Injection Molded Enclosure Design with John Teel

Welcome to the macro fab engineering podcast. I'm your guest, John teal.

And we are your hosts Parker

Dolan and Steven Craig.

This is episode 134. Before we get started, I like to announce that Derek Broder, also known as the current source will be a judge for the McAfee Web Design Contest blink and led sponsored by Mouser. Check out Derek he was on the map episode 103.

John Thiel is the founder of predictable designs, a company which helps startups, makers and small companies develop new electronic products. Previously, John was on Episode 106, of the macro fab engineering podcast, where John spoke about making the product development process as predictable as possible.

And this time around, we're going to discuss enclosure design, specifically how to prototype and design injection molded enclosures for your products. So I think the best way to get started with this is John, what is like the general process for injection molding?

Well, the you know, the simple description is, is that hot molten plastic is injected into a metal mold at high pressure, you know, that completely fills in the mold. And because of the higher pressure than the part is allowed to cool. The mold opens up and injector injector pins push the part out. And that's basically the simplified process. It's, it's really old technology, I believe it's the basic process has been around since like 1946, I believe. So it's a it's a really old technology. But that's pretty much the the simple, simple explanation, it gets a lot more complicated, obviously, once you start talking to details, but at a basic level, that's what injection molding is.

So it's like, it's like adult playdough right? Yeah, yeah,

basically.

Okay, so let's, uh, let's start talking about the challenges of injection molding, like, what?

How do you get started whenever you bring up product design, and everyone's like, Oh, yeah, 3d printed cases, and you know, modifying other cases. But the moment you say injection molding, it has this like, mystical aura around it. It's like the equivalent of like, RF design.

I think Rf is a really good analogy, that that's kind of a mystical area, you know, black magic from the electronic side, just like injection molding is from the mechanical side. But I would say, you know, most of that centers around the fact that there are, you know, it's a really old technology, and there are so many different restrictions on what can be done with it. So although it's a relatively simple process, you inject molten plastic, you let it cool, and you pop it out, that sounds simple enough, but it actually there's, there's a lot of, there's a lot of rules on exactly what you can, what you can create the shape. With 3d printing, you can pretty much 3d print any shape that you can come up with, there's really not any limit with that technology.

Versus can you 3d print the Mobius strip.

Okay, I guess I need to be careful about saying anything. But in general, you can, that's the biggest issue I see with a lot of people that are you know, developing a product, they've either hired someone to do the enclosure design, or they're trying to do it themselves. And they just give no thought whatsoever to you know, eventually the goal is to get this past a prototype into mass manufacture. And that requires injection molding technology. And if you design the product wrong from the beginning, and you know you you think you've got your your model All right, then you go to manufacture and you're realize this is this is nowhere near being something that can be manufactured and you're at that point you're forced to kind of start over so it's definitely something you want to know up front and understand that you know, all the requirements and limitations of injection molding,

expanding out that especially we're a lot of times your internal circuits depends on your external case as well your enclosure so doing this as soon as possible in your product iteration is probably very important.

Yeah, it kind of depends you know, if you're if your product is really size critical and you're going to you know your your goal is to work on the the printed circuit board layout and get it squeeze it as absolute as small as possible, then it can be difficult to do the enclosure ahead of time because you don't know how small you're going to be able to make the PCB so you don't want to, you know, count on being able to get it down to one inch square when it comes down to one and a quarter. So you have to be careful about not starting too early. If you have the if you have flexibility to some extent, and the size of your printed circuit board, and you're not really trying to squeeze every, you know, micrometre out of the the size of the product, then you you have more flexibility. And in that case, you can do that the to the enclosure and the electronics simultaneously in a lot of times,

well, in so many ways, I think this kind of speaks to the the idea of having like a product definition ahead of time, as opposed to just kind of be, you know, driving on, like, we'll figure it out when it happens kind of thing, like you have to design to a specification in a way.

Yeah, which is something that my experience, entrepreneurs are where people that are startups that are new to product development, they don't fully appreciate, you know, all the requirements and the specifications that can sometimes be necessary for a product versus an established company, obviously, you know, they have very detailed product specification document,

so I was gonna go back to the the mystic hole or around it. So is it is it because it's hard? Or it can't just because it's old technology? Got it? Because that's the thing about RF design is there's math and equations that you can design around, but for some reason that makes it even more mystical, I guess, is that the how it is with injection molding?

Yeah, I mean, I don't think there's, you know, nearly the the math that goes behind injection molding, it's more of some practical rules, I think probably the best way to understand it is for me to give a few examples of things that you have to you have to design for when you're doing injection molding, a lot of the early some of the the the rules that you have to follow comes from the fact that you have to be able to, you have to eject the part once it's cool. So as simple as that sounds rejecting part it can have it forces limitations on what you can do with the part. So there are two basic types of molds, there's one called just a simple Pomo mold. And then there are molds that have side actions. So a simple mode, pull mode is one that you simply open a mode and the parts can pop out, versus with a mold that requires side actions, let's say that you had a your product had a wall that was parallel to the direction that the part is, is pulled out. If that wall has a hole in it, then the the piece of the mold that has to go into to form that hole will will prevent the part from being able to be removed from the mold. It can make a little more sense if you if you see a picture. But it's really easy to if you design features in the product that force it. So once it hardens, now you can't get the product out of the mold. And that that can really complicate you can, you know there are two ways you either design your product or your enclosure so that it's a simple tool. And you don't have to have side actions. But if you needed, say, a hole or slot in a wall that's parallel to the direction that you're removing the part, then you have to use what are called side actions. So you could have a side action as part of the mold that that comes in from the sides. So that would be perpendicular to the poll direction, so that they come in when the part is molded, you know, when you inject the plastic, and then as soon as it cools, the side actions are pulled out of the mold, and then the mold is opened. And then that allows you to still pull the part out. So it really complicates and it really gets the cost of the modes to be really expensive once you start doing side actions. So it's something as simple as having a hole in a wall that's parallel to the pole direction that can prevent you from removing the part there, the easy way around that is to do like what is to put a slot under that so instead of it once again, it's something you it's really helpful to have a picture but if you you there are ways to instead of having a hole if you had a long slot, then that allows the product to be pulled out of the mold without having a side action. So side actions are one thing that really kind of complicate the the mold designing for injection molding. Another one is

so what a side action mold is, I imagine it's what makes the the mold more expensive. There's probably a higher degree of tolerance with that metal sliding on other metal in the mold. compared to just a simple you know, a two piece some, you know, pull mold like you're talking there's an increase the price after the molds been made.

It can it will increase the cost of the mold and it will increase the cost of the fabricated parts because there's just additional time associated with it. So a lot of it is, you know, what the what the mission, you know, the molding time is is going to also set the, the price.

Well, and and I think actually, probably most of our listeners have experienced, you know, the the effects of what you're talking about when dealing with enclosures that have draft angles on the walls to allow them to be released from the mold. Many enclosures that you you deal with have like a two to three degree angles such that they can actually be released from the mold once the once the pieces come apart.

Yeah, exactly. Oh,

are you talking about? Like how project boxes and the like have a draft on the on the sides?

That's right. Yeah. Yeah. And at first, if you don't, if you don't understand that that's coming out of a mold, it's like you, it's confusing at first, because it's like, why would you make an angled wall? I want a square box, you know, I want 90 degrees everywhere? Well, it's, it's because they actually, it has to come out of a mold at one point in time.

Yeah, that's exactly right. That, you know, drafting is a is a big part of it. And it's tends to be a little bit simpler thing to deal with, you know, you can just kind of add draft after, you know, typically, when you're doing the prototyping stage, you don't want to add the draft, that's something you can add later when you're ready to go to manufacturing, because it just tends to complicate the model and having draft in there. So my experience, I like to do the prototyping without the draft, and then add the, the draft and later, but that's different than dealing with the simple pool versus side actions. That's something that requires a fundamental change in the way you develop you design the product versus draft is something you can always, you can always add at a later point. For sure.

I think the best best way to explain like what you're talking about with the with the simple pole molds is like think of like a power drill. I don't know if anyone's seen a video like, you know, a ve tearing apart a power drill or whatever, it's always in two pieces. And it's like split down the middle. Yeah, that's exactly

most enclosures are, there's a top side and a bottom side that have to be molded separately. So that's, that's, you know, most enclosures that you can't, you can't really mold an enclosed enclosure in a single mold, you have to do it as two halves, and then, you know, either glue or ultrasonically weld or screw those two parts together.

And you know, it's it's, it's interesting, because I've certainly run into plenty of designs where that concept is not necessarily understood, where you know, somebody has just done a 3d CAD of what they hope that their enclosure will look like. And it's virtually impossible to actually create because it has overhangs or it has geometries that will basically hang on to the mold. And so there's sort of an art to understanding, you know, this, that this, you know, piece of plastic actually has to be handled in a specific way.

Yeah, it sounds so simple, you know, when you first describe what injection molding is, and, and you wouldn't think just pulling a piece of plastic out of a mold would, you know, create complex design rules, but it does. And that's, you know, a lot of them are associated with just having to remove the part from the mold,

because I've designed a lot of models for 3d printing. And some of those design rules are like limiting overhangs you can't go over, you know, depends on the 3d printing technology, of course, but like with a typical FDM printing, you can't go over like 45 degrees, like 50 degree overhang, you're starting to push it. Is there any kind of rules like that for injection molded?

Yeah, there are, you know, there's minimum wall thicknesses, you know, kind of runs between maybe one and two millimeters is minimum wall thickness. But that that, in general is one of the other main requirements for injection molding is it has to, you can't have any parts of the product where it's a solid block or chunk of plastic, everything has to be made out of uniform wall thicknesses. And the reason being, you want the you want the molten plastic to flow uniformly into the mold, but also you want that product, you want it to cool uniformly because if it doesn't cool uniformly, then you'll get warpage. So if you have, you know, this one part of the product, this is really you know, that's 10 millimeters thick, then that's going to cool off a lot slower than the, you know, a wall that's only one millimeter thick, and that that causes like a thermal differential that causes the part to warp. So that's another thing that a lot of people that aren't used to designing for injection molding have a hard time grasping as you you have to pretty much design the entire product to use the same wall thickness. And instead of using like thick blocks you have to use like a rib based design. You add the ribs to still give it the strength the mechanical strength But while maintaining the uniform wall thickness,

although, you know, maybe we're getting a little bit complex. I have heard of differential cooling before for some components to actually purposefully add stress to certain areas that might be too complex to discuss here. But have you had experience with that?

No, no, I haven't. Okay. Most of my experience comes, you know, with obvious I'm a, you know, electronics design engineer, not a mechanical injection molder molding expert, but my experience comes from having my own hardware product developed in on the market. And I started off hiring freelance mechanical engineers to do the 3d modeling and design the enclosure, but I got impatient and decided to learn it myself. And, you know, went through the entire process of having molds created in China. And you know, I've been through all this, but it's mainly most of it has been with one product. So some of these experimental techniques, like you're talking about isn't something I've really had any experience with?

Sure, sure. Well, okay. So let's, let's go ahead and kind of bounce off of that. Because there's a lot of questions that go, the practical questions that go behind, you know, how do I actually initiate all of this? How do I actually, like, get this done? And so, you know, what files are you going to need to create? And do you make the mold itself? Or do you pass that off to some expert, and they make the mold for you?

Yeah, generally you will, you you may create the 3d model for your product, but in general, the yo, yo need either your manufacturer that's going to do the injection molding? Or if you go to a third party to have the mold made, then that role, you know, need to be through them?

Are molds a universal? Or like, do you need to work with like a specific manufacturer, and they have a mold, like, like their machines are physically different between places?

Yeah, that the machines are physically different. I don't know exactly how many different styles of machines are, there may be an infinite number, there may be two or three. But I, you know, I have enough experience that when I've had molds made by one manufacturer, it wasn't something you could easily migrate them over to another manufacturer, because the molding machine was had a different, you know, it was designed for different molds than you know what the first manufacturer

and and it's been my experience in the past that even with a particular manufacturer, a lot of times they will give you options on what material the mold is made out of. And that usually has an impact on timing and the cost and things like that. But some, you know, I've had experience with can't remember, it was like 2000 injections on the low end, and then you could buy like a more premium mold that would go up to like 100,000 injections or something like that. So have you had experience with it?

Yeah, yes, I definitely have. So the the material that you're going to make the mold out of is going to depend on first of all, how much money you want to spend and how many parts you're going to make with it as you've kind of discussed. So if you're doing, you know, let's say less than 10,000 units, then you can you can usually get by us like when you first start, you want to start with the softest cheapest mold that you can and that's typically going to be made out of aluminum. So you want to start with an aluminum mold, that's going to be the lowest cost a single cavity, which I can talk about more in a minute. So start with a single cavity aluminum mold. And you know, the starting cost for that a simple pull mold, you know, for just saying an average, a small product you're looking at about $1,500 is sort of a starting price for a mold. I for for low volume molds in the molding, I have always I've used a company called proto labs.com So I know that's there's their cheapest mold is like $1,500 So that would be out of aluminum. Then you want to gradually step that up. So you may start with an aluminum mold that you pay 1500 for single cavity then the next step, you know, you'll probably find some bugs and work that out. Then the next step you would maybe want to go up to a steel mold still single cavity, but uh, you know, a softer steel, and then you can each time you can kind of keep ramping that up as your as your production volume ramps up because as you know, once you get into molds that are made to pump out millions of units. So they're they're made out of really hard steel, you know, they may have for a 16 cavities. Then like you said, you're you're getting up into the, you know, approaching $100,000 per mold And as you know, if you make the assumption to very minimum, you're going to need two of these for your enclosure, one for the top side and one for the bottom side, the prices can get out of hand really quickly. So, you know, I always tell entrepreneurs and startups, regardless of how, you know, you may feel confident your product is gonna sell a million units immediately. But you don't want to set up manufacturing for that immediately you want to, you want to ramp it up in steps, because the worst case is you spend 100,000, or $200,000 to have molds made, then, you know, you realize that there's a problem with the product, and you need to change that mold. And then that just creates an entire nightmare of issues. So it's always best to start with the simplest cheapest solution and then just continually take small steps up in the, you know, in the mold as far as how many pieces it can produce,

or your $800 juicer ends up being at Goodwill for $40. That's the other other thing that can happen. Yeah, that's one question I had was, because your essay, you're doing your first shot at 1500 1500 bucks, right? For your first mold and your first prototype stuff. Now, is there a way that you can let's say you're designing your enclosure for injection molding? Is there can you still 3d print that to at least get some prototypes rolling and like, show off the people to investors and that kind of stuff?

Yeah, I don't believe any, anything you're going to do to the product and make it ready for injection molding is not going to prevent it from being 3d printed. The big differences is, you know, a 3d printed prototype, or an enclosure can only get you so far, because it looks like a prototype, it doesn't look like the actual production plastic, with my own product, instead of doing 3d printing, I went with doing CNC machining process for the prototype. And the reason being is you can you can build a prototype, if you have a CNC machine, that is a production injection molded plastic. So instead of you know, stacking layers of a hot resin like with 3d printing, CNC machining just takes a block of production injection molded plastic and then carves away from it. So if you feel that having the actual final production, plastic is important for your prototypes and CNC machining can be an alternative to 3d printing,

especially where a lot of times with your device, the how it looks is very important for a first impression.

Absolutely, absolutely. And with my own product, the feel of the plastic had had a big impact on how the product felt to us and the quality of the product. So it it took a long time to to you know to get everything just right when it's something you know, with how the product is, how it feels or the plastic and you don't want to that's not going to be something that you're going to be able to model correctly with a with a 3d printing resin, it's not going to have the same flexibility and the same impact strength and all the other things as your final production plastic will.

Yeah, I'm sure you're not going to go take a 3d printed enclosure, prototype enclosure to go get, you know, professionally tested rugged UL tested, yet to get UL tested.

Yeah, definitely not for UL testing, but even presenting them. You know, a lot of you know, if you go to present it to a big retailer, they're going to be you know, they don't really want to see a prototype that looks like your prototype, they want to see something that can be manufactured and they know that they can tell the difference quite quickly.

Right, they want you to get as close as possible to the end product as you can.

Absol Absolutely. Absolutely. And you kind of have to be careful. I don't you know, I don't I at one point were not with my own product. I had a retailer that was interested in it. I sent them a sample that had been 3d printed. And I don't remember the details, but somehow the resin that was used was not a high temperature resin. So basically, during shipping, the sample morphed and the heat of the summer time, it completely warped you know, the retailer got the product and said, you know, told me he thought it was awkward to use and you know, of course, I was devastated until I researched it further and realized that he had one that basically melted in shipping. You may want to be careful.

That's a good lesson learned. So we were talking about having molds made and I've got an A question here about well, so we know that whatever whatever the mold is, his machine to the plastic is going to reflect that. So Regardless of if you have the actual shape of your device machined properly in the mold, you still have to make sure that the finish of the mold is the way that you want the end result finish of the plastic to be. So how do you specify that

I was helping design a enclosure for someone? And they just told me, I want it to look like plastic? And I'm like, I don't know what that means.

What? And if you don't know what that means, then the manufacturer doesn't?

Yeah, that's a pretty open ended

specification. Yeah, how do you specify that? Yeah, there

are surface finish specifications. And from what I recall, there are different grades that you can specify for how polished you want the obviously, the higher the polish the, you know, the typically kind of the higher quality and more reflective it will look, as far as I don't honestly recall what those different levels of surface finish are. But that's, that's definitely part of the mode. And that may be something you know, for your initial mode, you may not, you know, want to, you may not have to do or want to do. But as you increase the volume and start actually selling the product, then the surface finished, you know, can likely become more of a significant issue,

it's also likely something that you're the mold manufacturer can probably also provide you information or even samples on

Oh, absolutely, absolutely, that's probably going to be the best way for you to figure out what type of surface finish you want is to get the samples and look at other products and see what those surface finishes look like.

And you will probably have more fallout with the higher level surface finishes just because of just

read, I would think that a mirror finish a mold would degrade quicker, at least the the end result of what you get.

Yeah, yeah, definitely, I would imagine it would as well.

So your designs done? How do you go and find like a manufacturer to build your thing?

You know, there are a lot of different strategies. When you're when you're first starting out for your first time, I highly recommend that you stick to a manufacturer that's the mastic or at least moderately local to you. So you can you can go over there and you want to do the offshore.

I'm sorry. You can go over there and beat their knees in.

So you may lose my train of thought.

Yeah, that was a derail right there. Okay. Okay. So so yeah, okay, so you're looking for somebody who's local makes, it absolutely makes sense, especially if you've never done it before, because you can go talk to him, you can walk through the process, you could see the machines, which, if you've never seen a injection molding, like 100 ton injection molding machine, it's worth just going and looking at because they're really cool. They're really awesome to watch.

Yeah, in general, it's always best to start local from, you know, I always recommend that everyone start lower domestic for all aspects of the product development or their product manufacturing. So they can mainly so you can work closely monitor the quality, you know, unless you want to plan on going to China on a regular basis, it's much simpler to, to monitor the quality locally. And once you get, you know, once you've run in a few 1000 units, you work out all the bugs in your mold, you've got everything absolutely finalized, then it can make sense to move to an offshore molding facility. But in general, don't don't rush to that it takes everything takes much, much longer. When you're dealing with manufacturers in China, for instance, I mean, just the time delay and shipping the communication issues. And so you don't want to really be in a situation where you're trying to debug manufacturing issues, you have all those issues worked out and then then you can go offshore to you know, try to increase your profit margins.

It's like you open up the phonebook. If people don't get those, I bet you injection molding manufacturers aren't in there. So how do you just go about finding someone?

But I'll tell you, you know, there are various ways that I'll tell you my own my own story with finding a manufacturer for my product. I had bought somewhere I don't recall this as five or six years ago, but I just bought a list of US manufacturers that make like products or do similar type of products. So that was the first thing is I just got a list. And honestly I just like cold emailing them. Because first of all, if I need a manufacturer, what you really defined as a manufacturing partner, so unless you've already got investors and you're you're fully funded, I think it's it should be a priority finding a manufacturer that wants to be a partner and that believes in your product, because they can be one of your best sources of funds. They're

going to be more willing to help you out and make sure your product succeeds.

Yeah. To invest money. So with case I emailed I focused on a US manufacturer that had facilities in China, that way I kind of figured I got the best of both hello world. So I've reached out to, you know, I don't know, a couple dozen of these companies and they responded, one of them, they really, you know, are interested in a product. And at the time I had I had a prototype, and this is back in Blockbuster Video was actually a big company, I already had interest. So I was able to use that and leverage that to get them in factor interested. So this manufacturer facilities in the US, but also in China, they ended up, you know, we obviously, they came in met with me, they liked the product so much the day and ended up investing all the money for all the molds, which was, you know, over $100,000. And what they did was they have more ties those costs, so, the multiple $100,000. And then, for example, on the first 100,000 units, so I had to pay them an extra dollar to reimburse them for the mold cost. So that that can be a pretty common arrangement, if you can find a manufacturer that is injured, believes in your product and wants to help you get it out there, they also tend to have to be a manufacturer, that it's not at full capacity, if they're running full capacity, then they're not looking is seriously for new business. So you kind of have to find the right manufacturer that develops and the product is is not at full capacity. So they're they're looking for business deals. And in that case, you can have them with me and more ties to the the cost of the multiple, huge, huge benefit. Since you know, the whole cost tends to be kind of the biggest obstacle to scale, a hardware product or part of the team has manufacturing. The other thing that if you find like manufacturer with a partner, and it's gonna get a little bit, the second biggest issue for hardware companies eventually is cashflow, you only have to manufacture a product, then ship the product to the US, then you ship it to like a retailer that they paid 30 days later. So you're having to finance all this. And that was my manufacturing partner, I got them to agree to give me terms, it allowed me to pay them after I was paid by the by my customers.

So you could like you could like net six months them

at 90 days. So yeah, that's pretty good, that the standard manufacturer, most retailers will pay net 30. So you know, they get the product 30 days later, they pay you for it. So net 90 gave me because it leaves factory in China takes three to four weeks to get here by sea basil, and then ship time to them the other way, like 30 days after that. So you kind of have found everything for you know, two to three months. So if you can find manufacturing partner that once again believes in your product, that's something else that they can they can help you with and in my opinion is the most under looked at type of funding for startups, everyone focuses on mainly on equity funding. This way you get funding and you don't have to give away your company. So

be Kickstarter and that kind of stuff, too. Yeah, there's

there's Kickstarter, but you know, yeah, that that has its own set issue. So this is just a another possibility. So to answer your question. Yeah, yeah. Or yeah, there's, there's, you know,

my product got kick started, and then I spent it all on a house.

True story. So, I guess what, you've got to just discuss sort of answers to this question. But I have had this kind of come up before. If you're purchasing, or if you're working with your partner to create a mold, and they're charging you for the mold? Do you own it? Or do they own it?

In my case, it was in a more time since I basically they lent me the money. They owned it. But once I paid it off, then it wasn't it would be out of my ownership. So they don't do it for the money. But if you pay for the movement, in this case, they're lending money, then most likely won't own it until you pay them back for it.

I guess it depends on the terms. Because the same thing with like stencils and tooling, and PCB manufacturing as well. It's like, who owns it? Every situation

is different. And it really depends on the manufacturer, your product, how good it is, how much progress you've made, how well you can negotiate? There's, there's really no standard answer to this.

Sure. Well, and one of the reasons why I was asking that question is because I'm aware of one, you know, macro fab style injection molding company, I say Mac fab style as in, you upload your 3d file, they quote you a mold, and they quote you a price per unit, use that printer labs. It. I don't think it's that one, I think I think it's a different one. However, I know in their terms, you pay for the mold, but they own it, such that if you ever wanted to move to a different manufacturer, you'd have to go start over again. You know, you couldn't take that mold with you. Yeah, right.

Okay. Yeah, I think yeah, you're totally right. In situations like that. I have seen that. I don't recall if proto mold or proto labs does that as well. But for Yeah, that's part of the reason I think you're able to get the molds. Fairly low cost, you know, $1,500 is really quite cheap for any mold. So I suspect that's part of their reason that they can offer you that cheap as they they know that you're forced to give them basically an exclusive unless you want to have a different a different mold made

right that they keep you in the family. Yeah, absolutely. Yeah. So we kind of discussed, you know, a little bit of the upfront costs. With with this, but let's say I'm designing a new product. And I've got, you know, I've got a budget of 10k for the mold. Does that get me? You know, just for whatever standard product? Do you think that that would get me close enough to get some prototypes in?

So is this 10k? To actually have everything you know, the enclosure designed? Or are you just talking to the motor themselves,

let's say for the molds themselves? Yeah,

I mean, 10k will get you, you know, probably moderate volume molds, you could you know, you, that's enough to probably upgrade from an aluminum to like a soft steel. But it really, it really depends in a big way on how many pieces of plastic your product requires. I mean, the simplest is you're going to need two molds. But you know, a lot of products have Ford, you know, 30 different custom pieces of plastic in them. And anytime someone presents me a product that requires lots of different custom plastic pieces, you know, that that's a big red flag that you're looking at huge amounts of money to be able to set up manufacturing, because of the mold cost. But 10,000, that, you know, that's gonna get you a, you know, you could probably get a, maybe one mold that's, say, like a two cavity mold, that's a Steel's that mold. So you know, you're looking at volumes, maybe 25 to 100,000 units,

and how much at just roughly just like a guest, like, how much would you be paying per shot, then for the lifetime of that mold? Like, it'll save you a shooting ABS plastic?

Yeah, it really depends on you know, the kind of the main requirements, what's the cycle time and how much plastic is being used. So if as you increase the number of cavities in your mold, then your cycle time goes way down, and you know, each shot, you're making four parts instead of just one. So that that's drastically lowers the cost is by increasing the number of cavities.

So basically, by increasing your upfront costs, you lower your tail cost.

Exactly, which tends to be a common theme in a lot of areas, obviously, the more you spend up front, it's going to tend to save you on your your manufacturing cost. My advice is for, you know, once again, unless you're a large company, to not focus initially on trying to reduce your unit cost or increase your profit margins, but you need to instead focus on reducing your risk and cost to get the product to market. Make sure there is a market there for your product. Yeah, make sure there's a market before you spend the money on the really expensive molds and then, you know, then you can you can worry about after you've gotten the product on the market, you've proven there's a market for it, you've gotten feedback. You've made all the, you know, improvements that you think are necessary, then at that point, you can start focusing on trying to optimize your

property and finish up with a couple like prototyping questions, John? So cool. Let's do like a. So someone's skipped to like, what's the timestamp for right now? The 43 minute mark, do you have a TLDR for prototyping and injection molded enclosure?

So are you asking for a lengthy explanation or

I'd say a couple sentences if we can sum up just like how would you go about prototype so let's say you already have your enclosure your your electronics are designed, how would you go about prototyping injection molded enclosures like you know you're going to build 10,000 plus of these things, so 3d printing and enclosures out of the question and modifying an enclosure is going to be end up costing too much money in the long run.

Yeah, well, I mean that my first piece of advice is if you're going to outsource this make sure you ask the person doing this Do you understand injection molding and how to design for manufacturing? If they don't, then you need to find someone else. Because there are a huge number of people out there that can do 3d modeling and they're they're really good at it but they have no concept of injection molding so you you you spend all that money you get a product that you can't manufacture.

Is there any resources people can go online and look at like how to design for injection molded enclosures?

Oh, there yeah, there are huge numbers of I don't have any offhand but they're, you know, proto labs website, they have quite a bit on, you know, like, how to as far as designing for injection molding, and one thing I found that they have that I really used a lot as they their quoting tool has a built in interface so you can upload your 3d model and it and analyzes it and points out any issues with your design is from a from an injection molding standpoint.

So it's like a DFM for your model. Yeah, exactly,

exactly. And it's really user friendly. You know, you see the 3d model, and they highlight the areas in red and tell you what the problems are. And I used that extensively when I was designing my enclosure, and I would run it through there, find out the problems, fix all those, run it through again, it would usually find a few more, and then just keep going through that process until I got it right.

What's the next step after that? So you've got a design that you think can be injection molded?

Yeah. So that, you know, the next step? Well, first of all, you want to make sure you've you know, prototyped it enough, using 3d printing to make sure that it's going to meet your needs? I mean, that would be the Yeah, that's the right shape that your product fits into it. Obviously, do all that in the 3d model before you, you know, start doing the injection molding because obviously, that's, you know, the injection moldings once you're, you're past the prototyping stage. Well,

I yeah, I would agree, but you one of the big things was, uh, you know, making sure all your wall thicknesses are the same, where, and at an early stages of your, your enclosure design, it's probably better to start doing that first.

It is you don't want to Yeah, to go back. And, you know, you don't have to make necessarily every wall exactly the same. But you want that general concept and the design from an from an early standpoint, you don't, it needs to be you know, you may tweak the thickness, but you don't want, you know, like large blocks of plastic. And, you know, so everything has to be uniform. There are also an I don't, I think SolidWorks like 3d modeling software has, like an additional piece of, you know, the software that you can add to it that does injection molding simulations. So they will on your part, they'll show you have with Phil, you can kind of see oh, you know, this, the product isn't, you know, the plastic isn't flowing uniformly, I need to round this corner to make everything flow smoother. So that that's another tool that you definitely want to use before you actually have the molds made. And typically, the mold maker will do that as well. My manufacturer at the time is doing that process for me, because that was an area, you know, I hadn't had an experience with so they were they were doing the simulations beforehand.

Cool. So we got more yet in the process. We've got the enclosure designed and DFM.

Yeah, yeah, we prototyped it, it's a DFM, then the next step is to start with aluminum, single cavity, cheapest molds you can get, and then work up from there. And

Steven had the question on here is, what if I want to sample but we've already talked about that it's basically your sample is you make a really inexpensive aluminum mold, and that one shot mold and then make some

Yeah, I mean, you don't have to, you know, you may just want to do the injection molds. Not necessarily because you want to pump out 10,000 units, but because you want a professional market ready looking sample. And typically, the only way you're going to get that is with injection molding.

Right. Right. And and, you know, so So one of the things that that question was maybe worded incorrectly it's not what if I want a sample everyone wants a sample, right? Everyone for sure one for and and and the thing is, there are a certain there are certain things that really only work with injection molding. And what I mean by that is, you know, sometimes you'll have plastics that have glass beads that are injected in there, or sometimes you'll have glass fiber that sometimes you'll have, you know, specific electrical conductivity of the actual plastic that you want to test. And that's not something that you could 3d print or not something that you could like buy a block of and milled down, you would you would literally have to shoot it to just see if it's right. So it seems like buying the the cheapest aluminum mold to just make sure everything is right. That seems to be the best option.

Yeah, it is. And it typically when they first you know, when you if you have a new mold, they're not going to just, you know, just use it, you know, you know, make 100 units or whatever and just assume they're all right, typically, from my experience, you know, they're, they're going to make a few samples, send it to you, you're going to be like, you know, this parting line, or, you know, this other feature doesn't look right to me and you know, you may they may have to modify you know, not necessarily the mold, sometimes maybe that but also you know, the level of pressure and and Yeah, the temperature and some of the you know, they can increase the temperature to, you know, make the plastic flow more smoothly. So there's various knobs that they can turn to, typically you will go through a sampling process before you are ready to start manufacturing with those molds.

And one last thing is how do you pick the right material? Because there is a million different types of plastic? Is there a specific plastic that you should pick? Or for like an electronics project? Or is it kind of, you know, just not? Yeah, dealer choice dealer's

choice there?

Yeah, there are, there are probably 1000s of choices. But in general, for the two most common types by far are polycarbonate, and just our PC, and then abs, don't ask me to pronounce what the ABS stands for. But, so abs and polycarbonate, so apparently, polycarbonate plastic is going to is going to have a higher quality appearance, it's going to have a higher impact strain. And that's typically what you know, like higher dollar consumer electronics will typically use. So for most of the products that will be designed by people listening to this, the polycarbonate is going to be your best choice. But with those features comes additional costs. So if you're really cost sensitive and appearance isn't quite as critical, then an ABS plastic may be a better choice. But it depends on you know, if you're going to be in a high temperature environment with you know, an acidic environment, there are all these different requirements. But just in general, as a basic guideline, it typically is either polycarbonate or ABS,

I bet you whatever manufacturer you find, can probably recommend what kind of material they would like to use for whatever application you're using.

Yeah, absolutely, you can there will be some back and forth on you know exactly what material that you want to use. And you know, what, what, you know, why did the specifications and in what are the cost, obviously, that has a can have a, you know, an impact on the enclosure cost, although, for most of the products that I deal with, you know, they have decent, the complex electronics enclosure cost itself is pretty minimal compared to, you know, all the electronics and having the printed circuit board assembled and

right, especially if it was designed by an electrical guy, that's where the money is gonna go.

So, Steven, do you have any other questions for John?

Uh, you know, I don't believe so. We certainly hacked away a bunch of questions that that I came up with, for sure. That's for sure.

So John, we're definitely gonna have to have you back on the podcast again, because it's always I learned about an entirely new subject every single time you come on.

Okay, great. I like hearing that.

You want to sign us out, John? Yes.

So that was the macro fab engineering podcast. I was your guest John teal.

And we were your hosts Parker Dohmen.

And Steven Craig See you next time guys. Take it easy

Thank you. Yes, you our listener for downloading our show. If you have a cool idea of project topic or you done injection molding, and you want Steven and I to discuss it, tweet us at macro fab or email us at podcasts@macro.com. Also, check out our Slack channel. If you're not subscribed to that podcast yet, click that subscribe button. Wait that podcast? The podcast macro engineer podcasts describe it. That way you get the latest episode right when it releases and please review us wherever you listen, as it helps the show save visible and helps new listeners find us. I'm watching Stephen just crack up on the video screen over here.