Flat Head Screws – What angles are standard?

Q: I have a customer who is looking for some Inconel flat head screws and specifically called out 100°. Is this the standard?

A: Flat head screws, also known as countersunk screws, are able to be manufactured with 6 different angles – 60°, 82°, 90°, 100°, 110° and 120°. The most commonly used chamfered angles are 82° and 90°. Imperial sizes per ASME B18.3, 82° is the standard and 90° is the standard per DIN 7991 for metric screws. 100° angles are most commonly used in aerospace applications and when fastening into softer materials as it distributes the pressure over a larger area than the 82° screw. If 100° angle is needed, it would need to be called out in your request to ensure the proper dimensions are quoted.