1.Why not recommend it?
Insufficient Hardness and Wear Resistance:
Standard shelf positioning pins need to withstand the friction and impact from frequent shelf insertion and removal. They are typically made of medium carbon steel (such as 45# steel) and tempered (quenching + high-temperature tempering) to achieve high hardness and good overall mechanical properties.
Ordinary commercial cold-rolled coils (such as SPCC, DC01) are low-carbon steels. Even in their "fully hardened" state, their hardness is far lower than that of heat-treated medium carbon steel. As positioning pins, they are prone to wear, crushing, and even deformation over long-term use, leading to inaccurate positioning and, in severe cases, sudden breakage, posing a safety hazard.
Lack of Toughness, Prone to Brittle Fracture:
Cold-rolled coils, especially unannealed fully hardened materials, have poor plasticity and toughness. Positioning pins require a certain degree of toughness to prevent sudden brittle fracture under load (especially lateral impact or overload). Cold-rolled coils are insufficient in this regard.
Cross-sectional Shape Limitations:
Positioning pins typically need to be solid round bars. Cold-rolled coils are thin sheets, and to make them into cylindrical pins, they need to go through many complex processes such as rolling, welding, grinding, and straightening, which results in high production costs. Furthermore, the weld seam may become a weak point and a stress concentration point.
2.Under what circumstances can it be used "barely" or "temporarily"?
If cold-rolled coils must be used, they should be limited to extremely light-load, non-critical, and temporary applications, such as:
Lightweight storage shelves and display racks with minimal load-bearing capacity (e.g., each shelf holding only a few kilograms of books or miscellaneous items).
Temporary, non-standard sized shelf positioning.
As a prototype test or one-time use alternative.
3.How to choose materials?
Choose the thickest possible cold-rolled sheet (e.g., ≥3mm) to increase cross-sectional area and bending resistance.
Prioritize high-strength cold-rolled coil grades, such as certain high-strength low-alloy steel (HSLA) grades, which have higher initial strength than ordinary SPCC.
4.How to improve processing technology?
Rolling and Welding: Cut the steel plate into strips, roll them into tightly rolled round tubes, and weld them. The weld must be full, uniform, and ground smooth to reduce stress concentration.
Core Strengthening (Critical Step): To compensate for the shortcomings of the hollow structure, it is strongly recommended to wrap a low-carbon steel rod of matching diameter around the center of the strip before rolling, or to inject a high-strength filler such as epoxy resin into the tube after rolling, turning it into a "solid" or "semi-solid" structure to greatly improve compressive and shear resistance.
Heat Treatment: If conditions permit, the finished pins can be surface carburized or carbonitrided to improve surface hardness and wear resistance. However, this requires a professional heat treatment plant and is costly.
5.What are some usage recommendations for using cold-rolled coils to make formal, load-bearing shelf positioning pins?
The most economical and reliable method: Purchase standard-sized positioning pins directly from the shelving manufacturer or hardware market.
If non-standard sizes are required: Contact a machining plant to machine round steel (bar stock) for guaranteed material properties.
If it's only for temporary, light-load use: If you decide to use cold-rolled coils, be sure to conduct thorough physical load-bearing tests and regular inspections to ensure it won't deform, wear, or break.