Lightweight construction, new or modified manufacturing and coating technologies and materials, and autonomous vehicles are some of the trends that are presenting new challenges for a wide range of industrial sectors. Nevertheless, these have implications for industrial parts cleaning, too. On one hand, manufacturers now often have to meet more exacting standards of particulate cleanliness; while on the other hand, there is a growing focus on the need to remove film-type residues, staining and discoloration as well as, in certain sectors of the industry, biological and ionic contaminants. As a result, wet chemical for fine and ultra-fine cleaning will become more mainstream as will alternative cleaning processes, such as, CO2 snow blasting. This, in turn, will lead to increased demand for controlled manufacturing environments engineered for cleanliness.
Fine and ultra-fine cleaning
As with all wet chemical cleaning processes, the key to consistently reliable results, at affordable cost in fine and ultra-fine cleaning is a set of solutions (in terms of chemistry, media preparation and measuring/testing technology) that are all designed to work well together. When choosing a suitable cleaning agent, the chemical principle ‘like dissolves like’ is a useful guide. To enhance the effect of the cleaning medium and deliver it to the site of the contamination, a variety of physical processes are employed. These include spraying, immersion, ultrasound, pressure flushing, and cyclical nucleation (CNp). Like ultrasound cleaning, the last-named process is based on the physical effect known as cavitation, which is here combined with an asymmetric volume flow rate. This combination makes it possible to dislodge particulate and film-like contaminants even from very fine capillaries, borings and 3D structures with consistently reliable results and without damaging the substrate material. The cleaning is carried out under vacuum pressure in an enclosed chamber filled with a water-based cleaning agent.
When it comes to plant design, fine and ultra-fine cleaning operations can be carried out in closed-circuit systems with one or more chambers or in multi-stage immersion cleaning systems. Chamber systems, where the cleaning agent is delivered to the contaminated components, should be equipped with several flooding tanks, each with its own separate filtration system. Features, such as, an electropolished chamber with integral wall flushing and appropriate pipework, also help to avoid recontamination of the cleaned components by the backflow of dirt or the formation of dirt traps inside the chamber. Multi-stage immersion cleaning systems operate the other way round from chamber systems; instead of delivering the cleaning agent to the components, they bring the components to the cleaning agent.
Any number of treatment stations can be linked together in sequence. This makes it possible to integrate multiple cleaning stages using different media, with or without rinsing baths between stages or to incorporate rinsing stages using different water qualities.
In order to ensure constant cleaning outcomes when using water-based processes, it is important to monitor these processes and check key process parameters at regular intervals. A fundamental requirement is the continuous removal of dislodged contaminants from the cleaning bath. This is achieved through an effective bath maintenance regime based on the use of cartridge filters, micro and ultra-fine filtration and the removal of oil by means of distillation or gravity separators designed to deal with the specific type and quantity of contaminant.
Solutions for selective dry cleaning
Selective dry cleaning of functional surfaces and designated areas of components, as required typically prior to coating, adhesive bonding, sealing, laser welding or assembly and of pre-assembled parts can be carried out using processes, such as CO2 snow jet cleaning, laser cleaning or plasma cleaning. Another advantage of these processes is that they lend themselves readily to automation and can be integrated into networked manufacturing environments. Dry cleaning processes are also a practical alternative where lightweight materials are involved.
Controlled manufacturing environments
Precision-made components are highly sensitive to particulate contaminants, such as, manufacturing residues or dust and fluff. So, there is a growing need for controlled manufacturing environments engineered for cleanliness. This holds true for sectors from the car industry to medical technology, where components have mostly been produced hitherto in a ‘normal’ manufacturing environment. The objective is to protect the product against harmful particulate contaminants during manufacturing and processing. The question is whether that calls for a clean zone, white room or clean room. The main technical difference between a white room and a clean room lies in the type of ventilation and filtration technology used.
A clean zone is typically isolated from potentially critical areas by floor markings, moveable partitions or ceiling aprons. A white room is a permanently installed, structurally segregated enclosed space where the transfer of staff and materials is organised so as to avoid contamination and also, where the staff is specially trained. If the enclosed space is also equipped with clean air technology in the form of high-performance particulate air filters, then it’s called a ‘clean room’, when a specific ISO air purity class has to be maintained for the manufacturing operation. Clean room air quality has to be checked regularly and so-called particulate traps are available for measuring the ambient cleanliness of clean zones and white rooms.
In the so-called ‘clean machine concept’, which may be a more compact and practical alternative to the clean room for highly automated production lines, the requisite decontamination technology is confined to the actual production line itself. In parts cleaning applications, this solution is used in multi-stage immersion cleaning systems, where the cleaning baths are fully enclosed with their own supply of purified air. The cleaned parts are frequently discharged into a clean room via a material air lock.
parts2clean, a leading international trade fair for parts and surface cleaning, answers all questions in aspects of industrial parts cleaning, from what are the emerging trends in industrial parts cleaning to what solutions are available to meet current and future cleanliness specifications with consistently reliable results and at an affordable cost. The fair will take place on October 23 –25, 2018, at the Stuttgart Exhibition Centre (Germany). It provides comprehensive information about cleaning systems, cleaning agents, clean room technology, cleaning baths and tanks, handling and automation, and research and trade publications.
For fine-cleaning applications, features, such as, an electropolished chamber with integral wall flushing, help to avoid recontamination of the cleaned components by the backflow of dirt or the formation of dirt traps inside the chamber. Cyclical nucleation enables manufacturers to remove contaminants effectively, even from fine capillaries.
Easy to automate and integrate into networked manufacturing environments, CO2 snow jet cleaning permits selective cleaning of functional surfaces as well as that of complete components and assemblies. The cleaned parts are discharged into the clean room via a material air lock after passing through a fully enclosed cleaning line, equipped with its own supply of purified air.
With aqueous media, the concentration of cleaning agents can easily be monitored inline or with a mobile device.