Which Tap is Best for 303 Stainless Steel?

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Discussion Overview

The discussion revolves around the best tapping methods and tools for working with 303 stainless steel, specifically for producing M2 threads. Participants share their experiences and recommendations regarding tap selection, drilling techniques, and operational parameters for tapping this material.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Exploratory

Main Points Raised

  • Some participants inquire about the appropriate tap type and drilling parameters for M2 tapping in 303 stainless steel, expressing concerns about tap wear.
  • One participant suggests that standard taps may suffice for the application, while another questions the use of cheap taps, emphasizing the importance of quality for high-volume production.
  • A participant shares a personal experience, recommending slow drilling speeds, high pressure, and good lubrication to prevent work hardening of the stainless steel.
  • Another participant proposes using a slightly larger tap drill to achieve a different thread depth without compromising strength, based on past tests.
  • One contributor recommends using Cobalt High Speed Steel (CoHSS) tools for threading stainless steel, noting the higher cost but potential necessity for small threads.

Areas of Agreement / Disagreement

Participants express differing opinions on the quality of taps to use, with some advocating for higher-quality tools while others suggest that standard taps may be adequate. The discussion remains unresolved regarding the best practices for tapping 303 stainless steel.

Contextual Notes

Participants mention various drilling techniques and tap types, but there are no consensus definitions or specifications for optimal performance. The discussion includes personal experiences and recommendations that may vary based on individual circumstances.

Agrean
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Hello friends.
First, I apologize for my bad English. I need your experience. I want to produce a piece, but I have a problem with tapping. The material is 303 stainless steel. I need a M2 tapping to this part. Approximately 200-300 pieces of M2 tapping will be made. For 303 stainless steel which tap do you recommend? How many mm drill and speed / feed do you recommend?
 
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Agrean said:
Hello friends.
First, I apologize for my bad English. I need your experience. I want to produce a piece, but I have a problem with tapping. The material is 303 stainless steel. I need a M2 tapping to this part. Approximately 200-300 pieces of M2 tapping will be made. For 303 stainless steel which tap do you recommend? How many mm drill and speed / feed do you recommend?
Are your taps wearing out earlier than expected? I do not see the issue with using a standard tap for this application.
 
berkeman said:
Are your taps wearing out earlier than expected? I do not see the issue with using a standard tap for this application.
I haven't tried it yet. So you're saying cheap HSS taps would be enough? Example this?
Screenshot_20190520_020638.jpg
 
I don't use cheap taps. Why would you? Especially if you are planning on tapping many holes...
 
berkeman said:
I don't use cheap taps. Why would you? Especially if you are planning on tapping many holes...
Is there a tap you can recommend?
<< Spam links deleted >>
 
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Agrean said:
Is there a tap you can recommend?
<< Spam links deleted >>
I have a feeling that this has been a spam setup thread, and I bit the bait. Just buy normal quality taps from your local supply store.
 
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berkeman said:
I have a feeling that this has been a spam setup thread, and I bit the bait. Just buy normal quality taps from your local supply store.
I don't spam Sorry for upload pics. I am from Turkey and there is all local supply say don't have M2 tap. If you can give me brand or tap link I would be happy. Thank you.
 
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Screenshot - 5_20_2019 , 2_38_57 AM.jpg
 
I suspect the SS is work hardening.
In my experience of drilling stainless, slow speed and heaps of pressure, together with good lubrication/cooling, are the answer
Always use a slow rpm and a heavy feed rate. If at all possible flatten the point of the drill out more than the standard angle. Every thing that is hard to drill: use a wider point; every thing soft then a sharper point on the drill. Use mucho coolant.DON"T STOP until you the through or at your stopping point. It you stop, it'll harden and getting started again will be difficult.
 
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  • #10
What @Ranger Mike said, plus make the tap drill slightly larger. Most tap drills are sized to make a hole that results in (I think) 75% thread depth. I did some tests once with larger tap drills to get 50% thread depth and found no decrease in strength. Those tests were to help out the machine shop with a similar problem - tapping small deep holes in hard to tap material.
 
  • #11
When threading stainless steel you should use “Cobalt High Speed Steel” drills and taps. CoHSS.
It comes in two common grades, M35 and M42.
https://en.wikipedia.org/wiki/High-speed_steel#Cobalt_High_Speed_Steels_(HSS)
CoHSS tools are expensive, but it is often the only way to cut such a small thread. You may be able to buy a spiral tap in CoHSS.
Avoid spiral thread-flow taps that do not cut, they deform malleable materials.

Google 'cobalt M2x0.4 spiral tap' or search ebay
 
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