When you selects a fastener for a repair, you must ensure the fastener match the size of the holes. A fastener that is too large for a hole can ruin a piece of machinery, and a fastener that is too large can strip a threaded housings. Many person believe that all fasteners are the same, but fasteners has different sizes, different pitches, and different materials.
If you choose the wrong fastener, the error can be expensive because the wrong fastener can damage teh machinery. You must understand the anatomy of a fastener to avoid mistakes, and you must look at more than just the length and the diameter of a fastener. The threads of a fastener are a very important part of a fastener, and the threads determines if a fastener has a coarse profile or a fine profile.
How to Choose and Install the Right Fastener
Coarse threads, which people know as UNC, are used for fast assembly and coarse threads is useful for softer materials like cast iron. Fine threads, which people know as UNF, are used for precision, and fine threads offer better resistance to vibration. Fine threads also offer a more higher clamping force then coarse threads, so fine threads are often used in aerospace or automotive applications.
You must choose between the speed of coarse threads and the stability of fine threads. The material of a fastener is another important factor, and the material you choose depends on an environment where you use the fastener. Stainless steel is a good choice for a humid environment because stainless steel has corrosion resistance, but stainless steel may not have the same strength than alloy steel.
Grade 8 alloy steel provide high strength, but grade 8 alloy steel can rust if the environment are not controlled. The head style of a fastener is also important, and the head style determines how the fastener interacts with the surface of the material. A pan head distribute a load across a surface, but a countersunk head allow the head of the fastener to sit flush with the surface.
You must follow specific steps during the installation of a fastener to ensure the fastener is installed correctly. You should always start the installation of a fastener by hand, and you should start by hand because starting by hand prevent cross threading. Cross threading is a common mistake, and cross threading is a costly mistake.
You may apply thread locker to a fastener because thread locker prevents a fastener from backing out due to vibration. Finally, you must follow the torque requirement for the specific size of the fastener. If you apply too much torque, you may snap the head off the fastener, and snapping the head off the fastener will create a larger problem than the original problem.
