1. What Slotted Angle Iron Is
Slotted angle iron starts as a conventional hot-rolled equal angle and is then punched with a regular pattern of slots, usually along the centreline of one or both legs. The slots accept standard bolts and allow members to be joined at a range of positions, which makes the frame adjustable and easy to take apart. It is a fabrication-ready product rather than a plain structural section.
2. Grades and Properties
Q235 to GB/T 700 is the general structural carbon steel used for most slotted angle, with a minimum yield of about 235 megapascals and good weldability. Q355B to GB/T 1591 raises the minimum yield to about 355 megapascals for racks that carry heavier loads or span further between supports. The higher grade is chosen when the section size must be kept small.
3. Slot Patterns and Sizes
Slot dimensions, pitch and position are usually fixed by the racking system so that components from different suppliers remain compatible. Common angles run from about forty by forty millimetres up to eighty by eighty millimetres, with a slot pitch in the range of fifty millimetres. Buyers should confirm the slot size against the bolts being used and check that the punched edge distances satisfy the design code.
4. Design and Assembly
Because punching removes material, the net section at the slotted leg is reduced and must be used in the strength check. Connections are made with bolts and sometimes with corner brackets, and the joint should be checked for bearing and for slip. Where a rigid frame is needed, bracing members or welded joints are added, since a bolted slotted joint is not fully rigid.
5. Ordering and Finishing
Orders should state the grade, the leg size and thickness, the slot pattern, the length and the finish, which may be as-rolled, painted or hot-dip galvanized. Mill test certificates confirm the steel quality, while the slot dimensions are checked against the drawing or sample. For export supply the angles are bundled, strapped and marked by size and length.
Frequently Asked Questions
Q: What is slotted angle iron used for?
Adjustable shelving, racking, cable trays, supports and temporary frames that are bolted rather than welded.
Q: Why does the grade matter?
A higher grade such as Q355B carries more load from the same section, which matters on heavily loaded racks.
Q: Does punching weaken the angle?
Yes, material is removed, so the reduced net section must be used in the strength check.
Q: Can slot patterns be customized?
Yes, but a standard pattern is usually chosen so that components remain compatible.
Q: How is the surface finished?
Slotted angle is supplied as-rolled, painted or hot-dip galvanized depending on the environment.