February 1, 2006
Dryers play a significant but oft-overlooked role in a processor''s facility, and can determine whether parts leaving that cell are good or scrap.
Dryers have come considerable distance technologically in the past few years, though versions of the dehumidifying desiccant dryer still account for the lion''s share of those sold. No matter the type of dryer purchased, there are some functions-many gradually becoming standard, some still optional-that processors should strongly consider to maximize a unit''s efficiency while also minimizing waste product and energy use. "A little here, little there and it starts to add up," is how Wes Moffitt, water and dryer product manager at auxiliary equipment supplier Wittmann Inc. (Vienna, Austria and Torrington, CT), describes what he says are the multiple steps a processor should consider to maximize the efficiency of his dryers. Wittmann, of course, makes and sells dryers, and naturally isn''t shy about encouraging processors'' continued capital investment. Moffitt''s colleague Matthew Chaponi, inside sales dryers and materials handling equipment, compares hanging on to old auxiliary equipment with keeping an old car on the road. "You can only throw so many parts on an old car" before those costs outweigh any savings by not buying a new car. "That''s what a plant manager needs to consider-how much of his budget is eaten up in energy (wasted) or maintainance costs?"At competing auxiliary equipment manufacturer Maguire Products Inc. (Aston, PA), Terry Good, product manager, adds, "If a processor wants to remain competitive, he needs to turn his technology on average about every seven years." Plus, he says, the return on investment on modern dryers is often less than a year. "It''s just good business sense" regardless of the drying technology, he says.With that said, here some helpful hints to keep your current equipment in top shape plus some factors to consider when it''s time to invest in new equipment. Consider the entire facilityAmong hints experts offer, maybe the most significant to assuring dryer effectiveness is to make sure your drying equipment is properly sized for the job at hand-if it''s not then energy will be wasted, material too most likely. If not properly sized, then over time material may be over-dryed, eventually degrading it to a point that part quality suffers. The transition from good to bad parts may be slow enough that a processor is inclined to first blame his material''s supplier, notes Chaponis. Chaponis recommends a processor consider his entire operation and mentally group materials of a like nature when purchasing new drying capacity. Unless a processor is using a single material grade for a single product (in which case he may eventually face other substantial problems such as loss of a customer), then it makes better sense if the new investment is chosen with enough flexibility to run on a group of machines for a range of materials, and not be tailored for a single job, he explains. The employee who specifies the new dryers and is responsible for the acquisition "needs to know upfront everything it will be asked to do." Know your moisture levelMaguire''s Good says one common error is not determining the moisture content of plastics. "If you don''t know how moist it is, then you can''t assume the timeframe stated for drying (by the materials supplier) is sufficient," he explains. Plastics are shipped under different conditions and in different packaging; not every Gaylord bag or sack is sealed properly. For about $10,000 a processor would be wise to invest in a moisture measurement system, says Good. "With respect to the cost of the entire process cell, it''s a very minor investment," he notes. Moisture measurements take only about 10-min, he says, and the system takes only as much space as a laptop computer. Processors serving the medical and automotive markets, who are forced by customers and legal provisions to document their materials handling procedures, already have such equipment. Good maintains that no matter the market served, a moisture measurement system will prove valuable.Maintain your equipmentProcessors with an overflowing basket of personnel, customer payment and other problems may not want to hear it, but making time for proper maintenance of dryers-and most other equipment for that matter-makes a huge difference in efficiency over the long term. Regardless of drying technology, Good and others ask customers to follow what have become relatively painless preventive maintenance procedures. For Maguire''s LPD dryers, which use vacuum to dry material, the most important check is of a unit''s sealing rings, to ensure the vacuum stays optimal. For other dryers, such as the desiccant dryers made by Wittmann and others, "The biggest thing is that return air filters are clean.Air is the lifeblood of a dryer," says Chaponis. "You don''t want dust to get into your desiccant beds" as this lowers the desiccant''s efficiency. Chaponis also suggests having two return air filters on hand per dryer so that one can be cleaned (blown out with compressed air) while the other is in use. Other minor maintainance checks that can have major affects on drying efficiency include ensuring that hopper lids are fastened and aligned properly and that conveying hoses are supple and not cracked or pinched.Talk to the supplier The more a supplier knows about a processor''s operation, the more he can help suggest a proper a proper drying system. But knowing enough about drying to ask the right questions, and keeping current equipment properly maintained, will go a long way to preventing problems. Options pay offBelow a short list of options for dryers that Wittmann''s Matthew Chaponis says should be on the wish list of any new equipment specifier:Timers:
Help ensure material is not degraded. Seven-day timers come in handy by turning on drying equipment automatically, so that material is ready for processing when a first shift arrives (without having an employee arrive early)Filter clog alarms:
for those times when very dusty material clogs a filter before regular maintainance is scheduled or if that maintainance is missed. Keep two filters on-hand per dryer. Install loaders with small inventories:
These keep just enough material in the loader to hold for a shot, so there is less chance of regaining moisture. Regulated airflow:
This adjusts airflow to where it is needed, and reduces it when it is not needed. Energy is saved and material is not degraded. Make every minute count, tooFrequent material changes are the rule at many processors, among them automotive lighting parts manufacturer Koito. Its captive molding operation in Droitwich, Worcestershire, England faces frequent short production runs, often as few as 200 parts. To reduce wait time for materials'' drying between material transitions, the molder has installed eight LPD vacuum dryers from Maguire Products Inc. (Aston, PA). Mike Bullock, chief molding engineer at the processor, cites 75% energy savings over the previously installed drying equipment, and the new ability to conduct material color changes without stopping processing, as important advantages of the new equipment. Drying time was reduced substantially, says the molder. MDMatthew Defosse [email protected]
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