Are discs balanced when manufactured?

[breynnmike]

Tires are approved to safely carry passengers. You can get a ticket for bald tires. Discs are approved by a stoner making $13 an hour. Might not be perfect but how can you really tell? Maybe you throw an imperfect disc better after learning it.

 

[InnocentCrook]

I'll make a disc company with astrology disc mold names, make discs imbued with starstuff, have them blessed by Richard Dawkins, and laser balance them. They will be $60 per disc, and include a certificate of calibration (non-transferable).

See you suckers at the private tourney on my aircraft carrier.

Name them with Astronomy names instead of Astrology and I'm down for a couple first runs. Have Neil deGrasse Tyson bless them instead of Dawkins...I might pay $80.

 

[BirdieMachine]

MVP discs are all balanced because they have super GYRO technology. They fly the best out of all discs.

 

[BogeyNoMore]

The answer is no. The simply reason is because it's not necessary. A more detailed explanation is:

The quality inherent in the current manufacturing process is already sufficient. Disc uniformity is consistent enough that any existing imbalances are insignificant to the flight. The existing quality control procedures seem to be sufficient to prevent any meaningfully imbalanced discs from making it out of the plant. There's no need to employ additional processes that only serve to increase manufacturing costs while yielding no perceptible in product quality or adding any value to the company or it's customers.

When a manufacturer sees that their process does not maintain sufficient quality control, they typicaly take some sort of corrective action - perhaps balancing could be in order in that event.

 

[DanJon]

This is why I don't have the tires balanced on my wife's car.

BAZINGA!

 

[MPaq720]

Coupe: "Not all of them (see Aerobie Epic).

Oh ... and no disc is symmetrical if you cut it in half through its height."

haha ya got me there, smarta$$

 

[Meulen]

Easy answer NO, not even MVP does. They all check their discs for defects but they do not go out of their way to check if they are in balance

I agree.

How do you know?

a good injection molding machine has a balancing system in it... so?

Never heard of such a thing.

It could be that the process is good enough in this respect that verifying balance isn't necessary. It's probably even less necessary considering that the disc will hit something every single time it's used. Going to all the trouble to make sure it's perfect for a single throw probably isn't worth it.

This.

I'm not quite sure where to start. Injection molding can be as simple or as complicated as you would like to make it. Fact is, disc golf discs are not the easiest product to mold, definitely not the hardest, but they're no cake walk. Fundamentally, with regards to injection molding, you want the plastic to flow from "thick to thin". That is, the gate (injection point) would ideally be located at a thick section on the part and the plastic would flow outwards to fill the thin sections. It can be difficult to try to flow plastic through a thin walled section and adequately "fill out" thick sections several inches away from the gate. This is exactly what they do with discs.

The injection phase happens very fast, but the plastic immediately begins to cool when it comes in contact with the mold surface. If the flight plate cools before the wing is completely filled out, it would be called a short shot. If it is mostly filled out, but there are some spots that look like dips and depressions, these are called sinks. This can be seen on some early CE discs from Innova.

The term "balancing", when used with injection molding, typically refers to cavity balance. Discs are made on a single cavity tool. Many other products, lipbalm lids for example, are probably molded 32, 64, or even 128 at a time. When multiple cavities are involved, it is important to have them balanced, or filling at the same time. This balance is controlled by cavity layout within the tool as well as cavity/gate configurations. If you hear someone use the term "balanced" in the injection molding industry, they are most likely talking about how equal multiple cavity tools fill out.

The shape of the disc is dictated by the mold. If great care is taken to properly construct a mold that is radially symmetric, and proper cooling is designed into the tool, the discs should come out near identical to the mold, with some slight shrinkage/warping after removal from the mold. If I tried to build a mold in my garage with a dremel tool, I would be willing to bet the disc would not be balanced. Not just the first disc out of the mold, but EVERY disc that comes off this mold.

There could potentially be imbalance due to lack of "heavy spots". If the screw of the machine is working properly, i.e. mixing and blending material well, this is a non issue. Most of the material used is fairly homogeneous. The opposite of a "heavy spot" would be a light spot, or a sink. These are likely to be created, but are typically scrapped or sold as factory seconds when deemed so by the inspection process (quality team).

I may have missed something in there, so if anyone has a question, feel free to ask. Personally, I haven't ever once worried about a disc being imbalanced. Many people have made great points about impact/damage, poor technique, low rpm's, etc. Is there a market for a product like this? I don't know, maybe to someone with too much money. I can think of a couple other areas of the process that could be controlled and have a greater impact than balancing.

/endpost

 

[natedg1976]

I agree.



Never heard of such a thing.



This.

I'm not quite sure where to start. Injection molding can be as simple or as complicated as you would like to make it. Fact is, disc golf discs are not the easiest product to mold, definitely not the hardest, but they're no cake walk. Fundamentally, with regards to injection molding, you want the plastic to flow from "thick to thin". That is, the gate (injection point) would ideally be located at a thick section on the part and the plastic would flow outwards to fill the thin sections. It can be difficult to try to flow plastic through a thin walled section and adequately "fill out" thick sections several inches away from the gate. This is exactly what they do with discs.

The injection phase happens very fast, but the plastic immediately begins to cool when it comes in contact with the mold surface. If the flight plate cools before the wing is completely filled out, it would be called a short shot. If it is mostly filled out, but there are some spots that look like dips and depressions, these are called sinks. This can be seen on some early CE discs from Innova.

The term "balancing", when used with injection molding, typically refers to cavity balance. Discs are made on a single cavity tool. Many other products, lipbalm lids for example, are probably molded 32, 64, or even 128 at a time. When multiple cavities are involved, it is important to have them balanced, or filling at the same time. This balance is controlled by cavity layout within the tool as well as cavity/gate configurations. If you hear someone use the term "balanced" in the injection molding industry, they are most likely talking about how equal multiple cavity tools fill out.

The shape of the disc is dictated by the mold. If great care is taken to properly construct a mold that is radially symmetric, and proper cooling is designed into the tool, the discs should come out near identical to the mold, with some slight shrinkage/warping after removal from the mold. If I tried to build a mold in my garage with a dremel tool, I would be willing to bet the disc would not be balanced. Not just the first disc out of the mold, but EVERY disc that comes off this mold.

There could potentially be imbalance due to lack of "heavy spots". If the screw of the machine is working properly, i.e. mixing and blending material well, this is a non issue. Most of the material used is fairly homogeneous. The opposite of a "heavy spot" would be a light spot, or a sink. These are likely to be created, but are typically scrapped or sold as factory seconds when deemed so by the inspection process (quality team).

I may have missed something in there, so if anyone has a question, feel free to ask. Personally, I haven't ever once worried about a disc being imbalanced. Many people have made great points about impact/damage, poor technique, low rpm's, etc. Is there a market for a product like this? I don't know, maybe to someone with too much money. I can think of a couple other areas of the process that could be controlled and have a greater impact than balancing.

/endpost

Happy someone else in the industry tackled this for me. Thanks for this. I do quality checks in an injection molding facility. Unless the facility producing the discs is using true scientific molding with super tight tolerances, there will be imperfections in every disc. There is no such thing as a perfect part/disc. There are work standards and as long as the part/disc meets said standards it is used as a good part. Not perfect, just good.

 

[dehaas]

I agree.



Never heard of such a thing.



This.

I'm not quite sure where to start. Injection molding can be as simple or as complicated as you would like to make it. Fact is, disc golf discs are not the easiest product to mold, definitely not the hardest, but they're no cake walk. Fundamentally, with regards to injection molding, you want the plastic to flow from "thick to thin". That is, the gate (injection point) would ideally be located at a thick section on the part and the plastic would flow outwards to fill the thin sections. It can be difficult to try to flow plastic through a thin walled section and adequately "fill out" thick sections several inches away from the gate. This is exactly what they do with discs.

The injection phase happens very fast, but the plastic immediately begins to cool when it comes in contact with the mold surface. If the flight plate cools before the wing is completely filled out, it would be called a short shot. If it is mostly filled out, but there are some spots that look like dips and depressions, these are called sinks. This can be seen on some early CE discs from Innova.

The term "balancing", when used with injection molding, typically refers to cavity balance. Discs are made on a single cavity tool. Many other products, lipbalm lids for example, are probably molded 32, 64, or even 128 at a time. When multiple cavities are involved, it is important to have them balanced, or filling at the same time. This balance is controlled by cavity layout within the tool as well as cavity/gate configurations. If you hear someone use the term "balanced" in the injection molding industry, they are most likely talking about how equal multiple cavity tools fill out.

The shape of the disc is dictated by the mold. If great care is taken to properly construct a mold that is radially symmetric, and proper cooling is designed into the tool, the discs should come out near identical to the mold, with some slight shrinkage/warping after removal from the mold. If I tried to build a mold in my garage with a dremel tool, I would be willing to bet the disc would not be balanced. Not just the first disc out of the mold, but EVERY disc that comes off this mold.

There could potentially be imbalance due to lack of "heavy spots". If the screw of the machine is working properly, i.e. mixing and blending material well, this is a non issue. Most of the material used is fairly homogeneous. The opposite of a "heavy spot" would be a light spot, or a sink. These are likely to be created, but are typically scrapped or sold as factory seconds when deemed so by the inspection process (quality team).

I may have missed something in there, so if anyone has a question, feel free to ask. Personally, I haven't ever once worried about a disc being imbalanced. Many people have made great points about impact/damage, poor technique, low rpm's, etc. Is there a market for a product like this? I don't know, maybe to someone with too much money. I can think of a couple other areas of the process that could be controlled and have a greater impact than balancing.

/endpost

I don't know a thing about injection molding, so this was a very nice read. Essentially from a molding perspective you'd want to use injection points in the rim of the disc? Maybe like 4 of them spaced evenly, so that you're injecting from thick to thin? The obvious disadvantage to this would be nipples on the disc that would screw with its aerodynamics.

 

[Meulen]

Happy someone else in the industry tackled this for me. Thanks for this. I do quality checks in an injection molding facility. Unless the facility producing the discs is using true scientific molding with super tight tolerances, there will be imperfections in every disc. There is no such thing as a perfect part/disc. There are work standards and as long as the part/disc meets said standards it is used as a good part. Not perfect, just good.

Great input. The facility I work for is 100% medical device manufacturing. Therefore, we utilize scientific injection molding with tight tolerances, for the plastics industry at least (i.e. +/- a couple thousandths of an inch in some cases). Work standards are definitely necessary.

I don't know a thing about injection molding, so this was a very nice read. Essentially from a molding perspective you'd want to use injection points in the rim of the disc? Maybe like 4 of them spaced evenly, so that you're injecting from thick to thin? The obvious disadvantage to this would be nipples on the disc that would screw with its aerodynamics.

Its kind of a catch 22. From a fundamentals standpoint, the outside of the disc would be best. However, the nature of how the product is used also dictates some of the performance needs. The risk with injecting at the rim would be a weak flight plate, caused by where the flow fronts join together in the middle, sometimes referred to as a weld line or a knit line. It would be possible for the flow fronts to cool down enough where they don't bond on a molecular level when they join at the center of the disc. It also can create gas traps which may lead to dieseling (burning).

MVP does a really nice job of two shot molding. They make the flight plate first, and then inject the black rim around it in a separate operation. I haven't looked at one of their discs in awhile, but I'm pretty sure they use an edge gate at the parting line for the Gyro rim. They do a nice job of trimming so it is hard to tell. Obviously, Innova used the four injection points on the Atlas. Depending on the color of the rim, you can see four vertical lines on the rim. This is where the plastic flow fronts meet and create a knit line. The last issue one might encounter when injecting at the rim would be race-tracking, which is exactly what it sounds like. The plastic races around the edge of the part and can create air traps.

 

[Aim For The Chains]

Should have elaborated that I was referring to flow balancing not actually the disc which is done through what I think is called the runner system and good or bad ones can impact how the plastic flows..?

 

[Meulen]

Should have elaborated that I was referring to flow balancing not actually the disc which is done through what I think is called the runner system and good or bad ones can impact how the plastic flows..?

Ah, I see now. Yes, you can make an attempt to control how the plastic flows in the cavity. However, this isn't something you can turn a knob and change. It is related to where the gate (injection point) is located on the part. It might be a stretch to say that a runner is used to mold a disc golf disc. From most pictures I've seen, it looks like most manufacturers inject plastic directly from the sprue into the part. On a non disc golf part the plastic exits the orifice of the nozzle, goes through the sprue, then a runner system, and finally the gate before it enters the cavity that forms the part.

 

[pmatt1969]

And a disc will fly better than most of us can throw it. I cannot control distance or direction to within 6 inches at the end of a throw most the time anyway. I do not have to be that precise. Most shots do not call for that.

 

[ejvogie]

And a disc will fly better than most of us can throw it. I cannot control distance or direction to within 6 inches at the end of a throw most the time anyway. I do not have to be that precise. Most shots do not call for that.

Luckily, the throws requiring the most precision are generally the shortest distances. Yes, you COULD miss a putt by being 6 inches off, but not if it's thrown where it needs to be thrown.

And if you have a pro throw the same disc in the same manner 10 times, I'll bet none of them land within 6" of any of the others. Not only is it nearly impossible, it's unnecessary.

 

[KniceZ]

When a manufacturer sees that their process does not maintain sufficient quality control, they typicaly take some sort of corrective action - perhaps balancing could be in order in that event.

I don't believe that "balancing" is required but I don't the current manufacturing processes have great quality control. If they did why is there so many complaints about consistency.

 

[knettles]

As others have mentioned, the Aerobie Epic is the perfect example. When I can throw it as far as any other driver (backhand), and as consistent as any other driver, that proves the point. No "screw up" disc is going to be anywhere near as off balance as the Epic. So the minute off balances in a mold intended to be balanced won't cause any issues when a mold that is intended to be off balance flies fine.

Now, if only they made an Epic in a plastic that didn't get beat to crap so easily.

 

[bfoflyer]

I would like to thank everyone for the time and effort in answering my question. The points brought up here have gone a long way to clearing up what I have thought about for quite a while... I just need to swallow my excuses for my shorter drives and just go out and practice... Thanks Again Everyone.

 

[DannyThunders]

Discs are plenty balanced , just look at everyone on the pro tour, they ate balanced enough that those guys can trust them to put them on whatever line they want.