Drum Spring Shot Blasting Machine

This is the most important contribution of shot peening to springs.

1. Introducing Residual Compressive Stress

• Principle: Countless high-speed shots (small steel balls) violently impact the spring surface, causing tiny plastic deformations in the surface metal. When this layer of metal tries to return to its original state, it is restrained by the underlying undeformed metal, thereby forming a stable layer of residual compressive stress on the spring's surface.

• Benefit: Springs are subjected to alternating tensile stress during operation (repeated compression and extension). This pre-existing compressive stress effectively counteracts a portion of the operational tensile stress, thereby significantly delaying the initiation and propagation of fatigue micro-cracks. It's like putting a "protective suit" on the spring.

2. Eliminating the Harmful Effects of Surface Defects

• During rolling, coiling, and grinding, the spring surface inevitably develops minor scratches, folds, or decarburization layers. These areas are stress concentrators and are the most likely places for fatigue cracks to initiate.

• The shot peening process can "hammer flat" or obscure these minor defects, creating a smoother, more uniform stress layer and eliminating potential crack initiation sites.

Simple Analogy: This is similar to tempering glass. Ordinary glass shatters easily, but tempered glass has a compressive stress layer on its surface, multiplying its strength and impact resistance. Shot peening is a similar "tempering" process for springs.

II. Surface Cleaning Effect

This is the most basic function of shot blasting and is equally important for springs.

1. Removing Scale: After heat treatment (such as quenching and tempering), a layer of scale (blue or black oxide layer) forms on the spring surface. Shot blasting thoroughly removes this scale.

2. Removing Burrs and Rust: It removes minor burrs generated during the spring's manufacturing process, as well as any slight rust that may be present.

III. Achieving a Uniform Surface Appearance

After shot peening, the spring surface acquires a uniform, non-glossy, matte finish. This results in better appearance quality and also facilitates subsequent painting or plating processes.

Why Are "Barrel Type" Shot Blasting Machines Commonly Used for Springs?

This is closely related to the characteristics of springs and production needs:

• Batch Processing, High Efficiency: Springs are typically small to medium-sized components with high demand. Barrel shot blasting machines can load a large number of springs at once. As the barrel rotates continuously, the springs and shot mix and tumble thoroughly, ensuring every surface of each spring is treated evenly. This is ideal for mass production.

• Resistant to Impact: Springs themselves are resilient metal parts. Mutual collision inside the barrel generally does not cause damage, making them very suitable for this tumbling processing method.

• Cost-Effective: Compared to robotic or continuous pass-through shot blasting machines, barrel-type equipment has lower initial investment and operating costs, making it a highly cost-effective choice for processing standard components like springs.

Summary

Looking at the combination of "barrel shot blasting machine" and "shot peening springs," the main role and process can be summarized as follows:

Loading a large quantity of springs into the barrel shot blasting machine → Starting the machine, the barrel rotates causing the springs to tumble continuously → The blast wheel throws a large number of shots at high speed, uniformly impacting all spring surfaces → Achieving the dual purposes of 【Surface Cleaning】 and 【Introducing Residual Compressive Stress】 → Finally obtaining clean, aesthetically pleasing, and high-quality springs with a 【fatigue life extended by several times to tens of times】.