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8/1/1997 | 15 MINUTE READ

Replacing a Solvent Degreaser

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Environmentally safe, aqueous cleaning system saves Anchor Lakewood's finishing department...


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In 1993, the Anchor Corporation's Lakewood Metals Division faced a critical make or buy decision. We either had to find an environmentally acceptable and financially viable method of cleaning the metal shells we manufacture, or close our finishing department and contract for the anodizing work. At the time, a number of environmental and business factors weighted the decision heavily in favor of the "contract out" option.

However, with support from the State of Connecticut and technical advice from chemical and machine suppliers, Lakewood searched for a suitable cleaning technology. Ironically, after a year of evaluating equipment from all over the country, Lakewood contracted with Jensen Fabricating Engineers in nearby Berlin, Connecticut, for a custom-designed, aqueous cleaning system. The company delivered the system in September, 1995, and it has been running in limited production since November, 1995. The system was placed in full production in June, 1996.

Environmental compliance was Lakewood's prime motivation for purchasing the new system. Now, however, an additional benefit is emerging as lower finishing costs. The chemistry for the JenFab system is one-tenth the cost of degreaser solvent. As a result, we are now bringing back inhouse part of the finishing work that was sent out for anodizing. That bodes well for Lakewood's finishing department and the 55 people who work there.

Although the aqueous cleaning system is by far Lakewood's largest environmental investment, it is by no means the only positive action we have taken. We use only natural animal oils, rather than petroleum-based oils, in our eyelet drawing operation. We have converted from solvent-borne to waterborne lacquer in our finishing operation, and we were also using safer cleaning solutions in our dip-and-clean operation for oil removal.

Located in Waterbury, Connecticut, the Lakewood Metals Division of Anchor Advanced Products, Inc., manufactures aluminum and brass cosmetic packaging products. Our major product is shells for lipstick tubes and bottle caps used on cologne and perfume containers. Anchor markets these components to the cosmetic industry worldwide.

Product appearance is understandably a major concern for the cosmetic industry. Our customers demand a high-luster finish that is free from visible internal or external surface defects. We buff these components to obtain the requisite high luster, then apply a coat of clear lacquer as the final step in the finishing process. Between the buffing and lacquering, the shells must be cleaned of residual buffing compound and lesser amounts of oil and lint. Then they are thoroughly rinsed and spot-free dried. Water marks are, of course, unacceptable.

Prior to installing the system, Lakewood cleaned its metal shells in a vapor degreaser using 1,1,1-trichloroethane. During this entire period we were able to retain our low VOC (volatile organic compounds) classification. In 1993, we were advised by our solvent supplier that 1,1,1-trichloroethane had been tagged as an ozonedepleting com-pound and would be unavailable after January 1, 1996. In the interim, Lakewood would pay a hefty excise tax to use this solvent.

We were further advised that we could convert our degreaser to the 1,1,3- trichloroethane compound, which had been declassified as a carcinogen. This option required expensive stack afterburner and scrubber modifications, and was dismissed as not being effective in terms of either cost or environmental considerations. A conversion to 1,1,3- would also have terminated the division's low VOC classification.

At the time, it appeared that our best option might be closing the finishing operation and sending all the shells to anodizing vendors. Out of consideration for the community and our work force, we set aside that option while we considered alternatives.

Our evaluations included ultrasonic and aqueous systems. With ultrasonics, however, sufficient capacity combined with precise control are major issues. Lakewood deals with aluminum shells and caps as thin as 0.012 inch, which does not leave much margin for error in material removal. Ultrasonics can pit and etch the shells and even eat through aluminum quickly. Although ultrasonic systems with precision control features are available, they do not have the capacity to meet our production volume.

Some of Lakewood's competitors were using the aqueous cleaning systems. One of our anodizing vendors was using two systems, but only to remove oil. At the time, we were unable to locate a watersoluble chemistry that could remove buffing compound in one pass through the machine and then rinse clean without filming, marring or scratching the finish.

Bob Lavorgna of Matchless Metal Polishing Co., which at the time supplied Lakewood's buffing compound, set to work on the cleaning problem with Lakewood engineer Fred Cox and general manager Steve Hopkins. Mr. Lavorgna thought his company could develop the needed chemistry, but not before clearing some hurdles. "The chemical has to get rid of buffing compound quickly," he said, "but the parts have to look as brilliant coming out as they did going in. We were confident we could do it, but we also needed to find an aqueous system that could use our new chemistry."

During a 14-month period, Matchless performed development work and evaluations on several new cleaning formulations. Meanwhile, the search for the right aqueous system ensued. The first chemistry developed left some spots on the shells. Matchless went back to the laboratory for more refinement and eventually a satisfactory compound emerged.

Traded under the name Buff Clean 14L, the cleaner is a mildly alkaline, liquid, non-etch, soak cleaner. While the details of its chemical composition are proprietary to Matchless, 14L contains no phosphates or chelates, distillates or solvents. Buff Clean 14L is not, in itself, hazardous, which makes wash water disposal easier and safer.

Chemistry and second-tier ultrasonics were considered the optimum approach to Lakewood's metalcleaning requirements. Ultrasonics would lessen the required chemical concentration and thus simplify rinsing. The challenge was to design a cleaning system that could use Buff Clean 14L in combination with precisely controlled ultrasonics to clean buffed aluminum and brass without damage. When the cleaning system requirements were determined, the machinery search focused on finding a manufacturer who could design and package the total aqueous cleaning system Lakewood needed.

About this time, Jensen Fabricating Engineers became part of the Lakewood team. Jensen's sales manager Ed Tulinski and project engineer Charles D'Agostino, along with Lakewood's management, engineering and production people, hammered out the details of a system that best addressed our needs.

The Lakewood aqueous cleaning system removes buffing compound, without impacting the finish. The system presented new challenges to both Lakewood and the cleaning system manufacturer. However, the company never had direct experience in removing polishing and buffing compound from small aluminum and brass parts in high volume.

In addition to meeting the technical prerequisites and environmental considerations, the proposed system had to be ergonomically sound and allow operation by one person. Another essential for the cleaning system manufacturer was the ability to provide local support for the machine process. "They really bought into the project" said Lakewood production manager Phil Limbacher.

Between design and production, many alterations were made in equipment, procedures and chemistry. Alterations have been accepted as a necessary part of the methodology that would lead to an aqueous system that best matched Lakewood's total cleaning, rinsing and drying criteria.

Lakewood's production manager Phil Limbacher commented, "At first, the aqueous system was a mystery to us. If it was not cleaning right, we had no idea why. We would call the project and design engineer, and he would either talk us through it or come down to check it out himself. We called the design engineer so often, he eventually established a `hot' line so that we could get through to him fast."

System Description. Lakewood's aqueous cleaning system is a five-tank, sixstation, automatic, vertical agitation wash/rinse/dry system. It was designed to process one carrier, holding four racks of parts, every two minutes. The load elevator places racks into the pusher transfer mechanism, which moves the racks between tanks and to the recirculating hot-air dryer. An exhaust system vents all of the tanks through stainless steel hoods linked to a common header.

The Racks. Although adequate in the vapor degreasing operation, Lakewood's shellholding racks have not worked nearly as well in the aqueous system. Early in system operation, about 25 pct of the shells were falling off the racks during the cleaning cycle.

The racks work well in the degreaser because equal-pressure vapor jets are applied horizontally. The aqueous system provides vertical agitation for mechanical interaction between the parts and chemistry that sometime cause smaller-diameter shells to fall off the pin racks. After months of trying to modify the degreaser racks to work in the aqueous system, Lakewood Metals decided to purchase new racks.

"We were losing some of the shells to the aqueous system's vertical motion. It is a particular problem when we run small shells," said Mr. Johnson. "The racks have an effect on both cleanliness and yield. We have tried pinmount racks and spring-loaded racks. Our latest designs combine the best features of both."

Beyond shell retention, there are also process yield and flexibility issues. One operator has to be able to load and unload parts rapidly. "We do not want to end up with too many different kinds of racks in the system," said Mr. Limbacher. "Ideally, we'd like one, but we'll probably end up with two or three for different part sizes and shapes."

Wash Cycles. The two wash tanks are linked to a single agitation drive mechanism and are equipped for water filtering, oil coalescing, fluid level controls and water makeup from the rinse tanks. Both are equipped for rapid fill from the filtered rinse water source, or from an RO main water header. The water from tank one and two is filtered to remove particulate matter and then returned with proper chemistry. Makeup water for tanks one and two comes from the first rinse tank, tank three, through the filtration system. The design incorporates a sparger head above tank one to remove floating dirt and oils from the surface of the water.

The system design called for wash tank temperatures between 160 and 180F. Tank water heating is provided by low-pressure steam supplied through a self-operating Process Technology controller. Lakewood currently uses from 4.5 to 5.0 pct Buff Clean 14Ltowater in solution in tank number one. This tank soaks and breaks loose heavy particles. Agitation along with chemical cleaning eliminates 95 pct of the buffing compound, soil and lint on the polished metal shells.

Tank number two removes the final bit of soil. It is equipped with two 1,500 watt variable output, ultrasonic transducers and framemounted generators connected directly to a programmable logic controller. Total ultrasonic output is only 3,000 watts. The transducers are sidewall bulk-head-mounted. They are located near the top and bottom of the tank so that the components pass through the ultrasonic field as they are agitated up and down. The positions of the transducers are adjustable, which permits fine tuning their location.

These ultrasonics reduce the concentration of the chemical solution required in the second wash tank to between 0.05 and one pct. The low chemical concentration factor in tank two has two significant advantages: less contamination in the rinse tanks downstream; and generates a 90 pct savings in chemical costs.

Rinse Cycles. Rinse tanks three, four and five also are equipped for heat and water filtration. Rinse tank temperature at the outset was 80F. However, fine tuning the process and the 14L compound made increases in rinse water temperatures necessary. After some experimentation, Phil Limbacher and area foreman Bob Sedlak determined that optimum, rinse tank temperature as 130F in tank three, 120F in tank four and 110F in tank five.

The design reduces water use to two-to-three gpm or less, and eliminates the discharge of thousands of gallons of water each day. The overflow rinse water is regenerated to RO quality. Except for tank one, which must be discharged when the chemistry is exhausted, the system is closed-loop through filtration.

Water Source. Lakewood replaced the original DI system with a megohmetric reverse osmosis system. RO provides effective filtration through membranes. Particles as small as 0.001 inch are removed from rinse water. However, these filtration membranes are heat sensitive and can be damaged by higher temperature rinse water. To reduce the water temperature after the change in rinse water temperature, a chiller system was installed. The chiller system lowers the temperature of the flow-back-to-filter rinse water to the 100F range, with which the RO system is designed to work.

Ultrafiltration. An ongoing project at Lakewood is the development of an ultrafiltration system for tank one that will filter out the dirt and allow the reuse of the water and cleaning chemistry from even this tank. Such filtration will prolong the useful life of the washing solution in tank one from approximately one week to longer intervals and considerably reduce tank one discharge.

Automatic Parts Movement. Shells are mounted on racks, and racks are placed in carriers. An automatic, indexing-type carrier feed conveyor is designed to store and move several carriers up to the machine load elevator, one at a time. When the machine indexes, the conveyor is designed to electrically interlock for cycling and safety purposes.

A pneumatically driven load elevator raises the carrier to load height, then a pusher transfer mechanism introduces the carrier to the first process tank. The load elevator interlocks with the pusher to ensure positioning only when the pusher is in the proper stage. The pusher transfer mechanism also advances carriers from station to station, tank to tank and introduces carriers to the dryer. It consists of tubular, structural steel frames, on which individual stainless steel pusher bars are mounted.

During the load cycle, other carriers are processed through various tanks. At the completion of all process cycles for each tank, the individual tank platforms rise to the top position to permit automatic carrier transfer. All carriers are then conveyed to the next tank station. The platform then becomes the agitation mechanism as carriers are lowered into the tanks.

After tank five, or the third rinse cycle, the pusher delivers the carriers to a powered roller conveyor where they pass through six high-pressure blow-off headers that remove any puddled surface water. A self-contained blower with intake filtered air generates this high-pressure air knife.

From the air-knife station, carriers enter the electric drying station on the same powered roller conveyor transport system. Carriers are in the dryer for approximately 12-15 minutes. Only two pct of the air or less is discharged from the system for elimination of moisture. The air in the dryer is continually recirculated. The return air is re-heated to return it to operating temperature. This feature minimizes utility use over a conventional hot air dryer by as much as 80 pct.

A recirculating hot air system provides up to 250F drying heat. The system at Lakewood effectively dries shells between 150 and 180 degrees, depending on shell material. The dryer and heat ducts are constructed of 14 gauge, 304 stainless steel, insulated with two inches of fiberglass and covered on the outside by a stainless steel jacket. The recirculating dryer design heats only on-demand and does not require a continuously firing heat source.

Cleaning Action. Variable vertical agitation, speed and length of stroke for the stainless-steel agitating work platforms are controlled by means of PLC flow-through control valves and limit switches. Tanks one and two share one agitating mechanism; tanks three, four and five share a second.

Productivity. Presently, Lakewood is processing about 175,000 shells through the cleaner per shift. The design capacity of the system is about 400,000 shells at 100 pct efficiency, based on a 90-second cycle time. Currently, the optimal cycle time for satisfactory cleaning transfer and drying runs between one and two minutes. Productivity in the finishing operation is affected by factors other than cleaning. The major limiting factor is shell size. While 244 smaller shells fit on the racks now, larger shells fit only on every other pin. This limitation diminishes what can be accomplished in a shift. A maximum of 976 parts is cleaned every two minutes or less on one carrier.

The introduction of the aqueous cleaning system at Lakewood has seen some growing pains. There is no "Good Fairy" of aqueous cleaning. We initially had a problem with the drying system when operations began. Parts would tarnish above 180F drying temperature. That was solved when more came in and increased the airflow by adding more horsepower to the system, thus increasing the dryer cfm, and allowing us to dry in less time at lower temperature.

"There is instability in any process" said Limbacher. "I've seen the vapor degreaser shut this plant down for days. Our ultimate goal with the aqueous system is 250,000 to 300,000 shells in a shift. We shut down the vapor degreaser for good on July 15, 1996."

Initially there was a problem with the timing system, which was run by a 24-hour clock. "That meant we could only adjust what happened within a 24-hour period. On the weekends, the heat for the system would go on whether anyone was here or not. A seven-day clock was installed to remedy that problem. That's what most of the problems have been, simple adjustments," said Mr. Limbacher.

On the plus side, the parameters required to run the aqueous system are easier to maintain than the parameters required to run the vapor degreaser. This advantage is directly attributable to the Jensen-installed electronics. This state-of-the art process logic system, with digital readouts, controls specific process parameters. The controls are linked to a computer system that actually stores and manages all process parameters and variations. It will shut down the system if the process begins to run outside of parameters. The system also has a CRT that gives diagnostic messages and warnings. "We never had much control over the degreaser. If the vapor degreaser malfunctions, the result was scrap, unless someone watched it closely," said Mr. Limbacher.

Despite shakedown complications and learning curve delays, the aqueous cleaning system has become a prime asset in Lakewood's finishing operation. If we incurred an additional expense, they shared it with us. The system works, and works with water rather than CFCs or VOCs. The fact that it improves productivity even beyond the chemistry replacement is a bonus. In October, 1996 Anchor Advanced Products awarded the company a corporate appreciation award for outstanding service.