Insight Engineering Systems Product Portfolio
 
Six Stage Cleaning Machine
Round Automet
Walking Beam
Single Chamber Cleaning Machine
Double Chamber Cleaning Machine
Crankshaft Cleaning Machine
Engine Valve Cleaning Machine
Carburetor Cleaning Machine
Chocolate Mould Cleaning Machine
Conveyor Cleaning Machine
 

FAQ

 
1. What is Metal Cleaning ?
2. What are Cleaners and Cleaning Solvents ?
3. What is Ultrasonic Cleaning ?
4. How to Maximise Ultrasonic Cleaning Process ?
5. How to Maximise Overall Cleaning Effect ?
6. What is Ultrasonic Generator ?
7. What are Ultrasonic Transducers ?
8. How are the Components Handled ?
9. What is Jet Washing ?
10. What is Injection Flood Washing ?
11. What is Rinsing?
12. What is Vacuum Drying ?
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1. Cleaning of metal parts means cleaning the parts devoid of loosely adhered metal and fibre particulates without any way affecting the surface of the part or the substrate thereof. Since these loose metal particles are generally adhered to the metal due to some oily or emulsion substrate it becomes pertinent to dissolve the oil or emulsion to loosen the particles and remove them.

There is no singular solution cleaning and  for achieving the  defined residual soiling values (Millipore values) on the surface of components. Each cleaning problem  requires  a specifically  defined solution. The important  factors in this regard are the material or combination of materials, the soiling, the shape  of the component, the level of cleanness required in terms defined residual dirt and most important of all the production rate of production.

As good cleaning depends on the cleaning solution , the right choice of cleaning  solution     cannot be over emphasized. Cleaning solutions have to be compatible with the parts being cleaned, provide appropriate surfactants to enhance removal of specific contaminants, prevent foaming, prevent corrosion of parts etc.

 
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2. Regardless of the type or category, all cleaners remove soils by one or more of the following principles:

Solvent Action - This property enables the cleaner to dissolve the oils present on the metal surface.
Saponification - In this highly alkaline process, drawing compounds (lard oils, fatty acids) are chemically converted into a soap and rendered water-soluble.
Detergency - Surface active wetting agents reduce the interfacial tension of surface oils, enabling cleaning solutions to better penetrate and displace soils from the metal surface being cleaned.
Emulsification - The suspension of oil particles in an aqueous phase permits them to be rinsed away easily. This is normally accomplished in the presence of surfactants.

Cleaning is the combination process of the solvency of the substrate oil in the cleaning solution and dislodging of dirt particles with the aid of a impingement process which generally mechanical in nature.  The appropriate process is derived from the level of cleaning and the nature of cleaners used.

While high pressure spray and mechanical agitation techniques are used in aqueous based cleaners the use of ultrasonic power in cleaning is used both in solvent and aqueous cleaners.

 
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3. Ultrasonic cleaning is use of ultrasonic power to improve the solvency of the cleaners for the substrate oil and emulsion and also very effectively dislodging the dirt particle which are loose and on the component

Ultrasonic cleaning in introducing cavitation, the rapid formation and violent collapse of minute bubbles or cavities in a cleaning liquid. This agitation by countless small and intense imploding bubbles creates a highly effective scrubbing of both exposed and hidden surfaces of parts immersed in the cleaning solution. As the frequency increases, the number of these cavities also increases but the energy released by each cavity decreases making higher frequencies ideal for small particle removal without substrate damage.

Cavitation is produced by introducing high frequency (ultrasonic), high intensity sound waves into a liquid. Consequently, the three essential components of any ultrasonic cleaning system are: a tank to contain the cleaning liquid, a transducer to convert electrical energy into mechanical energy, and an ultrasonic generator to produce a high frequency electrical signal.

This type of cleaning process has the following major advantages.

Precision :
Because ultrasonic energy penetrates into crevices and cavities, any type of part or assembly can be cleaned. In many cases ultrasonic cleaning is the only way to meet specifications, as in the cleaning of precision parts or assemblies.
Speed : Ultrasonic cleaning is faster than any conventional cleaning method in the removal of soil and contamination from parts. Entire assemblies can be cleaned without disassembly. Often, its labour saving advantages make ultrasonics the most economical way of cleaning.
Consistency : Unlike manual cleaning, ultrasonics offers unmatched cleaning consistency, whether pieces to be cleaned are large or small, simple or complex, handled singly, in batches, or in an automated line.

 
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4. Process Parameters

Effective application of the ultrasonic cleaning process requires consideration of a number of parameters. While time, temperature and chemical remain important in ultrasonic cleaning as they are in other cleaning technologies, there are other factors which must be considered to maximize the effectiveness of the process. Especially important are those variables which affect the intensity of ultrasonic cavitation in the liquid.

Maximizing Cavitation

Maximizing cavitation of the cleaning liquid is obviously very important to the success of the ultrasonic cleaning process. Several variables affect cavitation intensity.

Temperature is the most important single parameter to be considered in maximizing cavitation intensity. This is because so many liquid properties affecting cavitation intensity are related to temperature. Changes in temperature result in changes in viscosity, the solubility of gas in the liquid, the diffusion rate of dissolved gasses in the liquid, and vapour pressure, all of which affect cavitation intensity. In pure water, the cavitation effect is maximized at approximately 60°C.

The viscosity of a liquid must be minimized for maximum cavitation effect. Viscous liquids are sluggish and cannot respond quickly enough to form cavitation bubbles and violent implosion. The viscosity of most liquids is reduced as temperature is increased.
 
For most effective cavitation, the cleaning liquid must contain as little dissolved gas as possible. Gas dissolved in the liquid is released during the bubble growth phase of cavitation and prevents its violent implosion which is required for the desired ultrasonic effect. The amount of dissolved gas in a liquid is reduced as the liquid temperature is increased.

The diffusion rate of dissolved gasses in a liquid is increased at higher temperatures. This means that liquids at higher temperatures give up dissolved gasses more readily than those at lower temperatures, which aids in minimizing the amount of dissolved gas in the liquid.

A moderate increase in the temperature of a liquid brings it closer to its vapour pressure, meaning that vaporous cavitation is more easily achieved. Vaporous cavitation, in which the cavitation bubbles are filled with the vapour of the cavitating liquid, is the most effective form of cavitation. As the boiling temperature is approached, however, the cavitation intensity is reduced as the liquid starts to boil at the cavitation sites.

Cavitation intensity is directly related to Ultrasonic Power at the power levels generally used in ultrasonic cleaning systems. As power is increased substantially above the cavitation threshold, cavitation intensity levels off and can only be further increased through the use of focusing techniques.

Cavitation intensity is inversely related to Ultrasonic Frequency. As the ultrasonic frequency is increased, cavitation intensity is reduced because of the smaller size of the cavitation bubbles and their resultant less violent implosion. The reduction in cavitation effect at higher frequencies may be overcome by increasing the ultrasonic power.

 
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5. Cleaning Chemical selection is extremely important to the overall success of the ultrasonic cleaning process. The selected chemical must be compatible with the base metal being cleaned and have the capability to remove the soils which are present. It must also cavitate well. Most cleaning chemicals can be used satisfactorily with ultrasonics. Some are formulated especially for use with Ultrasonics. Avoid the non-foaming formulations normally used in spray washing applications. Highly wetted formulations are preferred. Many of the new petroleum cleaners, as well as petroleum and terpene based semi-aqueous cleaners, are compatible with ultrasonics. Use of these formulations may require some special equipment considerations, including increased ultrasonic power, to be effective.


Temperature was mentioned earlier as being important to achieving maximum cavitation. The effectiveness of the cleaning chemical is also related to temperature.

Although the cavitation effect is maximized in pure water at a temperature of approximately 60 deg C, optimum cleaning is often seen at higher or lower temperatures because of the effect that temperature has on the cleaning chemical.

As a general rule, each chemical will perform best at its recommended process temperature regardless of the temperature effect on the ultrasonics. For example, although the maximum ultrasonic effect is achieved at 60°C, most highly caustic cleaners are used at a temperatures of 70 °C because the chemical effect is greatly enhanced by the added temperature. Other cleaners may be found to break down and lose their effectiveness if used at temperatures in excess of as low as 50°C. The best practice is to use a chemical at its maximum recommended temperature not exceeding 60°C.

 
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6. The ultrasonic generator converts electrical energy from the line which is typically alternating current at 50 or 60Hz to electrical energy at the ultrasonic frequency. This is accomplished in a number of ways by various equipment manufacturers. Current ultrasonic generators nearly all use solid state technology.

There have been several relatively recent innovations in ultrasonic generator technology which may enhance the effectiveness of ultrasonic cleaning equipment.

 

These include square wave outputs, slowly or rapidly pulsing the ultrasonic energy on and off and modulating or "sweeping" the frequency of the generator output around the central operating frequency. The most advanced ultrasonic generators have provisions for adjusting a variety of output parameters to customize the ultrasonic energy output for the task.
 
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7. Ultrasonic transducers are the set of piezo electric blocks bonded to a surface which generate the ultrasonic waves on application of the designed electrical signals.

These transducers are either boxed called as submersible transducers or the latest type of Rod transducers
The following applications are possible while placing the transducers in the cleaning tank

  • Base
  • Side emission (one or both sides)
  • Base and side

Effect
When matched to the respective application, transducers can be fitted to the base or side walls of tanks. The sound generated is directed extremely accurately into the liquid by the diaphragm. The high-grade transducer elements developed by Weber Ultrasonics using piezo technology ensure maximum sonic yield and thereby shorter treatment times.  

Rod transducers
offer optimized operational reliability and high performance and are therefore ideal for retrofitting and replacing products from other manufacturers.

  • Excellent service life due to a solid radiating element made of a special titanium alloy
  • Extremely homogeneous sound field without gaps or dips due to omni directional sonic distribution
  • Particularly suitable for cleaning work in vacuum and overpressure environments and for use with reactors, such as those used in ultrasonic chemistry
  • Extremely low space requirement
  • High efficiency of over 95 %
  • Available for the frequencies 25, 30 and 40 kHz

The rod transducers are vacuum- and overpressure-resistant up to 10 bar and are therefore ideal for use in cleaning units. Due to their low space requirements they are also extremely well-suited for subsequent fitting of containers and tanks. They always convince by their high performance

 
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8. Another factor in ultrasonic cleaning concerns the loading of parts or the design of the basket or containers for holding the parts. The loading of parts in the ultrasonic cleaning tank should be such that neither the parts nor the basket are on the tank bottom. The sum of the parts ' cross-sectional areas should not exceed 70% of the tank's cross-sectional area.

Elastomers and non-rigid plastics will absorb ultrasonic energy and should be used cautiously for fixturing. Insulated parts may have to be specifically oriented. Incorrect basket design, or a basket having too high a mass, can greatly reduce the effectiveness of the best ultrasonic cleaning system.
Any material more tightly woven than 50 mesh screen acts as a solid, while slightly larger openings scatter the ultrasonic waves. Openings larger than one-quarter inch tend to act as open material. Hooks, racks, and beakers can also be used to support parts.

The post process of cleaning is generally a good rinsing to remove any aqueous solvents and a good drying. While ultrasonic solvent cleaning and subsequent drying are relatively simple the drying process in aqueous cleaning may need an hot air blast and or vacuum drying.

 
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9. High pressure is obtained by pumping the  solvent under pressure through nozzles .  The nozzles are so located as to cover the entire cleaning area with solvent and to give maximum impingement. The mechanical action is used to force the contaminants off the part in conjunction with the solvating power of the cleaning solution.

 
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10. A very high-pressure spray of liquid in introduced with in the process liquid to create a strong turbulence. This turbulence in the liquid created a effective mass transfer between the chemical (detergent) and the contaminant (oil) and the saponification and the emulsification process is effectively carried out. Due the strong turbulence the liquid reaches all portions of the components including the tiny holes by overcoming the surface tension.

 
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11. Aqueous cleaning generally requires a rinse step to remove residual chemicals and avoid re deposition of contaminants. This is done either by spraying water or immersing the components in water bath. Ultrasonic can also be used in the water bath to effect better results. Rinsing is normally done in two stages. Soft Water rinse followed by rinse with Demineralised  Water.

As soft water contains dissolved salts, only a soft water wash followed by drying may leave behind  these salts on the component leading to staining .This is unacceptable  when the surface finish of the components is a critical factor as in the case of cleaning of  jewellery etc. This is taken care by washing the components with Demineralised water after the soft water wash.
 
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12. Here the components are subjected a very high vacuum of around 600 mbar or more. At this negative pressure water starts boiling at a lower temperature. The entire liquid phase of water is converted to vapour phase. For this the latent heat is drawn from the component. Hence the components have to preheated to a temperature of 80 deg or so. The vapours generated by boiling of water is sucked out by the vacuum pump

 
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