP’s products involve addition of liquids, the blender is equipped with an internal spray line. Ribbon blenders are well-suited to adding liquid ingredients to powders, and will not plug up with damp or pasty mixtures. A paddle-type, lever-operated gate opens wide for complete discharge of blends, whether free-flowing, or damp, and leaves little or no residue to contaminate subsequent batches. This is important because of cleaning requirements.
DCP must meet the standards for Good Manufacturing Practices (GMP), i.e., 21 CFR Parts 110, 210, 211, and 820, which means that the blender must be amenable to cleaning. To clean the system, the ribbon is left in place while the safety grating, bag dump baffle and PTFE cartridge filters are removed; these are cleaned in a wash-out/drying station. The blender is simply washed with pressurized tap (sanitary) water and allowed to dry. Rarely is scrubbing required. When it is, DCP follows a lock-out, tag-out procedure. During cleaning, all outer surfaces are wiped down thoroughly and equipment is reassembled, tagged out, and made ready for the next product blend.
The success of the new blender has caught on. Since its installation, the blender’s use has been extended beyond the enzymatic cleaner. It is now used to mix 10 different products (Figure 4). “The ribbon blender has worked out very well for us,” concludes Longo. “It has enabled us to garner some larger business accounts that we weren’t able to handle previously.” Prior to the installation, DCP was processing approximately 35,000 to 40,000 lbs. of product annually. The addition has now enabled the firm to process approximately 400,000 lbs. of product annually. This is almost a 900% increase! This capital expenditure has reduced the workload of a typical order from 52 batches in the old planetary mixers to 5 batches in the ribbon blender. Labor hours have been cut by over 60%, excluding hours spent for rework. Product homogeneity has been substantially increased.
Charlie Divine is a marketing manager at Munson Machinery Company, Utica, N.Y. E-mail him at email@example.com.