DIN 267 Grade 12 Nut - How is it made?

[Westlake]

Hi all, I've recently joined a company who's in the automotive industry, and I'm on a drastic learning curve with all the specs that are out there.

I've received a drawing for a standard Grade 12 DIN 267 M24 x 3 Nut... apparently buying them off the shelf and shipping them off isn't how its done and I need to figure out how to make them.

I've struggled like hell with this request, nobody seems to really know how to reach the grade 12 spec for a nut and has just been as vague as " heat treat some alloy steel ".
I've contacted steel suppliers and asked for materials that meet spec and still have no clue.

What I've found is that the Grade 12 requires a very high Proof load stress (min 1200 n/mm) which google tells me is similar to tensile strength but usually slightly lower, but also requires a moderate HRC and HB value.



I can't get my head round how you're supposed to hit over 1200 tensile strength without going over the max HB of 355 , or max HRC of 36. I really must be missing something.

Can anybody shed light on this subject? I'm going to need this information moving forward and don't want to wing it. Thus far I've been pointed in the direction of using 42CrMo4 or EN24 and tempering to a harder state, but then some of the values go over there max to reach the required tensile strength?

Any help on this would be greatly appreciated!!!!!

Thank you.

 

[Donkey Hotey]

Hi all, I've recently joined a company who's in the automotive industry, and I'm on a drastic learning curve with all the specs that are out there.

Good industry specifications are usually not open-ended. I would refer directly to the specification and adhere to it. It's a set of instructions: start with this material, do these things to it, under these conditions and create this. You shouldn't need to solve anything. The processes and materials should be defined.

 

[Westlake]

Good industry specifications are usually not open-ended. I would refer directly to the specification and adhere to it. It's a set of instructions: start with this material, do these things to it, under these conditions and create this. You shouldn't need to solve anything. The processes and materials should be defined.

Completely agree, unfortunately both the Din 267 specs and ISO 898 that are the specifications given are really vague, unless I am just missing something, which I assume I am! I'll attach both material specs from these specifications;

 

[technocrat]

Good industry specifications are usually not open-ended. I would refer directly to the specification and adhere to it. It's a set of instructions: start with this material, do these things to it, under these conditions and create this. You shouldn't need to solve anything. The processes and materials should be defined.

I'd have to disagree with that. When multiple materials can do the job, only the required properties should be specified and the choice of materials and process should be left up to the manufacturer.

 

[Donkey Hotey]

I'd have to disagree with that. When multiple materials can do the job, only the required properties should be specified and the choice of materials and process should be left up to the manufacturer.

Yyyyeah, okay? I agree and that might even be true in this case. The spec should at least suggest a few choices and not create an engineering challenge that will be solved differently by everyone who interprets it.

 

[William Lynn]

If an engineer wants the nuts made to a certain odd spec, they should note on the print what material to use. Every print I worked from had the material specifically listed and/or equivalent. Except the time honored napkin print, to which I used my own discretion.

 

[technocrat]

Yyyyeah, okay? I agree and that might even be true in this case. The spec should at least suggest a few choices and not create an engineering challenge that will be solved differently by everyone who interprets it.

It's a commodity nut. Everyone will make it differently and then converge on the cheapest way if there is sufficient market.