Aqueous Cleaning--An Environmental Solution

Aqueous cleaning methods have been used for many years to successfully clean a variety of materials. However, as technology advanced, we believed there were cleaning alternatives that were more effective than the simple aqueous process.

Columns From: 10/1/1997 Modern Machine Shop

Aqueous cleaning methods have been used for many years to successfully clean a variety of materials. However, as technology advanced, we believed there were cleaning alternatives that were more effective than the simple aqueous process. Manufacturers began using new chemical solvents in order to clean better and faster. As time passed, we found these solvents were doing harm to our environment, especially the earth's ozone layer. Before long, many of the chemical solvents that were so effective in our cleaning processes were heavily regulated or even banned. One such widely used solvent, trichloroethane 1,1,1 (also called TCA), has not yet been banned from use, but has been banned from manufacture.

To learn more about the effectiveness of aqueous cleaning, I recently met a recognized expert in the field, Carole LeBlanc, of the Toxics Use Reduction Institute (TURI) at the University of Massachusetts. Ms. LeBlanc has worked with many companies on cleaning alternatives for their applications. Her studies on aqueous systems have shown the following:

  • Aqueous systems can clean parts better than other systems in nine out of ten cases; however, they do expend more energy during the cleaning process. The energy use is generally greatest in the drying phase of the process.
  • There are four key factors in aqueous cleaning: time, agitation, concentration, and temperature. These factors are closely interrelated such that if one is changed, the others will be affected. You must closely monitor and control these factors.
  • Of the four key aqueous cleaning factors, temperature may be the most critical. Tests have found that a 10°F increase in temperature can lead to a two-fold increase in cleaning efficiency.
  • Once the cleaning is accomplished, the drying process becomes important. The drying cycle can make or break the overall process. Unfortunately, the drying process continues to be quite slow.

One problem that all companies face with respect to their cleaning processes is the question "How clean is clean?" Ms. LeBlanc states that, to date, there is no universally accepted technique for determining surface cleanliness. Cleanliness continues to be a subjective measure, making cleaning quality a difficult objective for any cleaning system.

Weiss-Aug Company, Inc., a manufacturer in East Hanover, New Jersey, recently changed from solvent-based cleaning to an aqueous system. Having coordinated the change-over, William "Kip" Cleverly, Weiss-Aug's environmental engineer, developed a model to help companies select the right cleaning alternative. Key components of the model include:

  • Forming a team consisting of representatives of areas affected by a change in cleaning technology and practices.
  • Educating the team on regulations affecting cleaning technologies.
  • Determining your cleaning requirements. Many make the mistake of not thinking through what they have to clean:

1.Parts that need to be cleaned: Do all parts have to be cleaned? How large are they? Do the parts have blind holes?

2.The location of the system: Can the system be located in one central area, or should it be mobile? Will it have to fit into the space of the existing system?

3.Cleaning speed required: Is it necessary to keep up with a manufacturing line? What daily output is required?

4.Materials to be cleaned: What lubricants need to be cleaned and from what types of materials?

5.Maintenance requirements for the system: What special service requirements are needed to keep the equipment in operation?

6.Ease of operation: What special skills are required of a system operator?

  • Identification of and analysis of cleaning alternatives to satisfy your cleaning requirements. Sources for obtaining this information include vendors, other manufacturers, state and federal agencies, and the Internet. Advantages and disadvantages of each alternative should be evaluated.
  • Pick an alternative and conduct a pilot.
  • Analyze the results of the pilot.
  • Implementation: Buy the appropriate system for installation in the plant.

Aqueous cleaning systems offer more than just environmentally friendly solutions to your cleaning needs. These systems also have reduced overall costs for many companies. Next month, I'll discuss cost savings that companies have realized by implementing aqueous cleaning.

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