[TheForge] Air Hammers Paul

Mon Apr 7 01:22:00 2003

ams 6487 (h-11 tool steel) not that that means much, but its not something
you want to wish on anyone who doesn't know what it is!

Its an obnoxious machining material that we make pump housings, and tooling
from associated with processing slurry, and also with injection molding of
plastic parts with integral abrasives.

As for the UHMW, I purchase and use about 200,000# a year, its an excellent
wear surface for the mill, and processing industry as long as we are talking
material handling, when it comes to abrasive material against the UHMW, like
metal, or fire scale the life is much shorter.  Also UHMW has a terrible
co-efficient of expansion, the minimum is .03% so a block that is 10# long
when exposed to a 10%  temperature rise can grow .030 .  This is why UHMW
when used as a wear plate or as a bearing surface is used where tolerances
are not critical.

As for wear surfaces as long as any two dissimilar metals are used, or one
metal is harder than the other the two surfaces will not gall together.

----- Original Message -----
From: "Ian" <[email protected]>
To: <[email protected]>
Sent: Sunday, April 06, 2003 10:39 PM
Subject: Re: [TheForge] Air Hammers Paul

> Ok I will bite, excuse my ignorance.
>
> 1.) What is nitride steel?
>
> 2.) I am making an assumption from your description below that with the
> bearing surfaces, all is ok as long as two dissimilar metals are used that
> do the rubbing on each other? Correct?
>
> Ian....
>
> ----- Original Message -----
> From: "Paul Hewitt" <[email protected]>
> To: <[email protected]>
> Sent: Sunday, April 06, 2003 8:27 PM
> Subject: Re: [TheForge] Air Hammers Paul
>
>
> > The slides on my original hammer were simply two different grades of
> steel,
> > I have an abundance of nitride steel laying around, so I used some
pieces
> of
> > that, and a few pieces of some 4140 for slides, I have long since sold
the
> > hammer, and the current owner uses it almost every day, to my knowledge
it
> > has never broke down and he has never had to adjust anything.
> >
> >
> > ----- Original Message -----
> > From: "Ian" <[email protected]>
> > To: <[email protected]>
> > Sent: Sunday, April 06, 2003 10:18 PM
> > Subject: Re: [TheForge] Air Hammers Paul
> >
> >
> > > This is interesting Paul cause I was also wondering how steel on steel
> > would
> > > wear when greased compared with brass on steel? Steel is certainly
> > cheaper!
> > >
> > > ----- Original Message -----
> > > From: "Paul Hewitt" <[email protected]>
> > > To: <[email protected]>
> > > Sent: Sunday, April 06, 2003 8:09 PM
> > > Subject: Re: [TheForge] Air Hammers
> > >
> > >
> > > > The problem with UHMW is that if "cold forms"  UHMW is actually
Ultra
> > High
> > > > Molecular Weight Polyethylene AKA Milk Jugs....  which are LDPE low
> > > density
> > > > Polyethylene.  high load forces, speeds and impact cause the
material
> to
> > > > deform, the larger the tolerance gap the move "slamming: it will do,
> > thus
> > > > the faster it will deform into an unusable state.  Also UHMW prefers
a
> > > > ground and polished surface in bearing type applications, which is
> hard
> > to
> > > > accurately do on the slide of a hammer.  The hammers I have built in
> the
> > > > past are not even brass, just simply greased steel on steel.
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: "Ian" <[email protected]>
> > > > To: "TheForge" <[email protected]>
> > > > Sent: Sunday, April 06, 2003 9:59 PM
> > > > Subject: [TheForge] Air Hammers
> > > >
> > > >
> > > > > Instead of using brass bearings for the hammer and slider, has
> anyone
> > > used
> > > > > UHMW which is a high abrasion resistant, low friction, chemical
> > > resistant,
> > > > > tough - hard wearing plastic. UHMW stands for ultra high molecular
> > > weight.
> > > > > This stuff is used in industry on things like fork lift chain
> guides,
> > > > roller
> > > > > lines for boxes etc. This stuff is tougher than you know what! My
> only
> > > > > concern about using this stuff would be that of heat from any
> possible
> > > > > friction between the hammer slider and the plastic. Any thoughts
> > there.
> > > > Oh,
> > > > > this stuff that I have seen is usually white.
> > > > >
> > > > >
> > > > >
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