DIN 921 - Slotted Pan Head Screws with Large Head

This product guide contains the specification for Slotted pan head screws with large head, a series of standard parts available from Westfield Fasteners. The basis of this specification is the internationally recognised DIN standard DIN 921.

Product Description

These large diameter headed screws offer excellent load distribution and an aesthetically pleasing low-profile head. The wide head also eliminates the need for a washer. Installed using a flat head screwdriver, the slotted pan head screw is useful in situations where a thumbscrew or a standard pan head screw is not suitable.

Scope of the DIN Standard

DIN 921 specifies the tolerances and the variation of detailing allowable for the slotted pan head with a large head, for sizes M1 up to and including M10. Table 1 below defines the overall dimensions and tolerances of this screw type.

Notes to Figure 1:

The top edge of the head of the screw can be chamfered at 45 degrees or just rounded.
The tip of the screw thread is chamfered as in DIN EN ISO 4753.
The length of the incomplete thread at the tip of the screw (u) is the same or less than 1.5 times the thread pitch.

Thread Size, d	p	a	d_k		k			n			r	t		v
Thread Size, d	p	max	Nom	min	nom	max	min	Nom	max	min	max	max	min	=
M1	0.25	0.5	3.50	3.20	0.70	0.82	0.58	0.25	0.45	0.31	0.10	0.50	0.35	0.20
M1.2	0.25	0.5	4.00	3.70	0.80	0.92	0.35	0.3	0.50	0.36	0.10	0.55	0.40	0.20
M1.4	0.3	0.6	4.50	4.20	0.90	1.02	0.78	0.3	0.50	0.36	0.10	0.60	0.45	0.25
M1.6	0.35	0.4	5.00	4.70	1.00	1.12	0.88	0.4	0.60	0.46	0.10	0.70	0.50	0.25
M2	0.4	0.8	6.00	5.64	1.20	1.32	1.08	0.5	0.70	0.56	0.10	0.80	0.60	0.30
M2.5	0.45	0.9	7.00	6.64	1.50	1.62	1.38	0.6	0.80	0.66	0.10	0.95	0.75	0.40
M3	0.5	1.0	8.00	7.64	1.80	1.92	1.68	0.8	1.00	0.86	0.10	1.15	0.90	0.45
M4	0.7	1.4	12.00	11.57	2.40	2.52	2.28	1	1.20	1.06	0.20	1.50	1.20	0.60
M5	0.8	1.6	16.00	15.57	2.70	2.82	2.58	1.2	1.51	1.26	0.20	1.60	1.30	0.70
M6	1	2.0	20.00	19.48	3.10	3.25	2.95	1.6	1.91	1.66	0.25	1.90	1.50	0.80
M8	1.25	2.5	25.00	24.48	3.80	3.95	3.65	2	2.31	2.06	0.40	2.40	1.90	0.90
M10	1.5	3.0	30.00	29.48	4.60	4.75	4.45	2.5	2.81	2.56	0.40	2.80	2.30	1.10

DIN 921 - Slotted Pan Head Screws with Large Head

Figure 1: Slotted Pan Screw with Large Head

Notes to Figure 1:

Table 1: Dimensions & Tolerances according to DIN 921