When cleaning finished machine parts, manufacturers have to meet the increasingly stringent cleanliness tolerances, while also operating a cost-effective cleaning process. Old standards no longer apply and manufacturers have to evaluate their operations to select the best cleaning process. Just utilizing best practices and monitoring your tank is not enough.
The first thing that should be assessed is the contamination generated in all stages of the manufacturing process. Engineers should have data on all processes and substances that parts have been exposed to. Cleaner and equipment suppliers should have reliable lab work to help understand the process and contaminants. Equipment and cleaner manufacturers should provide transparent testing and results to demonstrate the value and effectiveness of their solution.
The 3 Cleaning Energies
Every cleaning process will depend on a balance of 3 energies: chemical, thermal, and mechanical. If one form of energy is increased, the other two forms of energy can typically be reduced. The key to perfecting your aqueous cleaning process will be balancing the 3 energies.
Chemistry should be the first consideration in developing a cleaning process. The part material and contamination will determine the appropriate pH range of your aqueous cleaner. The goal is to minimize chemistry at the lowest temperatures and least costly form of mechanical energy to achieve cleanliness standards in the required time cycle.
Alkaline cleaners (pH 9-14) are ideal for removing organic contaminants such as oils, greases, coolants, etc. Acidic cleaners (pH 1-6) are ideal for removing inorganic contaminants such as oxides and rust. Neutral cleaners are excellent for use in systems that use more mechanical energy such as ultrasonic cleaning.
Depending on the part material, less or more aggressive cleaners will be appropriate. More neutral chemistries should be considered for softer and more reactive metals, such as aluminum, copper, or brass. A more aggressive chemistry could start attacking/reacting with the part itself. Less reactive metals can withstand stronger chemistries, higher temperatures, and more mechanical energy. Inert chemistries will require more mechanical energy to drive reactions and break down contaminants.
Heat is controlled in a cleaning system by different heating elements. What elements and how they are programmed are dependent on your goals and system. It is important to carefully monitor temperatures to prevent reduced heat element life and temperature capacity. Sensors and controllers are recommended to monitor cleaning systems and can help prolong service life and improve performance.
Heat increases the speed of molecules and faster molecules are better at breaking down bonds of contaminants. For every 17 F increase in temperature, reaction rates can double. This can accelerate the cleaning process. The optimal temperature in most systems is 120 F to 160 F. Too low of temperatures can lead to foaming and less effective cleaning.
Increased heat can reduce drying times and accelerate the cleaning process. It is important to remove pools of water using gravity or airflow. However, too hot of temperatures could create “flash rusting,” which can lead to parts being deemed off-spec or require additional cleaning or work.
The final piece of the puzzle is mechanical energy. This is determined by the equipment and process that is used. Vertical agitators are popular because of their forgiveness and ability to avoid oil loading. The main way to generate mechanical energy is creating agitation.
In immersion cleaning systems, agitation is created by moving the parts in and out or within a tank of cleaner. Spray washers introduce agitation by introducing energy into the cleaner by spraying it at high speeds onto parts. Spray washers can be used in conveyer systems that have multiple stages, such as washing, rinsing, and rust inhibiting.
Ultrasonic cleaning introduce the most mechanical energy and are ideal for cleaning processes with limited heat and less aggressive chemistry. Ultrasonic cleaning should be considered when conventional methods fail to meet cleanliness tolerances.
Balancing the three energies is key to perfecting a cleaning process. When selecting an aqueous cleaner, consider your equipment, process, contaminants, and part material. Twin Specialties offers a full-line of aqueous cleaners that can fit any cleaning process. Many cleaners are specifically designed for ultrasonic, spray, and/or immersion cleaning process. Contact Twin Specialties to learn more about our aqueous cleaners and see what product is right for you.