The key role of ultrasonic cleaning in the production of springs
The cleanliness level of springs is a crucial aspect of their production cycle. Especially when they are designed for critical applications. Springs are present in a wide variety of items. Some do not require high mechanical and quality characteristics. However, there are some specific sectors, such as the biomedical and aviation industry, in which these products have to meet very strict requirements. Especially in these sectors, ultrasonic cleaning plays a key role during the production process.
Springs vary in size from a few hundredths to tens of millimetres in diameter. The diversity of materials used is enormous. For specific applications you use titanium and precious alloys such as platinum-iridium, gold and tungsten gold. Finally, there are springs and actuators in shape memory materials, a class of metals with specific mechanical properties. They are able to revert to a preset shape due to the simple change of temperature.
The production cycle of springs
The first stages of a spring's production cycle are the same for all types of products. Once the product is defined, the process begins with making the spring itself. The wire is placed in a machine specifically equipped according to the type of product, such as a torsion spring or a tension spring, for example. Generally, you will proceed to wind the feather. For example, a drawing treatment and in the case of a compression spring, a grinding operation. You can have various processes followed on this operation. From increasing fatigue resistance from shot blasting with metal media, to galvanic protection treatment.
Finally, you can perform additional steps such as destructive and non-destructive tests, deburring operations or decontamination with glass beads. Within the production cycle you always clean the parts before, but sometimes also after the thermal treatment. Cleaning before the heat treatment is crucial and is carried out on almost all products.
Problems that occur
There are two main problems that can arise during the heat treatment. One of the problems is that the springs that have been touched with bare hands can corrode. The second problem may be due to the presence of dirt or material residues, which can contaminate alloys. For example, with nickel superalloys, microscopic particles of iron powder or dirt in the first heat treatment, which exceeds 1100 ° C, can result in contamination. That is why the parts must be perfectly clean.
In the case of industries that require the highest levels of quality, you even run the cleaning process several times: before and after the heat treatment, and at the end of the production process. Superficial grease or dirt can be removed with a mild cleaning process based on water and detergent, with spray washing and ultrasonic cleaning.
During cleaning, the springs lie on a specific mould so that the delicate products do not deform. The first cleaning phase consists of an immersion in the solvent at a low temperature. Ultrasonic agitation enhances the cleaning effect. In the second stage, the parts undergo a vapor cleaning step. The last particles and oil are removed by the distilled solvent. After the cleaning operations, the basket stops for drying. In a cold zone the solvent condenses and drips back into the tank. You continuously filter particles from the solvent. The closed distillation cycle keeps the solvent free from oil. Periodic tank cleaning therefore contributes to stable results. In order to meet the strict cleanliness requirements of some sectors, cleaning with solvents is a must, for example to obtain the Nadcap certification.
Do you have any questions about the cleaning process? Or do you want to apply this to your production? Then contact our cleaning specialist.
