Choosing Sheet Metal Thickness Without Guessing
Choosing sheet metal thickness starts with deflection, then strength, then what the brake can form. Why doubling thickness gives about 8x the stiffness.
Most people pick 16 gauge because the last bracket was 16 gauge. That's not a crazy habit, but choosing sheet metal thickness on purpose usually saves money or a redesign.
How Do Engineers Decide How Thick Sheet Metal Should Be?
Start from how much the part can deflect, then check strength, then check what the press brake can form. A thicker sheet is rarely the cheapest way to make a part stiffer.
That's the question an r/SolidWorks user asked about a bent steel bracket bolted down through two holes in its base plate: how do you determine your sheet metal thickness, and how do you check the design is strong enough?
Stiffness first when choosing sheet metal thickness
A flat sheet bends like a wide, thin beam. The Engineering ToolBox gives a rectangle's area moment of inertia as b h³ / 12, where h is the thickness. That cube is the whole story. Double the thickness and a flat panel gets about eight times stiffer, along with twice the weight and material cost.
A bend does the same job more cheaply. A flange turns a thin, flat section into a deep one, and the flange height is what gets cubed. That's why a stiffening rib or flange often beats going up two gauges.
Strength usually comes second. Most brackets flex too much long before the sheet yields. Holes, slots and sharp notches near the load are where cracks start, so check those spots.
The forming side
Thickness drives everything at the press brake. Thicker sheet needs a wider die, a larger inside radius and a longer minimum flange, as covered in choosing a V-die opening and the shortest flange you can bend. So a flange that worked at 18 gauge may not form at 11.
Gauge numbers don't mean the same thickness across materials either. Draw the decimal thickness, not just "16 ga".
What we check
Our sheet metal page covers "30 gauge up to 1 inch depending on material". The automatic checks include "Bend count, angle and inner radius against material thickness" and "Bend collisions and minimum flange length", so a flange that's too short for the gauge gets flagged before you order.
Pick the thinnest sheet that passes your deflection limit with a flange, then go up one gauge if it'll get abused in the field.
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