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Reaming hole in 45HRc steel

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Martin Dowing30/10/2020 21:56:26
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269 forum posts
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Hi,

I will need to ream holes made in rather hard (45 HRc) steel.

Can I use HSS for this end or only carbide reamer will do?

If I need carbide then what are the rules of their use not to damage them at first go?

Hole is to be 5mm in diameter, so should I drill 4.8 mm?

Chris Evans 630/10/2020 22:16:23
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1780 forum posts

I would avoid carbide, if one of those binds up and breaks in the hole your problems will start. I spent many years operating spark erosion machines and carbide takes some shifting.

We regularly finished injection moulds to around 44/45 HRc and then did final machining.

David George 131/10/2020 07:27:24
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1386 forum posts
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We used solid carbide drills with through coolant to drill these type of holes in pre hardened injection moulding tooling. They were started with a carbide smaller milling cutter interpolated a short depth then drilled to size.

David

Chris Evans 631/10/2020 08:46:54
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1780 forum posts
Posted by David George 1 on 31/10/2020 07:27:24:

We used solid carbide drills with through coolant to drill these type of holes in pre hardened injection moulding tooling. They were started with a carbide smaller milling cutter interpolated a short depth then drilled to size.

David

With the advent of wire erosion machines we left the holes out then used a start hole machine for the wire. All core pin holes and some ejector pin holes where finished with the wirecut machine.

old mart31/10/2020 19:34:13
2219 forum posts
164 photos

I would get solid carbide 5mm drills for hard material and forget reaming.

Martin Dowing02/11/2020 06:04:52
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269 forum posts
4 photos

Thanks for these comments.

With solid carbides I always have reservation about possible breaking of drill or mill in my workpiece, That due to rather low speeds of spindle at my disposal (up to 1200 rpm).

So if carbide has to be used then brazed versions are preferable in my case.

Regarding EDM - dont have it..

old mart02/11/2020 19:29:29
2219 forum posts
164 photos

I would run solid carbide drills at low rpm into hard materials and use light hand pressure to feel the drill cutting.

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