That's a really difficult question. It's hard to quantify operating costs because everybody's machine is different, everybody's parts are different, their contamination is different and their cleaning specification is different.

But given that caveat, there are a few general guidelines which may be helpful. To begin, tabulate all of your operating costs. The list below offers a few suggestions on costs to include in your tabulation.

Companies all over the world need to clean their precision metal stampings -- like the ones shown here. They often use vapor degreasers for this chore because vapor cleaning is the fastest, safest and least expensive option, when measured on a "per-part-cleaned" basis. In fact, the best way to compare the cost-effectiveness of different cleaning systems is to calculate the "total cost per part cleaned."

Labor: Operator, Cost Per Hour (fully-loaded labor rate) Labor: Inspection & Recleaning, Cost Per Hour, fully-loaded Labor: System Maintenance, Cost Per Hour, fully-loaded Electricity Consumables (Filters, etc.) Solvent Losses (Drag-Out) Solvent Disposal

Once you have determined all of your costs, divide those total costs by the quantity of pieces you produced. This "calibrates" your costs into an index which is based on a standard unit of production. This allows you to compare apple-to-apples when evaluating your cleaning choices.

The most typical cleaning cost index is the "total cost per part cleaned." Other variations on this theme might be "total cleaning costs per hour" if your people and costs can be tabulated on an hourly basis. Perhaps the "total cost per batch" works best for your firm. One customer even used "total cleaning cost per kilo" because the best measure for their tiny parts was by weight.

Notice that the cost of the solvent is not a major issue is the cost analysis. In fact, the only time the actual price of the solvent enters the issue is when evaluating solvent losses. For example, DuPont reports that a small, modern vapor degreaser normally loses about 0.118 lbs. of solvent per square foot of vapor area per hour of operation, or roughly one pound per day. Solvent losses can be minimized by the use of good operational practices.

One part of the solvent losses are caused by a phonomenon called drag-out. Drag-out is the solvent lost as the parts are removed from the cleaning system; Figure 53.2 and 53.3 highlight the drag-out issue. As the photos show, drag-out is extremely sensitive to operator training, good cleaning procedures and a couple of useful machine features. A good vendor should be able to document incremental operating costs and drag-out losses on a feature-by-feature basis. Furthermore, they should be able to highlight specific environments (e.g., types of contamination, cycle times) which can reduce solvent losses.

Labor and maintenance are additional operating costs. In general, vapor degreasers have very low labor costs and the maintenance should be equally limited. If these numbers seem high, double-check your processes or contact your equipment manufacturer for suggestions.

Micro Care has a spreadsheet which offers some guidelines for estimating the cleaning costs of running a vapor degreaser with Vertrel^®. Email us at TechSupport@microcare.com   for a copy of the spreadsheet.

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