This section provides an overview for round contersunk screws as well as their applications and principles. Also, please take a look at the list of 10 round contersunk screw manufacturers and their company rankings.
The head of a flat-headed countersunk screw is slightly rounded. Although the surface does not become flat after being set like a flat countersunk screw, it avoids snagging and also gives a softer impression than the flat countersunk screw. The tip is flat, not drilled like a tapping screw, because it is used where a female thread has been cut. As with the flathead screws, the surface of the screw's stop point should be counterbored to match the head of the screw.
Unlike the regular countersunk screw, the nominal length of the round screw is the length from the screw head brim. In any case, the length of the threaded part is shorter than that of other screws of the same nominal length.
Like regular screws, the dimensions are determined by the standard, and they are used for parts that have a countersunk fir (counterbored) finish on the surface of the attachment point in combination with the screw.
The basic uses of these screws are the same as those of the countersunk screws, but the rounded head gives them a gentler impression, so they are often used for design purposes in places that are easily seen by the human eye. Also, countersunk screws are used to prevent the possibility of slipping on a surface and getting caught in a mortise or cross-hole. Used to fasten door closers, fix door knobs, etc.
The screw part has a dish-shaped head with a slightly rounded conical surface. The screw head diameter (φdk), head height, screw pitch, and corresponding screwdriver size are determined by the standards for each screw size (nominal diameter of screw) and are summarized as M2, M2.5, M3, and so on. At the time of sale, the nominal diameter is combined with the screw material and nominal length.
Example: Stainless steel 3 x 6 (made of stainless steel, nominal diameter 3 (head diameter 6 mm), nominal length 6 mm)
Materials are mainly stainless steel, but also include iron and brass, etc. In addition, screw fabrics plated with nickel or black oxide coating are also sold. The screw threads are available in a variety of styles to match the shape of the screwdriver, such as with a general Phillips hole, with a mortise (minus groove), and with a star-shaped TRX.
There are also small head screws with a smaller head diameter (for use in tight locations where ordinary round countersunk screws cannot be used) and old screws with a pitch that was used before the ISO standard was unified.
The dimensions of round countersunk screws are standardized according to the bolt diameter, so it is necessary to select the appropriate screw for the purpose of use.
Also called cross-holed round countersunk screws, the head diameter and the cross (plus) hole vary depending on the type of bolt diameter. The tip of a Phillips screwdriver can be inserted into the cross-shaped hole at the head of the screw to fasten it.
The following is a list of commonly used screw diameters from M2 to M8.
Screw diameter M2 : Pitch 0.4 mm : Cross-hole number 1 : Head diameter Φ4 mm : Fastening section (height) 1.2 mm : Cross-hole (width) approx. 2.4 mm
Screw diameter M2.3 : Pitch 0.4 mm : Cross hole no. 1 : Head diameter Φ4.6 mm : Tightening section (height) 1.35 mm : Cross hole (width) approx. 2.7 mm
Screw diameter M2.5 : Pitch 0.45 mm : Cross hole no. 1 : Head diameter Φ5 mm : Tightening section (height) 1.45 mm : Cross hole (width) approx. 2.9 mm
Screw diameter M2.6 : Pitch 0.45 mm : Cross hole no. 1 : Head diameter Φ5.2 mm : Tightening section (height) 1.5 mm : Cross hole (width) approx. 2.9 mm
Screw diameter M3 : Pitch 0.5 mm : Cross hole no. 2 : Head diameter Φ6 mm : Clamping height 1.75 mm : Cross hole (width) approx. 3.8 mm
Screw diameter M3.5 : Pitch 0.6 mm : Cross hole no. 2 : Head diameter Φ7 mm : Clamping height 2.0 mm : Cross hole (width) approx. 4.3 mm
Screw diameter M4 : Pitch 0.7 mm : Cross hole no. 2 : Head diameter Φ8 mm : Clamping area (height) 2.3 mm : Cross hole (width) approx. 4.7 mm
Screw diameter M5 : Pitch 0.8 mm : Cross hole no. 2 : Head diameter Φ10 mm : Clamping area (height) 2.8 mm : Cross hole (width) approx. 5.3 mm
Screw diameter M6 : Pitch 1.0 mm : Cross hole no. 3 : Head diameter Φ12 mm : Clamping area (height) 3.4 mm : Cross hole (width) approx. 6.9 mm
Thread diameter M8 : Pitch 1.25 mm : Cross hole no. 3 : Head diameter Φ16 mm : Tightening section (height) 4.4 mm : Cross hole (width) approx. 8.6 mm
Bolt length varies depending on the product and should be selected according to the part to be fastened.
Round countersunk tapping screws are screws that can be fastened to materials that do not have threaded holes while drilling the threaded holes. There are various types of tapping screws available, and they must be selected according to the purpose for which they are to be used.
They are mainly used for lumber and are useful in the construction industry. Round countersunk tapping screws are also called round countersunk wood screws (as the name suggests, screws for wood) and can be easily fastened using an electric screwdriver or Phillips screwdriver.
*Including some distributors, etc.
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