What is self tapping screw?

What is self tapping screw?

As the name implies, it simply means a screw that can be tapped by itself. The difference between self-tapping screw and general screw is that the general screw must have a machined screw hole to screw in. Self tapping screw is not necessary, while screwing in the tapping itself. In order to achieve their own tapping purposes, the hexagonal drill tail screw is generally pointed, in order to facilitate the squeezing into the object to be screwed.


Video of Self-tapping Screw Production

Development History of Self-tapping Screw

The first person to describe a spiral was the Greek scientist Archimedes (287 BC-212 BC). Archimedes spiral is a huge spiral in a wooden cylinder, used to raise water from one level to another and to irrigate fields. The real inventor may not be Archimedes himself. Maybe he just describes something that already exists. It may have been designed by skilled craftsmen in ancient Egypt for irrigation on both sides of the Nile.
In the Middle Ages, carpenters used nails or metal nails to connect furniture to wooden structures. In the 16th century, nail makers began to produce nails with spirals that could connect things more firmly. That’s a small step from such a nail to a screw.
Around 1550 AD, the earliest metal nuts and bolts as fasteners appeared in Europe. They were made by hand on simple wooden lathes.
The screwdriver (chisel) appeared in London around 1780. Carpenters have found that screwing a screw with a screwdriver can fix things better than hammering it, especially when it comes to threaded screws.
In 1797, Mozley invented a precision screw lathe made of all metals in London. The next year, Wilkinson made a nut and bolt machine in the United States. Both machines can produce universal nuts and bolts. Screws were quite popular as fixtures because a cheap method of production had been found at that time.
In 1836, Henry M. Philips applied for a patent for the screw with cross groove head, which marked a significant progress in screw base technology. Unlike the traditional slotted head screw, the edge of the cross slotted head screw head of the cross slotted head screw. This design makes the screwdriver automatically centered and not easy to slip, so it is very popular. General purpose nuts and bolts can connect metal parts together, so by the 19th century, the wood used to build machinery houses had been replaced by metal bolts and nuts.

Speaking of the development of screw from 1914, when tapping screw was introduced into industrial construction in that year, it was made of a hardened steel. The self-tapping screw with A-shaped thread at the end was mainly used in thin gold metal connection connecting heating and ventilation systems, so it was also called “sheet metal screw”.

By the end of the 1920s, with the widening of the market and new applications, new design was emphasized and its application performance was improved widely. Next, Jin Meizi introduced four different stages of self-tapping screw development in the past 40 years: thread forming self-tapping screw, thread cutting self-tapping screw, thread rolling self-tapping screw and self-drilling self-tapping screw.
1. General self-tapping screw (thread forming self-tapping screw)
Common self-tapping screw is the direct product of the early thin metal screw. The principle is that when it is screwed into the prefabricated hole, the internal thread connected with the screw is formed by shifting the material close to the hole and pushing the material into the gap before the thread.
2. Self-cutting self-tapping screw (thread cutting self-tapping screw)
Because the thread forming of common tapping screw can be easily realized only on the materials with relatively thin and good toughness, the use of tapping screw is extended to the materials with thicker cross section and harder, brittle and other poor deformation ability. In this way, self-cutting and self-tapping screw is developed. Cutting groove or cutting edge is machined at the end of the screw rod. When the screw is screwed into the prefabricated hole, the screw plays the role of thread dimension and actually cuts the thread connected with itself.
3. Self-extrusion and self-tapping screw (thread rolling and self-tapping screw)
In the 1950s, screw fastener engineers began to realize that self tapping screws have the potential advantage of “structure”, rather than just accessories bearing light load, which led to the development of a new self tapping screw thread rolling self tapping screw (self extrusion self tapping screw). According to the design principle of cold forging forming tap, people specially designed the thread and At the end, the screw can pass through the top of its thread, not the side of the whole thread. The intermittent and periodic pressure is applied to form the internal thread of the connection, and the forming pressure is concentrated and limited. It makes the compressed material close to the hole easier to flow and better fill the side and bottom of the self-tapping screw thread. Because the friction resistance of the screw is much lower than that of the ordinary self tapping screw. Therefore, the self-tapping screw (self-extruding self-tapping screw) can be screwed into a thicker section. At the same time, it has better screw-in control and tightening torque, and greatly improves the connection strength and overall firm parts. The engineering standard of self-tapping screw stipulates the selection of materials, and the mechanical and working properties of heat treatment should be strictly controlled. These requirements far exceed the corresponding requirements for ordinary self-tapping screw and self-cutting self-tapping screw. Therefore, self-extrusion self-tapping screw (thread rolling self-tapping screw) is indeed a kind of “fastener” for structural parts.
4. Self-drilling and self-tapping screw (self-drilling screw)
People have done statistics. Among the costs that constitute the total assembly cost, the highest one is the processing of holes. In practical application, self-tapping screw needs to process prefabricated holes. In order to make prefabricated holes play a good role in practical application, it is necessary to control the size of these holes within a fairly strict range. In the early 1960s, self-drilling and self-tapping screw appeared. In order to reduce the cost of assembling, self-drilling and self-tapping screw has realized one operation of drilling, tapping and tightening without processing prefabricated holes.
5. Other Self-tapping Screws
In the four main stages of the design and development of tapping screw, two new products are also worth introducing. Both of them belong to special thread forms. One kind of high pond is used for plastics and other low strength materials, and the other is used for construction industry to connect cement chopper board, which is also called wall panel tapping screw.
With the development of the times and the continuous improvement of human technology, many self-tapping screw in order to better use and achieve higher fastening effect. So far, great improvements have been made. According to the needs of different enterprises, self-tapping screw with different specifications and threads can be customized. The application performance of self tapping screw is emphasized.

Structure of Self-tapping Screw

Each tapping screw consists of three parts: the head, the rod and the end of the rod. Each self-tapping screw has four elements: head shape, screwing method, thread type and end form.
1. Head shape
Head shape varies. There are round head (semi-round head), flat round head, round head flange (with cushion), flat round head flange (with cushion), plate head, plate head flange (with cushion), countersunk head, semi-countersunk head, cylindrical head, spherical cylinder head, horn head, hexagonal head, hexagonal flange head, hexagonal flange (with cushion) head and so on.
2. Twisting Method
Twisting means twisting the head of the screw when installing and fastening the screw. There are two basic ways: external and internal. Generally speaking, the allowable torque of external wrench is larger than that of any form of internal wrench (inner groove). External wrench: hexagonal flange, hexagonal flange, hexagonal flange, hexagonal flower, etc. Internal wrench: one-slot, cross slot H-type, cross slot Z-type, cross slot F-type, square slot, compound slot, internal spline, inner hexagonal flower, inner triangle, inner hexagonal, inner 12-angle, clutch slot, six-blade slot, high-torque cross slot, etc.
3. Thread types
There are many kinds of threads, such as tapping threads (wide tooth threads), machine threads (common threads), dry wall threads, fiberboard threads, and other special threads. In addition, threads can be divided into single lead (single head), double lead (double head), multiple lead (multiple head) and high and low teeth double head threads.
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Types of self tapping screw

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Types of Special Self-tapping Screws and Use of Screw Rubbing Board
 4. End form
There are two kinds of end forms: conical end and flat end. However, according to the need of use, in the end of the rotary part, can be machined with cutting function of grooves, slots, incisions or similar parts of the bit shape. In some standards, the same is the cone or flat end, there are also different forms such as round end.

Characteristics of Self-tapping Screw

  • 1. Self-tapping screw is a kind of screw with a drill bit. The inner hexagonal bolt is constructed by special electric tools, drilling, tapping, fixing and locking are completed at one time. Self-tapping screw is mainly used to connect and fix some thinner plates, such as color steel plate and color steel plate, color steel plate and purlin, wall beam, etc. Its penetration capacity generally does not exceed 6 mm, the maximum does not exceed 12 mm.
  • 2. Self-tapping screw is often exposed outdoors and has strong corrosion resistance; its rubber sealing ring can ensure that the screw does not seep water and has good corrosion resistance.
  • 3. Self-tapping screw is suitable for the use of wood materials, which is what we often call wood screw. Usually manual operation, due to human constraints, this kind of screw is generally very small, the scope of use is relatively narrow.
  • 4. Self tapping screw combines tap and bolt. The front is the tap and the back is the thread. In general, soft materials, drilling a good hole can be directly screwed in. The threads are tapped from the tap, followed by the threads of the bolts. If the diameter of the screw is small, the material is very soft. You don’t even have to punch a hole first, like screwing it into wood.
  • 5. Self-tapping screw is usually described by three parameters: diameter series of screw, number of threads per inch and length of screw. The diameter series of the screw is 10 and 12 grades, and the corresponding diameter of the screw is 4.87 mm and 5.43 mm, respectively. The number of threads per inch is 14, 16 and 24 grades. The more the number of threads per inch, the stronger the self-drilling ability.

How can self-tapping screw get in easily?

The biggest characteristic of tapping screw is that it does not need to be used with nuts, and can rely on its own thread locking and connection. It is a very common and commonly used screw in daily life. When self-tapping screw is screwed into the hole of plastic metal material, the internal thread can be formed in the hole by extrusion, which is the secret of self-tapping and self-drilling of self-tapping screw. Among them, a special self-tapping screw for metal hole threading is called tapping.
In the use of self-tapping screw, many people may be faced with the lack of some tools, or do not know what tools should be used to screw self-tapping screw, this article for you to briefly introduce how self-tapping screw into.
In fact, the screw can be drilled with air batch, screwdriver, gun drill, and electric hammer, which is usually needed to hit the concrete. The concrete wall marked above C10 can not be nailed with ordinary nails. If the load bearing requirement is not high, cement steel nails can be used directly. If the load bearing requirement is high, expansion screw is needed. The ordinary plastic expansion tube is fixed with self-tapping screw machine.
How to tap the self-tapping screw into the simplest, see what netizens say:

  • 1. Self-tapping screw is used for non-metal or soft metal. It does not need bottom hole and tapping, but it is not suitable for wall directly. When using the wall, we need to drill holes, put plastic material “screw sleeve” into the holes, and then screw in the tapping screw (similar to the nature of expansion screw).
  • 2. Self-tapping screw is suitable for wood material use, which is what we often call wood screw. It is recommended to use cement nails for hanging clocks and watches on the wall. It is recommended to use 2.5-3 cm long. When smashing nails, it is better to measure the hanging position first, then mark it well, then paste it on the mark with transparent tape. The tape size is 3CM*3CM, so that the wall skin will not fall off when smashing nails. Today’s houses are framed, and the walls are all cement, which is hard and needs to be nailed with cement.
  • 3. The head of self-tapping screw is pointed. It can be screwed directly without drilling first. But self-tapping screw is not suitable to be screwed directly on the wall. It can be screwed directly on wood, plastic and metal with low hardness. When drilling holes on the wall, it is better to use a percussion drill, screw down the plug, and bare-handed nails are definitely not enough.

When to use self-tapping screws?

When tapping screws are screwed into wood, plastic or metal, they will cut precise threads to drill their own channels. For products that require regular maintenance, such as air conditioning units or awnings, it is helpful to use tapping screws, on which you need to disassemble and reassemble components along the same thread. Self-tapping screw can be inserted with hand-held or electric screwdriver.
It is helpful, though not mandatory, to drill a guide hole in the material before using the tapping screw. This ensures that the screw is easily accessible and positioned correctly. When drilling guide holes, make sure to use a bit smaller than the self-tapping screw itself. Otherwise, if the hole is too big, there is nothing to connect the thread. Then straighten the screw and screw it into position with a flat head screwdriver or cross screwdriver (depending on the screw head). If the screw is twisted, it may cause the head to fall off. Next, tighten the screw until it is no longer easy to turn. Be careful not to tighten the screw too tightly, as it may cause thread peeling.
Self-tapping screw with a pointed, pointed or flat, blunt head. The pointed screw is designed to drill its own holes in softer materials such as wood and plastics, so that no guide holes are needed. The advantage of flat head screw is that it won’t get stuck in the material and break. When you drill into harder materials, such as metal sheets, you need to drill a guide hole in advance. For thicker metals, more than one screw may be needed to drill through the surface. In order to save time and effort, self-drilling and self-tapping screw can be used to drill into metal. Although these screws are expensive, they can be drilled and fastened step by step.

What is the Difference Between a Self-Drilling Screw and a Self-Tapping Screw?

One of the most important commercial fasteners in use today is the Self-Tapping Screw. Among the earliest “engineered” fasteners, Self-Tapping Screws were made from hardened steel and its use was instrumental to the Industrial Revolution. Still in use today, there are now many types and styles of Self-Tapping Screws made to perform specific fastening jobs.

Unlike Military or Aerospace Fasteners, terminology used in the Commercial Fastener Trade is often imprecise and can sometimes cause confusion; one example is the distinction between Self-Tapping and Self-Drilling Screws.




  • A Self-Tapping Screw can be referred to as simply a Tapping Screw. However it is also often called a Sheet Metal Screw because they are primarily used in sheet metal.
  • Whichever name is used, these names are for screws that form mating threads (“tapping” the threads) in a pre-drilled hole in the substrate into which they are driven.
  • A Self-Drilling Screw is a Self-Tapping Screw with the added feature of a drill point. The drill point looks a lot like the point of a drill. It will drill a hole and form the mating threads in one operation.
  • Here is where the confusion comes; many times the person specifying a screw will interchange the term Self-Tapping Screw (or “Self-Tapper”) with Self-Drilling Screw. If a screw will drill its own hole it is a Self-Drilling Screw.

Other screws that might be considered to be in the Self-Tapping Screw category are:

  • Thread-Cutting Screws (TCS) – These are screws that can be used to cut threads in a pre-drilled hole. There are many types of TCS and each has a different thread-form to accomplish that goal.

  • Thread Rolling Screws (TRS) – These are screws that will roll or extrude threads in a pre-drilled hole in the substrate without removing any material creating a fit with zero clearance.

While the terms Self-Tapping and Self-Drilling are not interchangeable, these screws come in numerous configurations and are widely used in the commercial, industrial and construction markets.

Source: china self-tapping screw provider: www.titaniuminfogroup.com



How does a self tapping screw work?

Self-tapping screws are fasteners that are designed to drill their own hole as they are screwed into wood, plastic or metal. By using a screw driver and self-tapping screws, precisely fitted threads are created.

What is the difference between a self tapping screw and a normal screw?

Basically a self drilling screw is a tapping screw that doesn’t need a pilot hole. They both technically tap their own threads, all screws do this to varying degrees. But, the self drilling screws skip a step in the process.

When should you use a self tapping screw?

When you’re drilling into harder material such as sheet metal you need to drill a pilot hole in advance. For thicker metal, it may require more than one screw to drill through the surface. To save time and labor, you can use self-drilling self-tapping screws to drill into metal.

How do you use a self drilling screw?

Place a self-drilling screw into the hex head adapter. Depress the trigger of the drillslowly, while the drilling tip of the screw rests against the metal. Increase the speed of the drill when the screw finds its center. Stop drilling when the head of the self-drilling screw tightens against the surface of the metal.



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