Whether the length of a bolt includes the head depends on the type and purpose of the bolt. Here are some common situations:
1. The case where the head is not included
In most cases, the length of the bolt does not include the head. This situation mainly applies to the following types of bolts:
- Hexagonal flange bolts
- Square head bolts
- Ordinary hexagonal head bolts
- Cross pan head machine bolts
After use, the heads of these bolts are usually exposed, so the height of the head is not included in the length of the bolt.
2. The case where the head is included
The length of some bolts includes the head, which mainly applies to the following types of bolts:
- Cross countersunk machine bolts: After use, the entire head is sunk inside, so the length includes the height of the head.
- Set bolts: Similarly, after use, the head is sunk into the connected parts, so the length includes the height of the head.
3. The case where the head is partially included
There are also some bolts whose length includes part of the head, which mainly applies to the following types of bolts:
- Cross semi-countersunk bolts: After use, half of the head is sunk into the hole and the other half is exposed outside, so the bolt length includes half of the head thickness.
Conclusion
Whether the length of a bolt includes the head depends on the type and purpose of the bolt. When selecting and using bolts, the length of the bolts should be determined according to specific needs and application scenarios.