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China Factory Suppliers of Galvanized Countersunk Cross Tapping Screws - Quality Self Tapping Solutions
| Thread specifications | ST2.2 | ST2.9 | ST3.5 | ST4.2 | ST4.8 | ST5.5 | ST6.3 | ST8 | ST9.5 | |||
| P | Pitch | 0.8 | 1.1 | 1.3 | 1.4 | 1.6 | 1.8 | 1.8 | 2.1 | 2.1 | ||
| a | Max | 1.6 | 2.2 | 2.6 | 2.8 | 3.2 | 3.6 | 3.6 | 4.2 | 4.2 | ||
| dk | Max | 3.8 | 5.5 | 7.3 | 8.4 | 9.3 | 10.3 | 11.3 | 15.8 | 18.3 | ||
| Min | 3.5 | 5.2 | 6.9 | 8 | 8.9 | 9.9 | 10.9 | 15.4 | 17.8 | |||
| k | Max | 1.1 | 1.7 | 2.35 | 2.6 | 2.8 | 3 | 3.15 | 4.65 | 5.25 | ||
| Slot Number | 0 | 1 | 2 | 2 | 2 | 3 | 3 | 4 | 4 | |||
| M1 | Cruciform | 1.9 | 3.2 | 4.4 | 4.6 | 5.2 | 6.6 | 6.8 | 8.9 | 10 | ||
| M2 | Zigzag slot | 2 | 3 | 4.1 | 4.4 | 4.9 | 6.3 | 6.6 | 8.8 | 9.8 | ||
| y | Reference value | Type C | 2 | 2.6 | 3.2 | 3.7 | 4.3 | 5 | 6 | 7.5 | 8 | |
| Type F | 1.6 | 2.1 | 2.5 | 2.8 | 3.2 | 3.6 | 3.6 | 4.2 | 4.2 | |||
| Type R | / | / | 2.7 | 3.2 | 3.6 | 4.3 | 5 | |||||
How to Choose a Suitable Self Tapping Screw
- 1 Select by material: Select different self tapping screws based on the material characteristics that need to be nailed in. For example, for hard materials, choose self tapping screws with high strength, appropriate length and diameter.
- 2 According to thread selection: Self tapping screws usually have two types: coarse thread and fine thread, and different threads are usually suitable for different materials.
- 3 Select according to the shape of the head: The pentagonal head self tapping screw is more sturdy than the ordinary round head self tapping screw, but the price is also relatively high.
Frequently Asked Questions
Q What is the difference between coarse thread and fine thread self tapping screws?
Coarse thread self tapping screws are generally used for softer or thicker materials, providing faster driving and stronger grip in wood or plastic. Fine thread self tapping screws are better suited for harder or thinner materials, offering more precise fastening and greater resistance to loosening under vibration.
Q What does the "ST" designation mean in self tapping screw sizing (e.g., ST4.2)?
"ST" stands for "Sheet metal Tapping" screw. The number following ST indicates the nominal outer diameter of the screw thread in millimeters. For example, ST4.2 means the screw has a nominal thread diameter of 4.2 mm.
Q What is the advantage of galvanized self tapping screws over regular ones?
Galvanized self tapping screws have a zinc coating that provides excellent corrosion and rust resistance, making them ideal for outdoor applications or environments with high humidity. They offer a longer service life compared to uncoated screws.
Q What is the difference between Type C, Type F, and Type R self tapping screws?
Type C screws have a blunt point and are typically used for thicker metal sheets. Type F screws have a sharp point resembling a machine screw thread, suitable for thin metal. Type R screws have a gimlet point and are designed for use in wood or soft materials, providing easy penetration without pre-drilling.
Q How do I select the correct length of a self tapping screw for my application?
The screw length should be long enough to penetrate through the top material and into the base material by at least 3 times the screw diameter for a secure hold. Always consider the combined thickness of all materials being fastened when choosing the screw length.
Q Can countersunk cross (Phillips) self tapping screws be used in metal applications?
Yes, countersunk cross self tapping screws are widely used in metal applications. The countersunk head sits flush with the surface, providing a clean finish. It is important to select the appropriate thread size and material grade based on the thickness and hardness of the metal being fastened.