The HSM20 Alternating Bending Fatigue Machine is a further evolution of the popular HSM19 Rotating fatigue Machine. Rather than rotating a specimen to fatigue failure, the HSM20 induces an alternating displacement to the free end of a cantilevered test specimen in order to fatigue fail the part.
A heavy base plate houses the control box, motor, fluctuating components, test specimen and digital counter. All these parts are enclosed by a transparent safety guard, which ensures rotating components are kept away from the user but full view of parts and count is kept.
A rotating faceplate carries an adjustable eccentric bearing driving a connecting rod attached to the cantilever. The frequency of the reciprocating force is around 24Hz for plastics or 100Hz for metals. The bridge to which this test piece is clamped can be adjusted vertically so that the imposed displacement can be varied. A digital counter is triggered from a proximity sensor as the motor rotates and the counts to failure are recorded. Dual micro switches detect specimen failure and turn the power off the motor but not the counter, thus keeping the count visible to user for further recording.
Specimens in plastic and metal can be tested. A set of metal specimens is supplied, with dimensions of 100 mm in length, 5-10mm in width and up to 5mm in thickness.
Two speeds of rotating can be achieved through adjustment of the main pulley gears on the unit; 5700 and 1425rpm. The speeds can easily be adjusted prior to testing.
To test a specimen a special dial gauge enables a calculated deflection to be set for the actual maximum bending stress of the specimen. An instruction manual containing a set of nomograms is provided to assist the user.