Reach for the TOP

Article From: Products Finishing, , from Diversey Corp., DuBois Division

Posted on: 1/1/1996

A perspective on effective pretreatment... 

Performance standards for product finishers are getting tougher and tougher. The drive for higher quality has forced many companies to review their approach to pretreatment. During this period of self-reflection, several fundamental issues have been revealed. One such issue is Total Operational Performance (TOP).

TOP is the integration and control of all process-related variables to maximize pretreatment results. Broadening the scope of review and control enables one to sustain higher levels of pretreatment performance. This broadened scope includes, but is not limited to, such non-traditional areas as soil management, parts-handling procedures and air blow quality. The following illustrates the concept and benefits of TOP.

The initial step in pretreatment is to successfully identify all key operating variables. Often, this involves a detailed review of the system coupled with the monitoring and control of parameters such as pressures, pH, concentrations and temperatures. TOP begins where these leave off, broadening one's perspective and helping improve overall efficiency.

While it is critical to identify, isolate and ultimately control the aforementioned variables, it is essential to go beyond this cursory review. A survey of companies indicated that only 20 pct of those polled go beyond this level of performance control.

The first step in reaching TOP is to assume a proactive role and conduct a detailed review of all variables involved in the pretreatment process. From the soils introduced as parts are processed, to paint application methods, each variable must be identified, isolated and eventually controlled. The logical place to begin this exercise is the interrelationship of soils and substrates.

Soil Management. There are many types of soils. A soil is any contaminant placed on the part as it is processed. There are also many cleaners. The only way to maximize your performance is to select the cleaner chemistry that best suits the soils.

While this is generally the goal for chemical selection, all too often a detailed review of soils is not conducted. For example, you may know that you are attempting to remove cutting fluids in your pretreatment process. A more detailed look might provide insight as to whether you are attempting to clean a straight oil, water-soluble oil, synthetic or semi-synthetic fluid. This information is important because each soil presents a different cleaning challenge. For instance, you may choose to use a complex phosphate cleaner for a mineral-oil-type soil versus a heavy caustic formulation.

The soils and chemicals selected must be viewed in relation to the substrate. Selecting a heavy-duty alkaline cleaner for processing nonferrous substrates could be disastrous unless adequately inhibited. By working cooperatively with your chemical supplier you can maximize your cleaner selection based on the soil/substrate criteria.

Soil management allows you to effectively select cleaner chemistries based on the type of soils encountered. Though this seems logical, soil management is perhaps one of the most neglected facets of effective pretreatment. It is all too common that one assumes, regardless of the soils, the traditional pretreatment process is hearty enough to remove varying soils. While this may be successful, it is more efficient to control what enters the process.

A Midwest manufacturer of consumer goods relied on its traditional five-stage pretreatment system to adequately prepare parts prior to painting. Things were working smoothly until one day the parts were no longer getting cleaned. The chemicals were checked, as was the entire washer setup. Nothing in the system was out of specification. To eliminate the new cleaning problem, extensive time was spent attempting to resolve the problem chemically.

After thorough review, the company determined the culprit was a change in the soils. A new stamping fluid was being tested that was different in nature than the previous soils. If this issue had been communicated beforehand and pretested for ease of cleaning, the cleaning problem could have been avoided. Effective soil management could have saved both time and money.

The fundamentals of soil management are simple. Simply stated, you need to know what types of soils are on the substrates and how to remove them.

  1. Work with suppliers to identify, document and communicate soil types and changes.
  2. Work with your chemical supplier to ensure that the soils can be easily cleaned with the selected chemistry. The place for testing for soil removal is the laboratory, not your plant.
  3. Work with the supplier of the various soils to ensure you have the right product for the application. Where possible, seek to reduce and/or consolidate the soils.
  4. Ensure any and all changes to incoming soils are effectively communicated and controlled.
  5. Develop a history for fluctuations in soil loading characteristics.

Through effective soil management and continuing through effective parameter control, you begin building a solid pretreatment system. It is not enough to rely on your spray wash system to deliver the quality you desire. Quality can only come through complete review and control of all the upstream and downstream processes that lead to your traditional pretreatment system.

The implementation of TOP also includes enhancements to your traditional pretreatment system components. The traditional view of the pretreatment system consists of those items both chemical and mechanical that are used to prepare parts prior to painting.

Water quality. If one seeks to enhance the performance within the confines of the traditional pretreatment system, one must begin with water quality. The rinse water quality is extremely important for enhanced pretreatment performance. Consult your chemical supplier about your water quality and its impact on your pretreatment system.

Cleaning chemicals. The next area of consideration should be the selection, use and control of the chemistries chosen. The premise behind TOP is a complete integration of products and processes. The results generated from any pretreatment system are only going to be as good as the system itself. Therefore, to maximize the performance of the traditional system one must harness the synergy between the chemicals and mechanics. This approach is vital to long term success. Three basic steps to effective systems management include:

  1. Determine the goal of the process. Qualify and quantify results.
  2. Identify and document relationships between key operating parameters.
  3. Minimize variation in key operating parameters.

If these steps are followed, one can expect to achieve improved results consistently.

Total Operational Performance offers a new perspective on effective pretreatment. If your goal is to continually improve your pretreatment process, you must identify, isolate and ultimately control all the process related variables. The days of concentrating solely on the phosphating system are over. Improved performance begins by reviewing the raw stock as it enters the plant and does not end until final shipment. TOP is the bridge that links these seemingly unlimited variables together and is a proven perspective for consistently achieving your desired pretreatment results. As you evaluate your pretreatment system do not be afraid to reach for the TOP _ Total Operational Performance.

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