Below you will find a list of various technical data and test procedures for testing CTB hose clamps. From the data below, it is evident that Rotor Clip CTB clamps of SAE 6150 performed comparably, if not better than the more expensive 6150 material used by the competitor.

• 6150 vs. 1074
• Pressure/Temperature Leak Test
• Fatigue Test
• Radial Force Test

• 6150 vs. 1074

  Traditionally, CTB clamps have been made from 6150, a chrome-vanadium steel which is heat treated to the required hardness. The vanadium is a grain refiner which increases fatigue life, and the chromium improves hardenability. This is ideal for a heavier-gauge spring under cyclic loading that requires fatigue resistance. However, these are not requirements of a CTB clamp. And because vanadium carbides both tie up the carbon crucial to the heat-treating process and are very stable, clamps made of this material have a longer, more costly heat-treating cycle. Research by Rotor Clamp, Inc. has determined that SAE 1074, a high carbon steel, instead responds more readily to heat treating, producing a lower-cost part with identical performance. In 1074 steel the carbon is not tied up with the alloying elements. Thus, it is more accessible for hardening, and heat treating can be accomplished with less energy and less operator monitoring. Austempering 1074 steel to a bainitic structure also improves ductility and makes the material less susceptible to quench cracks. The following tests, such as pressure/temperature and radial force test, yield similar performance results for hose clamps made of 6150 and 1074 materials.

• Pressure/Temperature Leak Test

  The Pressure/Temperature leak test is designed to emulate the testing performed by the Goodyear Tire and Rubber Company in Lincoln, Nebraska. The products tested were CTB-24 hose clamps produced in both 6150 alloy and 1074 high carbon steel made by Rotor Clamp. As a control, size 24 clamps manufactured by a competitor were also tested. The test itself makes evident the effects of temperature on a joint system at a constant pressure. Each test station in the pressure manifold is made up of a hose and plug assembly (left). The plugs and hoses are the same in dimension and material as those used in the automobile industry. The station is filled with approximately 25 grams of a 50/50 water and ethylene glycol mixture and accurately weighed. The manifold with all the test stations is placed in the environmental chamber and cycled through the temperature extremes at a constant pressure. At the conclusion of the cycle, each station is re-weighed. The criteria for failure would be a loss of 5 or more grams of weight in the station, assuming the loss is fluid.* Referring to the figure titled Pressure Temperature Leak Test, Tabular Data, the .Fluid Loss. column sums up the test results. It is concluded that parts made of 1074 alloy are comparable to the 6150 alloy, and both leaked less than 1 gram in any one station.

   

  
• FATIGUE TEST

  Fatigue testing evaluates CTB hose clamps with respect to fatigue and ductility, using as a guide the GM spec. written by the Powertrain division. The test matrices for the Ambient Fatigue Test are as follows: The particular clamp being tested is started at the nominal diameter, then opened to 90% of the difference between the nominal diameter and the full open diameter. The clamp is relaxed back to the nominal diameter and the cycle is repeated for 250,000 cycles. A broken or fractured clamp at any point during the test or during removal from the fixture is considered a failure. A Rotor Clamp Pneumatic Hose Clamp Plier tightens and relaxes a test clamp at varying intervals at a uniform force. Rotor Clamp used the 1074 steel for their testing, while using the competitor.s 6150 chrome vanadium material for comparison.

   

  
• RADIAL FORCE TEST

  The Radial Force Test is designed to test the force a constant tension band hose clamp exerts on an automobile coolant hose. The products tested were CTB-24 hose clamps produced by Rotor Clamp and size 24 clamps manufactured by 2 competitors used as controls. Rotor Clamp audits product compatibility through testing on a regular basis. The test station consists of eight shear beam type load cells with adjustable segments arranged in a circle with eight independent displays relating the force data. The diameter of the circle is set to the nominal clamping diameter, rounded to within .0002 inches.