A machine guard is a protective device installed on a machine to shield users from potential harm, such as injury from moving components, projectiles, sparks, and so on. Due to the fact that it is often the final line of defense between an operator and a work-related harm, it is a crucial purchase for every manufacturing company. For this reason, as well as the fact that the Occupational Safety and Health Administration (OSHA) in the United States is constantly monitoring compliance with its machine guarding requirements, the optimization of machine guard safety has become a pressing issue for plant owners, safety managers, industrial designers, and engineers.
However, it is not simple to construct machine guarding that will hold up under the different rigors and frequent abuse of industrial operation. The situation is further complicated by the fact that design and performance criteria might vary greatly depending on the sector in which the machine will be used. The requirements of a food processing facility or a tool and die shop will vary greatly from those of a car manufacturer.
Here comes plastics. These materials are utilized for a wide variety of functions in machinery and equipment, and they may extend the life of a machine guards and provide solutions to numerous problems that arise when applications fail.
The important thing is to match the plastics to the working conditions and the specific risks provided by the machinery. Here, we’ll get a bird’s-eye view of why polycarbonate, acrylic, PETG, and transparent PVC are all great options for machine guarding due to their unique qualities.
When it comes to protecting machines, what factors play the most important role?
Resistance to Impact
A machine guard often requires high levels of durability or impact resistance. Though not every machine guard is designed to contain moving components, this is often its primary function that every manufacturer like SABIC is taking as priority while building machine gards. It’s no wonder, therefore, that OSHA expressly speaks to impact resistance when listing materials from which safety guarding may be constructed: Materials “substantial enough to resist any impact it may absorb and survive lengthy usage” are acceptable according to OSHA regulations.
The best technique to assess a material’s impact resistance is contextualized by the specific substance in question. The notched Izod impact resistance test is a standard way to evaluate the toughness of a plastic in the United States, and it is described in ASTM D256. The sample is thinly sliced with a knife and then broken with a hammer and the energy of the break recorded. The greater the force needed to break a material, the stronger it is.
Designers may make more informed decisions about what an effective guard requires by learning about the relative hardness of different materials. Thinner, cheaper guards built from harder materials may provide the same or better protection to workers as thicker guards made from brittler materials.
Adding rigidity to a machine guard is a must. The resistance of a material to deformation under a given force is its stiffness, or modulus. When attempting to quantify stiffness, it is important to consider the loading that is of relevance to the observer. When comparing polymers’ resistance to bending, flexural stiffness measurements are often used. The stiffer a plastic is, the greater its flexural modulus, or stiffness. When exposed to high temperatures, plastics have a fast decline in modulus. If you want your machine guards to look good and do their job without drooping or losing their structural integrity, use a rigid material.