Bolts are often used in hardware fasteners, but there are many bolt sizes. The bolts used in different areas are different. If the bolts are too large or too small, they will not be used. What are the specifications and models of bolts? How is it expressed? Let's take a look at the relevant knowledge right away.

一、螺栓的规格型号及表示方法

1、 Specification, model and representation of bolts

螺栓的规格型号一般用字母“M”表示，规格有M6、M8、M10、M12、M14、M16、M18、M20等。以M 16-5g6g为例，其表示普通螺纹公称直径为16cm，右旋，公差带中径 5g，大径为 6g的意思。如果是M16×1 LH-6G，代表细牙螺纹，公称直径为16，螺距1cm，左旋，大径为6G，旋合长度根据中等长度来考虑。

The specifications and models of bolts are generally represented by the letter "m", and the specifications include M6, M8, M10, M12, M14, M16, M18, M20, etc. Taking m 16-5g6g as an example, it means that the nominal diameter of ordinary thread is 16cm, right-handed, the pitch diameter of tolerance zone is 5g, and the major diameter is 6G. If M16 × 1 lh-6g represents fine thread, with nominal diameter of 16, pitch of 1cm, left-handed, major diameter of 6G, and the screwing length is considered according to the medium length.

二、螺栓种类有哪些

2、 What are the types of bolts

1、根据受力情况分，有普通螺栓及铰制孔用螺栓。

1. According to the stress conditions, there are ordinary bolts and bolts for reaming holes.

2、根据头部形状分，可分为六角、方形、圆型、和沉头……其中六角属于较为常见的螺栓。

2. According to the shape of the head, it can be divided into hexagon, square, round and countersunk... Among them, hexagon belongs to the more common bolt.

3、按螺纹牙型分为粗牙、细牙两种。

3. According to the thread profile, it is divided into coarse teeth and fine teeth.

4、按螺栓性能等级可以分为3.6、4.8、5.6、8.8、10.9以及12.9等等，8.8级以上的属于低碳合金钢材质螺栓，拥有高强度，而8.8级以下算普通螺栓。

4. According to the bolt performance grade, it can be divided into 3.6, 4.8, 5.6, 8.8, 10.9 and 12.9. Bolts above grade 8.8 belong to low-carbon alloy steel bolts with high strength, while bolts below grade 8.8 are ordinary bolts.

5、按螺栓制作精度分为三级，分别是A、B、C，属于精制螺栓，常常用在于车床加工，一般性能等级为8.8， C属于粗制螺栓，等级为4.8级，常常用在临时固定。

5. According to the bolt manufacturing accuracy, it is divided into three levels: A, B and C. they are refined bolts, which are often used for lathe processing. The general performance level is 8.8. C is a rough bolt, which is level 4.8. They are often used for temporary fixing.