Tapping Screw Size
Self-tapping screws, also known as sheet metal screws, are a type of screw that can tap their own threads as they are driven into a material. They are typically used to join two materials together, such as metal, wood, plastic and more. The self-tapping screws have a sharp point that can drill into the material and create threads, so there is no need to pre-drill a hole. They are known for their reliable strength and fast installation, are widely used in construction, decoration and mechanical manufacturing.
The following are common specifications of self-tapping screws.
| TAPPING SCREW ASA TYPE A | |||||
|---|---|---|---|---|---|
SIZE | 牙數 P (T) | Major Diameter (D) | Rolling Diameter (d) | ||
| Maximum (MAX) | Minimum (MIN) | Maximum (MAX) | Minimum (MIN) | ||
| NO: 0 | 40 | 1.52 | 1.44 | 1.20 | 1.15 |
| NO: 1 | 32 | 1.90 | 1.82 | 1.50 | 1.45 |
| NO: 2 | 32 | 2.23 | 2.13 | 1.80 | 1.75 |
| NO: 3 | 28 | 2.56 | 2.46 | 2.10 | 2.05 |
| NO: 4 | 24 | 2.89 | 2.79 | 2.30 | 2.25 |
| NO: 5 | 20 | 3.30 | 3.20 | 2.65 | 2.60 |
| NO: 6 | 18 | 3.58 | 3.45 | 2.80 | 2.75 |
| NO: 7 | 16 | 4.01 | 3.86 | 3.15 | 3.10 |
| NO: 8 | 15 | 4.26 | 4.11 | 3.35 | 3.30 |
| NO: 9 | 14 | 4.55 | 4.40 | 3.50 | 3.45 |
| NO: 10 | 12 | 4.92 | 4.77 | 3.75 | 3.70 |
| NO: 12 | 11 | 5.60 | 5.46 | 4.40 | 4.35 |
| NO: 14 | 10 | 6.45 | 6.29 | 5.10 | 5.05 |
| NO: 16 | 10 | 7.11 | 6.96 | 5.70 | 5.65 |
| NO: 18 | 9 | 7.77 | 7.62 | 6.10 | 6.05 |
| TAPPING SCREW ASA TYPE AB (B) | |||||
|---|---|---|---|---|---|
SIZE | 牙數 P(T) | Major Diameter (D) | Rolling Diameter (d) | ||
| Maximum (MAX) | Minimum (MIN) | Maximum (MAX) | Minimum (MIN) | ||
| NO: 0 | 46 | 1.52 | 1.44 | 1.25 | 1.20 |
| NO: 1 | 42 | 1.90 | 1.82 | 1.60 | 1.55 |
| NO: 2 | 32 | 2.23 | 2.13 | 1.80 | 1.75 |
| NO: 3 | 28 | 2.56 | 2.46 | 2.10 | 2.05 |
| NO: 4 | 24 | 2.89 | 2.79 | 2.30 | 2.25 |
| NO: 5 | 20 | 3.30 | 3.20 | 2.60 | 2.55 |
| NO: 6 | 20 | 3.53 | 3.42 | 2.85 | 2.80 |
| NO: 7 | 19 | 3.91 | 3.78 | 3.20 | 3.15 |
| NO: 8 | 18 | 4.21 | 4.08 | 3.40 | 3.35 |
| NO: 10 | 16 | 4.80 | 4.64 | 3.85 | 3.80 |
| NO: 12 | 14 | 5.46 | 5.30 | 4.40 | 4.35 |
| 1/4 | 14 | 6.24 | 6.09 | 5.15 | 5.10 |
| 5/16 | 12 | 8.00 | 7.82 | 6.75 | 6.70 |
| 3/8 | 12 | 9.65 | 9.42 | 8.45 | 8.35 |
| 7/16 | 10 | 11.17 | 10.94 | 9.75 | 9.70 |
| 1/2 | 10 | 12.80 | 12.57 | 11.40 | 11.35 |
| TAPPING SCREW M/M TYPE A | |||||
|---|---|---|---|---|---|
SIZE | 牙數 P(T) | Major Diameter (D) | Rolling Diameter (d) | ||
| Maximum (MAX) | Minimum (MIN) | Maximum (MAX) | Minimum (MIN) | ||
| M2 | 40 | 2.0 | 1.90 | 1.70 | 1.65 |
| M2 | 32 | 2.10 | 2.00 | 1.75 | 1.70 |
| M2.3 | 32 | 2.40 | 2.30 | 2.00 | 1.95 |
| M2.6 | 28 | 2.70 | 2.60 | 2.20 | 2.15 |
| M3 | 24 | 3.10 | 3.00 | 2.45 | 2.40 |
| M3.5 | 18 | 3.65 | 3.50 | 2.85 | 2.80 |
| M4 | 16 | 4.15 | 4.00 | 3.30 | 3.25 |
| M4.5 | 14 | 4.65 | 4.50 | 3.60 | 3.55 |
| M5 | 12 | 5.20 | 5.00 | 3.95 | 3.90 |
| M6 | 10 | 6.20 | 6.00 | 4.80 | 4.75 |
| M8 | 9 | 8.20 | 8.00 | 6.45 | 6.40 |
| TAPPING SCREW M/M TYPE AB (B) | |||||
|---|---|---|---|---|---|
SIZE | 牙數 P(T) | Major Diameter (D) | Rolling Diameter (d) | ||
| Maximum (MAX) | Minimum (MIN) | Maximum (MAX) | Minimum (MIN) | ||
| M2 | 40 | 2.0 | 1.90 | 1.70 | 1.65 |
| M2.3 | 32 | 2.3 | 2.20 | 1.90 | 1.85 |
| M2.6 | 28 | 2.6 | 2.50 | 2.15 | 2.10 |
| M3 | 24 | 3.0 | 2.90 | 2.45 | 2.40 |
| M3.5 | 20 | 3.5 | 3.40 | 2.85 | 2.80 |
| M4 | 18 | 4.0 | 3.85 | 3.30 | 3.25 |
| M4.5 | 16 | 4.5 | 4.35 | 3.60 | 3.55 |
| M5 | 16 | 5.0 | 4.85 | 4.10 | 4.05 |
| M6 | 14 | 6.0 | 5.85 | 5.05 | 5.00 |
| M8 | 12 | 8.0 | 7.85 | 6.80 | 6.75 |