Parts cleaning

Parts cleaning is a step in various industrial processes, either as preparation for surface finishing or to safeguard delicate components.

One such process, electroplating, is particularly sensitive to part cleanliness, as even thin layers of oil can hinder coating adhesion.

In contrast, perfectly clean metal surfaces are hydrophilic and retain an unbroken sheet of water without beading or draining off.

It is important to note that this test may not detect hydrophilic contaminants, but they can be displaced during the water-based electroplating process.

There are some specialists who prefer the term "industrial parts cleaning", because they want to exclude maintenance of buildings, rooms, areas, windows, floors, tanks, machinery, hygiene, hands washing, showers, and other non-commercial objects.

They may comprise non-processed or hardly processed sections, sheets and wires, but also machined parts or assembled components needing cleaning.

Long, thin, branching, threaded holes, which could contain jammed chips, feature among the greatest challenges in this technical field.

When dealing with large amounts, bulk charging can be used, but it's difficult to achieve a sufficient level of cleanliness with flat pieces clinging together.

Companies often want the charging, loading and unloading to be integrated into the production line, which is much more demanding as regards size and throughout the ability of the cleaning system.

Such cleaning systems often exactly match the requirements regarding parts, contaminants and charging methods (special production).

The following procedure is quite common: Each of these steps may take place in its own bath, chamber, or, in case of spray cleaning, in its own zone (line or multi-chamber equipment).

The traditionally used chlorinated agents, TCE and PCE, which are hazardous, are now only applied in airtight plants and the modern volume shift systems limit any emissions.

Aqueous cleaners have advantages as regards to particle and polar contaminants and only require higher inputs of mechanical and thermal energy to be effective, whereas solvents more easily remove oils and greases but have health and environmental risks.

Nowadays, with proper industrial parts washer equipment, it is accepted that aqueous cleaners remove oil and grease as easily as solvents.

Another approach is with solid cleaning media (blasting) which comprises the CO2 dry ice process: For tougher requirements, pellets are used while for more sensitive materials or components CO2 in form of snow is applied.

In order to delay the bath exchange as much as possible, there are sophisticated treatment attachments in use, removing contaminants and the used up agents from the system.

Quite little waste is generated in processes like CO2 blasting and automatic brush cleaning at the expense of higher energy costs.

A standardization of the quality requirements for cleaned surfaces regarding the following process (e.g. coating, heat treatment) or from the point of view of technical functionality is difficult.

Where this is not sufficient, especially in case of external orders, because of missing standards, there are often specific customer requirements regarding remaining contamination, corrosion protection, spots and gloss level, etc.

It was not until recently that bigger advancements in this area have been made [5] The general situation has changed, meanwhile, because of dramatically rising cleanliness requirements for certain components in the automotive industry.

Because of the rising innovation speed, the industry cannot afford to identify possible failures at a relatively late stage.

The classification follows basically the metal work theory: In time, empirical values were established, how efficient the cleaning has to be, to assure the processes for the particular guarantee period and beyond.

Developed by the Surface Cleaning Program at the Research Triangle Institute, Raleigh, North Carolina, USA, in cooperation with the U.S. EPA (used to be available under: http://clean.rti.org/).

It contains furthermore an integrated evaluation tool, which covers the areas of technology, quality, health and safety at work, environmental protection and costs.