Washers are mechanical tools often used to offer high resistance in tight spaces, they don’t break down easily under axial loads provided the weight is manageable. However, there are various factors that can cause wear and tear of washers such as:
I. Differential thermal expansion
Washers can expand when heated causing a condition referred to as differential thermal expansion, different materials may increase in size under different temperature levels thus creating inefficiency in operation. If two or more components of a washer are constructed from materials that enlarge at different rates, the resultant difference in heat expansion can make the item to leak or get damaged.
Similarly, materials contract when cooled and this may result in similar effects as thermal expansion. Under certain conditions these applications are often subject to the outcomes of intense cooling, which can include component failure.
Differential thermal expansion may further be compounded by repeat alterations in temperature. Usually, a single washer component will be exposed to regular cycles of heat rise and cooling. The resulting malleability not only affects smooth operation of the tool, but also heightens wear and tear effect on parts and accelerates their failure rate.
II. Working temperatures
Every material has a unique ‘working temperature’ range, or maximum/minimum heat levels at which it will continue functioning optimally. While some are designed to withstand particularly high or extremely low temperatures, others are best fitted for use in situations where the temperatures aren’t extreme. If the washers are designed from components that can’t withstand the temperatures of their environment, this can lead to increased risk of wear and tear.
III. Load stress
It’s important to know the average limits of a washer before putting it into service in any application, calculating load stress can help you determine the expected point of failure for your device. This helps in gauging how much force or stretch the device can take before it fails. Sometimes, the load/deflection relationship can also be affected by using multiple washers in series or parallel arrangement.
Load stress can also be affected by defection rate of the material, which is the amount of torque required divided by corresponding rebound of the equipment. Every washer has its own deflection rate, depending on factors such as geometry and material. The situation may even be made worse if the tool is used in areas with continuous thrusts that may lead to heavy wear.
IV. Bolt loosening
From the moment a washer is pre-loaded, some of its bolts almost always begin to loosen up. Various factors can cause this to happen such as relaxation of bolts, vibration, temperature fluctuations, overtightening and under-tightening just to mention a few. In cases where conical washers or Belleville Disc Springs are used in extreme temperature conditions, heat expansion/contraction is a common cause of bolt release.
V. Excess torque
Torque is the amount of rotational force applied to a rivet to tighten the washer being supported, when it becomes excess then this can cause wear and tear. The best way to prevent it from happening is through flat loading, this refers to the amount of axial power required to level a washer. When done correctly, flat loading will ensure that bolts don’t loosen up when the equipment is in use. It will extend the device’s life and ensure optimal functioning. Nevertheless, different washers require different quantities of torque in order to be flat-loaded, this entirely depends on the product’s design and material.