How is there 25g weight range same mold?

[seedlings]

For the same plastic and same mold, what happens to allow a 25g or more difference in weights of the discs coming out?

Is the plastic more dense for heavier weights? (I don’t notice increased stiffness)

Is the flight plate thinner or a void in lower weights?

[wims]

They add weighting agents to make the disc heavier. Some plastic types gets stiffer when they add weighting agents. I got two star Leopard3s from the same run, one is 175, the other one is 168. The 175 is noticeably firmer. To get some discs down to very low weight they sometimes add air bubbles to reduce the amount of material in the disc

[Moose33]

Some plastics are different densities as well, that’s why you will see some champ plastic with air bubbles at Max weight.

[wims]

As for the air bubbles, I don't think they blow them into the disc. I believe it's also a weighting agent that is reducing the weight by altering the way the polymer sets (molecules bind in a way that generates air bubble pockets)

[seedlings]

Originally Posted by wims

They add weighting agents to make the disc heavier. Some plastic types gets stiffer when they add weighting agents. I got two star Leopard3s from the same run, one is 175, the other one is 168. The 175 is noticeably firmer. To get some discs down to very low weight they sometimes add air bubbles to reduce the amount of material in the disc

Ok, added weight agents. Does this change the plastic, or do they float around in the plastic? Very curious.

Originally Posted by Moose33

Some plastics are different densities as well, that’s why you will see some champ plastic with air bubbles at Max weight.

I have a 150g Star Teebird. It’s not air bubbly, just regular Star. Star Teebirds also come in 175g+.

[captain jack]

Originally Posted by wims

They add weighting agents to make the disc heavier. Some plastic types gets stiffer when they add weighting agents. I got two star Leopard3s from the same run, one is 175, the other one is 168. The 175 is noticeably firmer. To get some discs down to very low weight they sometimes add air bubbles to reduce the amount of material in the disc

Metal salts are the common weight additive for TPE discs

[seedlings]

Originally Posted by captain jack

Metal salts are the common weight additive for TPE discs

Great insight! Thanks all for answering my question.

[Rastnav]

Originally Posted by seedlings

Great insight! Thanks all for answering my question.

Not that it’s likely to be a designed feature for producing different disc weights, but it’s worth mentioning this video from Jesse aka Trash Panda.

He’s trying to make DIY discs from recycled plastic and is documenting his journey. At 3:11 he mentions that he managed to make three discs, in the same mold, from the exact same plastic, and the weights were 150g, 162g, and 170g. Ultimately that probably came down to higher and lower injection pressures pushing more or less plastic into the mold, resulting in different densities of disc. Really easy to do when you are hand operating the plunger that forces the plastic into the mold. I have to imagine that variation in plastic temperature could play a part as well, as I don’t think his equipment has particularly finely graded tolerances.

In any case, I can easily imagine vagaries like that meaning that it becomes very hard to produce discs that weigh exactly a certain number of grams. Hence you see things like the discs in the Lat64 Easy-to-use line as being advertised to weigh between 150g and 160g.

[Ess-dog]

Originally Posted by wims

As for the air bubbles, I don't think they blow them into the disc. I believe it's also a weighting agent that is reducing the weight by altering the way the polymer sets (molecules bind in a way that generates air bubble pockets)

In the Blizard type disc that's sort of true. At those weights the bubbles are helping the disc form fully packed out with an amount of plastic that doesn't usually produce a good disc. the only time I tested nucleating agent additives was to evaluate the relationship between sink/cycle times and try to increase dimensional stability in extremely thin walled products. The parts would have sink spots at a certain cycle time(reduce pack/cooling and eject part from the mold sooner) but you could start introducing the agent and slightly alter certain pressure and get an acceptable part at the same cycle time. MIght be less flexible, sonic weld worse, and feel like styrofoam but could make them quicker. I've noticed even max weight Champion or Star discs will have a touch of sink just inside the edge of the rim on top of where the wall thickness is greatest. The discs with noticeable splay near the rim(foaming agent used) seem to not have this sink. I think the only reason they would want the disc to look like garbage by introducing surface defects that foaming agents cause is to reduce the amount of pack and cycle times so they can pump out a few more discs per hour. Maybe Innova is also able to add more of a cheaper weighting agent and use considerably less virgin materials when they use the foaming agent in max weight discs so profits should increase if people will buy the bad looking product.

[Ahildy13]

That's nothing. I've got a 138g and a 180g dx stingray