Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-l] Energy Transfer with hammers



I recall that folks who need to select materials on which depend lives or performance or cost,
tend to use what amounts to a Figure of Merit approach to render their judgment more objective.

For some reason, I am reminded of that great pre-agricultural invention, the throwing stick (though I am fairly sure it has some more definitive name). This was the device that amplified the utility of the spear, so that the spear flew further, faster and higher. A matter of aggregating the force available at the hand and
its launching speed capability over a longer arc and a higher launch speed with the available manpower.

In this case we would want to maximize the product of force at impact with the time for which it is available, so as to maximize the proportion of available energy which is applied to a nail.
There must be some optimal speed which can vary with head mass and handle length, some optimal hammer head durability for point loads, some resistance to spall and shatter, and of course some cost comparison - by valuing the material cost ratio versus the usual material.

It is evident by reviewing yield strengths of some cast steels, aluminums, and titaniums versus density,
that titanium has its virtues: a reason why some aircraft structures are made of titanium, though aluminum is lighter and cheaper, and steel can be stronger and cheaper.
It is pondering figures of merit of this kind, that one can easily visualize a composite hammer head, with body of aluminum, its head hard faced with steel or cobalt. Another approach currently available is a light plastic structure whose head contains lead shot. This is the 'dead-blow' hammer, whose flying shot extend the time for which a force is provided from its face.

Brian W

Moses Fayngold wrote:
I do not see a straightforward way from the relevant characteristics of Titanium to the claims made.
In terms of the Young modulus and specific gravity, the basic characteristics determining other properties like speed of sound etc., we have from Phys. Handbook:
Young modulus (GPa) Specific gravity
Stainless steel 200 7.9 Titanium 109 4.5
Aluminum 70 2.7

In both these characteristics, Titanium is between steel and Aluminum. If Titanium's mechanical properties are, indeed, responsible for its performance allegedly superior to that of a steel hammer, then the Aluminum hammer could be expected to do even a better job. Also, I did not see in the referenced sources any reproducible experimental tests; instead, we have just statements based mostly on personal experience of some workers, most of whom remain unknown except for their email ID. At this level, the whole thing seems unsubstantiated.
Moses Fayngold,
NJIT


________________________________
Bob LaMontagne, <RLAMONT@providence.edu>, wrote:



Sounds a lot like the claims made in ads for selling golf clubs in various magazines!

Bob at PC

________________________________________
From: phys-l-bounces@carnot.physics.buffalo.edu [phys-l-bounces@carnot.physics.buffalo.edu] On Behalf Of Jack Uretsky [jlu@hep.anl.gov]


What makes you think that the statements are correct?
Regards,
Jack


On Mon, 13 Jul 2009, chuck britton wrote:

http://www.finehomebuilding.com//item/8391/titanium-hammers-up-for-
grabs-want-one
has an interesting 'claim' about energy transfer.

"My reason for going with titanium: energy. A titanium hammer
transfers 97% of your energy from swinging the hammer to the nail
head, while a steel hammer transfers only 70% of your energy to the
nail. Titanium drives a nail more efficiently and there?s less recoil
energy to travel back into your arm."

This seems to BEG for some simple 'Mechanics' analysis.
Maybe 'Impedance matching'? admittedly - NOT a topic usually covered
in intro mechanics but maybe it SHOULD be?
_______________________________________________