I'm just gonna purchase taps and dies for my most commonly used metric screws. I want them to last for as long as they can (not that they will be used so often, I just want them like that). I also will be hand cranking them, so actual high speed cutting won't be done. So which is better for my application, HSS-E or HSS coated in TiN??

  • Off-topic for Engineering. I'll move this to a site where it may be on-topic.
    – user2776
    Jul 18, 2017 at 11:43
  • 3
    I'm voting to close this question as off-topic because not related to automotive maintenance or repair.
    – CharlieRB
    Jul 18, 2017 at 13:31
  • 2
    Am I the only automotive repair enthusiast who believes that my tap and die set is an essential tool in the arsenal?
    – zipzit
    Jul 18, 2017 at 15:58
  • I make tools of my own sometimes. I'm getting by with just embedding/soldering bolts onto something, but I figure this might come in handy.
    – Dehbop
    Jul 18, 2017 at 16:17
  • This question is totally on-topic. Ask me how I know :)
    – Zaid
    Jul 19, 2017 at 21:10

1 Answer 1


HSS-E steels are HSS steels alloyed with Cobalt.

Cobalt makes steels harder and increase the heat resistance. Detriments are the increased breaking susceptibility and reduced toughness. Source in German

Since heat resistance is of no concern in your application I would choose TiN coated HSS taps.

  • Kinda contradictory that HSS-E should be able to cut faster, yet the you say it is more prone to breaking and has reduced toughness.
    – Dehbop
    Jul 18, 2017 at 16:18
  • That's unless my ebay order gets clandestinely swapped while in transit.
    – Dehbop
    Jul 18, 2017 at 16:23
  • @Dehbop - I'm failing to see where he says HSS-E is able to cut faster? Jul 18, 2017 at 16:23
  • @Pᴀᴜʟsᴛᴇʀ2 Just generic stuff that I read online, not in the German page he provided.
    – Dehbop
    Jul 18, 2017 at 16:23
  • @Dehbop on machining operations an important wear factor is heat, heat tolerant tools allow faster cutting speeds thereby decrease machining costs. In case of hand cranked taps the heat resistance is of no concern, more important is resistance against operator errors
    – Martin
    Jul 18, 2017 at 20:17

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