Modern warehouses rarely store just one type of material. A typical metal service center, for example, may handle steel pipes, aluminum extrusions, copper tubing, and plastic profiles—all with different weights, surface sensitivities, and length requirements. Using separate racking systems for each material type wastes floor space and complicates inventory management. Herochu has developed a versatile double single side shelving system that functions as a heavy-duty cantilever racking solution capable of storing both aluminum and steel products in the same footprint. This article examines the dual-material design considerations, surface protection strategies, load capacity differentiation, and operational workflows enabled by this hybrid storage system.

Understanding Double Single Side Configuration

The term “double single side” refers to a rack configuration where two independent single-sided racks share a common central column line but face opposite directions. This is distinct from a true double-sided rack where arms on both sides are fixed to the same column. In the double single side system, each side has its own set of columns that are bolted back-to-back. This allows the two sides to have different arm lengths, different vertical spacings, and different load ratings. For example, the steel side might have short, heavy-duty arms rated for 1,500 kg, while the aluminum side has longer, lighter arms rated for 800 kg. The separation also prevents cross-contamination of materials, important when storing aluminum and steel together, as galvanic corrosion can occur if dissimilar metals are in prolonged contact.

Material-Specific Surface Protection

Aluminum storage requires special attention to surface marking. Aluminum extrusions and sheets are easily scratched, and even minor surface damage can render them unacceptable for architectural or automotive applications. Herochu addresses this by fitting the aluminum side of the rack with full-length nylon arm covers instead of the standard UHMW strips used for steel. These nylon covers are softer and have a lower coefficient of friction, allowing aluminum profiles to slide without scratching. The arm tips are fitted with bulbous rubber nose guards that prevent the sharp aluminum ends from contacting the steel arm structure. For the steel side, standard galvanized arms are used, as steel’s higher hardness means it is less susceptible to surface damage during normal handling.

Load Capacity Gradients Within the Same Rack

A key advantage of the double single side system is the ability to have different load capacities on each side without compromising structural integrity. The steel side columns are fabricated from 4.5 mm thick SS401 steel, while the aluminum side columns use 3.0 mm thickness. This thickness difference is accommodated by the back-to-back bolting arrangement, where each column set is independently anchored to the floor. The steel side arms are rated for 1,500 kg each, with a maximum per-level load of 3,000 kg when using dual arms. The aluminum side arms are rated for 500 kg each, with a per-level maximum of 1,000 kg. The floor anchoring system uses separate anchor bolts for each column set, allowing the concrete slab to receive loads from both sides without overstressing any single anchor point.

Aluminum Storage Considerations for Long Profiles

Aluminum is often supplied in very long lengths, sometimes exceeding 12,000 mm for extruded sections used in window frames or curtain walls. Herochu’s double single side system can accommodate these lengths through extended arm designs and increased column spacing. For aluminum, arm spacing can be reduced to 1,000 mm because aluminum’s lower modulus of elasticity makes it more prone to sagging between supports compared to steel. The nylon arm covers are extended to cover the full arm length, and additional intermediate supports can be added between the primary columns. For extremely long aluminum profiles, Herochu offers a roller track attachment that converts the cantilever arms into a gravity-fed storage system, where profiles are loaded from one end and roll toward a stop, allowing first-in-first-out inventory rotation.

Steel Storage on the Opposite Side

While the aluminum side focuses on surface protection, the steel side prioritizes raw strength and impact resistance. Steel pipes, bars, and structural sections are typically heavier and more abrasive than aluminum. The steel side arms are left uncoated except for galvanization, providing a durable surface that can withstand the sliding of steel bundles. Arm capacities on the steel side are calculated conservatively, with a 2:1 safety factor against bending. For storing steel coils or short heavy sections, Herochu offers optional coil cradles that bolt to the cantilever arms, converting them into curved supports that prevent rolling. The steel side also features reinforced column bases with 10 mm thick gusset plates to absorb the higher impact forces associated with steel handling.

Warehouse Space Utilization Metrics

The double single side configuration delivers exceptional space utilization because it eliminates the need for separate racking zones for different materials. A typical warehouse storing both steel and aluminum might dedicate 40% of floor space to steel racks and another 30% to aluminum racks, with the remaining 30% for aisles. With the Herochu double single side system, the same storage volume can be achieved in approximately 50% of the floor area because the central aisle serves both material types. The total floor space reduction varies based on material mix, but most facilities report savings of 25-35% compared to separate rack systems. Additionally, inventory accuracy improves because pickers can access both steel and aluminum in the same aisle sequence, reducing travel time between different storage zones.

Operational Workflow and Picking Efficiency

The double single side system supports two distinct picking workflows. For high-turnover materials, pickers can work from the central aisle, accessing both steel and aluminum without moving to a different aisle. This is particularly valuable when picking orders that contain both material types, such as a fabrication job requiring steel structural sections and aluminum trim pieces. For lower-turnover materials stored at the back of the arms, operators can walk around the end of the rack to access the opposite side. Herochu recommends a minimum end aisle width of 1,500 mm for this purpose. For facilities with very high throughput, an overhead bridge crane can be positioned to serve both sides of the double single side rack, with the crane’s long travel axis aligned with the rack’s length.

Customization for Mixed Material Inventories

No two warehouses have the exact same mix of steel and aluminum products. Herochu offers extensive customization options for the double single side system. Arm lengths on each side can be specified independently, from 400 mm to 1,200 mm. Column heights can differ as well, with the steel side potentially taller to accommodate longer vertical clearances for heavy sections. The number of levels per side can vary; a warehouse might have four levels on the steel side for storing various pipe diameters but only two levels on the aluminum side for storing tall extrusion bundles. All custom dimensions are modeled using finite element analysis to ensure that the asymmetric loading does not cause the back-to-back columns to separate or lean. Installation includes laser alignment verification, with final tolerances of ±2 mm in level and ±3 mm in plumb.

Long-Term Maintenance and Component Replacement

Both the steel and aluminum sides of the rack are designed for independent maintenance. Worn nylon arm covers on the aluminum side can be replaced without disturbing the steel side arms. Similarly, a damaged steel side arm can be unbolted and replaced while the aluminum side remains fully loaded. Herochu maintains a spare parts inventory for all standard components, including arms, column protectors, pivot locks, and nylon covers. For the aluminum side, replacement nylon covers are available in rolls, allowing warehouse staff to cut them to exact length on site. The recommended inspection interval for mixed-material racks is every six months, focusing on the interface between the two column sets for any signs of loosening or corrosion.

Conclusion

The Herochu double single side shelving system offers a practical solution for warehouses that store both aluminum and steel products. By providing independent configurations on each side of a common column line, this heavy-duty cantilever racking system maximizes space utilization while respecting the different handling requirements of each material. Surface protection for aluminum, high load capacity for steel, and flexible customization options make this system suitable for metal service centers, fabrication shops, and distribution warehouses. Investing in a purpose-built mixed-material rack reduces floor space needs, improves picking efficiency, and protects valuable inventory from damage.