Integrated and independent solutions for special requirements
CLEANING TECHNOLOGY » TECHNOLOGY
Cleaning processes ensure flawless processing
At stoba Customized Machinery, the term cleaning refers the necessary preparation of workpieces, as well as the cleaning, preserving, and drying of workpieces after they are machined. The machining corresponds to the selected process, such as metal-cutting machining, electrochemical machining, or laser machining, etc.
There is a wide range of cleaning processes. stoba Customized Machinery primarily uses cleaning processes that are effective for working with ECM and laser processes.
The pre-cleaning process
Cooling lubricant adhering to the workpiece, scaling, dirt, chips, and similar can hinder or even prevent the subsequent processing of the workpieces. The pre-cleaning process therefore usually consists of an actual cleaning step.
Dipping procedure: Immersing the workpieces in cleaning fluid
Medium: Freshwater, freshwater with cleaner, freshwater with corrosion protection, dewatering oil
Mechanics: Simple flushing of the workpieces with cleaning fluid, flow mechanics during descaling, solubility of the cleaning fluid
Use: Simple flushing of the workpieces with cleaning fluid, removal of loosely adhering dirt, dilution of adhering electrolyte from ECM processing, dissolving dried salts, etc.
Dipping procedure with jet nozzles: Immersing the workpieces in cleaning fluid
Medium: Freshwater, freshwater with cleaner, corrosion inhibitor
Mechanics: Targeted flushing of the workpieces with cleaning fluid from directed nozzles or jet lances, intensified and targeted generation of flow mechanics, solubility of the cleaning fluid
Use: Targeted and intensified flushing of the workpieces with cleaning fluid, removal of loose and strongly adhering dirt, in particular in areas of workpieces where the cleaning fluid is only able to reach when immersed as well
Dipping process with ultrasonic support – immersing the workpieces in cleaning fluid and cleaning with ultrasonic pulses
Medium: Freshwater, freshwater with cleaner, freshwater with corrosion protection
Mechanics: Flushing the workpieces with cleaning fluid, cleaning the workpieces via ultrasonic pulses –> The ultrasonic vibrations create the smallest possible bubbles in the cleaning fluid and on the workpiece, which immediately collapse after they have formed. The collapse of these bubbles generates local currents and turbulence, which break off the dirt on the items being cleaned.
Use: Intensified flushing of the workpieces with cleaning fluid, removal of loose and strongly adhering dirt, in particular in areas of workpieces where the cleaning fluid is only able to reach when immersed as well
Dipping process with ultrasonic support and jet nozzles
Works analogously to the “dipping process with ultrasonic support”, but with additional support of the cleaning by jet nozzles and jet lances, which reinforce the cleaning effect inside the workpieces. This is due to the fact that the ultrasonic vibrations are more effective on the outer contour of the workpieces, but weaker in the inner area.
Spray cleaning process – Spraying the workpieces with cleaning fluid
Medium: Freshwater, freshwater with cleaner, freshwater with corrosion protection
Mechanics: Spraying the outer and inner surface of the workpiece with cleaning fluid –> Aligned nozzles and nozzles, which reach into the workpiece via lances, result in part in more intensive cleaning. The workpiece cleaning is achieved and intensified by the mechanical action of the liquid jet. It is possible to more intensively spray partial areas with strongly adhering dirt with nozzles, for which the pressure of the cleaning fluid can be individually set.
Use: Targeted and intense spraying of the workpieces with cleaning fluid, removal of loose and strongly adhering dirt, in particular in areas of workpieces where the cleaning fluid is only able to reach when immersed as well
The post-cleaning process
Medium from machining adhering to the workpiece can disrupt subsequent processes and may lead to reactions with the workpiece surface, such as corrosion. For this reason, the post-cleaning process steps usually include post-cleaning, preserving, and drying.
Preservation process (corrosion protection)
The post-cleaning process not only results in the workpieces being cleaned, but it also gives them an unprotected surface. Many steels immediately react with the ambient air and begin to corrode. It is therefore necessary to preserve the corresponding workpiece immediately after machining by applying a corrosion inhibitor.
These processes are very similar to the processes used for cleaning. In many cases, immersing the workpiece is sufficient to protect it. However, with some workpieces additional spray lances should be used in order to ensure application of corrosion inhibitors to the workpiece interior.
Medium: Water or oil-based corrosion inhibitors
Mechanics: Deposition of the corrosion inhibitor on the workpiece surface
Use: Various agents to provide the workpiece with long or short-term protection against corrosion –> In general, oil-based corrosion inhibitors provide longer protection than water-based and are also more robust in their durability. Therefore, they are often used at the end of a production chain before the workpieces are put in storage or transported. If the corrosion inhibitor is to be applied only for interim storage until the next processing step, water-based corrosion inhibitors are advantageous since oil-based ones must be cleaned off before the next processing step (e.g. workpiece hardening). Water-based corrosion inhibitors, however, must be applied during a controlled drying process.
A drying process is necessary if workpieces wet with fluid medium are to be available quickly and dry. The adhering fluid is otherwise carried off with the workpiece. The result is the contamination of the environment, manufacturing, assembly sites, and other workpieces. In the simplest case, it would suffice for the workpieces to have enough time to drain and dry in the air. However, in general there is not time for this. This is where drying processes come into play, which shorten the drying time. When water-based corrosion inhibitors are in use, the option to individually design the drying process for the workpiece results in a uniform distribution of the active medium on the workpiece.
Draining: It’s a lengthy process, but requires no mechanical effort, mainly for oil-based corrosion inhibitors
Blowing off: With compressed air or a blower, it is not very easy to control, has a low degree of mechanical complexity, is expensive, and, in the event of air flow that is too strong, tends to leave behind a film from the corrosion inhibitor.
Recirculating air drying with hot air: Electric air blower with heating, easily controllable regulation of the air flow speed and its temperature –> The mechanical complexity increases. During circulating air drying with hot air, water is evaporated with a controllable hot air flow with high air performance. Use on smooth surfaces and workpieces without scooping effects
Vacuum drying: An electric vacuum pump creates a vacuum in a chamber where the workpiece is located. Vacuum drying ensures effective and fast drying of workpieces with complex geometry. It is used with water-based cleaning agents when, for example, the workpiece structure contains deep and narrow blind holes. By reducing the ambient air pressure in the vacuum chamber, the boiling point for the liquid adhering to the workpiece is simultaneously reduced. The water evaporates completely even at low temperatures. With water-based corrosion protection solutions, the corrosion protection settles as a very thin film on the surface of the workpiece while the water evaporates.
CLEANING TECHNOLOGY » Applications
Stand-alone cleaning systems for special requirements
stoba Customized Machinery supplies cleaning systems combined with machines for electrochemical machining as well as stand-alone units. The stand-alone cleaning machines are often special equipment used to clean metallic workpieces after conventional manufacturing. The cleaning process usually involves the steps of cleaning, preserving, and drying. Cleaning is carried out according to customer specifications and within the common purity class of the respective industry.
In combination with electrochemical systems, the requirement for the cleaning step is, in most cases, the cleaning off of the electrolyte solution and metal hydroxides, the application of corrosion protection to the workpieces, and the drying of the workpieces.
In many cases, the workpieces go through a final cleaning process at the customer after production. In addition, it is often necessary that they be desalted following ECM treatment, because in most cases the washing system is not designed for entry of salt water.
To desalt the workpieces, they are immersed in water-based rinsing baths and are often sprayed around and through with nozzles as well. This way the adhering salt water is diluted with the rinse water. A maximum acceptable salinity previously set for the bath controls the process. If the single-stage pass is not sufficient, another step can be added if necessary. After desalting, the entry of salts into the washing machine is not critical.
Desalting tank for workpieces: Use after electrochemical machining –> The workpieces are covered with electrolyte, i.e. salt water. Many cleaning machines are not designed for entry of salt water. If they are supplied with even smaller amounts of salt water for a long time there is a risk that individual components may rust at the very least. When treating the workpieces in the desalting tank, they are either immersed in fresh water or sprayed off to reduce the amount of adhering salt water to a safe level for the subsequent cleaning process.
The workpieces are cleaned once or repeatedly in downstream steps. The cleaning stations may include all previously described processes. For cleaning, mostly water-based solutions are used with a cleaning additive. The cleaning takes place in manually or automatically loaded tanks as well as in special cleaning chambers or stations. It is necessary to spray the cleaning fluid through targeted nozzles or flush for very fine workpiece contours.
Preserving the workpieces is based on a similar principle as cleaning.
With workpieces made of steel alloys in particular, it is usually imperative that they are preserved immediately after cleaning to prevent corrosion. In this case, it has proven to be highly effective that the preservative be injected specifically by means of nozzles into the workpiece structures. For preserving, mostly water-based solutions are used with a preservation additive. Oil-based preservatives however may also be used. Oil-based preservatives usually have a stronger corrosion protection, but they must first be cleaned again for many other manufacturing steps.
Drying the workpieces
The drying takes place almost exclusively after cleaning and preserving with water-based solutions. With oil-based preservatives, it is sufficient to allow the workpieces to drain off on their own.
For water-based processes, only the drying process in which the water has evaporated from the workpiece and the preservative rests as a uniformly thin film on the workpiece inside and outside provides the desired result.
CLEANING TECHNOLOGY » Products
beta – system solutions
Combined machining cells with integrated workpiece cleaning
- Cells integrated into the processing station for the pre- and post-cleaning of the workpieces to be machined, preservation and drying of the machined workpieces
- Stationary multi-chamber cleaning systems that are adapted to the special cleaning requirements of the respective workpieces
- The cleaning and post-treatment of the workpieces takes place predominantly with water-based cleaners and preservatives. Oil-based post-cleaning is also possible.
- The processing and cleaning process is fully automatic.
- The combined cells ensure that the workpieces are machined and treated in the shortest amount of time possible and feature space-saving construction, high availability, and low operating costs.
- Combined with stoba ECM/PECM systems
- Control: SIEMENS, Beckhoff
epsilon – Cleaning system
Many years of expertise in system design for industrial cleaning technology
- Suitable for processes such as pre-cleaning, post-cleaning, preserving, and drying
- Water-based mobile or stationary multi-chamber cleaning systems
- Standardized or customer-specific solutions adapted to the needs of the customer
- Manual and fully automated concepts
- Subsequent extension and expansion possible
- Low operating costs with high availability
- Can be combined with stoba ECM/PECM systems
- Control: Siemens, Beckhoff
omega – Cleaning system
The workpiece optimized special solution for parts cleaning
- Stand-alone processing machine using rotary transfer concept with integrated treatment stations
- The omega is designed as an 8 or 4-station machine. Equipped as a special machine, which is specifically used for the precise cleaning of long workpieces
- Treatment steps required to effectively clean, safely preserve, and effectively dry workpieces
- The cleaning technology ensures that cleaning is carried out so effectively inside and outside even with long workpieces that the highest cleanliness requirements are achieved
- The treatment takes place in a chamber tanks. The individual chambers contain cleaning tools adapted to the workpiece to treat the workpieces by means of flooding, spraying, blowing off, hot air, and vacuum drying.
- Specific cleaning of serial production parts
- Can be combined with stoba ECM/PECM systems
- Control: SIEMENS