1. What screws are generally used for door and window installation? There are 3 commonly types of screws for installation of doors and windows, expansion screws, self-tapping screws, self-drilling (drilling tail) screws. 1. The expansion screw is covered with an expansion pipe fitting. It uses the movement of the thread to make the expansion piece "open and expend", so that the formed extrusion force achieves a fixed effect. 2. Self-tapping screws, which have a sharp head, can "drill, squeeze, press, and tap" the fixed body through their own screws to make corresponding threads, so that they are tightly connected to each other. 3. Self-drilling screws, also known as self-tapping self-drilling/drilling tail/dovetail screws, compared with self-tapping screws, has a blade like tail on its head, so it can be directly driven into the fixed body without pre-drilled hole. 2. How to choose the type of door and window screws Although doors and windows may use a lot of different type of screws, but if the focus is on the installation, then mainly in the door and window frame fixing, as well as hardware installation (slide brace) will use screws, When the door and window frame is fixed, expansion screws or self-tapping screws with larger size (longer length and larger diameter) are usually used. In terms of safety, as long as the product and construction are reliable, both types of products can be selected. Of course, There are also some special cases when the door and window frame is fixed, mainly when the wall is red brick, porous brick, aerated brick, it is not recommended to choose expansion screws. During hardware installation (sliding support), self-tapping screws or self-drilling screws with the size of the slotted hole are usually used. Both types of products can be selected, but self-drilling screws are more convenient to use. 3.How to choose screw products ? From the material, specification (dimension) of screws, to the shape and thread of screws, the selection is also exquisite: The screw material should be made of stainless steel as much as possible. In most cases, 304 stainless steel is preferred, 316 stainless steel is used in coastal cities, and 410 stainless steel is selected for the connection parts of doors and windows with thick walls or high-strength scenarios. Regarding whether the expansion screw is made of nylon casing or the kind of stainless steel blasting screw, my personal suggestion is that as long as the main body of the screw is not carbon steel but stainless steel, it can be used. Of course, if you have a budget, you can choose a larger stainless steel blasting screw. Its security is relatively more guaranteed. In addition to the material, the second most important aspect of the screw is the specification (size). The larger the specification, the greater the "fixing force" that the screw can provide for the fixed body. Taking nylon expansion sleeve screws as an example, the common sizes are 6 / 8 * 60 / 80 / 100 (unit mm), 10 * 80 / 100 / 120, etc., and the common sizes of stainless steel expansion screws are 10 * 70 / 90 / 110 etc. In the selection of hardware (sliding support) mounting screws, in addition to the material, the specification should also be considered. Generally, the size of the sliding support screw hole is about 5 mm, so the diameter of the screw should be about 4.8 mm, and the diameter of the screw of about 3 or 4 mm is easy to leave safety. hidden danger. In addition, the sliding support also needs to consider the problem of screw loosening (the thickness of the hardware wall is so small, and the screw thread is easy to tighten if it is not tightened), so it is recommended to choose a fine thread (the screw thread is more "tight") self-tapping or self-drilling screws.