Over the past few years there has been a wide demand to clean engine components to a higher standard in a more cost effective manner. In the article below, Greg Organ of Diesel Green (Aust.) takes an in-depth look at the role of ultrasonic cleaning in automotive industries; why it’s more efficient and cost effective than traditional methods, and how it could help improve workplace OHS and productivity in your business.
Since the emission control standards from Tier 3 to the present emission standards, we are experiencing more and more of the components such as EGR valves – EGR Coolers – Intake manifolds and DPF either heavily choked or blocked from a mixture of engine oil and combustion materials. Using the rotary hot wash cleaning systems are costly energy users, costly caustic cleaning products, and often takes hours to clean the engine components, so is there a better and cheaper running cleaning units?
Ultrasonics are the most powerful and affordable cleaning units for the Automotive based industries. One system is powerful enough to remove the toughest contaminants such as rust, paint, carbon and oil on all non-absorbent materials such as steel, alloy and hard plastics in a fraction of the time it takes you now, with the bonus of being safer. The advantage of ultrasonic cleaners is it reduces wasted time on repetitive and laborious cleaning tasks, when you could be using your valuable time more productively.
- It cleans faster, reducing the time required for a cleaning cycle and is superior method for cleaning parts with cavities and blind holes.
- It is efficient and requires less handling of parts – reducing the need for disassembly in order to clean.
- Using water-based detergents reduces the need of harsh solvents which makes the process safer.
- Ultrasonic cleaning requires minimal manual labour intervention, meaning staff are free to carry out other work.
- Ultrasonic cleaning gives consistent results and does not require operator skills.
- Ultrasonic cleaning means non-contact cleaning – only the contamination is removed, not the substrate.
- Petrol and Diesel engine components
- Cylinder heads and engines blocks – including V8 blocks
- Fuel injectors – Diesel Injection pumps
- Emission units – EGR valves
- Metal, fabric and ceramic filters
- Heat exchanges and intake manifolds
- Carburettors and fuel supply pumps
- Hydraulic pump and motor bodies and parts
- Hydraulic control valves Outboard and motorcycle heads and barrels
Ultrasonic cleaning uses cavitation bubbles induced by high frequency pressure (sound) waves to agitate a liquid. The agitation produces high forces on contaminants adhering to substrates like metals, plastics. glass, rubber, and ceramics. This action also penetrates blind holes, cracks, and recesses.
The intention is to thoroughly remove all traces of contamination tightly adhering or embedded onto solid surfaces. Water or other solvents can be used, depending on the type of contamination and the workplace. Contaminants may include dust, dirt, oil, pigments, rust, grease, algae, fungus, bacteria, lime scale, polishing compounds, flux agents, fingerprints, soot, wax and mold release agents, biological soils like blood, and so on.
Ultrasonic cleaning can be used on a wide range of shapes, sizes and materials, and may not require the part to be disassembled prior to cleaning. Objects must not be allowed to rest on the bottom of the device during the cleaning process, because that will prevent cavitation from taking place on the part of the object not in contact with water.
HOW DOES IT WORK?
In an ultrasonic cleaner, the object to be cleaned is placed in a chamber containing a suitable solution (in an aqueous or organic solution, depending on the application). In aqueous cleaners, the chemical added is a surfactant, which breaks down the surface tension of the water base.
An ultrasound generating transducer built into the chamber, or lowered into the fluid, produces ultrasonic waves in the fluid by changing size in concert with an electrical signal oscillating at ultrasonic frequency. This creates compression waves in the liquid of the tank which ‘tear’ the liquid apart, leaving behind many millions of microscopic ‘voids’ or ‘partial vacuum bubbles’ (cavitation). These bubbles collapse with enormous energy; temperatures and pressures on the order of 5,000 K and 20,000 lbs. per square inch are achieved; however, they are so small that they do no more than clean and remove surface dirt and contaminants. The higher the frequency, the smaller the nodes between the cavitation points, which allows for cleaning of more intricate detail. Ultrasonic cleaners are used for industrial cleaning, and also used in many medical and dental techniques and industrial processes.
Ultrasonic activity (cavitation) helps the solution to do its job; plain water would not normally be effective. The cleaning solution contains ingredients designed to make ultrasonic cleaning more effective. For example, reduction of surface tension increases cavitation levels, so the solution contains a good wetting agent (surfactant). Aqueous cleaning solutions contain detergents, wetting agents and other components, and have a large influence on the cleaning process.
Correct composition of the solution is very dependent upon the item to be cleaned. Solutions are mostly used warm, at about 50-65°C (1 22-149°F), however, in medical applications it is generally accepted that cleaning should be at temperatures below 38°C (10 °F) to prevent protein coagulation. Water-based solutions are more limited in their ability to remove contaminants by chemical action alone than solvent solutions; e.g. for delicate parts covered with thick grease. The effort required to design an effective aqueous-cleaning system for a particular purpose is much greater than for a solvent system.
Some machines (which are not unduly large) are integrated with vapour degreasing machines using hydrocarbon cleaning fluids: Three tanks are used in a cascade. The lower tank containing dirty fluid is heated causing t he fluid to evaporate. At the top of the machine there is a refrigeration coil. Fluid condenses on the coil and falls into the upper tank. The upper tank eventually overflows and clean fluid runs into the work tank where the cleaning takes place. Purchase price is higher than simpler machines, but such machines are economical in the long run. The same fluid can be reused many times, minimising wastage and pollution. Carbon tetrachloride was used in the past, but is now prohibited as a health hazard. Chemicals used in the modern Ultrasonic cleaning units:
- FERROCARB – removes carbon, paint, rust and lead deposits on ferrous metals.
- ALLOY SYSTEM – removes carbon, oils, grease and pint from alloy and ferrous metals.
- ANTI-RUST – rust inhibitor rinse tank and surface treatment.
- DESLUDGE – rapid penetration and removal of most soils off all surfaces.
I have been using and I have found that the ultrasonic cleaning machines are cleaning a wide variety of parts quicker and more effectively, reducing exposure of technicians to toxic chemicals and laborious manual cleaning. The Ultrasonic cleaning machine has proved more effective than mechanical or chemical cleaning. While traditional parts cleaning systems only seem to clean exterior surfaces, the KLEENTEK unit I have been using and testing have a very good range of ultrasonic cleaners, which the ability to not only clean exterior surfaces but also remove contamination in interior channelsand cavities that are nearly impossible to clean by hand.
Ultrasonic cleaning is quick and easy and reduces the need for complete disassembly while providing consistent results. Special Thanks to KLEENTEK – Advanced Cleaning Technologies for the material used in this article.