1.What are the advantages of using cold-rolled coils to make springs?
High precision and good surface finish: Cold rolling is carried out at room temperature, resulting in springs with high dimensional accuracy and a smooth surface, making them ideal for precision components with strict tolerance and appearance requirements.
High material strength: Cold-rolled spring steel (such as commonly used 65Mn and 60Si2Mn) has already undergone cold strengthening at the factory, possessing inherent high strength. After cold rolling, it typically only requires stress-relieving tempering.
Suitable for springs with small wire diameters and simple shapes: For springs with small wire diameters (usually less than 13-15mm), such as various small-sized flat and round springs, spring clocks, and retaining rings, cold-rolled coils (or cold-drawn steel wire) offer high production efficiency and lower costs.
2.What if the cross-sectional dimensions are large?
If the diameter of the spring wire is large (e.g., more than 16mm), it is difficult to cold roll it at room temperature because the material is too hard. In this case, hot-rolled materials (such as hot-rolled bars or wire rods) are needed for hot rolling.
3.Can it withstand heavy loads or strong impacts?
For large springs such as automotive suspension springs and railway buffer springs that need to withstand huge impacts and alternating loads, hot-rolled alloy steel (such as 60Si2Mn hot-rolled material) is usually used. After hot rolling, it is subjected to quenching and tempering heat treatment to obtain the optimal comprehensive mechanical properties and fatigue resistance.
4.How to choose the right material grade?
"Cold-rolled coil" is the form of material supply; more importantly, it refers to the "material grade." To manufacture springs, specialized spring steel must be selected, such as the commonly available 65Mn and 60Si2Mn cold-rolled coils/strips. These are materials specifically designed for making springs.
5.Is heat treatment required?
Even cold-rolled coils, after being processed into springs, typically require a low-temperature stress-relieving tempering process to stabilize dimensions, eliminate internal stress, and achieve optimal elastic properties.
Simply put, if you are making small springs for precision instruments or electronic products, or snap rings or compression springs with small wire diameters, then cold-rolled coils (such as 65Mn cold-rolled steel strip) are a very suitable and commonly used choice. However, if you are making automotive suspension springs or large buffer springs for heavy machinery, then hot-rolled spring steel should be chosen.