Slotted pan head screw | With shoulder | A1 | DIN 923
Slotted fillister head screw with shoulder in stainless steel A1 (AISI 303 / 1.4305) according to DIN 923, also known as a shoulder screw, features an unthreaded shoulder under the head and is intended for mechanical assemblies where a smooth, cylindrical surface is required for guiding or centering. The threaded end provides firm attachment into the load-bearing structure.
DIN 921 and DIN 923 are two versions of the same product family, slotted fillister head screws (German: Flachkopfschraube mit Schlitz). DIN 923 has an unthreaded shoulder under the head. DIN 921 instead features an extra-large head for a wide contact surface. If you need a slotted screw with a large head, see Slotted fillister head screw | Large head | A1 | DIN 921.
AREA OF APPLICATION
The product is used in machine building, device construction, and other mechanical contexts where a screw requires an unthreaded shoulder for guiding or centering an adjacent component. The smooth surface of the shoulder provides a defined contact, while the threaded part allows for firm attachment into the load-bearing structure.
TECHNICAL SPECIFICATIONS
Product type: Screw
Product family: Slotted fillister head screw (DIN 921 / DIN 923)
Also known as: Slotted shoulder screw, shoulder screw, slotted machine screw
Head shape: Fillister head
Material grade: A1 (AISI 303 / 1.4305)
Standard: DIN 923
Thread type: Metric thread
Drive type: Slotted
Design: Unthreaded shoulder under the head
Sales unit: Piece
FREQUENTLY ASKED QUESTIONS (FAQ)
What is a slotted shoulder screw (DIN 923)?
It is a slotted fillister head screw with an unthreaded shoulder between the head and the threaded part. The shoulder provides a smooth cylindrical surface that can be used for guiding or centering, while the threaded end secures the screw into a load-bearing part.
What is the difference between DIN 923 and DIN 921?
Both are slotted fillister head screws belonging to the same product family. DIN 923 has an unthreaded shoulder under the head. DIN 921 has an extra-large head that provides a wide contact surface. See slotted fillister head screw with large head DIN 921.
When is a shoulder screw used instead of a standard machine screw?
When the assembly requires a smooth, unthreaded surface for guiding or centering, such as against a lever, linkage arm, or bushing, rather than just a threaded fastening point.
How do I choose the right length?
The length is specified as the total screw length from the underside of the head to the tip. The length of the shoulder follows the standard per thread size (see dimension drawing), and the remaining part closest to the tip is threaded. Choose a length that provides sufficient thread engagement in the load-bearing part.
What does stainless steel A1 mean?
A1 is an austenitic stainless steel grade (equivalent to 1.4305 / AISI 303) used primarily for screws and other turned/machined parts. It has good general corrosion resistance but is not as resistant to chlorides and salt environments as A4 (acid-proof). The choice of A1 should be based on the actual environment and the corrosion resistance requirements for the installation – for marine use or severe chemical exposure, A4 is recommended instead.