Stainless steel (SUS) is a material that is not easy to rust as its name suggests, and is used in various applications. However, from the perspective of mechanism designers, it is a material that is not easy to worry about. I think many people have had several painful experiences. To avoid problems, it is necessary to use stainless steel based on the understanding of its characteristics.
Overview of Stainless Steel (SUS)
Stainless steel is an alloy that is not easy to rust. It has iron (Fe) as its main component (more than 50%) and contains more than 10.5% chromium (Cr). Many types, including martensitic, ferritic, austenitic, etc., have different mechanical properties.
Huaxiao Metal believes that Stainless Steel (SUS) has its Characteristics
“Advantages of stainless steel” include high strength. Specifically, when the thickness of sheet metal parts must be controlled below 1mm, ordinary steel plates can be easily deformed by hand. Stainless steel has sufficient strength as a mechanical part, so parts with a thickness of 0.6mm can also be used. However, using SUS has many disadvantages, and stainless steel can also be a headache.
Disadvantages of Stainless Steel (SUS)
① Stickiness
Stainless steel is a sticky material.
For example, stainless steel is not easy to slide compared to other metals, so sometimes the spring force is insufficient and the mechanism does not work. The reason is that the friction coefficient of stainless steel is about twice that of steel plate.
② It becomes hard when bent
When stainless steel is used to test sheet metal parts, it becomes quite hard during bending. The reason is that hardening occurs during processing, and its index n value is about twice that of steel plate, so special attention needs to be paid. Since it is not reprocessable, it must be processed in one go.
Advantages of Stainless Steel (SUS)
① High Rigidity
Elastic modulus and allowable stress are rigidity indicators, and stainless steel has higher values, so it is a material that is not easy to bend or deform. Therefore, if parts that are not strong enough when using ordinary steel plates are replaced with SUS, the design can be easily completed.
② Cleanliness
Stainless steel is also a material that meets the standards of food factories, so it is also used in sinks that are familiar to families. It is also a material that can cope with special uses such as food production equipment and chemical plants.
Precautions for Stainless Steel (SUS)
The Meshing phenomenon of Stainless Steel (SUS)
The most important thing to be careful about with stainless steel is the phenomenon of meshing (sintering).
This phenomenon is particularly evident in SUS screws, etc. If you use an electric screwdriver to tighten the screws, the external and internal threads will stick together and cannot be unscrewed. Therefore, during maintenance, the screws cannot be removed, resulting in fatal consequences. In the worst case, all related parts need to be replaced.
| High Friction Coefficient | Low Thermal Conductivity | High Thermal Expansion Coefficient |
|---|---|---|
| Frictional heat is generated | Frictional heat does not dissipate | Screws stick |
How to Avoid the Meshing Phenomenon?
In the case of SUS screws, the meshing can be reduced by applying a surface coating. In addition, the meshing can be reduced by properly managing the tightening torque or not using an electric screwdriver.
In Conclusion
Stainless steel (SUS) is a material that requires careful use, but it can achieve designs that cannot be achieved with other materials. The design quality can be improved as long as the material is used according to its nature.