For an M6 bolt that utilizes an internal hex drive, such as a socket head cap screw, the required socket (or hex key) size is 5 mm.
M6 refers to a metric bolt with a nominal thread diameter of 6 millimeters. However, the specific socket size needed depends on the bolt's head style. When the term "socket" is used in relation to an M6 bolt in this context, it commonly refers to the internal hexagonal drive found on socket head cap screws. These fasteners require an Allen key or a hex bit socket to be driven.
Understanding M6 Bolt Socket Sizes
The dimensions for common metric socket head cap screws are standardized. The following table illustrates the typical internal hexagon socket sizes for various metric socket head cap screws:
| Bolt Size (Nominal Diameter) | Hexagon Socket Size (mm) |
|---|---|
| M5 | 4.0 |
| M6 | 5.0 |
| M8 | 6.0 |
| M10 | 8.0 |
Key Considerations for M6 Socket Bolts
- Type of Bolt Head: It's important to distinguish between different bolt types. While an M6 hex head bolt (which has an external hexagonal head) typically requires a 10 mm wrench or socket for its external flats, an M6 socket head cap screw uses an internal hex drive, which is 5 mm. The question, in conjunction with the reference data provided, points towards the internal hex drive.
- Accuracy is Crucial: Always use the exact 5 mm hex socket or key for an M6 socket head cap screw. Using an imperial (SAE) size that seems to fit but is slightly off, or a worn tool, can strip the internal hexagon of the bolt head. This can make the bolt very difficult to remove or properly tighten.
- Metric vs. Imperial Tools: Ensure you are using metric tools for metric fasteners. There can be instances where an imperial size might appear to fit a metric fastener, but this can lead to rounding the corners of the fastener's head, causing damage.
By understanding the specific type of M6 bolt you are working with, especially if it's a socket head cap screw, you can confidently select the correct 5 mm socket size for secure and effective fastening.
