There are three common types of screws. It is very important to know the types of screws as it is necessary to decide which type of fasteners is required for the task. Before buying screws from any machine screw manufacturer, you should know basic information about at least basic information about common screw types.
- Completely threaded shank
- Used usually with a nut
- Comparatively smaller than other average screws
- Designed to be attached to an existing tapped hole
Machine screws are referred to as machine bolts. These are generally smaller than other average screws. These are usually in the range up to ¾ of 1 inch but can come in larger variations also. Machine screws are manufactured to fasten to a tapped hole on the surface of a metal, usually in combination with a matching nut. The main distinguishing characteristics are overall size, slot type, the shape of a head, thread type, and length, material.
The two key drive types related to machine screws are flat head and Phillips. There are many specialized drives, they are associated with tamper-resistant screws. The complete length of machine screws’ shanks is always threaded. Threading of the machine screw is important as the holes that screws are being fastened into are tapped for a specific type and size of screw thread. The two characteristics of screw threads are the outer diameter size of the screw threads and the distance among each thread. Machine screws can be made to have either right-handed or left-handed threads.
Sheet Metal Screws:
- Threaded shank
- Versatile fastener, used in plastics, metal, and wood.
- self-tapping screws require a pre-drilled hole
- Hardened, sharp screw threads,
Sheet metal screws have entirely threaded shanks with sharp threads. The sheet metal screw tip allows it to cut through wood, metal, plastic, and various materials. The size of sheet metal screws is usually shown in the sequence of three numbers. The numbers of sheet metal represent the length of fastener diameter, and its thread count.
There are two basic kinds of sheet metal screws: first self-tapping screws and other self-drilling screws.
They have a sharp tip, designed to cut through metal, but the metal should be pre-drilled before using screws.
These screws have a drill point tip without a pre-drilled hole, they can easily cut through metal.
There are various styles of the head of the sheet metal screws. Round and pan head sheet metal screws have extended heads that extend above the material surface after installation. Oval or flat countersunk type of screws flushes with the material surface top. These metal screws come with flat, combo, or Philips drive.
Sheet metallic screws are made up of carbon steel and typically one of the most economical. They are disposed to corrosion and rust when exposed to water, moisture, or any chemicals. Galvanized steel screws are intended to resist corrosion and rust, but cost more than other standard steel screws. Sheet metal screws are coated with nickel or zinc to modify the appearance.
- Do not require a nut
- Available in English sizes and also metric sizes
- Fasten machine parts- consumer electronic devices or home appliances
- Large heads, the diameter is bigger than the threaded portion