6 min read · Power Clean applications team
Everyone already knows aqueous cleaning. It is what happens in a washing machine, in a dishwasher, in the sink: water, plus a detergent or soap, plus scrubbing action, usually with heat. Industrial cleaning is the same thing with far more sophistication and much tighter control, because the result has to be consistent on every component of every shift.
Four elements do the work: the cleaning agent, water, heat and agitation. Change any one and the result changes — which is what makes aqueous cleaning controllable in a way solvent dipping never was.
Choosing chemistry and equipment
Chemical selection follows the soil: the product has to dissolve, emulsify or lift what is actually on the part. Equipment selection follows the substrate and the amount of soil. Modern aqueous chemistry exists for both ferrous and non-ferrous metals at high efficiency and repeatability, and whether you need a single-stage or a multi-stage system depends on soil type and load, the equipment, the substrate, and how much heat and agitation you can apply.
Aqueous cleaning agents are more complex than they look. They combine surfactants (surface-active agents), coupling agents, building agents and sequestering agents, among others. Between them they remove lube oil, water-soluble oil, silicone and petroleum greases, dust, fingerprints and loose burr.
Three ways to apply mechanical energy
- Immersion — the simplest and most economical. Parts are submerged and the bath is circulated; turbulation during the wash cycle dramatically increases efficiency. Best for large parts with light soil and hidden surfaces a spray jet can never reach.
- Spray and hi-jet — very effective where contamination is heavy. Exposed soils are removed quickly by jet impingement, drastically reducing cleaning time.
- Ultrasonic — best for small, intricate components with profiles, bores and crevices, because cavitation reaches everywhere the liquid reaches. Immersion and spray are often combined with ultrasonic for precision cleaning at high throughput on a short cycle.
TACT — and why precision work adds a W
Aqueous cleaning delivers a better result when four variables are balanced. Greater agitation means more cleaning in less time. Time is often the simplest and cheapest adjustment. The right chemical concentration depends on the soil, the agitation and the equipment. And a higher temperature reduces soil viscosity and makes the chemistry more aggressive. Together these are TACT: Time, Agitation, Chemical, Temperature.
Wash, rinse, dry — and keeping the bath alive
A typical system is three stages: wash, rinse, dry. The wash removes the soil, the rinse removes the cleaning agent, and drying removes the water. Rinsing can sometimes be skipped where a slight residue is of no consequence to the next operation — but it is the exception, not the rule.
Bath life depends on contaminants, oil skimming, filtration, topping up to hold concentration, and keeping the equipment and temperature under control. Removing oil and grease by skimming, and heavy particulate by filtering, extends life enormously — an oil skimmer plus a filtration system makes soil removal automatic.
Foam can rise from contaminants, spray pressure or water quality, and is controlled with a defoamer. Corrosion is handled by drying thoroughly after wash and rinse, by the rust inhibitors already built into the chemistry, and where longer protection is needed, by a rust preventive or vapour corrosion inhibitor.
Aqueous cleaning meets the toughest cleanliness requirements in manufacturing today and is the preferred way to move away from toxic solvents — precision, all-round safety and savings in the same process.
