Selection of Screws To select the right screw for appli […]
Selection of Screws
To select the right screw for applications, the following three considerations are taken into account:
1. What is the Head Type of the Screw?
The head is the uppermost part of any fastener. There are different types of heads for varying uses and applications. Some of the popular ones include:
o Flat Head: Flat heads are mainly countersunk. These screws designed to sit low in the surface that they are drilled into.
o Pan Head: Pan heads are a bit rounded with short vertical sides that provide a relatively low profile once they are driven into a surface.
o Truss Head: Truss heads have a rounded top with a large, flat underside, which offers an ultra-low profile, still remain above the surface line.
o Oval Head: Oval heads offer a combination of flat and pan head types. The head is slightly rounded, and has a countersunk underside.
2. What is the Thread Type of the Screw?
Screw threads are the combination of recesses and ridges on the body of a screw, which help fix it into place. There are various thread types for consideration, some of the important ones include:
o Self-tapping Screws: The self-tapping screws feature a sharp tapered point, which allows them to be drilled directly into a surface.
o Wood Screws: These screw threads are specially designed for use in the wood. These screws have a sharp, and tapered point. Their wide threads allow them to be drilled into a wooden surface directly, and do not need a pre-drilled hole to fit into.
o Machine Screw Threads: The machine screw threads are specifically designed to fit perfectly with an already drilled interior thread of a tapped hole. These threads offer a high degree of precision when it comes to screwing them into their partner thread.
o Sheet Metal Thread Screws: These threads feature sharp threads, which help a screw to attach to metals. These screws often feature a tapering point similar to wood screws, which allows them to be drilled directly into a surface.
3. What is the Drive Type of the Screw?
The drive types of a screw helps determine the type of screwdriver needed to fasten or unfasten them. Here are the different types of drives:
o Star Drives: Star drives have a star shape recess with six rounded points.
o Phillips Drives: Phillips drives have cruciform shape, and are specifically designed to work with Phillips screwdrivers.
o Hex Socket Drives: These drives feature a hexagonal recess, and are driven with the help of a hex screwdriver or a hex key.
o Pozi Drives: These screw drives are a development of the Phillips drive. These drives feature two cruciform slots. The second slot is less distinct than the standard cross drive.
o Slotted Drives: Slotted drives are traditional, yet popular type of drives, which employ a simple, single slot for a flat-tip screwdriver.
There are different types of screws available in the market. Some of the popular ones include round head slotted screws, precision shoulder screws, steel machine screws, and knurled thumb screws. All the points mentioned above will help you in selecting the right type of screw for your applications.