CLEANING MEDIA FOR WET CLEANING
Wet cleaning media
In industrial parts cleaning, wet media are used in 70 to 90 % of all cleaning processes. Wet media include aqueous solutions – similar to detergents we use to wash our dishes or laundry – as well as non-aqueous solvents.
For each cleaning task, project engineers must choose the best wet medium, taking into account ecological and economic considerations.
Workpieces and parts are produced in fine-tuned production processes that often require the use of special consumables and process chemicals. Parts are generally made from specific materials, and their contamination after machining is determined by the processes they have undergone.
When assessing the environmental impact of cleaning media, one sometimes comes to surprising conclusions. First of all, the energy input and use of resources must be assessed. Also to be taken into account are the risks associated with the handling of the cleaning media, and the measures that need to be taken to prevent contamination of the ground and the ambient air.
For the assessment of the environmental impact of a process, the way the medium is treated inside the cleaning unit is often the key factor.
Cleaning media at a glance
PERO develops and builds cleaning systems for all types of wet media.
Cleaning with aqueous media
Acidic, neutral or alkaline wet media Aqueous media remove dirt particles from surfaces and rinse them off. Aqueous detergents disperse particles, and form or separate emulsions. They act on the surfaces of parts. If required, aqueous media can be used to alter the surface properties of parts by passivation (phosphatising), pickling, etc. In all applications, the treatment of the medium itself is of crucial importance. Aqueous media are powerful detergents.
Cleaning with solvents
Solvents are wet media that are able to dissolve substances without actually reacting with them. The most commonly used cleaning solvents are hydrocarbons and modified alcohols with a flash point > 55°C, and halogenated hydrocarbons. Solvents remove dirt particles from surfaces and rinse them off. Advantages: Short cycle times, energy-efficient drying, low solvent consumption, long medium service life and easy treatment. Where it is possible to use solvents for a specific application, they are generally the best choice. Solvents are powerful degreasing agents..
Cleaning with combined wet media
Where a single wet medium is not able to achieve the required cleanliness, combining different wet cleaning methods is often the solution. Units for cleaning with combined wet media can however be costly and might not be the best option for certain parts. That is why it is often more cost-effective to link two or more separate units to build a cleaning line.
Principle of "like dissolves like"
Where a single wet medium is not able to achieve the required cleanliness, combining different wet cleaning methods is often the solution. As such units tend to be rather expensive, the viability of the investment needs to be assessed in advance. In many cases, it is more cost-effective to link two or more separate units to build a cleaning line.
Wet media differ greatly as regards safe handling, service life and cost of treatment.
- Surface tension
- Degreasing properties
- Cleaning properties
- Drying properties
- Filtration properties
Medium treatment methods:
The cleaning media require different measures:
Aqueous media & solvents
- Bag filter
- Cartridge filter
- Screen basket filter
- Settling chamber
- Stock bath
- Bath treatment/Titration
- Bath change
The less space between the parts, the more difficult it is to remove particles and contaminants with a wet medium. The handling of the parts and the design of the parts carriers are therefore important aspects for optimised cleaning.
Wet media are used in units with 1-, 2-, 3- or even more baths where the parts are cleaned and rinsed, and, if required, treated with preservation agents.
Environmental protection and occupational safety
For all cleaning methods, operators must comply with the applicable statutory regulations at local, national and international level. The handling and the treatment of the cleaning media are two important aspects that must be taken into account when assessing cleaning tasks and suitable methods.