Depending on the soils being removed and the part materials being cleaned, most finishing operations choose to run either an alkaline or acid cleaning chemistry. At either end of the pH scale, traditional cleaning chemistries require neutralization and, often, special waste treatment permits to allow discharge to city sewers.
Striking a balance between the pH extremes are GX series neutral-pH cleaners from Galaxy Associates Inc. (Cincinnati, OH). According to the company, the products reduce surface tension and lift soils away from the surface being cleaned rather than attacking them. Galaxy says the cleaning chemistries not only outperform other neutral cleaners on the market, but also have out-cleaned heavy-duty acid and alkaline chemistries in some applications.
Besides improved cleaning, the materials also provide other operating advantages, according to Galaxy’s David Chalk. “These cleaners can operate at near-ambient temperature, but they perform best at 100–120°F,” Chalk says. “Even at that temperature range they can provide considerable energy savings compared with conventional cleaning chemistries.”
The materials allow cleaning and phosphating in three stages: clean, phosphate and rinse. According to Chalk, the neutral-pH cleaners can even replace iron phosphate in some limited applications. An example he cites is painted cans for oil filters used in heavy truck engines. The filters are changed frequently and so don’t require long-term corrosion protection, he says.
Solutions can be filtered to 0.025 μm without stripping out surfactants, Galaxy says. With pH of 7.4, they also simplify waste treatment and most municipalities allow discharge to sewer after filtration. Other benefits include a safer environment for operators, reduced dragout, and less washer maintenance. “The inside of the washer stays very clean and descaling is practically eliminated,” Chalk says.
Cleaners are available in four formulations—general-purpose GX Clean 5180, heavy-duty GX Clean 5185, GX Clean 5187 and GX Clean 5189. All provide rust protection for parts in process, although the 5187 chemistry provides added corrosion inhibition. The first three formulations are controlled conductimetrically, while GX Clean 5189 can be controlled by titration.
The cleaners work by lifting and sequestering soil, preventing it from redepositing on the substrate. They are said to have very good degreasing capability and clean a wide variety of soils, including chlorinated paraffins.
Although they were developed mainly for use in spray applications, the cleaners are also suitable for operation in soak tanks with some agitation, belt washers, and ultrasonic cleaning systems. All the formulas are completely organic, have low VOCs and contain no alkalines or acids and minimal phosphates, Galaxy says, and all are suitable for multi-metal operation.
In one application, a customer was cleaning parts fabricated from dirty hot-rolled steel sourced in China by spraying a foam alkaline cleaner, allowing the parts to soak for a couple minutes, then rinsing with a high-pressure wand. The process was inefficient and didn’t provide very good cleaning, according to Galaxy. The predictable result was paint adhesion problems.
The user now injects a 1% solution of GX Clean 5185 into the high-pressure wand. The cleaning process is faster, and one step has been eliminated. Part surfaces are clean and adhesion problems are eliminated. And, the company no longer requires special permits for wastewater.