Originally published in the July/August 2013 issue of metal finishing magazine (p. 20-21)
BY DORIS SHCHULZ, OWNER, SCHULZ PRESSE TEXT, STUTTGART, GERMANY
Leaner, Greener Cleaning
= Measurable Results
Superior Products LLC makes switch from nitric acid dip cleaning to closed-loop solvent method.
Making the change from a nitric acid aqua-based cleaning machine to a closed-loop solvent system has paid off for Superior Products, LLC. The Cleveland, Ohio-based company reduced the water consumption annually from 2 million gallons to zero, dropped labor for cleaning, and achieved better overall cleaning results in the process.
Superior Products, LLC started in 1946 as a general screw machine company and has grown its product lines to serve the welding, medical, beverage, cryogenic liquid and specialty gas industries worldwide with fittings, manifolds and assemblies. The company’s product range includes about 3,000 unique parts, which are developed and manufactured at the facility. Superior machines 10 to 15 million pieces annually which are primarily made of brass and stainless steel.
After machining, the parts are contaminated with chips and swarf as well as cutting fluids and oils. As they are used in connection with compressed gas in industrial, medical, and specialty gas applications, the parts have to be cleaned to an “oxygen clean” standard. The Compressed Gas Association (CGA) allows no more than 47.5 mg/sq.ft. of organic material on the parts. “If a dirty part isused in an oxygen system, there is a chance of fire because it is compressed gas that can lead to explosion,” Superior Products general manager Iain Hodgekins explained. Superior’s previous cleaning solution, a nitric acid bright dip cleaning system, reached a level of about 17 or 18 mg/sq.ft and thus satisfied the cleanliness requirement. However, the cleaning system was about 30 years old, and many parts had to be re-cleaned. Additionally, the system used about two million gallons of water annually that had to be processed for heavy metals in the wastewater.
“We wanted a modern system that would allow us to drastically reduce the impact on the environment,” Hodgekins recalled. “Furthermore, we wanted a more reliable cleaning process that would require less re-cleaning and improve our efficiency and quality.”
For selecting the appropriate cleaning solution, Superior Products evaluated available cleaning procedures — from aqueous methods to solvent-based techniques — and talked to several cleaning machine manufacturers. Based on cleaning tests conducted at Dürr Ecoclean’s facility in Wixom, Mich., the company decided on the Universal 81C. This is a single chamber, solvent-based, closed-loop cleaning system that uses no-chlorinated hydrocarbons. The fact that it operates completely under vacuum negates the need for additional explosion protection when using combustible solvents such as isoparaffinic hydrocarbons. Additionally, the machine offers multiple monitoring of safety-relevant temperatures and pressures.
“With this closed-loop system we have achieved excellent cleaning results, we don’t need water for cleaning, and we have no wastewater management issues,” Hodgekins said. The old system, he noted, required two operators for eight hours a day to clean parts. Due to the fully automatic cleaning process with the Universal 81C, the manual labor for cleaning has dropped to one hour per day. “We save the equivalent of 15 hours’ work each day.”
A user-friendly design feature of the Universal 81C is the machine’s ability to store eight freely programmable and selectable cleaning programs in its controller. The parameters include rotating and swiveling movements in the work chamber during cleaning and drying, temperature settings, ultrasonic characteristics, and IFW settings. In this way, the cleaning treatment can be customized to every part batch.
“We are currently using three programs, and we are very satisfied with the cleaning results,” Hodgekins stated. “There are no parts that need to be re-cleaned, and the cleaned parts surfaces show a rest-level of organic materials of only 5 to 6 mg/sq.ft. Compared with our old system’s results, contamination has dropped by two thirds. This gives us very good peace of mind knowing that the machine is cleaning well above the standard.”
Another plus: the vacuum drying technique ensures that even parts with a complex geometry – e.g., bores, blind holes and undercuts – emerge from the process fully dried. The fully automatic vacuum distillation unit as well as full-flow and bypass filtration, which come as standard, remove oil and grease, chips, and swarf from the solvent on a continuous basis. As a result of these features, the cleaning fluid has a long life span.
The batches get transported into the machine’s cleaning chamber by an automatic conveyor feeding system, which is equipped with a proximity sensor that identifies the parts and chooses the appropriate cleaning program automatically. Depending on the program, the cleaning cycle takes between 8.5 and 9 minutes to complete.
“Not only can we put anybody on the cleaning machine and they will do a good job, but the proximity sensor also saves a lot of manual labor,” Hodgekins stated. And that translates into something that’s priceless for the general manager: peace of mind.