Renaud Daigle

A New Test Method to Evaluate the Cut Resistance of Glove Materials

A new method to evaluate the cut resistance of protective glove materials has been developed. The method consists of sliding a straight blade on a sample material and determining the horizontal blade displacement requiredto cut the material at a given load. A special arrangement allows a load applied on the sample material to be kept constant throughout the test. The effect on the cutting results of a) degradation in blade sharpness, b) blade speed, c) sample holder geometry (semi-circular or flat), and d) the load applied was characterized. The results demonstrated that a) the blade edge degraded even with soft materials such as neoprene; b) the blade speed had a negligible effect on the cutting results; c) the holders geometry does not have a significant effect on the variability in the cutting results, but the use of a semi-circular holder is recommended; and d) the applied load is a function of the materials cut-resistance. It was found that the blade displacement increases non-linearly with the applied load. The cutting test conditions were set as follows: the blade is 70 mm long and its speed is 150 mm/min; the blade edge must be used only once. To evaluate the resistance of a material to cutting, tests must be performed with at least two different loads. The load required to cut a material to a standardized distance, namely 10 mm, is calculated by interpolating the experimental values. However, in the preferred method, the cut test is performed with three or four different loads and the load required to cut to 10 mm is calculated by a non-linear regression. Results are reproducible with a coefficient of variation (CV) lower than 16% with homogeneous materials. However, higher CVs are obtained with knitted materials such as Kevlar gloves, or steel reinforced materials.

Comparison of Two Methods to Evaluate the Resistance of Protective Gloves to Cutting by Sharp Blades

Two methods for evaluating the cut resistance of gloves were compared: one developed at ITF-Lyon (Institut Textile de France) and one developed at the IRSST (Institut de recherche en sante et en securite du travail du Quebec) in Montreal, Canada. The ITF method uses a circular blade with a pressure of 5 N applied on the blade. The blade speed is sinusoidal with a maximum of 100 mm/s. The value to be measured is the number of cycles to cut the material and is compared with that of a reference material. The IRSST method uses a straight blade and the pressure is applied on the sample holder. Series of tests using at least two different weights must be performed at a constant blade speed. The cut resistance for the IRSST method is measured as the load required to cut the material at a 10-mm blade displacement. Eighteen glove materials of different levels of cut resistance were compared. With uniform materials such as neoprene, no variability is observed with the ITF method, while a coefficient of variation of approximately 10% is observed with the IRSST method. These results may be due to different sensitivities of the test methods. The ranking of cut resistance obtained with both methods can be considered as equivalent and the results are comparable with a correlation coefficient r of 0.89.

Test method using energy to evaluate the cut resistance of protective clothing against chain saws

Work with chain saws involves the risk of injury; workers wear protective equipment to protect themselves against these injuries. The question arises: How can the resistance of the protective equipment be evaluated? It can be evaluated either by using one of the test methods described in current standards or by using a new test method that has advantages over existing methods. The new test method is chosen because it measures the energy needed by a chainsaw to cut the protective equipment to be evaluated. The energy then becomes the performance criterion to classify the equipment and is an overall physical measurement parameter for evaluating the cut resistance of the material to a chainsaw. In the test method developed, a motor drives a fly wheel that acts as an energy reservoir, which in turn drives the chain. Once the test velocity has been reached, the motor is disengaged and the flywheel becomes the only source of energy driving the chain. The chain then comes in contact with the protective equipment to be evaluated. The total cut-through energy, selected as performance criterion, is determined by evaluating the difference between the initial and final kinetic energies of the rotating system. Also, a sensor installed between the flywheel and the chain records the torque transmitted by the flywheel to the chain. This method determines the energy dissipated when the equipment evaluated is being cut. The test phase was used to validate the operation of the test bench and to verify the feasibility of the measurement principle. The energy dissipated during cutting was evaluated for different materials and under different test conditions. The results obtained show that the energy necessary to cut through a sample is a repetitive measurement independent of the initial test velocity. In contrast to existing test methods, the method developed is independent of the drive system used, and consequently the motor driving the flywheel can be replaced or undergo maintenance without affecting the results. This ensures that the test method will retain its precision over time.

Safe Tarping Systems for Wood Chip Trucks

Falls from semi-trailers whose heights exceed three meters result in major and sometimes even fatal injuries. To protect workers against falls during tarping operations, carriers use tarping systems. These systems have shortcomings that result in the users not using them (i.e., they are homemade or have been developed by trial and error without engineering support and without precise design criteria). Four of the most common tarping systems used by wood chip carriers in Quebec were evaluated. All are operated from the ground. The main factors that prevent their use and generalization on wood chip trucks in Quebec include the difficulty in installing them and their unadaptability to the northern climate. This study selected two tarping systems and identified the criteria required for a better design of future tarping systems that take into account both the workers task and the constraints of the Quebec climate.