Metal Finishing Guide Book


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may not want to put all your eggs in one basket. It is important to determine what sorts of cleaning agents "work" in a given cleaning system. An answer that the system can always be adapted is not enough. Sometimes, if the cleaning chemistry is changed, seals have to be changed; or different filters may be needed. The operational temperature range for the equipment may not be optimal for other cleaning agents under considerations. Trust but verify. Demonstrate that the process works with the chemical in question. Beyond cleaning well and not damaging the product, understand the safety and environmental regulatory hurdles. Sometimes, the equipment company may not be aware of the safety and regulatory issues involved with a particular chemical. Some chemicals require low flashpoint systems or they oxidize to form flammable or combustible compounds. In other instances and depending on your regulatory microclimate, there are worker safety or environmental regulatory issues that require solvent containment, monitoring, permitting, or waste management. If the equipment vendor is unaware of these issues, is unwilling to work with regulatory agencies, or – even worse – shows disdain for regulatory agencies, beware! 4 - What's the throughput? How many parts can be cleaned per day? How long is each run, including drying and cool-down time? If you are accustomed to a 2 to 5 minute solvent process in an open-top degreaser, be aware that, depending on the parts and soils to be removed, an airless or airtight system can take 30 minutes or more per run. There are formulas to determine throughput; and reps can often provide estimates. How long does the process actually take? Follow up to refine the estimate and include factors specific to your manufacturing requirements. If the vendor provides an estimate of throughput, check both the math and the assumptions behind the math. For example, if throughput is estimated at 50,000 parts per 8-hour shift; but you know you have to clean 25,000 parts during a specific two-hour period, a process that accounts for the "bump" in throughput will be needed. In addition, given the sticker shock involved in pricing new cleaning equipment, throughput may be estimated a bit optimistically. You may hear comments like "well, the process time is 30 minutes, but most of our customers say they need less time." Well, maybe – but are the parts clean enough? Even with automated equipment, if parts have to be fixtured, loaded, unloaded, and perhaps allowed to cool, all those factors should be factored into the throughput estimate. Automated equipment may require the participation of assemblers; and people need lunches and take breaks. Determine the frequency and complexity of routine maintenance. What happens at the beginning of the workday? For example, ultrasonic systems have to be degassed and often must be heated. Your estimates of throughput should include room for growth (business could get better!); and a bit of wiggle room for process uncertainty. We see the unfortunate consequences of underestimating throughput. With insufficient capacity, operators overload cleaning tanks; and they may short-change the process time; this means cleaning will not be effective. Overloading can also stress the cleaning system; this leads to more breakdowns and more repairs. Buying cleaning equipment with inadequate throughput will compromise the entire surface prep and surface finishing operation. Visualize how the cleaning equipment will be used in your facility. Even better: observe a system under actual manufacturing conditions. 101

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