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What is the best material and heat treatment for forging jackhammer shafts and bodies?


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Hello,

I am new to forging and have a very limited knowledge about the proper materials and heat treatments required for forged materials.  I appreciate those who might take the time to educate me.

My company is in the process of determining the best material and heat treatment to provide the strongest and most crack/break resistant part, designed to fit a jack hammer to remove flooring and other materials.  The hex shaft is about 10" long and about 1 1/4" wide.  The body is about 7" long, 6" wide, and about 2" thick.  According to our CAD model, they are designed as a single forged unit that will weigh in at around 11 pounds, not counting the blade or the bolts.

We have heard that 1045 is a good material for forging.  Is this the best material to handle repeated impact and stress?  If so, what would be the heat treatment (through hardened versus case hardened) required to produce the best result?  If possible, I want to err on the side of strength and the most resistance to breaking.

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I heard that using 4130 or 4140 is about twice as expensive as 1045, so for that reason I felt that 1045 might be the best fit.  We have chemically analyzed a jack hammer shaft and the report came back as a probable 1045 material.  I have also heard that because of the high impact involved that using a case hardening process might better preserve ductility, so that might rule out other material that can only be through hardened.  Again, I'm not an expert and am repeating what information I have run across.

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Steve beat me too it; we can probably come up with some excellent suggestions to be forged in inert atmosphere furnaces and running several thousand dollars a piece.  Also why is a company asking random people questions about making a product---that's what you HIRE a Metallurgist as a consultant for. The S series of steels will certainly make a superior bit; but be way more expensive.

Jackhammer bits for asphalt have been made from 1050 for about 100 years; if your flooring removal does not require hammering THROUGH the floor but instead shearing off tile, linoleum, vinyl, etc then that is not considered a high force job. The impact issues occur on the hitting end. Removing concrete floors does profit from more shock resistance in the bits.

 

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I strongly doubt your "company" has enough expertise to successfully manufacture jack hammer bits in competition with the companies who have been making them for maybe a century. 

No, case hardening is for abrasion resistance and is ZERO use for your intended use.

Frosty The Lucky.

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Specify:  Most of us are hobby blacksmiths with a working knowledge of the material we use.  I would not make a commercial decision on any advice we can provide.  Jackhammer bits are a mature technology which has a vast reservoir of knowledge acquired of the the last 100+ years by manufacturers and users.  So, if your company is looking to compete with the established manufacturers using some less expensive material or process I suggest that your company needs to retain the services of an industrial metallurgist who can professionally advise you on materials and processes.  

You may want to look at the US Government procurement specifications for jackhammer bits and see what their criteria for materials, testing, and performance are.

How you have framed your questions and how you have responded to the replies indicate to me that you may well be inexperienced in this area and somewhat out of your depth of knowledge.

Finally, where you and your company are located in the world will help us frame any replies.  Relevant answers may differ if you are in India or if you are in Germany.

"By hammer and hand all arts do stand."

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Here I thought we were going to discuss forging old jackhammer bits again, which I would totally be in favor of since one followed me home the other day and I was going to start forging a hotcut hardy.  

 

 

Once it gets above 0 F again that is. 

Edited by Chad J.
Afterthought
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My main hardy is the broken off bit of a jackhammer bit. 1050 steel. Hammered down the stub of the shaft to fit the hardy of an anvil, then hammered it down more to leave a peg to knock it loose as students can't  grasp the idea that tools may be anvil specific...

Heat treat with a spring temper for the edge, softer for the stem.   I don't know how long it will last though; only around 30 years so far...

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Check with rental outfits they usually have a bucket of dull and broken jack hammer and air hammer bits waiting for a dump run. Some places ask scrap price, others make you take the whole bucket.  

They are really nice medium carbon stock. 

Frosty The Lucky.

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I'm going to head to the tool rental store today to see if they have any. It's been about six months since I tried. Last time they didn't have any which I thought was weird. It made me wonder what condition the bits were in they were sending people out with. 

Pnut

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Pretty bad I'd bet. I had a friend of the family's BiL show up at my smithy on a holiday weekend with a broken jack hammer bit asking me if I could repoint it. He'd hired the jackhammer for the extended weekend and the bit broke on him the morning of the first day...I'd never done one but remembered the description by GS and so did it and handed it off with a "bring it back if this didn't work and I'll try something else".  Didn't see him the rest of the weekend.

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I don't know about your area but I have 5-6 rental places within 20 minutes, two big boxes, Lowes and Home Depot. One of them always has worn bits. The place that made me take the whole bucket, including the bucket stocked me up for a long time.

Frosty The Lucky.

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