Inconsistent Physical Property Test Results

Manufacturer: We are latex catheters manufacturer. For the last 6 months, our Q/C department has been having problem of inconsistent test results from our tensile testing. Our latex compound formulation, production processes have not been changed. The test pieces are cut from films prepared using both casting and coagulant dipping methods.

We would appreciate your input on how to ensure that we achieve consistency in our testing.

John Woon (Senior Latex Consultant): Briefly, please ensure the following:

1) The tensile machine is well calibrated especially the separation speed of the clamps.

2) The thickness gauge is working properly and frequently calibrated.

3) Die cutter must be sharp enough to ensure that there is no jagged edges of the test pieces after cutting.

4) The rubber films are free of micro-flaws caused by air trapped, collusion of dirt, dirty formers or casting plates, etc. (Thicker films could be a better choice)

5) The test pieces must be well conditioned in the testing room at consistent relative humidity and temperature.

6) There is no slippage of the test pieces from the clamps/grips during testing.

Generally, a higher range of results such as tensile strength is more accurate and acceptable than a lower range of results which could be due to any or a combination of the above mentioned factors not being under control.