Market research has revealed a significant technology gap between industries as far as recycling theme is concerned, particularly among those specialized in the processing of high-value metals used in the aerospace industry and associated manufacturing environments.
In fact, materials such as aluminum alloys and titanium require a considerable amount of resources: these high quality components are machined from a solid block thus forming a large quantities of turnings.
This waste material can be reused as long as it is properly cleaned.
The last four years have seen huge investments by FIRBIMATIC for the production of hermetically sealed solvent degreasing machines for cleaning waste materials, able to guarantee perfect cleaning of the turnings and their subsequent reuse.
Solvent washing of turnings and legislation on emissions
For several years, industrial operators have focused on a series of processes (centrifuge, pressure washing and open tank systems) that used organic solvents such as trichlorethylene.
Over time these substances have proved to be dangerous for the health of operators to the point that many European and international citizens have asked for their disposal.
Trichlorethylene has been progressively replaced by alternative organic solvents such as modified alcohols and perchlorethylene, both characterized by high solvency values (Kauri Butanol) and, for this reason, ideal for the removal of cutting and processing oils used in engineering precision.
>> Click on the link for more information on the safe use of Perchlorethylene for washing metals.
However, the type of cleaning solvent used for metal washing is only part of the overall solution.
It is essential that the washing system used:
- complies with emission regulations and guarantees total operator protection at all times;
- is able to guarantee a high level of cleanliness of the turnings and respectful of the TOC (Total Organic Compound) standard, usually equal to 0.04%;
- returns the turnings, at the end of the dry cleaning cycle, ready to be recycled.
This last point represents the challenge of companies like ours.
With a batch size of typically 500 – 750 kg the turnings must be completely immersed in the cleaning solvent and mechanically handled during the washing process so that the solvent comes into perfect contact with the material .
The mechanical movement described above is also required when parts with a smaller surface area are treated, mainly during the drying process.
This particular phase of the washing cycle, due to the residual thermal dispersion generated by the latent heat of evaporation, must be a combination of vacuum and recirculating hot air.
The rotation of the basket allows this mechanical action and remains the most efficient method of achieving intense and uniform cleaning and drying.
Furthermore, additional plates or “paddles” strategically placed in the machine basket further improve turnings separation.
Turning size and basket size
The size of the turnings to be washed also determines the choice of the mesh size of the basket.
Analysis and industry tests have revealed that a rectangular basket with a square section is perfectly suitable for this type of application, allowing the use of solvent washing systems with fully automatic loading and a dedicated unloading system.
This configuration allows operators to get involved in other activities.
Of course, during the cleaning cycle the solvent will be contaminated and therefore it must be filtered and cleaned: a double distillation process is required which makes the distilled solvent available ready for use at each washing cycle.
Finally, the steam rinse completes the cycles and assure excellent cleaning results.
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