Technology / product information

In the machinery and automotive industries, metal fatigue is a primary cause of premature cracking and failure in high-stress components such as gears, shafts, and powertrain parts. The Shot Peening process is a mechanical surface treatment that enhances fatigue strength by creating a compressive residual stress layer on the metal surface. This compressive stress counteracts tensile forces that cause cracking, extending component life without introducing heat or altering the material structure.

Process Principle
Shot Peening uses high-pressure air to shoot small metallic or ceramic shots onto the surface of the workpiece. Each impact creates microscopic indentations that produce a compressive residual stress field, strengthening the surface and increasing resistance to fatigue and cracking. Because the process is conducted at room temperature (approximately 25 °C), it does not affect the metallurgical structure of previously heat-treated materials. The intensity and coverage can be precisely controlled according to the component’s geometry and functional requirements.

Properties After Treatment
Surface hardness: 800–1000 HV
Formation of compressive residual stress that reduces fatigue and crack propagation
Enhanced wear resistance and impact toughness
No change or reduction in the existing martensitic structure or hardness
Compatible with previously hardened or carburized components

Applicable Materials
Shot Peening is most effective on steels that have undergone quenching & tempering or carburizing & quenching, maintaining a stable martensitic structure, such as SCM420, SNCM439, SCr420 and other alloy steels used in high-strength, fatigue-prone mechanical components.

Applications & Use Cases
Widely applied in automotive, machinery, and power transmission industries to enhance fatigue strength of critical parts, including Bevel Gears, Pinion Gears, Counter Shafts. The process accommodates workpieces up to φ500 × 500 mm or φ270 × 900 mm, using Nozzle Type and Impeller Type peening machines that deliver stable air pressure and consistent impact energy.

Advantages of Shot Peening
Extends metal fatigue life by several times
Improves surface hardness and resistance to cracking
No heat input eliminates risk of dimensional change or distortion
Ideal for maintenance and reconditioning of high-load components
Highly controllable process parameters such as air pressure, shot size, and peening distance

Summary
Shot Peening is a surface strengthening process performed at room temperature to enhance fatigue resistance by generating compressive residual stress on the metal surface. The treated surface achieves hardness levels of 800–1000 HV without altering the base structure, making it ideal for gears, spindles, and drive shafts in high-load applications that demand long-term reliability and fatigue strength.

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