Sometimes -- but not always. For example, aqueous cleaning systems need to be very large to accomplish the cleaning and drying processes. The equipment is much more expensive, consumes more energy, takes up more floor space, and takes longer to process parts than the typical Vertrel^® cleaning system. So, when looking at the TOTAL COST PER PART CLEANED, the Vertrel^® system usually is less expensive to buy and operate.

Installation costs are a large part of aqueous systems. Up-front capital costs include the actual cost of the machine, freight, site preparation and set-up costs. Most engineers also include building renovations, ventilation enhancements, electrical upgrades and water-treatment subsystems required to support the new system. These expenses can be as costly as the cleaning machine itself, so be sure to include your facilities manager, your health and safety people, your environmental people and your fire safety team as well as the production people in developing these plans.

Engineers should include the cost of the funds that will be tied up in the machinery. With a spreadsheet, it's easy to use the "Payment" (PMT) financial function to estimate the cost-per-month of the equipment, which can easily be converted into a cost-per-part factor.

Another consideration is the actual cost of the space required by the cleaning machine and the support systems it requires. Many aqueous and semi-aqueous systems require more floor space than solvent-based systems. Aqueous systems require water-treatment facilities which can be as large as the cleaners themselves. Aqueous systems also have slower cycle times, so more space is needed for work-in-progress, supplies, conveyor systems and access aisles.

The floor space requirement usually is described as a multiple of the physical size of the machine. A general rule of thumb is to multiply the basic size of the cleaning machine by a "footprint factor" of 5X or more. For example, an aqueous cleaner with a 200 sq. ft. "footprint" on the factory floor can be expected to require 1,000 sq ft. of total floorspace (200 x 5 = 1000). For vapor systems, a 4X factor would be a reasonable rule-of-thumb.

To estimate floor space costs, call your financial people and ask them for the "fully-loaded per-foot costs" for the space in which you are interested. This usually will be expressed as a "triple-net" rent per square foot. Included this number should be the cost of the space itself, plus heating, cooling and lighting costs, and some portion of the cost of shared facilities, like aisles.

Total one-time costs should be "calibrated" to reflect the productivity of the machine. For example, if the machine is planned to clean 100 parts per year for ten years, it will clean a total of 1,000 parts in its economic lifespan. The total one-time costs should be divided by the throughput (in this case, 1,000 parts) to calculate the true "total one-time costs per part cleaned."

Water cleaning systems typically have higher operating costs than solvent systems. Include in this analysis should be the cost of the solvent, the cost of the electricity and the cost of consumables (e.g., saponifiers, filters, etc.) which are required by the system. Waste disposal costs must also be factored into the analysis.

In particular, aqueous systems use vast quantities of electricity. There are pumps to move the water around the machine. There are electricity-intensive heaters which raise the temperature of the water to the normal cleaning range, which is 50°C or more above the normal temperatures for solvent systems. Then there are big and noisy air knives which blast residual water off components. Finally, there is the electricity used to operate the waster water treatment system. Make no mistake about it: water may be environmentally safe, but all the coal burned to generate the electricity used in water cleaning makes it a definite loser.

A good vendor should be able to document incremental operating costs on a feature-by-feature basis. Furthermore, they should be able to highlight specific environments (e.g., types of contamination, cycle times) which optimize the usefulness of each feature.

Labor and maintenance is another operating cost. Aqueous systems are complex chemical processes. Typically they require the support of a process chemist or sophisticated technician to keep the system operating efficiently. Aqueous systems often require extensive rework. Close inspection of existing aqueous systems reveals they often require technicians to perform auxiliary inspections, hand-spraying, re-cleaning and drying the products outside of the cleaning machine. This is quite common with aqueous systems, but quite rare with vapor degreasers.

To price out labor costs, obtain the "fully-loaded labor rate" for the technicians who will operate and maintain the machine (this number typically will be at least 2-3 times the actual take home pay). Remember to include the value of the supervising engineer's time, who will be required to make sure the aqueous system remains within specs and the waste treatment systems are operating correctly. Also include the cost of training, the costs of the maintenance techs, and any chemical safety training. If turnover is a problem, add additional funds for quarterly supplemental training.

Labor: Operator, Cost Per Hour (fully-loaded labor rate) Labor: Inspection & Recleaning, Cost Per Hour Labor: System Maintenance, Cost Per Hour Labor: Analytical/Process Chemist, Cost Per Hour Analytical Tests of Discharge Waste, Lab Time, Lab Equipment Electricity Water Consumables (Filters, etc.) Solvent Losses (Drag-Out) Solvent Disposal

Operating costs should be "calibrated" to some type of throughput or performance requirement. Typically this index is the number of parts per day, week or month,

To compute a total cost per part cleaned, add the calibrated one-time costs to the calibrated operating costs. All things being equal, the least expensive choice should be optimal.

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