Conical Mandrel Bend Tester

QT-CMT Operating Principle

Instead of swapping out multiple separate cylindrical bars for a single test series, the QT-CMT Conical Mandrel Bend Tester utilizes a solid metal cone that transitions smoothly from a wide 38-millimeter base down to a very narrow 3.1-millimeter tip across a 203-millimeter length. The core scientific principle here is satisfyingly straightforward: as the bending radius gets smaller toward the tip, the outward-facing paint layer experiences significantly heavier tensile stretching. 

In one single, fluid motion, your painted metal sheet undergoes a broad spectrum of physical stress simultaneously. This unique geometry allows quality assurance operators to easily spot the precise mathematical point where the protective finish exceeds its physical tolerance and begins to show the very first hairline fractures.

Test Procedure & Execution

• Prepare your physical sample: Apply your liquid formulation to a flat metallic surface, such as smooth, cold-rolled steel or treated sheet metal. The unit easily handles flat test pieces up to 200 millimeters long, just under 100 millimeters wide, and up to 0.8 millimeters thick.
• Secure and apply strain: Lock your metal sample into place using the highly convenient clamping mechanism, which completely eliminates the frustrating need to wrestle with awkward hand-bolts. From there, you just rotate the levered roller frame smoothly around the cone. The coated surface faces completely outward, ensuring it stretches to its absolute maximum physical capacity.
• Assess the structural damage: Inspect the painted exterior closely for the first signs of splitting, flaking, or peeling along the entire length of the tapered core. You can record a simple pass/fail outcome based on specific official testing protocols, such as ASTM D522, ASTM D1737, ISO 6860, and BS 3900E11, or measure the exact length of the surface fracture with a standard ruler to calculate the exact flexibility percentage.