Machine screws

Machine screws
Machine screws were the first parallel-threaded drive screws used in ancient clocks and firearms. In the early 1900s, it was the king of small, cheap, low-grade screws and fasteners. Machine screws have changed a lot over the past 100 years; unless the screws are very small or in small quantities and not preferred, the threads are rolled up and not cut. With the exception of the micro screws, the screw heads and drivers are again cold forged.
Head and drive type
Machine screws are available in a variety of drives and head styles, the most popular heads are Pan and Countersunk, although there are various types of head styles available. These include Slotted, Phillips, Pozi, Hex Keys, Allen Keys, Torx Hex Stars, Square Drive Socket Heads and Safety Heads that are easy to assemble but difficult to disassemble.
Mechanical screw material
Machine screws are mainly made of low-strength steel, but are also available in brass, aluminum and stainless steel.
 Machine screw application
Machine screws are used to secure components to machines, machine tools, and have many functions in phones, appliances, electronic equipment, and vehicles.
Thread
Machine screws are available in a full range of metric coarse threads, uniform process, digital and fine line as well as British Whitworth, BSF and BA threads. Machine screws are used in threaded holes, thin plate thread preforms or cut holes or nuts on the opposite side. Small diameter and micromachined screws are typically cut threads with slotted drivers.
Uniform Threads Uniform threads maintain the same diameter throughout the entire length of the threaded portion of the fastener. Where screws with tapered threads, such as wood screws and self-tapping screws, are used to cut their own threads into softer materials.
Machine screws and bolts
Machine screws are slightly smaller than bolts; if the first tightening of the fastened joint is accomplished by turning the head of the screw, machine screws also tend to be designated as such. When working with bolts, the main tightening process is usually performed by turning the nut and inserting the bolt through the hole. Machine screws have low tensile strength, whereas bolts have medium to high tensile strength. Machine screws are hot and have washer faces.