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Approximate Cycle Time differences by material

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vtcnc

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I'm considering a major process change in the business that would require switching from cold/hot rolled raw material to 300 series material. Yes, the cost in material is considerably higher, but there are cost reductions further down the line that may offset the material cost - hence the need to estimate costs and see if it makes sense to go in this direction.

My general question is: what would be a good estimate for the following factors:

  1. Difference in cycle time (inc/dec) by % switching from mild steels to stainless?
  2. Difference in tooling cost (inc/dec) by % switching from mild steels to stainless?

Other factors to consider?

Like all things, I'm looking for educated guesses based on experience and/or facts on the ground from people that can speak to this. With that said, I'm not looking for precise answers just general ranges. If somebody said expect a 10-30% increase in cycle time...that is good enough for me to use - don't need to hit a bulls-eye in order to put some ranges in front of the top executives. I'm really looking to throw a dart at the wall and know that I'm at least going to hit the dartboard and that is good enough for discussion purposes.

Any thoughts or suggestions?
 

derf

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Probably not much difference in cycle times, but one benefit is the lack of needing a finish. Carbon steels may need black oxide, paint or plating for a finish. This is why you see so much more stainless steel used in the firearms industry.
 

JimDawson

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It depends on the alloy, 303 is free machining and machines much like mild steel, a bit tougher, speed reductions of about 20%. 304 is a PITA, tough material, but once you find the proper feed and speed it really machines pretty well. 316 machines about like 304 but slightly more user friendly. Both 304 and 316 are about a 30% speed reduction from mild steel. Proper tooling is the key to economical machining strategies.

Quality tooling for SS is not substantially different in cost vs. other quality tooling. Using cheap utility tooling in a production environment is false economy. Indexable inserts are within about $1 of each other. Assuming you are using carbide endmills, the cost is about the same. Moving from HSS endmills to carbide is a jump, but are people using HSS in production anymore? Check with your tooling vendor for recommendations, there have been a lot of advancements in geometry and materials in the last few years. In milling, tool paths can make a huge difference in machining time. In the lathe, using ''peck'' cuts where possible keeps the long stringy chips from forming, chip breaking is a bit problematic in SS.
 

vtcnc

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Probably not much difference in cycle times, but one benefit is the lack of needing a finish. Carbon steels may need black oxide, paint or plating for a finish. This is why you see so much more stainless steel used in the firearms industry.
Bingo! That's the purpose of the exercise so we will see if it pays off - at least on paper.
 

P. Waller

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There will be considerable differences between the 300 alloy SS materials.
If the application allows 303 go for that.
If 316 is required there are several proprietary alloys that machine much faster then generic 316 alloys.

As far as cycle times the first calculation will be the difference in cutting speeds, slowing a process from 1000 SFM to 600 SFM is a considerable difference.
 
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