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Self-tapping screws into plastic: step by step Guide 2020

self tapping screws into plastic

It is customary to call a fastener a self-tapping screw. Externally, the self-tapping screw resembles a screw, has a pointed rod tapering towards the end with a special thread on the outside and a head. Among the many fasteners, such as screws, bolts, or screws, self-tapping screws are very common. This type of fastener has its own characteristics and is divided into many types (size, shape, type of material, etc.

Do you know what is the main difference between self-tapping screws and ordinary screws? Do you know where to use each screw? In this article, we will show you how to use the screws correctly.

What screws to use for plastic?

Type B  self-tapping screws is used to securely fasten plastic products, polycarbonate and other tapping plastic to a wooden frame or base. Applicable when working with a window profile. They have an anti-corrosion coating, as a rule, zinc white or yellow, which makes it possible to install in high humidity conditions. Let's consider the most popular ones.

How do you utilize plastic self-tapping screws?

Features of screws for plastic:

  • Thread forming screws for plastic is intended for fastening metal fittings to plastic window profiles material.
  • Screws for plastic tip allows easy entry into the plastic.
  • Special coarse thread profile up to the head.

Application area:

  • The main purpose of the stainless steel cutting screws is to form fasteners in plastic materials and between parts of their plastic structures. It can also be used to fasten gypsum fiber sheets.
  • Finds application in those areas where work is carried out with structural elements made of plastic with the need to fix them without damage

Features thread profile screws for plastic:

  • To install and remove the forming screws, manual screwdrivers or power tools with suitable bits are used
  • This screw does not require pre-drilling of mounting holes
  • Possesses outstanding anti-corrosion properties and resistance to high temperatures

Varieties of thread forming screws

Several types of hardware belong to window screws, and each of them has specific differences and purposes. Before buying fasteners, you need to understand their thread cutting characteristics.

Fitting screws

This is one of the most common flank angle screws. Among the advantages of the products are:

  • Galvanized coating (silver, gold) for protection from external influences, including temperature;
  • Wide thread cutting pitch provides simplified pilot hole screwing of hardware into plastic bases;
  • Sharp tip for high precision thread material mounting;
  • Special shape and size of the head of 7 mm for full recession into the base;
  • Versatility - Suitable for wood, sheet metal, and other material
  • Wide range of threads cutting sizes - standard thickness is 4.1 mm, various lengths are provided (19, 22, 25, 30, 35, 38 and 45 mm).

Do not forget that this type of fastener is designed to work with plastic structures. If hardware with a long length is used, installation through at least 2 walls of the PVC profile is mandatory for high strength and reliability of fastening. Even if the self-tapping screw is unevenly located, the head still sinks into the base as much as possible.

Some products have special ribs on the inside of the head. This eliminates spontaneous scrolling of the fastener, ensures reliable fixation. If you make a choice, then in favor of a similar design. Please note that the protrusions must be sufficiently raised, otherwise the desired effect cannot be achieved.

Another modern option is with a double thread forming screws. The design feature is that the turns of different heights facilitate the installation process and significantly increase the strength of the flank angle thread cutting connection.

Thread forming screws are often equipped with a slot for a PH2 screwdriver. This is one of the most popular and convenient options. Manufacturers also provide products for PZ2, so we recommend that you familiarize yourself with the type of bits in advance before purchasing.

Some users are interested in whether it is possible to install hardware in plastic windows? Will it not affect their strength and other characteristics? In fact, if quality fasteners are used, then problems are excluded. Additional convenience is provided by the fact that thread forming screws do not require preliminary preparation of the hole and are screwed in immediately.

Hardware repair screws

These fasteners are similar to the previous ones, and at the same time differ from them:

  • Designed for the installation of fittings and similar structures in cases when the threads breaks off in ordinary hardware. Repair screws have an increased diameter (4.8 mm), so they are firmly held in the base.
  • The larger diameter ensures high bond strength. It is allowed to use fasteners while working with plastic, wood.
  • Ribs are provided on the inside of the head for maximum reliability and avoidance of spontaneous scrolling.
  • The head diameter is 7 mm, the upper part is semicircular. This ensures the maximum recession of the head into the base, even if the hardware is not at a right angle.
  • The most common standard sizes are hardware with a length of 25 and 38 mm.

The fastener is installed without additional devices and can be easily twisted into the hole from the old hardware screws. If you are installing into a plastic base without a hole, you do not need to drill it. When working with a screwdriver, it is recommended to first use a 3.5 mm drill bit, since it will be difficult to screw in the fasteners by hand.

Countersunk self-tapping screws with drill bit

This kind is distinguished by the following technical features:

  • These screws are equipped with a drill, which allows you to work with reinforcing metal profiles of window structures and other bases.
  • A relief on the head is provided for a stopper and increasing the reliability of the connection The semicircular shape of the cap provides sinking even when the hardware is unevenly installed.
  • The drill bit and small thread pitch make it difficult to work with wood and similar structures. Poor fixation is possible due to the absence of a reinforcing metal profile.
  • For a self-tapping screw, a bit or a PH2 screwdriver is used, the length is from 13 to 38 mm, while the thickness of the hardware is 3.9 mm.

It is difficult to install this type of fastener by hand, therefore it is recommended to use a screwdriver with an appropriate bit. Please note that these screws are rarely used in everyday life.

How do you make a self-tapping screw?

Self-tapping screws with a semicircular head

These fasteners are common in various fields, including used for the installation of PVC windows. Features include:

A wide range of sizes allows you to install various designs. This screw thickness varies from 4.2 to 6.3 mm, length from 13 to 70 mm.

The flat base of the cap is provided. This ensures a good grip on flat structures. There is no sinking into the base.

These screws are suitable for the installation of mechanical impost connectors, as well as roller blinds, roller shutter systems and others.

Galvanized coating is provided. When buying, pay attention to the fact that the zinc layer on the surface should be even, without streaks.

The standard bit PH2 is used for mounting. The fastener does not break due to the large cap.

If you plan to install hardware in place of reinforcing metal structures, take care of preliminary preparation of the hole. Moreover, its diameter should be slightly less than the size of the screw. The best option is hardware with a drill bit.

Self-tapping screws with a press washer

Fasteners of this type are widespread in various fields. They are also suitable for the installation of window structures since they have the following advantages:

Versatility. Hardware are suitable for solving various problems in industry and everyday life.

A special washer is provided under the head, due to which the area of the clamping part is increased to 11 mm. As a result, the hardware presses well the sheet structures.

On the market, there are both sharp hardware and those equipped with tips in the form of a drill. This allows most structures to be installed without hole preparation.

The standard thickness is 4.2 mm. The length varies from 13 to 75 mm.

Another advantage is zinc coating. If necessary, you can choose colored fasteners so that they are invisible on the base.

Self-tapping screws for window frames

This option is also called dowel, turbo screw, concrete screw. Hardware differs significantly with other types of the following parameters:

Suitable for fixing door and window frames and other structures. If necessary, it is allowed to connect PVC elements to each other.

Designed for windows with and without slopes, can be used as anchors. Note that excessive twisting is less likely to break the base.

For installation, you need a TORX T30 bit, made in the form of an asterisk.

The thickness indicator is 7.5 mm, the length varies from 52 to 202 mm.

Before installing the hardware, you need to prepare the installation site. Be sure to clean the base from old elements. The holes are prepared in advance, so it is necessary to mark the drilling locations.

For installation, a concrete drill is used, the diameter of which is 6 mm. The depth of the holes depends on the thickness of the frame, as well as the distance from the structure to the base. It is recommended to adhere to indicators of 50-70 mm, while the depth of the hole should exceed the length of the self-tapping screw by 10 mm.

Please note that the drilling mode must be selected for installation. When working in perforation mode, the hole diameter will be much larger, which affects the strength of the connection and increases the likelihood of base failure. The frame is positioned according to the level, do not forget about wedges or bars. It is recommended to carry out the installation with an assistant in order to install the structure evenly.

Threaded connections are one of the most common types of fastening in installation technology and are classified as split connections. For a threaded connection, you must use:

  • Connecting element - screw;
  • A nozzle for transmitting a rotating force to a screw;
  • Device for creating a rotating force when tightening a screw (screw).

The threaded connection technique allows you to create detachable connections that do not require destruction or damage to the connecting element and the connected parts. The standard connection for this technique is the screw.

The basis of the screw connection is the positive connection of the thread, but the main contribution to its strength is made by the force lock due to the compressive force between the screw and the parts to be connected.

To create a positive fit, two connecting elements are required to mesh with each other. One of them is the screws thread, the other is the thread in the material (typical for screws) or an additional nut element.

This concept of screws covers screws used without nuts. For this reason, they are only suitable for soft or elastic materials and sheet metal. Small diameter screws usually cut into wood without first drilling a hole. For larger diameters and when using high-strength wood, it is advisable to first drill a hole. When screwing screws into plastic, holes are drilled (punched) in any case.

Screws are classified according to:

  • Type of threads, threads pitch, and thread shape;
  • Threads shape;
  • In the shape of the slot.

The screws have an external special (screw) thread with a wide pitch and characteristic tips. Their shanks are either cylindrical or tapered. The special thread has a triangular, pointed profile, and a wider root in comparison to the width of the tooth.

There is a wide variety of screw heads and screws, some of which have been designed for special applications.

Do self-tapping screws need pilot holes?

No, these type of screws does not require a pilot hole.


There are many types of fasteners on the market that are suitable for various jobs with plastic material. The most important thing is to choose the appropriate hardware option and apply them correctly.

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