What Is a Grub Screw?

Flat head screws are screws that are mostly used in construction sites and other projects. It is characterized in that the axial surface of the screw body is formed with an axially extending screw tooth, and at least one cutting groove is provided at a tail end portion thereof.

The flat head screw has a screw body. The axial surface of the screw body is formed with an axially extending screw tooth. At the end of the screw body is provided with at least one cutting groove.

Flat head screw: The axial surface of the screw body is formed with an axially extending thread, and at least one groove is formed at the tail end. A chip groove is dug in the slot to the center of the screw. The chip groove should penetrate the screw body and exceed the center line by a predetermined angle. The main purpose is to prevent chips from blocking the slot opening.

Countersunk head screws: 90 °

1. Countersunk hole design of metric flat head screw (FHSS):

		Head size		Wire hole size	Head size
uncommonly used	Commonly used	D	H	A	B	C
M3		6	1.7	4	8	2
	M4	8	2.3	5	10	2.5
	M5	10	2.8	6	12	3
	M6	12	3.3	7	14	3.5
	M8	16	4.4	9	19	5
M10		20	5.5	11	twenty three	6
M12		twenty four	6.5	14	27	6.5

At present, the standard parts on the market are mainly carbon steel, stainless steel and copper.

Carbon steel. We distinguish low carbon steel by the carbon content of carbon steel.

Flat head can be divided into full countersunk head and half countersunk head, flat head cone angle generally has three types of countersunk head: 900, 1000 and 1200. In the Russian standard system, 900 and 1200 flat heads are used. The 1200 flat head is mainly used for thin-walled structures (such as thin skins), but because the thickness of the head is thin, the depth of the screwing groove is not controlled, the groove is too shallow, and the screwing performance is too poor. ; If the groove is too deep, the strength of the nail head will be weakened and it will easily turn around. In the ISO / TC2 standard system, there are only 900 flat heads, while in the ISO / TC20 / SC4 standard system, there are only 1,000 flat heads and 1000 small flat heads. The small flat head refers to the type with reduced head height. It is used for thin-walled structures of aerospace vehicles. Due to the characteristics of the flat head bolt structure, the strength of the head is generally lower than the strength of the screw or the thread. When the flat head bolt is subjected to a tensile failure test, The bolt head is always broken first. ^[1]