When we work with machines or equipment we have to be aware that their mechanical parts and components are subject to cyclic or variable loads that can trigger in a fracture due to fatigue. The manufacturing process, the technology used or the materials are key to avoiding these problems. Keep reading and discover our 10 recommendations!

Possible causes of a fatigue tear

Rupture due to mechanical fatigue can be triggered by some of the following causes:

• Presence of internal irregularities or discontinuities.
• Irregularities originating in their own machining processes of the pieces.
• Type of geometry of the part. This will influence the speed of crack propagation.
• The influence of the environment: thermal fatigue and corrosion fatigue.

The presence of a small crack in a part can also cause a premature fatigue of the piece. The ends of the crack suppose stress concentration points and Amplify the effect of the action of cyclical or variable loads. Cyclic loads give rise to an internal stress state that It will make the crack progress at its ends, since these points are where a greater concentration of tensions originates. In turn, that crack will increase progressively until its sudden breakage. Despite this, there is no need for high stress levels to occur for the production of a fracture due to fatigue, keep in mind that these can be much lower than the material's own flow limit:

Su = break limitSy = flow limitS'n = fatigue limit

You might be interested in: “Driveshaft Design: Deformations and Problems”

Take note! Elements to consider to prevent fatigue breakage of materials

1. First of all, it is necessary to bear in mind that any variation in the sections of a part or mechanical element constitutes a special area where a concentration of tensions will be generated that will affect their mechanical resistance to fatigue.
2. El geometry type of the part will also influence the speed of propagation of that crack. A design that favors the appearance of areas of stress concentration, changes in section, the presence of key rings, holes or incoming corners, will allow a faster development of the crack.
3. El layout it also has a great influence on the breakage due to mechanical fatigue. Any geometric discontinuity acts as a stress concentrator and is where the fatigue crack can form. The sharper the discontinuity, the more severe the concentration of tensions.
4. Avoid irregularities structural or making modifications to the design, eliminating sudden changes in the contour that lead to sharp edges, will lead to a superior fatigue resistance.
5. Las dimensions of the piece they also influence, increasing their size we obtain a reduction in the fatigue limit.
6. Improving the surface finish by polishing, to avoid small stripes or grooves that appear on the surface of the part as a result of the cut.
7. Hardening surface through carburization and nitriding processes, in which a component is exposed to an atmosphere rich in carbon or nitrogen at high temperatures. This layer is usually 1 mm deep and is harder than the core material.
8. La Alternating or cyclic tension is another element to consider. Its loads act at a high number of cycles before the fault occurs, being one of the main parameters involved in the fatigue resistance of materials.
9. Una Average traction tension worsens The behavior a metal fatigue, since it widens the crack. Instead, one of understanding the improvement.
10. Increase performance by residual efforts of compression within a thin surface layer. The net effect is that the probability of Nucleation of the crack and of fatigue breakage is reduced.

“CLR is investing heavily to provide the best nitriding treatments for our customers' parts”

With all the tips above you can reduce fatigue breaks in your mechanical parts, but it is also vitally important to have vendors that manufacture and manufacture the relevant fatigue tests that help achieve the optimal life cycles of each product. CLR we understand your needs and translate them into products, always complying with the most demanding quality standards, for this purpose we study each case in our testing laboratory, testing the operation of the parts, their limits and each of their features. Do you want to improve your knowledge about manufacturing mechanical parts? This eBook is for you.