DIN 547 Round Nut with Two End Holes

The nut with two end holes is a fastener with no direct equivalents. It was developed in Germany and complies with DIN 547.

This type of nut is used in construction, mechanical engineering, shipbuilding, instrument making and household applications.

Design features

The nut with holes has a round shape. Sizes vary. The most common are those with a thread diameter of 5, 6, 8 and 10 millimeters. They are used together with other fasteners (bolts, screws, threaded studs) of matching sizes.

The holes in such nuts are made with a much smaller diameter — 2, 2.5, 3 and 3.5 millimeters. After installation, the fastener is secured through them — for example, with metal wire or a special clip. This design makes the connection more reliable and practically eliminates self-loosening of the nut during operation. This factor is important for the automotive industry, where moving vehicle assemblies constantly experience mechanical loads and vibration.

Manufacturing of nuts with end holes

Nuts with end holes are manufactured on machines by cold stamping: a round metal blank of the required diameter is cut into pieces, holes are punched in them, and internal threads are cut.

The nut material depends on the application: brass, aluminum alloy, high-strength steel or stainless steel. There are also versions made of hard plastic.

Additional corrosion protection — for example, against temperature fluctuations and precipitation — is provided by zinc coating. This expands the range of applications for the fasteners and extends their service life.

Installation of nuts with holes

A special wrench with two prongs matching the diameter of the holes in the fastener is used to install such nuts.

Dimensions of round nuts with two holes DIN 547 in mm:

d	M5	M6	M8	M10
dk	12	14	18	22
m	4.2	5	6.5	8
t min	2.3	2.8	3.3	3.8

d	M2	M2.5	M3	M4	M5	M6	M8	M10
dk	5.5	7	8	10	12	14	18	22
m	2	2.2	2.5	3.5	4.2	5	6.5	8
t	nut height		1.3	1.8	2.3	2.8	3.3	3.8
dt	1	1.2	1.5	1.5	2	2.5	3	3.5

Designations:

d - nominal thread diameter

dk - nut diameter

m - nut height

t - hole depth

dt - hole diameter