Ross Flex Testers

Product Description

Ross Flex Testers are widely used by the clients to cater to the testing requirements in an efficient manner. Pierced strip test specimen is freely bent over a rod to an angle of 90^o and further cut length is frequently measured at different intervals for the purpose of determining cut growth rate. Besides, special shaped piercing tool initiates the cut. Testing estimates the ability of rubber vulcanised for resisting crack growth of a pierced specimen. There is no exact correlation between the test results and service is implied for varied nature of service conditions.

Procedure:

• Measure and record the median thickness of the test specimen, which is taken at three points across the width at the cut’s point
• Holder arm of the flexing machine in a horizontal position, clamp side by side test specimens to make sure that the cuts are at the centre point of the rods
• Adjustable top rollers are lowered down until they just touch the test specimen and lock in this position by wing nuts
• Free travel of test specimens are permitted between the rollers during bending movement
• Start the machine and record the number of cycles by using counter
• Make frequent observations
• Record the number of cycles and the increase in cut length measured to the nearest 0.5 mm for the purpose of determining the rate of increase in cut length
• When cut growth is observed, the holder arm shall be at an angle approximately 45^o vertical
• Test shall be continued until the cut length has increased 500%, that is, until the combined length of the cut and crack has increased to a total of 15.0 mm (0.60in) or when 250 kilocycles has been reached with slow cracking samples
• In some cases, the cut growth is not in a straight line as a continuation of the cut made by the piercing tool, and ‘star–shaped’ cracking may develop
• In this type of event, cut growth is measured as the length of the longest continuous crack
• When operation of the machine is stopped temporarily, the holder arm shall be in a horizontal position, so that the test specimens remain horizontal while not being flexed

Report:

• Sample identification
• Specimen medium thickness
• Test temperature if other than 23+2oC (73+3.6oF)
• The average number of cycles for each 100% increase in cut growth above the initial pierce of 2.5 mm
• (0.10in.) of the tested specimens, upto and including 500%, where possible