Do Tapping Screws Require Threaded Holes
Tapping screws are crucial in sheet metal fabrication. They provide a non-permanent means of joining two or more workpieces accurately while preserving the structural integrity of the base metals. From woodworking projects to shipbuilding and car assembly, there are many applications of tapping screws in manufacturing industries.
When using tapping screws, it is common to wonder if they always require threaded holes. In general, tapping screws do not need pre-threaded holes to function because they can cut their threads easily. However, there are instances where threaded holes may be important to ensure safety and optimal performance. Read on to find out everything about tapping screws and threaded holes.
What is a Tapping Screw
Tapping screws are types of fasteners that join two or more workpieces. They are versatile and work with a variety of materials including metals, plastics, fiberglass, and wood. Tapping screws have a head, drive and shank. The head is the top portion of the screw that distributes the load. It can come in various shapes including round, flat, hexagonal, and star. The shank makes up a large part of the body. It is usually threaded and extends from the head to the tapered tip. There are two main types of tapping screws you can use for part alignment and assembly. They include self-tapping screws and self-drilling screws.
Self-Tapping Screws
This type of tapping screw requires a small pre-drilled hole that gradually expands as it goes in. These holes serve as a guide and ensure stability. Note that there are two main subtypes of self-tapping screws. Some have sharp cutting edges that cut through the workpiece. Others do not cut the material. Rather, they displace it to form the inner threads.
Self-Drilling Screws
Self-drilling screws work without pre-drilled holes. They can drill and tap holes at the same time. Self-drilling screws are more efficient and ensure faster operations. Additionally, they provide a strong connection that does not get loose with time. Furthermore, self-drilling screws are used to join metal to metal. However, they also have applications in dissimilar material joining such as metal to wood.
What is a Threaded Hole
Threaded holes in simple terms are holes with inner threads cut into them. These threads serve as a connection mechanism. They accommodate fasteners such as screws and bolts during part assembly. Threaded holes can either be blind or through. Blind threaded holes can only be seen from one side of the workpiece. They have limited depth and are a fraction of the part’s total thickness. Through holes, on the other hand, are drilled to the other side of the part. They have two openings and you can see through them.
Furthermore, there are different methods you can use to create threaded holes. You can tap the holes using specialized tools. The tapping method is suitable for hard materials such as stainless steel. You can also thread-roll the workpiece with rotating dies. The last method of making threaded holes is the use of inserts. This method is ideal for soft metals and plastics.
Do Tapping Screws Require Threaded Holes
Threaded holes are not generally needed when using tapping screws. Not all tools require pre-threaded holes as they can create threads themselves. Note that the need for threaded and pilot holes depends on the particular type of tool you are using, the workpiece properties, and the thickness of the part.
Self-tapping screws work perfectly without an already threaded hole. They create their threads as you drive them into the workpiece. However, they need a pilot hole that may or may not be threaded. On the other hand, self-drilling screws do not need pilot or pre-threaded holes. They drill and cut inner threads simultaneously.
Furthermore, most engineering materials do not need threaded holes. You do not have to create threaded holes before using a tapping screw to join workpieces together. However, having pilot holes for hard metals, plastics, and wood is an added advantage. Note that there are some instances when you should use threaded holes with tapping screws. These include high-load applications, critical assemblies, and materials prone to stripping.
How to Use a Tapping Screw
Tapping screws are an important type of fasteners that help to secure workpieces. You use them during the sheet metal assembly process in product development. Let’s look at a step-by-step process for using tapping screws.
#1- Preparation
The first step is adequate preparation. This preparation step is in two phases. Firstly, clean the workpiece to remove all forms of contaminants using alkaline or neutral agents. You then secure the workpiece to avoid unnecessary vibrations. Furthermore, select the right type of tapping screw based on the material properties and what you want to achieve. Consider the size, head type, and thread design.
#2- Mark the Screw Position
Thereafter, mark the position for the screw. You do this using a light pencil or marker. Proper indication of the position enhances quality and reduces errors. You will be sure of even spacing and symmetry.
#3- Drill a Pilot Hole
The next step is to drill a pilot hole if needed. To carry out this step, select the right size of the drill bit. Place the drill bit on the mark made for the screw position and drill carefully to create a hole. The length and diameter of the pilot hole depends on the size of the tapping screw you want to use. The diameter of the should be smaller than that of the screw. Additionally, it should be as deep as the length of the screw’s shank.
#4- Screwing Step
Whether you are using a pilot hole or not, insert the tapping screw into the workpiece. Turn the tapping screw slowly manually or with the use of a machine. As the screw enters, it cuts threads into the material without damaging it. Thereafter, tighten it till the head of the screw syncs with the surface of the workpiece.
#5- Inspect
You can then inspect and assess for visible flaws and defects. Ensure the screws are straight and they properly align with the workpiece. Additionally, check for signs of over or under-tightening and make necessary adjustments.
Conclusion
Rather than welding, many part manufacturers often opt for different fastening options. You do not need heat or pressure to use tapping screws. As a novice or seasoned sheet metal fabricator, it is normal to ask how important pre-drilled holes are to tap screws. Tapping screws have the innate ability to create their threads as you drive them into a workpiece. Hence, pre-drilled holes are not a prerequisite to using them.
