Screws are ubiquitous in our lives, and we probably don’t give them much thought. From DIY projects around the house to industrial applications, screws are there to make sure that whatever it is that’s being fastened together is held securely in place. They come in a variety of sizes, shapes and materials, making them useful for just about any application you can imagine. In fact, the very design of the screw gives it an inherent advantage over other types of fasteners such as welds or adhesives.
The threaded portion of the screw is able to be tightened by turning it. This can be done with hand tools or powered tooling, but the mechanical advantage that comes from screw use allows you to apply more pressure per inch when driving in the screw compared to hammering a nail and helps ensure that your project is as secure as possible. The self-locking capability of the screw is also why screws are used in places such as screw top container lids, vises and C clamps, and screw jacks that can raise a heavy object without letting it fall when the shaft is released.
Depending on the application, a screw may be manufactured from a number of different metals and alloys including steel, brass, copper, zinc, lead, tin, bronze, and even plastics. Screws are also available in a variety of grades of stainless steel, which are characterized by their levels of chromium and other metals that add strength and durability.
In North America, screws are categorized by the size of their head and the thread pitch. A screw’s diameter is often specified as well, but it can be abbreviated to simply the “gauge” figure (e.g., 3/8″-16 means a screw with a 3/8″ head and 16 threads per inch). The length of the screw is usually given last and can be abbreviated as well (e.g., L8 means a screw with an 8 mm long threaded portion). Screws are also available in metric sizes where the diameter and thread pitch are both indicated in millimeters (e.g., M8 is an 8 mm wide screw with 1 mm of threads).
The use of screws in manufacturing products has many advantages over other fastener types. For example, screws can be threaded into the same holes that bolts are and don’t require the use of washers, which can increase assembly speeds. This can save time and money in the factory, as fewer parts need to be assembled and there’s less chance of washers being misplaced or lost in the production process. Screws are also easy to repair if the need arises, and can reduce waste by allowing manufacturers to eliminate the need for welds and glues that create waste material that needs to be disposed of. This is especially important for companies with limited storage space for inventory. In addition, using screws can help companies meet regulatory requirements that may require them to keep track of their fastener inventory. US screws