Delrin was (Re: all-thread question

Alex,

Nylon is stronger than delrin. Delrin's advantage comes in it's
machinability. Nylon is nasty to machine.

Delrin machines very well. It has a very high coefficient of thermal
expansion so you have to be careful to keep it cool during machining
if the parts are fairly high tolerance.

In my experience, it seems the black delrin machines better and is
softer than natural. I assume it has to do with the pigment added to
color it black. I like the shiny look of machined black delrin, but
if I were after strength and wear I think I'd use natural.

Doug

--- In CAD_CAM_EDM_DRO@y..., "Alex Canale" <alex.canale@r...> wrote:
> Hi Dave,
>
> From what I've gathered Delrin (Acetal), Delrin is the Dupont
tradename, is
> a bit shinear then Nylon. Nylon tends to be duller and not as
strong. Here
> are their respective properties.
>
>
> Physical Properties Nylon Unfilled (English Units)
>
> Density 0.0379 - 0.0475 lb/in³
> Water Absorption 0.35 - 2 %
> Moisture Absorption at Equilibrium 1.8 - 2 % 1.8 - 2 %
> Water Absorption at Saturation 2 - 5.5 % 2 - 5.5 %
> Linear Mold Shrinkage 0.0028 - 0.01 in/in
> Melt Flow 3 - 6 g/10 min 3 - 6
g/10 min
>
>
> Mechanical Properties
>
> Hardness, Rockwell R 69 - 105 69 - 105
> Tensile Strength, Ultimate 4640 - 13500 psi
> Tensile Strength, 3920 - 6240 psi
> Elongation @ break 2.5 - 360 % 2.5 - 360 %
> Elongation @ Yield 3.2 - 13 % 3.2 - 13 %
> Tensile Modulus 131 - 653 ksi
> Flexural Modulus 160 - 653 ksi
> Flexural Yield Strength 5950 - 17400 psi
> Izod Impact, Notched 1.46 - 20 ft-lb/in
> Izod Impact, Notched Low Temp 4.68 ft-lb/in
> Charpy Impact, Unnotched NB NB Grade Count = 4
> Charpy Impact, Unnotched Low Temp 2.86 - 10.9 ft-lb/in²
> Charpy Impact, 4.76 - 35.2 ft-lb/in²
>
>
>
> Physical Properties Delrin Unfilled Extruded (English Units)
>
> Density 0.0509 lb/in³
> Water Absorption 0.2 %
> Moisture Absorption at Equilibrium 0.9 %
>
>
> Mechanical Properties
>
> Hardness, Rockwell M 89
> Hardness, Rockwell R 122
> Hardness, Shore D 86
> Tensile Strength, Ultimate 11000 psi
> Elongation @ break 30 %
> Tensile Modulus 450 ksi
> Flexural Modulus 350 ksi
> Flexural Yield Strength 13100 psi
> Compressive Yield Strength 16000 psi
> Shear Strength 8990 psi
> Izod Impact, Notched 0.993 ft-lb/in
> Compressive Modulus 450 ksi
> Coefficient of Friction 0.25 Dry vs. Steel
> K (wear) Factor 200 10-10 in3-min/lb-
ft-hr
> Limiting Pressure Velocity 2570 psi-ft/min
>
>
> Hi Russ,
>
> Let me know the size piece you need for the Delrin.
>
> I have some of what I think is black Delrin plate, 1" and a 2" rod
> too.
>
> If you wanted to buy that stuff, McMaster Carr again. A 2" bar, 12"
> long goes for about $13.00.
>
> My question is how to tell if the stuff is black nylon, or black
> Delrin. Is there a simple test ? (fire, file, folding?)
>
>
> Dave
>
>
>
> --- In CAD_CAM_EDM_DRO@y..., "Russ Revels" <n4ft@a...> wrote:
> > Thanks Smoke and Dave,
> >
> > After reading your replies I looked in the McMaster Carr catalog
> and found
> > some bronze bushings that look like what you describe. I have 1"
> 5tpi rod
> > and the bushings are 1" id and 1 1/4od by 1 1/2" long. Judging by
> your
> > description I should be able to pin the bushing to the thread and
> then run
> > the bushing into a bearing. It appears like that will be an
> inexpensive
> > solution to what could be a costly machine shop task.
> >
> > I remember someone mentioning a while back that they had made nuts
> from
> > delrin. Is there a tap for acme 1 x 5? Or is this something that
> would
> > have to be done on a lathe? I am not familiar with the metal
> working
> > machines all of my tools are for wood. Is anyone aware of a source
> of delrin
> > or uhmw nuts that would work on a small router table setup?
> >
> > Thanks again,
> >
> > Russ N4FT
>
>
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