[Compare] The Physics of why plastics have different stabilities

[BogeyNoMore]

My gut tells me that, assuming all other variables are kept equal, (which probably doesnt happen often)...

Different plastics exhibit different stabilities from the same mold, primarily due to how the different materials cool after coming out of the mold, and how that affects PLH.

From seedling's spoiler:

Spoiler

I agree with you though. Leave the discs in the mold longer to cool? It's impossible that there hasn't been some staff meeting where this conversation hasn't happened. It's either impossible, undesirable, or cost prohibitive.

 

[Casey 1988]

^Your wild guess is pretty much the same as the message board consensus afaik. People on here usually point to the cooling process as the source of variation in discs of the same mold and plastic.

I also have a theory that Innova now has two different plastics for Champion, This would make sense and why a more constant run of very stiff can be made that some jolly Launcher F2 would not be PDGA legal if checked by PDGA and a gummy that runs from a stiff gummy that I like as this is some classic Champion to a flexible plastic that would remind people of the old clear Supreame plastic made for the Ching Juju.

DX might be the other exception where they have the original R-Pro with DX toughness used now only for the Dragon, was sued for the Hydra before the R-Pro was made. Then a Classic Aviar where the plastic is the base idea for XT.

Not sure on R-Pro there might be a stiff version of plastic used for the Wahoo and the stiff R-Pro Rhyno then plastic that runs the gambit from stiff like Whaoo to as soft and bendy like Steady Ed Plasric used on the Blowfly/II and Gumputt molds.

 

[oldmandiscer]

My gut tells me that, assuming all other variables are kept equal, (which probably doesnt happen often)...

Different plastics exhibit different stabilities from the same mold, primarily due to how the different materials cool after coming out of the mold, and how that affects PLH.

From seedling's spoiler:

Spoiler

I agree with you though. Leave the discs in the mold longer to cool? It's impossible that there hasn't been some staff meeting where this conversation hasn't happened. It's either impossible, undesirable, or cost prohibitive.

The plastic likely takes a long time to cool. What make one or two discs an hour? You're going to make discs cost 50 dollars at that point just from man hours and not have much product to sell.

I don't see that as really feasible. Cool it with water in the mold? Would it get stuck into the mold as well? Then you got water to deal with. I'm sure it's simply not cost effective to make a perfect product.

 

[bnrstnkr]

Honestly I think it's more than just parting line height. Because you could find a disc with a higher plh in a plastic known to be less stable, and it will still be less stable.

These are different complex polymer compounds with different densities. Concepts like rheopecty and thixotropy come into play. This can shift the plastic inside the disc itself into areas of high and low density. If more weight is distributed towards the edge it makes it more high speed stable. That's the simple physical attribute of angular momentum that mvp gyro discs use. I have an f2 destroyer and there's a part in the rim that's translucent because there's just less plastic there.

 

[wims]

When they are talking about cooling the disc, they are talking about cooling it in the mold. There is coolant running through the mold pieces (not inside the cavity where the plastic sits, but rather through the mold metal itself)

 

[seedlings]

When they are talking about cooling the disc, they are talking about cooling it in the mold. There is coolant running through the mold pieces (not inside the cavity where the plastic sits, but rather through the mold metal itself)

Thanks!
"The discs are cooled down enough for the robot to extract the disc" according to latitude64. I missed that line the first time I watched this video: https://youtu.be/Tkr5W90hXnQ

Edit: later in the video "the disc is then placed on a ventilated surface for 10 minutes, it's at this stage that the disc contracts and gets it's final shape" - so there is risk outside the mold for mishandling and deformation,

 

[BogeyNoMore]

Edit: later in the video "the disc is then placed on a ventilated surface for 10 minutes, it's at this stage that the disc contracts and gets it's final shape" - so there is risk outside the mold for mishandling and deformation,

That's 10 min per disc.

If they left every disc in the mold for an add'l 10 min, the cumulative increase in cycle time over the course of a day would greatly reduce output, driving up the manufacturing cost, and ultimately, retail prices.

 

[seedlings]

That's 10 min per disc.

If they left every disc in the mold for an add'l 10 min, the cumulative increase in cycle time over the course of a day would greatly reduce output, driving up the manufacturing cost, and ultimately, retail prices.

Yes, plus if it were cooled further in the mold, there would be additional preheat time for the next run. I wonder if lighter discs, say 155g of the same material, have any more consistency than a 180g disc because mass would affect difference in cooling time?

 

[aphilso1]

Yes, plus if it were cooled further in the mold, there would be additional preheat time for the next run. I wonder if lighter discs, say 155g of the same material, have any more consistency than a 180g disc because mass would affect difference in cooling time?

That's an interesting question. Back when Innova had a monopoly on light/bubble plastic, I think the unequivocal answer was that lighter discs are even less consistent. The common explanation was that some Innova Blizzard discs came out with the majority of bubbles in the rim, while others had the majority in the flight plate...and that made a substantially different flight characteristic. And some had bubbles so close to the surface that the disc felt pockmarked off the shelf, which adds another variable to flight behavior. Essentially, lighter discs = bubbles = inconsistent density.

However, I have thrown a handful of Trilogy's "Air" discs (also bubble tech) and haven't experienced noticeable variance. Instead, each Air disc I've thrown started out essentially the same as an equivalent ~170g disc, but beat in way faster. So despite adding the variable of bubbles, somehow Trilogy has figured out how to make a relatively reliable lightweight disc. I've heard the same story with gyro bubble discs (Fission), but I don't recall ever throwing one myself.

 

[ThrowaEnvy]

From what I've read the plastic used for discs will shrink after cooling and the difference is dramatic. I believe Champion style shrink the least while Base plastics like DX shrink the most. Then you have different thicknesses between the flight plate and rim so obviously the plate will cool faster. There are a lot of factors involved.

Just to confirm I measured two Beasts. The DX feels skinnier then the Champion and is substantially.

DX- 1.98 rim width

Champ- 2.04

It's basically a different disc at that point just from how much that plastic shrinks then of course the PLH and dome differences as well as well as overall width and depth.

Damn.. That's interesting.. Might shoot a hole or two in some of my theories.... I was going to say that:

I think the hardness of the plastic also affects the flight from air friction, a champion/Z/proton run will typically be the fastest, straightest (turn/fade ratio) and longest most stable version. (Of course if the diameter is wider then duh! )

From one of the other threads about why a beat up disc glides further.. It had to do with the abrasions and imperfections creating air pockets around it in flight. So why wouldn't a grippier plastic straight out of the factory create more micro air disturbances than a smooth plastic?

Though I often thought the dome caving in to a puddle top on soft plastics had a lot to do with it.. Which of course doesn't apply in this scenario.

 

[oldmandiscer]

Damn.. That's interesting.. Might shoot a hole or two in some of my theories.... I was going to say that:

I think the hardness of the plastic also affects the flight from air friction, a champion/Z/proton run will typically be the fastest, straightest (turn/fade ratio) and longest most stable version. (Of course if the diameter is wider then duh! )

From one of the other threads about why a beat up disc glides further.. It had to do with the abrasions and imperfections creating air pockets around it in flight. So why wouldn't a grippier plastic straight out of the factory create more micro air disturbances than a smooth plastic?

Though I often thought the dome caving in to a puddle top on soft plastics had a lot to do with it.. Which of course doesn't apply in this scenario.

I'm not sure how much abrasions effect the flight. I'm sure it has an effect but I believe the majority of the beating in is the wing bending down making the disc less stable and thus more glidey (changes the PLH). Glidey supposedly isn't a word or my spellcheck sucks. lol