Optimize Plastic Part Designs: Injection Molding Simulation in Autodesk Fusion 360

TIM VANAST: Hello, everybody. Thanks for joining us today. We are going to talk about Optimizing Plastic Part Design using Injection Molding Simulation in Autodesk Fusion 360. So first, we just want to throw up the Safe Harbor statement for any forward-looking statements that we might make, although I don't believe we would be doing any of those today.

So my name is Tim Vanast. I currently live in Grand Rapids, Michigan. Just a little bit of history and background of myself-- I attended Western Michigan University. Go, Broncos.

After University, I started working for a company in Ohio that does custom molding, injection molding. And so I started working for Bryan Custom Plastics as a part designer. I also started to do some simulation work there as well.

My next job was actually with Celanese, which is a resin supplier. So when I was with them, I was really working with our customers to help them design and simulate their parts to make sure that they would be good parts, and they would work with the material that we were selling them. After Celanese, I actually moved, then, to Grand Rapids, Michigan area working for Cascade Engineering-- again, another custom molder. And while I was there, I would basically used simulation to verify and validate that any jobs we were going to run, we would be able to and that they would work well.

So about six, six and a half years ago, I actually started working for Autodesk where, here, I get the opportunity to work with customers, basically teaching them how to ensure that their plastic part designs are good either through design, design for manufacturing, and simulation.

I am a Moldflow Certified Expert. . And with me today-- we'll be presenting-- is my colleague, Mason Myers.

MASON MYERS: Thanks, Tim. My name is Mason. I am from Erie, Pennsylvania. I got my start in the plastics field, studying plastics at Penn State University. So I'm a degreed Plastics Engineer from Penn State.

After graduation, I started working with a small engineering firm called Beaumont Technologies. After about five years of designing runner systems, I took a job in the thermoset industry with Lord Corporation. This was a great opportunity for me to get experience with various types of thermoset materials, injection molding, thermosets, compression molding, transfer molding.

I loved my job at Lord, but I had a bad day one Friday. I sat down at my desk and said, I just want a job running simulation, and everyone leave me alone. The following Monday, my buddy from Autodesk called me about an instructor position.

So like Tim, I've been at Autodesk for just over six and a half years now, helping people work with their Moldflow products. Like Tim, I am also a certified Moldflow Expert. And Tim and I also sit on the Certification Team at Autodesk, helping our customers become certified in Moldflow Insight.

Today, Tim and I are going to talk to you about Fusion 360 and simulation. But before we get into that, one question that should be asked is, what is Fusion 360? Now, some of you may know Fusion 360 as maybe a CAD platform or something to help you with your designs. Or maybe you use it for your CAM, or Computer-Aided Machining.

Maybe you do this for 3D printing. But Fusion 360 is all of the above. It's really a platform that can help you design various components and help you manufacture those components.

As I mentioned, Tim and I are going to be talking about simulation quite a bit. Now, we're completely biased because we've done a lot of simulation in our careers. But simulation is a great tool that we can use in combination with any of our design technologies.

We can use simulation to better produce designs earlier in the design cycle. This is really going to help us avoid problems before they become expensive problems. Now, within Fusion 360, we have a lot of different simulation capabilities ranging from static and nonlinear stress analyses. We can do modal frequencies. We can even do some type of thermal analyses as well as buckling and event simulation.

But today, we're going to be talking about a relatively new feature that is plastic injection molding simulation in Fusion 360. Now, as I mentioned, Autodesk has a very rich simulation portfolio ranging from structural mechanics to thermal and fluid flow. We can also do some various molding processes as well as composite materials and even help you simulate your 3D printing of metallic components.

So some of you may be more familiar with our Inventor Nastran, or our CFD, maybe Moldflow, or Netfabb. A lot of these underlying simulations have been produced into the platform that is Fusion 360.

TIM VANAST: OK, so we want to really look at your part and your design to see if it's manufacturable. So the first thing is, you designed a part. Congratulations. Nice work.

But it really is the question, can this be produced? And maybe as the designer, you're thinking, well, I'm the idea man. I don't care. Someone else will have to make this.

And I'm here to tell you, that's not true. You do care. And why do you care? Well, you care because of cost.

Your part can be produced significantly less expensively if it is designed for manufacturing in the first place versus sending it to a manufacturer, having them look at it and say, hey, this isn't right. That isn't right. And then it takes your time and everything to try to fix that and get it done right. So cost, of course, is the big one.

Secondly, it's quality. If you don't design it to be manufactured, whoever is making it, they're going to struggle. And they're going to have higher scrap, and they're going to just have issues. And they're going to charge you more because of that, which, again, gets back to cost, right?

As well as, if they just don't produce good parts every time, what if those get shipped to a customer? Well, then the customer see these parts. And they're like, they're kind of cheap. They don't work very well. Again, going to come back to they're not going to buy again or tell their friends to purchase this. And so it's going to come back to cost in the end.

And really, the last thing too, again, time to market-- I kind of mentioned that-- that if you get someone to try to make this and they have all of these changes that need to be made, or they make a part, but it's not very good-- back to the drawing board. And you've got to figure out what you can change and how you fix it. All of that takes a lot of time and sometimes a lot of money to do that, which-- I'm assuming you've caught on by now-- really comes back to cost.

If you can do this stuff up front, it's going to be much smoother. It's going to be faster. It's going to cost you less to produce your parts.

So with that, I'll stop one moment for a quick commercial break here. And I'll just throw this out as far as designing a good part or a good plastic part design. We have something within Fusion called the Product Design Extensions. And the commercial here is, well, for Autodesk University on Thursday at 1:30, there's going to be a presentation called Creating the Autodesk University Factory Name Badge with the New Product Design Extension.

And if nothing else, we can just see on the screen here where there's the Plastics tab there that gets you to specific features for plastic design. And then you'll notice when you do this, you basically have to select a material. What kind of plastic are you using? And based on that, there will be a whole variety of rules built in for you. And of course, you can modify them if you realize what you're doing is a little outside of norm. But you can modify that, and it just helps guide you along the way.

So again, Thursday-- it's going to be great. At least one of the presenters is going to be really good. Oh, and I'll be there too. So anyways, that's a good one. Make sure you try to attend that one.

MASON MYERS: All right. So we're going to go through a review of the injection molding process. Tim and I both have experienced using injection molding machines, and we felt that it was beneficial to talk about the process while we're dealing with parts that are going to be manufactured using this process.

So the Injection Molding Machine is an integral part of the injection molding process. And if we take the machine, we can break it down into three distinct units. First, we have our injection unit. This is where plastic palettes are introduced into the hopper and then pass through a heated screw-in barrel.

An interesting phenomenon about plastics is that when we heat them up, they expand and relax. And when we cool them down, they shrink. We're going to come back to this when we start talking about design and simulation. But that is a key factor of what happens to plastics throughout this heat cycle.

The next part of the injection molding machine I'd like to mention is the mold. So this mold can be interchanged to make different types of plastic parts, different shapes, different sizes. And then, finally, we have our clamping unit. The clamping unit is responsible for keeping that mold fixated in the injection molding machine during that cycle. Both the sizing of the clamping unit and the injection unit can help us select which injection molding machine is right for our needs based on the part size and what we're trying to achieve.

So if we take the injection molding cycle, there are several key aspects of the cycle that we need to identify. First is the filling phase. Then, we have a packing phase followed by a cooling phase and then a mold-open or ejection phase. And we're going to go through each one of these in greater detail just so we understand what's happening during that cycle.

As I mentioned, the first one is the Filling phase. The mold's closed. Plastic material is injected into the mold itself. This is actually a very high-pressure, very rapid section within the injection molding cycle itself. Once the cavity is filled, we then go into the packing phase.

As I mentioned, plastics shrink when they are cooling down. So what we're doing is we're actually packing additional material into the mold cavity to combat some of that shrinkage that we discussed earlier. We do this until the runner system or the gate has reached a certain temperature, at which point, then, pressure is released, and we go into the next phase. That is the Cooling phase.

So during the Cooling phase, the part sits within the temperature-controlled mold itself. And we're just basically waiting for that part to cool down to a magical ejection temperature that is specific for each plastic material that we decide to use. At the same time while the part is cooling, the screw is rotating backwards to build up a charge for the next filling cycle.

The final stage the, Mold Open phase-- as we can see, the mold opens. The part is ejected from the mold, at which point the mold closes, and the entire process is repeatable-- repeated, rather. So this is a really economical way to make thousands, if not millions of identical plastic parts over the life of a given mold.

So if we take that injection molding cycle, a nice average Cycle Time is around 22% seconds. Now, this is subject to change based on the size of the part or the material that we're using. But usually, around 20 to 30 seconds is a common cycle time that we would often see.

As I mentioned, the Filling Time is usually the most rapid portion of that. Filling times usually range about one to two seconds, again, depending on the part size. Pack Time is probably a very important step, but this is also going to vary as well. So depending on the thickness of the part, we may see pack times anywhere from five to nine seconds.

Followed by the Cooling Time-- the cooling time is usually the largest portion of the cycle. Again, we're waiting for that plastic to cool down to the ejection temperature. And as you can see here, an average cooling time could be 10, 12, 15 seconds. And then, finally, Mold Open Time-- this is just the mold opening and closing again-- so again, largely depend on part size. But if we have a cycle time of around 20 seconds, we're probably looking at a mold open time of around two seconds.

So I love this slide because it really shows you the complexity of an injection molding machine as well as a controller that we use to control the process. Now, there's a lot going on here. And people spend a lot of time learning how to use these machines.

But if we break it down into three key aspects, we have the controller unit that is controlling how the plastic is being introduced into the cavity. And then we also control the temperature of the plastic in the screw-in barrel. And finally, we also control the temperature of the mold. Now, this is a pretty oversimplification of the process, but those are three areas that we have control of in the injection molding process.

The reason why I bring that up is when we get into showing you simulation in Fusion, we have those same settings, ranging from Injection Time, Melt Temperature, and Mold Surface Temperature. Now, we have options. Like, injection time, we can either do automatic or specified. If this is your first time running an injection molding simulation, I probably would recommend that you use the automatic injection time setting.

For both the melt and mold surface temperature, when you select a certain classic material from our database, we will modify the midpoint melt temperature and mold surface temperature, and we'll actually populate those values as the starting point. That's usually a good recommendation to start with these values. If you decide to vary them, I would highly recommend that you stay within the recommended ranges of the material that you are trying to simulate.

So when you go to pick a plastic material in any simulation, this can be a very complex process. We've tried to make it easy in Fusion for you in that, while we do have over 12,000 materials to pick from, the default screen highlights a lot of our generic materials that you can select if you know the material family that you want to use. For example, if you know you want to use an ABS, or a polypropylene, polyethylene, or a polyamide, or a nylon material, you can just use one the generic shrink keratinized material abbreviation families.

Now, there's other ways to find different materials in the database. We can use the Search functionality. We can use some of the browsing features as well as the filters to find the exact material that we want to utilize. And we can do that. As you can see on the right-hand side of the screen, we've selected a TFX-210, which is an ABS material that we're going to be using here momentarily.

TIM VANAST: Cool. Thank you, Mason. So Rules for Good Plastic Part Design-- let's take a look at those a minute. So shout out to Fight Club if there's any fans out there.

So the first rule of plastic part design is uniform wall thickness. And the second rule of plastic part design is uniform wall thickness. It's that important. I think, yeah, I mean, if you're going to focus on anything, focus on that one, for sure.

And we're going to dig into these. So that's, by far, the most important. But we're going to cover a couple others as well-- Radii being one, Draft, and Undercut. So let's look at uniform wall thickness first.

So again, it's the number one rule-- uniform wall thickness. But I'll be really honest with you. The first rule that we break is uniform wall thickness, all the time. But we're hopefully going to show you why you should keep it as uniform as possible and when the exceptions might make sense.

So having our part being very uniform wall thickness is really going to help us to produce even pattern of filling as the resin is filling through into the cavity. It's going to make temperatures and pressures more uniform. It's going to make cooling more uniform because you won't have more heat in one area versus another area.

And ultimately, all of this is driven towards trying to get the shrink that Mason mentioned of-- again, as the plastic is cooling, as it's shrinking, we're trying to get that shrink to be as uniform as possible because when it's not uniform, it ends up turning into warp or, basically, out of shape-- basically, your part becomes out of the shape you intended it to be.

So on this part, or on this slide here, we can see this top one, which, honestly, you could argue, well, that's very uniform. Well, it is. But this is actually more of a metal design where you have a block, and then you basically cut out the features you want. Well, for plastic designs, we really don't design that way.

We typically say, we're designing in the features we need, and we're connecting those features. And so the bottom one is definitely more of a true plastic design versus the top. And again, trying to be as uniform as possible in that wall thickness.

So within Fusion, there's an option in there for design advice. We can actually look at the wall thickness. And here, we see this part. And we see there are some variations there. And that's OK.

Again, we know that we break rule number 1 all the time. But we just want to know and use this tool to say, hmm, is there anything I'm not expecting? Is there something that highlights as super thick or super thin that I didn't know about? Because those are the things that are really going to cause us problems. So within Fusion, we can actually measure that as well.

So one more example here or an example-- again, we have this Bluetooth speaker box on the left. Again, if we look at all of the ribs and everything there, we see it's very uniform. If we look at the one on the right, I've done my best to make this a horrible design, with wall thickness variation all over the place-- not something you want to do. But I really wanted to show the effect of when you have something that's not good like this.

So first of all, we're going to watch the filling pattern here in just a second. And it's going to show how these parts would fill. So we put an injection location basically in the center on the back of this part on both of these. If we look at the one on the left, it's pretty uniform. It's going front to back, side to side, pretty uniform as it goes.

But if we look at the one on the right, we see this front wall feels significantly faster. The back wall feels slower. In fact, those speaker cylinders-- the one on the right is filling faster than the one on the left.

And so it's just simply not very uniform. It's not very balanced. And we're likely to have some issues.

So let's look at what some of those issues might be. So the first one here is injection pressure. This is the pressure it takes for the machine to push the plastic into the cavity itself, into the mold. And if we look at the one on the left, we see the values there, I made those a little bigger, easier to see. That's taking 54 megapascals of pressure.

And interestingly enough, usually, low pressure is good. We prefer to have less pressure. And if we look at the part that's not very uniform, we actually have low pressure. But in this case, more importantly, look how nonuniform it is.

The back wall has zero pressure already. It's high pressure in the middle. The rest of it has just a bigger variation. And that variation is going to create us problems later on.

If we look at the one on the left, again, this is pressure. And so we always have a pressure drop from the gate to the end of fill. But in this case, it's very uniform and symmetric across the part.

So if we look at some of the issues, first of all here, time to reach ejection temperature. So Mason mentioned when the part is in the cooling phase, or it's still in the tool, it's in the cooling phase, we're just waiting for the plastic to cool down enough to be able to eject it. So in this case, our part on the left, it says, oh, it's 68 seconds, and then we could eject this. So while he mentioned a 22-second cycle, a minute cycle is not unheard of. So we're a little bit long but not too bad-- so 68.

But if we look at the one on the right, 383 seconds. Oh, my gracious. This is going to cause you problems.

Let's be honest. This is probably a deal breaker as far as your design goes right here. If I would have designed this as we did on the left, I could have produced five, if not almost six parts by the time the part with a nonuniform thick section wall part cooled down. And so that's going to relate directly to the cost that's required to produce your part.

So a couple of other ones that we look at-- this one is volumetric shrinkage. And again, this measurement of, what is that shrinkage? How much does this part shrink? And if we look at the one on the left, again, it's pretty uniform. It's at least symmetric. It's not perfect, but it's not too bad here.

If we look at the one in the right, the values are slightly higher, but I'm far more concerned about the nonuniformity. The shrinkage on this front wall is going to be significantly more than the back wall. The shrinkage in the left speaker cylinder there versus the right one is going to be different. So when you try to assemble this, the speaker on the left is going to fit differently than the one on the right you're going to have problems with this part.

And really, this volumetric shrinkage ultimately leads towards our total deflection, which is a measurement of the warpage of the part. And in this case, we see on the left, it's about 1.7 millimeters of total movement. On the right, it's about 2.19. Again, so it does create higher deflection but also, again, the uniformity of it on the right, we see the front wall is different than the back wall. And when you go to assemble this, again, you could definitely have some assembly issues.

So ribs-- this is a subset of uniform wall thickness. So normally when we put ribs on a part, we actually recommend they're 50% to 75% of what our typical wall thickness is, which, remember, I said, in the first place, number one rule, uniform wall. And already, I'm telling you, well, except for ribs. Make those thinner.

And the reason we do that, ultimately, is if we have those ribs, that intersection between the ribs and the main wall, it creates a larger section. And what can happen because it's slightly larger, it's going to have more heat. It's going to shrink a little bit more. And if we do this poorly enough, we're going to end up with what we call sink or sink marks.

The picture on the right is highlighting, these are the areas that you might have sink marks. And there's a value here of about 0.014 millimeters. I don't know that I trust the value exactly, but it is good as far as relatively, hey, you're likely to have some imperfections visibly on the surface of this.

Now, in some cases, you might not care. But if this is a consumer part at all, they're going to look at this and be like, wow, why is that back surface kind of wavy? Why are there weird dents on this part? And they're going to perceive that as poor quality.

So let's look at the next one right. Let's jump to radii. One of the things with plastic designs-- any time we have an interior corner, we want to put a radii there because sharp corners create stress concentrations. And so if we look on the right, we've got radii. On the left, we've got sharp corners.

So actually, all within Fusion here, we run a structural analysis-- same parts, except for the radii, same loading. And if we look, the one on the left has about 5 megapascals of stress. The one on the right is about 3. Why do we care about this? Well, less stress in our part with the same load means our part is going to be more robust, less likely to break. And so that really is an important thing when we're doing our designs, to have proper radii across our part.

So like all things, when we say, adding radii is good, it is good. But if you go too far, if you put too large of a radius, like we did on the left, that will actually become bad. What happens, if you look at where that intersection is, look how thick that is. We can see the effective wall thicknesses there is significantly thicker than either the snap tab or the base wall.

That, of course, will create significant-- because of the extra material there, you will have significantly more heat. More heat will create more shrinkage. And we will have issues with potentially warpage, but for sure, sink marks.

So make sure we put radii. Too much is not good. I think the rule of thumb with plastic design for radii is about half of what our average wall thickness or our nominal wall thickness is.

OK, so the next rule is draft. We have to put draft in our part designs. If we look at the incorrect one in the top right here, we see it's basically the die draw, or, basically, the direction that the mold will open. Those walls are designed perfectly straight up and down.

And when the mold halves start to open, it's going to be hard to pull that off the mold because if you did pull it, it would scrape the sides of both of those walls. It would actually create a vacuum in there. It'd be hard to pull off of there.

And so we need to add draft. If we look at the very top right, we've taken those walls, and we've just tilted them out a little bit. That will then allow us, when we try to pull the mold halves apart, to relieve that significantly easier.

And the amount of draft will depend on a number of things. First of all, it depends on what plastic you're using. Certain resins require higher draft angles.

Certain ones require less. Surface finish-- if you have a really glossy finish, well, maybe you can get away with a very low draft. But if you've got a deep grain or a deep stipple on the surface, you're going to need it to be a little bit larger so that it can break away from any of those micro grooves across the surface of your part.

The other thing also, then, is, basically, the length of the draw. If you have a very short feature, it takes less to actually pop that out of the tool. But if you have something that has a very deep draw or a very deep part, at that point, you might need to actually include even greater draft in your part for that.

So again, when whatever draft you've designed into your part within Fusion in the design workspace, on the intersect or inspect-- sorry-- there is a Draft Analysis feature here. We can select our part. We can select the die direction that-- the direction the mold is going to open and close. And we get a visual display, OK, what are the draft angles that I have here? And we could, again, change those values to say, hey, I've been told by the mold maker, for this material, for this grain, it needs to be at least 1, or at least 3, or whatever that is. So it's a great option here to double check your design to make sure you have included the draft that you need.

So another one here that's very important for plastic part designs is undercuts. So undercuts are anything that basically prevents the tool from opening after the tool has been made. Our example here of this tape dispenser. When we take the little wheel of tape and we snap it in there, there's those features around that center hub that, I guess, I would say, they're undercut or they're die locked, which is good because it's going to hold your tape in place there and not fall off. But of course, if you were to mold this just with the two halves of the tool, you're not going to be able to separate them because they're locked together by that plastic design.

If we look at the little snap feature down below, we see, well, there is a way to do It. We can create what we call action in the tool, where we actually have a piece of steel that, before the mold opens, this piece of steel will actually move out of the way so that it can open, and the part can actually be ejected. But this is where we have to be smart with our plastic designs. One option, as we show in the middle picture there, is maybe you have a hole in the back side, and there's a piece of steel that comes up from the other side because, at this point, it's no longer locked in the tool, and it could open.

So the reason that we care about this is really cost of the tool. If we could make our design so that the tool can simply open and close without any other action, our tool design will be significantly less expensive. You will have less maintenance, less issues with the tool overall. But we know that we create these all the time. So it's not the end of the world, but we just have to know it, and realize it, and know that there is a cost associated to creating undercuts.

So just like looking at our draft within the design workspace, we can also looked look for undercuts. Here, it's called the Accessibility Analysis. Again, we get to select our mold open/close direction. And we can check that.

And again, when we do this, we just don't want surprises. If we know that we put an undercut in our design, that's OK. But just know your tool will be a little more expensive.

So when I look at this one, it looks pretty good from here, doesn't it? But actually, if you look carefully, we'll see that there are just a few undercuts on this. Yep. So these are four little indents, and these are intended for when the cover snaps on here it stays in place.

Again, this is OK. But we just have to realize, then, that our tool will be a little bit more expensive than it would have been if we could have come up with a different way to do it. And maybe we don't, and that's OK. But again, these are things to be aware of when we are doing our designs just to make sure that we have a good, solid design that can be produced in a tool and easily manufacturable.

MASON MYERS: All right. Thanks, Tim. I'm going to go through a review of the injection mold itself.

Now, we've designed a good part. We've talked a little bit about injection molding process. We're going to dig in and look at the actual mold itself and what that means to our simulation.

So first, before we get into the mold, oftentimes in injection molding, we're not just making a single part. Within the mold itself, we may actually have multiple part cavities, as I'm showing you here. This case, we're making two cases at one time.

Now, we need two way to connect the injection molding machine to the part itself. And we do that through a Gate and Runner, also called a Sprue as well. So you can see that sprue is that long cylinder in the middle. That connects the machine nozzle to the rest of the runner system.

This is all solidifying plastic. It's molded with the part itself. But you can see the sprue comes down and splits two ways into the primary runner. That runner then feeds a gate area, and then the gate attaches to the part. So we have a path for the plastic to flow from the injection molding machine itself, through the mold, into the part cavity.

Now, you've got to love the plastics industry. We have terms for everything. Sometimes we have multiple terms.

Tim and I have said the word tool, mold, die-- all of those essentially are meaning the same thing. So I do apologize for our industry, but I didn't make all these terms. I'm just here to help you through the process.

When we talk about the mold itself, you can actually break it into two distinct halves-- the stationary half and the moving half. The stationary half is bolted to one side of the injection molding machine that stays put. The moving half is bolted towards the other platen that actually moves or opens during the mold open cycle.

Now, if we go back to the stationary half, sometimes we call this the A-side. Sometimes it's referred to the Cavity side. If we go to the moving half, sometimes we call that the B-side, or the Core side.

Now, there's a lot of different forms for our injection molds in themselves. This is an example of a h plate cold runner. Some of you may be able to count here and saying, Mason, there's more than two plates in that picture.

And I agree. But when we talk about a two plate, we're really focusing on the brown and blue plates. This is a simplistic tool construction where you can see we're still making two cavities here, but the runner system is on parting line, or it's around the perimeter of the part.

So when we have this simplistic two-plate tool construction, it is a very inexpensive tool, but we're limited as to where we can place the gate or where the plastic is introduced into the park cavity. It's got to be somewhere on the perimeter of the part itself. Now, another example would be a three-plate cold runner. In this case, we've added another plate to house that runner system.

Now, the runner system looks a little bit different here. Because we have a three-plate cold runner, we have that additional plate that encapsulates the runner. This helps us with gaining flexibility.

With a three-plate, we're no longer constrained with gating on the perimeter. In this case, the three-plate allows us to gate now on the center of that case. Now, that sounds good. Tim looked at a previous example where we gated in the center as well.

But we have to watch that that's not a show surface. Sometimes we may not be able to put a gate on that spot, even though it would be ideal. We have to watch out for show surfaces.

In both the two-plate and three-plate cold runner, we call them cold runner because the runner solidifies with the part. As you can see in this three-plate example, it actually separates from the part upon ejection.

Now, there's another form of mold that's commonly used in the plastics industry, and that's called a hot runner. Now, I've simplified the A-side a little bit here just so we can see inside of there. But you see that red looking fork design.

That is my hot runner design. In this case with the hot runner, we do have the ability for gating flexibility, very similar to the three-plate cold runner. But the hot runner keeps the runner system molten in this particular case, so we don't have that added runner waste that is the solidifying runner.

Now, these may be slightly more complex. They might be a little bit more costly. But we do have some savings in terms of scrap because we're not producing those runner systems anymore.

So what does this all mean? Getting back to simulation, when we run an injection molding simulation in Fusion, we have the option to pick our injection location. This is where the gate would ultimately reside.

The image on the left, you can see I'm gating on that center show surface of the part. That would be representative of a three-plate or a hot runner mold design, where the image on the right, the injection cone is at parting line, or it's on the perimeter of the part. That would be representative of a two-plate cold runner design. So Fusion injection molding simulation will let you do whatever you want. Just know that where you place that injection cone is going to have ramifications as to which type of tool you need to use.

Now, when we do this, again, there's no right or wrong answer, per se. I'm showing you two separate filling animations. The image on the left, we're getting from the center. The image on the right, we're getting from that short end at the top there.

We're showing you the filling animation here. This is what the filling pattern of the plastic would look like during the filling phase itself. The gating from the center radiates from the inside out. It has a pretty balanced filling pattern, left to right. Whereas gating from the one side there, we have a much more linear filling pattern where we go from one side to the other.

Now, in this case, we're both filling the part in just about 3 to 4 seconds. But again, where we place that injection cone is going to have differences in terms of our filling pattern. It's also going to have variation when it comes to our injection pressure.

The image on the left, gating from the center-- as Tim mentioned, we typically like to see lower pressures here. And gating from the center has a shorter flow length, and that actually helps us have a lower injection pressure. Now, the image on the right when we're getting from the end, we have a much higher injection pressure, and we have a much different injection pressure distribution. Now, I would agree with Tim that, typically, we try to keep our injection pressures low, but we can use this injection pressure value to help us size the injection molding machines that we need in order to mold this particular part with this material at that particular gate location.

Another thing we can look at is deflection. And what I love about this industry is there's a lot of conflicting results and problems that we need to solve at the same time. We told you we like to keep pressure low, and we stand by that. But in this particular case, gating it in the center, as we can see on the left, does have a low pressure. But it actually has slightly more deflection or distortion than what we see from gating it on the end.

What's typically happening here is that gating from the end is causing that higher pressure. That higher pressure is actually helping us, in this case, produce a part that's slightly less deformed than if we're gating in the middle. Again, all of these we can do through various simulations to play what-if game. What if we put the injection location here? What if we used this material? What if we used this design to compare and contrast to see which design fits our needs before we go and design and build that costly injection mold?

All right. Enough PowerPoint. Tim and I, we're going to jump into Fusion 360. We're going to show you how to set up your first simulation, and then we're also going to look at some results that we get after a simulation has solved out of Fusion 360.

So in this particular case, you can see that I am now in Fusion 360. Normally when you are working in Fusion, you probably are starting off in the Design space, as you can see here. A lot of the features that Tim had mentioned, whether he was talking about the inspect analysis, doing a Draft analysis, or an Accessibility analysis can be found here. We also have the Plastics tab that Tim referenced. You can refer back to his secondary paper on the plastic design advice as well.

But we're here to talk about simulation. So the first thing that we're going to do is switch from the Design space to that of the Simulation space. And when we do that, it's asking us, do we want to create a new simulation? We're in luck because that's exactly what we want to do. Now, in this case, you can pick a wide range of different simulations that you can run out of Fusion. But today, we're going to be focusing on the Injection Molding simulation. So we're going to go ahead and click that particular simulation and hit Create Study.

Now, in this particular case, I am working on an assembly. So Fusion is currently asking me, what body do you want to simulate? I have the top of my speaker case. I have the larger bottom or case of the speaker itself, and that's what we're going to simulate. So I'm just going to go ahead and click the bottom area here, and that's what we're going to focus on.

Again, if you make a mistake here, I'm going to just walk you through some of these options on the left here. You'll notice that when I make a change, I click on this little pencil icon or the Edit feature. If you make a mistake, you can always revert back and change that.

So once we have our target body established, we're going to go ahead and pick our study materials. Again, I'm going to hit this little Edit button here, and that's going to open up our material database. As we looked at before, it defaults to a lot of our generic materials that, if you know family abbreviation, whether it be polypropylene, or polystyrene, polyethylene, you can pick your material in a generic sense.

If you know your exact material, you can go ahead and type it into the search field. We'll come back to this in a minute. You can also browse by some of your recently used materials. You can also use some of the filters to find your favorite material manufacturer. If you know the material structure you want to use-- semicrystalline versus amorphous-- you can select and filter from that capacity.