Knurled nuts flat shape DIN 467-5 zinc plated blue M3

The knurled head is grooved on the side, which is why the knurled screw is particularly easy to grip when tightened by hand. Most of the time they are only tightened "hand-tight" without tools. The component can be easily and conveniently fixed after setup using the large, easy-grip knurled head.

Only one number is used for nuts. This indicates up to which strength class of the screw you can use the nut. For example, you can use a nut strength class 5 with a screw 5.8, but not with a screw 8.8. If you use nuts with a strength class that is too low, there is a risk of the thread stripping. Higher ones can be used without hesitation, but should only be used if the load on the screw is above the yield point.

Steel is an iron-carbon alloy with a maximum carbon content of 2% by mass. The steels achieve their intended physical and mechanical properties through various hardening, annealing and tempering processes. It is also possible to harden the edge zone by surface hardening, case hardening or nitriding. Well-known steel grades are structural steels, free-machining steels, case-hardening steels, nitriding steels, tempering steels, tool steels and stainless steels.

Blue galvanised finishes are produced either by electroplating in accordance with DIN EN ISO 4042 or by mechanical plating in accordance with DIN EN ISO 12683. For fasteners with a hardness exceeding 390 HV, there is a risk of hydrogen embrittlement during galvanising (electrolytic process). This necessitates specific measures (such as annealing), although these do not provide a 100 per cent guarantee against embrittlement.