Bearing Manufacture

A leading manufacturer of precision bearings for military and NASA applications had an unacceptable failure rate of parts due to contamination of process baths, fixturing, and equipment. BFK Solutions evaluated the total process flow and determined that much of the contamination was due to having both oil-based and water-based lubricants at various stages of manufacture. The combination of lubricants and other contaminants formed a complex, adherent mixture which was difficult to remove. Suggested modifications included changing process fluids and process flow. The modifications also greatly extend the lifetime of the cleaning solutions.

One problem was that the selected lubricant had changed, but the associated cleaning steps remained the same. Notably, the major, automated cleaning system contained a solvent step followed by several aqueous steps. The solvent had been added for historical reasons, to remove a metal working fluid which was no longer used. Continued use of solvent resulted in undesirable emulsions and precipitate. This resulted in inefficient cleaning and shortened bath life. The solvent cleaning step was eliminated. In addition, recontamination of parts at a critical point in the process was corrected by preventive maintenance and a slight variation in process flow.

Repair, Refurbishing, Precision Pumps; Conversion from Solvent to Aqueous Processes

Western Hydrostatics, Riverside, CA, is a growing company that rebuilds pumps for high-end, engineering applications. Because the company is in Southern California, project goals included elimination of cleaning with mineral spirits or any other solvent which is considered a VOC (volatile organic compound). In addition, management wanted to optimize the de-painting and rust removal process, and find efficient, cost effective methods to remove heavy machining oils, assorted dirt, and heavy lapping compound.

Depainting, general cleaning, and precision cleaning of a variety of metal parts were evaluated. This project involved site visits to similar applications to compare equipment performance as well as in-house evaluation. In addition, the heavy lapping compound was successfully replaced with one that could readily be removed with water-based cleaning agents. While there was initial concern on the part of employees about process changes, choosing effective products and involving the employees resulted in eventual enthusiastic acceptance.

Consulting for this ambitious, extensive solvent substitution project, particularly with a relatively small company, required coordination with upper management, supervisors, and assemblers. A combination of non-solvent and aqueous cleaning processes have been successfully adopted at Western Hydrostatics. These include steel-shot impingement, aqueous cleaning, and steam cleaning.

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Assembly and Repair: Refrigeration Equipment

The company produces some 90% of the airline galley refrigeration equipment in use world-wide; and they set processes for field repair by airline technicians world-wide. The goals of the project included implementing reliable, cost-effective cleaning processes, replacing chemicals which with cumbersome regulatory restrictions, expanding aqueous and non-solvent cleaning wherever feasible, and standardizing processes for in-house cleaning and field repair.

Process replacement involved a combination of cleaning tools. After in-house evaluations of a number of products, aqueous cleaning was standardized and expanded. Steam cleaning was adopted for some final-cleaning applications. In some instances, aqueous cleaning is not feasible. For example, in cleaning a sixty-foot long coil to be exposed to refrigerant, any residue of water could produce catastrophic system failure. For such applications, solvent cleaning was adopted. Solvents were evaluated in terms of performance, cost, safety and environmental considerations and reliability. Initially, a brominated solvent was selected; and the existing degreaser was retrofitted. Commercially available flushing equipment was determined to be unsuitable. To meet the needs of in-house build and field repair, a compact tube flushing station was developed. In addition, BFK Solutions provided appropriate instructional seminars to in-house personnel and to appropriate personnel from commercial airlines.

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Metal Stamping, Job Shop

A metal stamping facility was removing oils from a variety of stamped metal products. Because the facility is a job-shop, the product volume and mix varies markedly and unpredictably. There is a wide assortment of metals; some of the products are very delicate and readily damaged during process. Parts were cleaned in large, open top vapor degreasers. Because of customer constraints, the company was using HCFC’s; one was very costly, the other would soon fall under a usage ban. Solvent loss was unacceptably high. The company had expended extensive time and financial resources in an unproductive attempt to introduce aqueous cleaning.

After reviewing the options, it was determined that the process would be most effectively and responsibly performed using a chlorinated solvent in an enclosed solvent system. Available systems were investigated in terms of cost, performance, reliability, throughput, and customer satisfaction. Solvents with effective stabilization packages, suitable for long-term use, were recommended. The project involved a review of national and local regulatory requirements as well as interaction with the local regulatory agency.

A large, airtight system with materials handling capability was chosen along with a semi-contained back-up system. The larger airtight system has resulted in over a 60-fold decrease in solvent emissions.

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