A screw is used when the objective is to make a connection between two mating objects. In many cases, screws in New York City are identifies with wood and bolts are identified with metal connections, but this is not always the case. A cap screw is also commonly used when fastening metal machine parts and components, you will often see then in use if you look at most home appliances or consumer electronic goods.
A conventional bolt mates with a nut, cap screws in New York City are tightened directly into a pre-threaded hole in the object. From a physical point of view, on one end there is a cylindrical thread of a given size and length, on the other end there is a large head which can be one of a number of shapes, round and pan head are favorites. The threaded portion and the head abut at 90 degrees and do not have any sort of a bevel such as one associates with a wood screw. The cap screw is sized so that the thread form on the screw is identical to the thread form in the tapped hole. As the screw is rotated, it advances in the threaded hole until it is seated; in some cases the final procedure is to torque the fastener to design tightness.
As a cap screw is often associated with machine tools, there are a number of had forms and tightening methods. The most common of all is a cylindrical head screw with an internal broached hole which allows the screw to be tightened with an Allen wrench. The Allen wrench style is a hexagon and it is used on button head and pan head cap screws as well. There is some equipment which is not designed to be dismantled by anyone other than an authorized service representative; in these cases the cap screw will often have a proprietary design for fixing.
Cap screws are commonly available in both Metric and English screw sizes, the thread forms are either course or fine depending on the application. The material of choice is carbon steel but they can be purchased in stainless steel, various alloys including brass and even nylon and various other plastics. Click here for more information.