Direct operating costs. Electrical costs are a big issue for most cleaning systems. Typically, the total electrical costs of an aqueous system are five to ten times the costs of a vapour degreaser due to the need to heat the water, pump the water, spray the water and dry the water. Waste-water treatment systems are also very energy-hungry.
Water is cheap to buy but expensive to re-purify. Solvents and saponifiers can be expensive and are subject to drag-out. (Drag-out is wasted cleaning fluid that is trapped inside or around the parts as they are removed from the cleaning system.) Vendors should be able to estimate fluid consumption based on the sample parts provided to them.
Big machines have big maintenance problems, and large aqueous systems have the most complexities. Filters must be checked and replaced. Blowers, motors and conveyors must be maintained. Complex water-treatment and recycling processes must be monitored. Alkaline additives boost the cleaning power of many systems; these additives coat the machine’s interior and cause additional maintenance problems. All of these should be included in the system’s direct operating costs.
Labour costs should be carefully tabulated. Most of the labour is involved in loading and unloading the systems, which is pretty straightforward. Also look for time wasted by technicians in performing auxiliary inspections, such as hand-spraying, re-cleaning or hand-drying products outside the machine. In today’s world, manual intervention should be rare. If it is not, something is wrong. To measure hourly labour costs, many companies use fully-loaded labour rate for the technicians who will operate the system.
Indirect costs. Indirect labour can be difficult to measure. This might include the cost of a supervising engineer’s time, the cost of training, the hourly cost of maintenance technicians and the cost of any chemical safety training. If employee turnover is a problem, add additional funds for quarterly supplemental training.
There is an essential element to indirect labour that is often ignored: the complexities of managing water-based cleaning systems require many hours of well-trained, experienced technical experts. Their time is spent managing the water purification systems, the pH and additives of the water in the system, and the resulting waste-water treatment systems. The commitment in engineering required to operate a water system properly typically results in ongoing costs that far surpass those of vapour systems.
Another indirect cost is floor space, and sometimes a large one. Aqueous and semi-aqueous systems require more floor space than solvent-based systems and water-treatment facilities. These systems can be as big as the cleaners themselves. They also have slower cycle times, so more space is needed for storage, work-in-progress, supplies, conveyor systems and access aisles.
For example, I have seen an aqueous cleaning system that used 20 square metres of floor space in the factory. But the system actually consumed 140 square metres of floor space when work-in-progress and ancillary systems were included. That is a seven times floor-space factor (140 sq.m/20 sq.m). For comparable vapour systems, which are smaller with equivalent capacity, a 4x factor would be reasonable.
To estimate floor space costs, include the cost of the space itself, plus heating, cooling, lighting, and some portion of the cost of shared facilities like the lavatories. Assuming factory space in India rents for about 1000 rupee/sq.m/month, the cost of the large aqueous cleaner cited above would be approx. 136,600 rupees per month. If the system cleans 10,000 parts per month, that adds 13.6 rupees to the cost of each part cleaned.
Fixed acquisition and installation costs. The final costs to include are the fixed and acquisition costs.
Up-front capital costs should include the costs of the machine and sub-systems, freight, site preparation and setup, building renovations, ventilation enhancements, electrical upgrades and water-treatment subsystems required to support the new system. It is essential that all of the sub-systems are included in the cost analysis.
Savvy engineers also consider making extra investments in optional features that speed cleaning or reduce costs; trading up-front capital investment for lower operating costs. For example, aqueous systems have money-saving options such as air-knives and extra drying chambers that speed cleaning but increase electrical consumption.
Planners should include the cost of the funds that will be tied up in the investment. Use the payment financial function in a spreadsheet to estimate the cost-per-month of the equipment, which can easily be converted into a cost-per-part.
Once the total purchase and installation costs are determined, divide that cost by the total number of parts expected to be cleaned by the system over its operational life. For example, a large 10 million Indian rupees cleaning system might be expected to last 12 years and clean 10,000 boards/month. In that case, the cost-per-part-cleaned is about 6.94 rupees.
The winning score
As we have seen, there are many factors to tabulate when selecting a new cleaning system. A detailed spreadsheet is available for downloading (from the website ‘http://www.microcareprecisioncleaners.com/assets/documents/uploads/Degreaser_Costs_Compared.xls’) that could serve as a template for engineers planning this comparison. But, in general, use the following cleaning scoreboard to find the winning technology for your company:
1. Determine the likely cleaning requirements for today’s products as well as those of tomorrow. Average those requirements into an hourly rate of required throughput.
2. Compare different cleaning technologies. Send samples to the equipment makers to prove the ability of their systems to clean the components to your specifications.
3. From among the remaining candidate systems, collect comparative data on every important characteristic. Be sure to include up-front capital costs, plus the direct and indirect operational costs (supervisory and engineering labour costs, plus energy, water, solvent, labour and maintenance costs).
4. As the various costs are collected, divide them by the expected throughput of the system to calibrate them into a cost-per-part-cleaned index.
5. Sum all the data into a single performance index, the total cost-per-part-cleaned.
6. Select the system with the lowest total cost-per-part-cleaned.
Using standard statistical tools, engineers can model all the operating costs for systems of different types and sizes. If this process is completed accurately, thoroughly and impartially, the savvy engineer can be confident that the selected system will become a valued part of the production process for years to come.
The author is a vice president at MicroCare Corp.—a critical cleaning solutions provider. MicroCare’s products include water-based cleaners, a wide array of solvent, hydrocarbon and terpene cleaners, and innovative benchtop tools that help reduce cleaning costs