4 Simple Tricks To Enhance Ultrasonic Cleaning

Arranging parts in an ultrasonic cleaner

It is always advisable not to place the components on the lowermost part of an ultrasonic tank. It would be similar to placing a thumb on a speaker diaphragm. Not only does it prevents the proper movement of the diaphragm but also tends to interfere with the ultrasonic energy that is generated. There are some basic issues that need to be taken care of while designing tanks for optimum ultrasonic cleaning efficiency.

The various components should be placed properly in a basket or work holder in an Ultrasonic Parts Washer that is specifically designed for each individual component. It is of special significance in high end cleaning systems where it is essential to achieve good cleaning of various components. Make use of a stainless steel basket because soft components tend to absorb the ultrasonic energy. Do not use plastic or other lighter materials. If the component is of a kind that is damaged easily, racks composed of stainless steel that come with Nylobond or Teflon coatings can be used in tanks for optimum ultrasonic cleaning efficiency.

How many parts can be cleaned in a tank?

The total space of components that are to be cleaned during ultrasonic cleaning should be less than the tank volume as measured in cubic inches which translates into about 50 square inches of cleaning area per liter of tank capacity. The volume of the tank should be such that when the object is placed into the basket there should be a minimum of 1.5 inches on each side and top and at least 2 inches of liquid on the bottom parts. The design of work fixtures and corresponding baskets is significant to a good cleaning process.

Should we filter the cleaning solution in the ultrasonic tank during ultrasonic cleaning?

It varies depending on the size of the tank in an Ultrasonic Parts Washer.  In case of a small tank, you may change the solution for a fresh one rapidly but a larger tank can require up to 2-3 hours for changing the solution and then reheating to the proper temperature. It would also be dependent on how much cleaning the components require. If high volume of cleaning is required, then a frequent changing of cleaning solution becomes necessary.

The solution to these issues is a filtration system that will help in re-circulating the cleaning fluid through a filter of the appropriate type which keeps re-circulating the solution and then returns it to the tank. Keep in mind the following things while using a filter system:

1. It is recommended that you make use of the filter at not more than 5-10 liters per minute (assuming a tank capacity of 100 liters) if you are using the ultrasonic simultaneously. Air will be introduced by the pump in a filter system and it can lower the ultrasonic activity if it is allowed to run at higher rates. It is always advisable to make use of filter between cleaning cycles.

2. Even if you make use of a filter, it is always suggested that the tank be emptied and cleaned as soon as the soap or other cleaning agent is exhausted.

3. Filters should be regularly changed.

Rinsing parts after cleaning in an ultrasonic tank

As a rule washing will enhance the end result but keep in mind that when you utilize a cleaner of any sort you will also be leaving a deposit of that cleaner on a component. The most ideal approach to expel this buildup is to flush in DI water spray as well as another Ultrasonic tank loaded with a nonstop over stream of Hot DI water. This will expel any hints of the cleaning substance.

Spray Rinse Tanks are intended to be somewhat bigger than the ultrasonic tank that is utilized. The splash is conveyed from 2 or more spray bars on the topsides of the tank. The channel is typically double the extent of the bay. As a rule a state of utilization DI water radiator is utilized to convey a hot spray wash. The tanks may be composed of Polypropylene or stainless steel.

At a point of use DI water warmer uses ceramic heaters to quickly raise the temperature of the DI water as it streams into the tank. A switch that is sensitive enough to the stream of water into the radiator activates the system as per demand. A definitive temperature will then be attained that is determined by the stream rate of the water and the force of the warmer. It must be estimated to the interest of the system.

Merits of an Aqueous Parts Cleaning System

Aqueous Based Systems

The alternative to Solvents is aqueous based systems, which use water or emulsions as a cleaning media. Emulsions are relatively simpler to handle, wash and recycle. But there are issues that are faced during the disposal of the emulsion waste when the media is to be cleaned.

All emulsions are categorised as water in oil or oil in water types. 

The emulsions are made of emulsifiers which have hydrophobic and hydrophilic ends.  When they are brought in contact with water, the hydrophobic end attaches itself to water molecule and the hydrophilic end is free and can easily attach itself to any oil, grease or similar contaminant. This helps in removal of the contaminant from the media or the substrate.

Emulsions are made by mixing water and the emulsifier under immense shear and pressure to create a colloidal solution that has a dispersion of emulsifiers in water. Emulsifiers have the same property as any hydrocarbon making it an ideal compound to be used in the cleaning. The emulsions are  also made of stabilisers, buffers and other chelating agents.

There are many advantages of using Emulsions. Temperature of washing can be increased and it can also be operated in an open system. It’s also compatible with most metals, non-metals, plastics and alloys. Most emulsions are stable over a wide range of ph, temperatures and can accommodate additives needed in the washing process.

However emulsions need a process of rinsing and subsequent drying. The rinsing is compulsory as we need to remove the detergents and soap remains from the component. This process is not required when dealing with a solvent based system.

A typical aqueous cleaner is 3 stage:  

1) Washing

2) Rinsing

3) Drying.

Most aqueous cleaning agents are made of various compounds to accommodate different processes.  They can incorporate Chelating agents, sequestering agents, anti-rust compounds, anticoagulants, buffers, stabilizers and other such compounds. These Chemistries are detailed in a different book.

 In summation it can be said that most metals clean and dry faster in solvent based systems, but we need to study the economics of using the solvent must be studied in detail. Aqueous technologies are safer, healthier and less expensive too.

Both Methods have disposal issues.  There is a change in the mind-set of existing users who are moving towards thee aqueous based solutions. Class 1 level of washing needs be augmented with a newer generation of chemicals.

Enhancing Life of Ultrasonic Cleaners

                                 

Just recently, I read somewhere that villagers in Haryana bought massive amounts of  gold from a particular man just before the great Recession in 2008. Apparently, the con man said he had massive debts to pay off for his factories and was selling the gold at half the price. The public bought the yellow metal. It was Gold..but just about 20% of it and the rest 80% was copper.

Now.. Isn’t that a GROSS? Buying yellow metal instead of gold, just because the colours are the same. About 45 people were done in!

Unfortunately, such things happen regularly in the industry. Unless one buys from a BIS certified shop or material, one can't be sure. It’s also rumoured that many jewellery stores are still selling higher percentages of copper in gold. The issue said to be rampant in other forms of valuables like diamonds and platinum as well.

This phenomenon is not restricted to India alone, but most parts of the world where Standardisation of the Value is not performed.

Industrial Products and consumables are also affected where purchases are based on a single page ‘literature’.

I am narrating an experience, similar to which many of you may have already experienced.

We have a Electronic Security Division and had quoted in a tender at AAI for installation of CCTV cameras at the airport. The specs called for 1200 tvl (TV Lines) and Day night Functionality of certain High Performance Cameras.

When bids were opened, we found some suppliers to have quoted at 40% lower than the estimated cost. The catalogue was the only proof of backing the claim. Any clarification required by the Airport from the supplier.. was made on a letterhead.

We had a situation where nobody could verify the claim that the cameras indeed had 1200tvl.  However due diligence and other factors were employed in subsequent tenders.

Care to be taken in Purchase of Ultrasonic Cleaners

Engineering Goods generally don’t have such issues, due to the availability of test houses and BIS, JIS, ASTM and other norms that have been made.

However, these will be difficult to prove in the Ultrasonic Cleaning Business. By making some hypothetical comparisons, I hope to draw your attention to some adversely affecting scenarios:

a) How can one be assured of a correct power rating of the Ultrasonic? Have we bought a 500 watt Ultrasonic or is it a re-labelled 300 Watt?

b)  Is the design good enough to ensure the entire tank gets the ultrasonic waves? Or is it active in some areas only?

c) Is the ultrasonic transducer working with 30,40, 50 or 90% efficiency? Imagine paying a market price of Rs.50,000/- for 250 Watt Single tank Cleaner. If a good Ultrasonic Cleaner works with 90% efficiency and the one we have purchased is working at 30% efficiency…its same as paying Rs.1, 50,000!

d)  Is there a guarantee on the life of the Ultrasonic? Can someone support it after warranty? When the Ultrasonic transducer fails, it is almost always necessary to change the tank too. Low cost Chinese models will find it hard placed to do so. By the way... I offer lifetime warranty on all transducers on our equipment!

 Why Transducers are Important

Transducers are of mainly of three types : Piezoelectric  and Magnetostrictive and Pull Push.

Piezoelectric is made of a piezo ceramic disc sandwiched between two strips of tin. When power is applied to the tin bits, it creates a displacement which is what creates the vibration. When the frequency of vibrations are high, it creates the cavitation in the tank through the stainless steel enclosure.

Magnetostrictive transducers are similar except that it has lead rings that can be activated for shrinkage by getting magnetized. The advantage is that the rings do not get magnetized over an extended period of time.

Pull Push transducers are fitted inside the tanks. They are rod like and have an insert sleeve with the cavitation being created on both ends of the rods. These transducers can produce about 98% efficiency.

To be really effective, three aspects have to be taken care of:

1) Bonding

2) Efficiency

3) Inertial Mass

Inertial mass is something like the pressure needed to create movement.. If you need to move a train, you need engine with power and momentum that is greater than the train.. Right?  Can’t move it with a matchstick. It doesn’t matter if the matchstick is held by a railway engine. It just won’t move.

The same way a loaded Ultrasonic tank (water plus material), will need a series of transducers, which are more heavier than the tank plus the liquid weight put together.

The book has an elaborate and simple explanation about transducers, That will also explain in detail, why efficiency and bonding are better with Magnetostrictive transducers.

Though there are other components to an Ultrasonic Cleaner, the heart is the transducer and its up to us to take a call on what is the long term cost we can pay , for Cleaning!

A Layman's Guide : Wet Cleaning of Industrial Parts

Chemistry of Wet Cleaning

The washing of Small Industrial Parts and Components is carried after an assessment of the safest process that can be employed. The factors that determine the decision also takes into consideration effect of water , detergent, oil, or solvent on the component.

Types of Media Used for Cleaning

Though water is the safest and most reliable media for cleaning, it effects some metals. Another factor could be that certain contaminants are not removed by water and may require special process or attention. The choices of available media are:

·                     Water: Cold, Warm or Steam.

·                     Solvents: Hydrocarbons or Fluorocarbons.

·                     Air: Gasses like CO2.

·                     Chemicals: Alkaline or Acidic.

·                     Energy: Radiation, Laser or Plasma.

The first question is whether or not to use water? Can it achieve the cleanliness by air blowing?

It's only when the answer to both the questions is a resounding NO, does one proceed further.

Cleaning in air can be achieved for materials that have less degree of dirt or have such surfaces and contaminants that can be easily blown off. In such cases, contaminants also can be blown away or wiped off using steam.

Processes used in Wet Cleaning

For cleaning with water, chemicals and solvents some of the popular processes are:

1.    Rinse : Room Temperature, Hot or Cold 

2.    Power Wash: Using water and detergent under high pressure in closed compartments made of MS or sheet metals cabinets. 

3.    Bubbler or Gas Rinse: Forcing air through the liquid media to pass through the parts. Sometime Co2 is also used. 

4.    Rotational: Movement by Rotation, Pivoting or Oscillation etc. 

5.    Ultrasonic: The technologies include Acoustic and Resonance.

6.    Megasonic: High Frequency Ultrasonic.

7.    Turbulator: The water is made to churn within the Tank like that of a Home Washing Machine. 

8.    Sprinkler: Like a shower 

9.    Spraying: Using a Nozzle jet that can force water , solvent or Oil out with force.

10.  Hydroson: A technology that combines water and Ultrasound.

11.  Dunking: The component is pulled out of the Media and dumped back.

12.  Liquid Co2: High pressure Co2 is used as a blasting media

Equipment used in Parts Cleaning:

The different type of equipment used depends on the complexity of the ideal washing process.
Most popular systems include:

1.    High pressure Water jets

2.    Sand Blast Systems

3.    Glass Blasting Systems.

4.    Ultrasonic Cleaner

5.    Megasonic Cleaners

6.    Oil Tanks.

7.    Compressed Co2 Systems.

8.    Laser Ablation.

9.    Chemical Scouring Agents

We will discuss each of the above mentioned processes in the next few posts.

How Four Power Factors Affect Ultrasonic Cleaning

Effect of Power on Ultrasonic Cleaning.

Hello again..

Well, since I have been talking about the various things we are learning in finishing industry,it might be apt that we also speak the factors that affect the performance in ultrasonic cleaning.

Ultrasonic Power is a critical factor in deciding the effectiveness of a cleaning System.

It’s generally accepted that 50 W per litre is acceptable level to induce cavitation in a cleaning bath of the system. However there are factors that must be considered.

What’s loaded in the tank?

The washing component could be made from  plastic or cast iron . Will the power requirement capacities change? An honest answer is yes, In order to maximise the cavitation efficiency the power will have to be altered. The ability of component to absorb the energy and vibrations are extremely important. 

The relative density of the medium?

The medium in the tank could be could be water or a solvent ( specific gravity < .099 or > 1.44) Will the power rating differ? Yes, it will.

Changes in the media , when bath temperatures of 66-75 degree celsius is achieved?

There are materials whose properties change dramatically with temperatures. Thereby the ultrasonic power would need to be adjusted accordingly. Certain fluids drop in Viscosity at elevated temperatures.

What about using different viscosities of fluids to clean?

The relation between the power and the viscosities of the fluid is directly proportional. The thicker the fluid, the more power would be required, The thinner the fluid, the lesser the need of power.

People always want to know what is the ideal cleaning power of a tank. The answer to this varies from person to person due to different perspectives. They have their own standard or interpretation to such a question.

The cleaning ability depends on a few set factors, such as:

1.    Actual electrical power input

2.    Cleaning solution used

3.    Transducer matching

4.    Physical construction of the tank

As the manufacturers of these systems, we use universal electrical power expressed in RMS Volts or Watts to evaluate cleaners. The tanks are then properly sized according to the industrial standards of power levels for cleaning levels, as is, so many watts/gallon. Like I mentioned above, 50 Watts/litre is typically and widely used and is categorised as a high power cleaner. In a few cases, 35 Watts/litre is used and is categorised under lower power industrial cleaner.

Industrial Ultrasonic Cleaning - Advantages and Limitations

Ultrasonic Cleaning: Handicaps and Limitations

Hi…

Thanks for dropping by!

This is Chandrakant from ESP Ultrasonic .

Last week, while I was visiting an Auto Component manufacturer, I was asked by their production manager Mr. Thirumuragan, what was exposure that i considered most valuable , as a Sales Professional.

Without hesitation I blurted out, “We don’t have a solution for every need.”

It’s true, we don’t!

We deal with various Industry verticals and each one of which are so well tuned with their expectations of process fit, budget considerations, Safety standards and Production . No two experiences are the same.

More often than not, we have to devise solutions. By networking with like minded professionals, process experts and by reviewing resources online , we work out a fitting solution. The internet has changed the outlook to successful marketing personnel to that of a marketing consultant. We source popular solutions and work with industry defined norms of acceptance and economy.

Our ability to offer solutions is important because we can offer technical options, which generally are not available to an outsider or on the internet. 

The Limitations of Ultrasonic Cleaning

Industrial Cleaning is evolving and so is technology, process and metallurgy . 

As salesmen, we have the most exciting occupation . Each client has a different challenge.

After about six months of follow up, I met the Senior Vice President of a company and he put forth his requirements .

“Can you dry clean a component”, he asked me.

In my head, I was thinking, ‘Obviously, NOT!

Since I could not offer them any of the wet cleaning options, I took time off to check alternatives. Finally,we arrived at a solution that could give them the ‘dry cleaning’ that they required.  

Ultrasonics do have their limitations. There are two obvious challenges: 

a) The Montreal protocol has prohibited the use of various solvents by restricting the use of the most compatible ones.

This was a body blow to the industry. After working on development of alternatives, the result was the emergence of water soluble solvents and aqueous based systems. The trends are emerging that this seems to be the best way out for most component cleaning challenges.

b) The other limitations of Ultrasonic Cleaning is that it doesn’t work in moving (flowing) media (be it water or solvents).

Yet considering the general methods of cleaning, Static media can’t flush out contaminants in deep recess parts or inside the intricate designed component.

In order to bridge the gap between these two challenges, Ultrasonic technology emerged by using slow flowing media or intermittent pressure jets or rotating component basket. Equipment designs have arisen where media is subjected to sudden turbulence created by blade propelled movement.

Another technique is to gently rock the component back n forth to dislodge deep set contaminant.

Hybrid technologies have also developed.

The good news is that cleanliness levels of 0.04 mg have been achieved using aqueous equipment.

The application of creativity and plethora of chemicals has ensured that almost every requirement for cleaning systems are addressed using Ultrasonic in total or in conjugation with other technologies. This has prompted most professions to adopt a solution based approach rather than a technology based approach.

Strengths of Ultrasonic Cleaning

Well, I think we should also look at the bright side of using Ultrasonic in cleaning.

The ideal system is built on using the combination of the technologies that mask the handicaps and limitations of the other.

Let’s take  another example - Cleaning Materials Exposed to Radioactive Particles.

This has traditionally been a stronghold of Vapour degreaser and High Pressure jets. However the flushing of beta and gamma radiations have been a very closely guarded technology as exposure is fatal and the contaminant cannot be disposed off.

With the challenge for recycling the irreplaceable resource, it was decided to develop a nano-filtration system that works to collect the particulate matter and remove the metal or non-radioactive substances.

Now 99.999% of the required can be achieved with beta filtration using multiple Ultrasonic tanks and jet spray arrangement.  This system is well set to increase the profitability of the cleaning process.

Also, new designs have emerged in the stainless steel tank construction, micro polishing of inner surfaces and use of acoustic technology like resonance, etc.

Ultrasonic Cleaning has emerged as a modern, flexible and dynamic cleaning technology. The technology can be tuned to adapt strengths from water blasting, to that of vapor based cleaning.

In washing, ultrasonic has ceased to exist as a technology.  Its now a solution based to a specific challenge.