Doubt about steel 5

[Galvano]

Good Morning,
I have a piece of a machine, which is a sheet of steel 0.3 mm thick.

On this sheet are mounted some rollers that press a notebook that passes through a conveyor belt. The function of the sheet is to act as a spring. (After bending, he returns to his initial position)

I have seen that there is a type of steel according to German standards, I think it is CK75. Would it be suitable for manufacturing that sheet? What other types of steel are there that are valid to manufacture this 0.3 mm thick sheet? Is there any other equivalent designation other than the German one?

Greetings

 

[TugboatEng]

I didn't realize you had holes. You've added significant cost now. For already hardened material, C45-50 are pushing the limits of basic tools to drill. A water jet or laser would be best for mass production but the tool up costs will be several hundreds of dollars US minimum. You could probably make a single piece by sandwiching it between to sacrificial plates and drilling with a carbide tipped drill by hand.

Buying annealed and heat treating adds tool up costs again. Heat treatment isn't particularly expensive, a run usually costs a few hundred dollars but that costs is the same whether you're making one or a thousand.

 

[Galvano]

Yes, but my question is... Should I indicate hardened C75S on the drawing? Because the C75S steel is supplied without heat treatment I suppose... Yes, the hardness is 40 to 50 HRC I think.

 

[TugboatEng]

You need to specify what you want. If your sending the material to a vendor to get punched, you will want to specify soft in the drawing. If you're sending it for water jet or laser you're going to want to specify spring temper. The part may have different drawings depending on what stage of production it is in.

 

[Galvano]

I will make a manufacturing plan and the company's workshop left it to an external company that has laser cutting, etc.

That is, the plan must contain all the necessary annotations for its manufacture from the beginning.

I have also seen that if you bend the sheet a lot, it does not return to its original shape.

That is, it only recovers its shape if the deformation is small. If you exert a lot of force, it stays curved.

 

[Galvano]

AISI 301 is stainless and I read that it would also work. Certain? This would be better because it is stainless. And as I said before, I think we should ask him to hold on to serve as a spring.

 

[TugboatEng]

301 stainless is not heat treatable and can only be work hardened to 41 HRC which is less than 1075. If you need more corrosion resistance than 1075, 420 stainless steel may be a good option.

 

[Galvano]

But I see 301 is used too in the manufacture of springs with a hardness of 40 to 50 HRC
Hardness 4/4 or 5/4 that will be equivalent to those in that table.

 

[EdStainless]

You can buy a lot of different SS alloy sheet to ASTM A666 and have it cold rolled to 3/4 or full hard for descent spring properties.
You will still need to waterjet or laser cut the holes.
Just see which SS you can get that hard.
It might be 301, or 304, or even a 201.
They will all have similar corrosion resistance.
The 200 alloys should cost less.

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P.E. Metallurgy, consulting work welcomed

 

[Tmoose]

"I have also seen that if you bend the sheet a lot, it does not return to its original shape.
That is, it only recovers its shape if the deformation is small. If you exert a lot of force, it stays curved."

So you //almost// have some real, useful empirical clues about the loading the part must endure.

Like others said, from practically the first reply, understanding all of that stuff is necessary to make a good material choice.
Unless you have some parts that perform OK, and then you have the material analyzed, including yield strength, which cannot be directly derived from hardness.

 

[Galvano]

I have verified that the foil is somewhat magnetic (I think the 301 can be magnetic when heat treated)

On the other hand, I attach a photo of the sheet. When I hold it in the center and apply a force of about 1kg, it later recovers its shape. Dimensions are 86mm long, 30mm wide and 0.3mm thick.

 

[TugboatEng]

300 series stainless steel can become magnetic after cold working. There is no heat treatment.

 

[EdStainless]

Thanks TBE.
Yes, most autenitic SS grades will become magnetic when cold worked.
Some will become very magnetic.
The only HT for SS is solution anneal (Unless it is a PH or martensitic grade).

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed

 

[Galvano]

I have seen the drawing of a sheet with the same spring function.

The flat steel says that it is the equivalent to 304 but I suppose that it will also have to be treated later so that it can serve as a spring in that flat spring.
I definitely think that the 301 4/4 or also called full hard will be valid.

I see that 304 can also be hardened and that both obtain the same hardness but for laser cutting 304 is better and resists oxidation more.

 

[Galvano]

AISI 301 4/4 ¿Yes?

 

[IRstuff]

You continue to randomly stab at different materials; THIS is not the way to do design. You need to come up with actual and numerical requirements, and then select the materials that fit the requirements.

And again, a material assay should be performed on the existing component.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[Galvano]

I don't know how to do those calculations, I only know the dimensions and the approximate strength (I put it before)