Leader-Fastener® is a manufacturer and distributor of ASME B18.5.2.1M Round Bolt. We have a complete line of service from having invested in production plants, export department and to having a quality control team and center to meet your requirements. We regard quality as the life of the company. We persist in good quality as the first policy and have established a set of quality control and inspection system according to the international standard.We have carried out ISO9001 Quality Guarantee System in every course of production, transportation and selling.We do hope we could be your partner in business by topping quality, knight service and competitive price in the near future and be your friends as well.
This Standard covers the general and dimensional data for metric series round head short square neck bolts recognized as an American National Standard and intended primarily for applications in thin metals.
The inclusion of dimensional data in this Standard is not intended to imply that all sizes described are production stock items.Consumers should consult with suppliers concerning lists of stock production items.
Leader-Fastener® ASME B18.5.2.1M Round Bolt produced to this Standard are functionally interchangeable with bolts which conform to ISO 8678:1988. Differences between this Standard and ISO 8678 are: size M14, materials other than steel, and minor variations in tolerances,such as, permissible swell, fin, or die seam on the body of bolts with nominal engths longer than 150 mm. Dimensional requirements in addition to, or different from ISO 8678, are shown in bold type in this Standard.
Round head bolts are frequently used in rail, heavy equipment, and agricultural applications. The bolts have a low profile head that does not interfere with many applications where a dramatic protrusion from a hex head or other style would. There are a variety of styles that include under head features to hold the bolt in place while a nut is being tightened.
Thread Size d |
Pitch | ds |
dk max |
k | s | k1 | ||||
max | min | max | min | max | min | max | min | |||
M6 | 1 | 6 | 5.21 | 14.2 | 3.6 | 3 | 6.48 | 5.88 | 3 | 2.4 |
M8 | 1.25 | 8 | 7.04 | 18.0 | 4.8 | 4 | 8.58 | 7.85 | 3 | 2.4 |
M10 | 1.5 | 10 | 8.86 | 22.3 | 5.8 | 5 | 10.58 | 9.85 | 4 | 3.2 |
M12 | 1.75 | 12 | 10.68 | 26.6 | 6.8 | 6 | 12.70 | 11.82 | 4 | 3.2 |
M14 | 2 | 14 | 12.50 | 30.5 | 7.9 | 7 | 14.70 | 13.82 | 4 | 3.2 |
M16 | 2 | 16 | 14.50 | 35.0 | 8.9 | 8 | 16.70 | 15.82 | 5 | 4.2 |
M20 | 2.5 | 20 | 18.16 | 43.0 | 10.9 | 10 | 20.84 | 19.79 | 5 | 4.2 |