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 Post subject: ball material
PostPosted: 08 Nov 2019, 15:21 
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http://www.ittf.com/wp-content/uploads/ ... oD2018.pdf

Hmm.

Quote:
We need better materials, and manufacturers are still encouraged to search for these and
optimize them.


So most balls nowadays are ABS. I'm no materials expert, but I wonder what other materials could be experimented with, to create balls that have just as much or more spin than the current plastic balls.

1) Any thoughts regarding what other materials may be suitable? PLA?
2) Can anyone explain why plastic balls have less spin than cell? Surface roughness, elasticity, density etc?

Thanks


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 Post subject: Re: ball material
PostPosted: 08 Nov 2019, 17:37 
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SCIENCE OF MECHANICS TO ACCOUNT FOR THIS.

Those ABS plastic balls, they all have a thicker outer wall of around 0.35 millmeters. Those preceding balls of celluloid material they all were of 0.25 mm thick or even thinner sometimes..
Just get ABS plastics of same outer wall as the celluloid, you will respectively have same rotation rate.(rps)
It is some basic elements of science of Mechanics, for the answer see the Rotational Motion Formulas for a Thin Hollow Sphere.

/Be happy/.


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 Post subject: Re: ball material
PostPosted: 08 Nov 2019, 19:19 
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ABS isn't just ABS. There are probably thousands of different ABS formulations. There's stuff you can add to the ABS - other polymers, plasticizers, etc. If there were only one type of ABS it wouldn't have taken so long to develop orange balls - they would have had to tweak the formula until they found one that worked. Whatever it is it's either a trade secret or it's been patented. And you can bet they continue to test new ones.

As to why less spin. The new balls are larger in diameter. And they're heavier. So 1) you get less RPM for a given tagential speed and 2) if you generate the same sideways force (via the Coanda effect) there is more mass to be acted upon. See if you can find some of the old 38mm balls, THAT was a huge change. Those balls would probably be uncontrollable with today's bats.

Iskandar


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 Post subject: Re: ball material
PostPosted: 08 Nov 2019, 20:20 
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iskandar taib wrote:
ABS isn't just ABS. There are probably thousands of different ABS formulations. There's stuff you can add to the ABS - other polymers, plasticizers, etc. If there were only one type of ABS it wouldn't have taken so long to develop orange balls - they would have had to tweak the formula until they found one that worked. Whatever it is it's either a trade secret or it's been patented. And you can bet they continue to test new ones.

As to why less spin. The new balls are larger in diameter. And they're heavier. So 1) you get less RPM for a given tagential speed and 2) if you generate the same sideways force (via the Coanda effect) there is more mass to be acted upon. See if you can find some of the old 38mm balls, THAT was a huge change. Those balls would probably be uncontrollable with today's bats.

Iskandar


Yes, Exactly,

The common ABS composition (for many consumer goods) is known to be a relatively lighweight material with specific gravity of 1,10. The celluloid use to be a high density of 1.40
We need to improve ABS composition to 1.35 at minimum. It is a tricky task indeed, we are bound to keep all the ball's ballistics near the same. Meanwile, I was reported DHS keeps working vigorously for an optimal plastic composition. GOOD LUCK!!


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