Podcast – How Can You Choose the Right Injection Mold Steel?

Various types of injection mold steel samples displayed on a workbench.
How Can You Choose the Right Injection Mold Steel?
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Okay, so let's, let's jump into this whole world of injection mold steel. Yeah, I, I find it pretty fascinating how choosing the right material can really make or break a product. Like, you think about it, it can be something super complex like a medical device, or it can even be something as simple as like a little everyday gadget we all use.
Yeah, it really is true. You know, choosing that right mold steel, it's almost like you're laying the foundation for a building. You know what I mean? You absolutely need a material that's going to be tough enough to handle the pressure, and I mean literally handle the pressure of that injection molding process so that you can create really high quality parts consistently every single time.
So. So where do we even begin with this? I've got all these articles and notes here and I've seen all this stuff about different steel properties, wear resistance and hardness and corrosion resistance. It's a lot to take in.
It can be, yeah. But let's try to like break it all down and simplify it. I want you to think about these properties as the essential ingredients for a successful mold. So each one of these properties, it plays a crucial role. And if you really understand the nuances of each one, that's going to be the key to making those informed choices.
Okay, that makes sense. Let's start with wear resistance then. I imagine this is especially important for molds that are going to be used to make a ton of parts over and over. Like high volume production.
Exactly. Imagine this. You're designing a mold for something like a gear, and this gear is going to be used in a really high performance engine. That gear is going to be going through constant friction and wear and tear. So you're going to need a mold steel that can withstand millions and millions of cycles without degrading. So in a case like that, Ace SA S136 steel from Sweden, that would be a top contender for sure. It has really impressive hardness. After the heat treatment, we're talking HRC 48 to 52.
So S136 is like the marathon runner of mold steels. It's built for endurance. Yeah, but what about projects that don't really require that level of wear resistance? I'm guessing those super tough steels probably come with a pretty high price tag.
Yeah, you're right. Cost is always a factor to think about. For smaller production runs, you know, or projects that involve materials that aren't as abrasive. A more budget friendly option might be the affect something like P20 steel. It might be Perfectly adequate. You see, it's all about finding that sweet spot, you know, balancing out the performance requirements with cost effectiveness.
This kind of brings up something that I was thinking about, and I'm seeing a lot of different information in these articles about that, about the whole cost benefit analysis of choosing a steel that costs more. How do you know when it's actually worth it to invest in that premium material versus choosing a more economical option?
Well, that's where things get interesting. It's not as simple as just looking at the initial material cost. You also have to think about the potential long term savings. So, yeah, a high performance steel, it might cost more upfront, but it could end up saving you money in the long run because it'll last longer and need less maintenance.
So it's like if you're buying a car, you might spend more to get a higher quality car, but then you're probably going to save money on repairs and maintenance over the life of the car.
Exactly. You got it. It's all about taking that holistic view, you know, and thinking about the whole life cycle of the mold. And sometimes that means spending more on the steel up front can actually save you money overall.
Okay, that makes sense. All right, let's move on to hardness. I remember reading that hardness is super important for maintaining the shape and precision of the mold. But why is that?
Okay, so think of it this way. During the injection molding process, the molten plastic is getting injected into the mold under extreme pressure. So if that steel isn't hard enough, it can deform under all that pressure, and then you're going to end up with parts that aren't consistent.
Oh, so it's kind of like if you're trying to sculpt something really detailed out of clay, but the clay's too soft. You need a material that can hold its shape exactly.
You need that firm material. A good example would be H13 steel. It's known for its hardness. It can get up to a hardness level of like HRC 42 to 50, which makes it a good choice for those high precision applications where it's really important to have those tight tolerances.
But didn't we talk about how if the steel's too hard, it could become brittle? So how do you find that balance?
Well, that's where the art and science of heat treatment comes in. Heat treatment is kind of like you're fine tuning the properties of that steel. You want to get that ideal balance of hardness and toughness. So, for example, age 13 steel, it goes through a specific heat treatment Process. It's called quenching and tempering. And that process helps it to get to that point where it has that high hardness, but it also has enough toughness to prevent it from cracking.
Okay. So it's not just about choosing a steel because of one single property. It's about understanding how all properties work together and how you can use processing techniques like heat treatment to fine tune the material so that it's going to meet the specific requirements you have.
Absolutely. And that brings us to another really important property, corrosion resistance. And this becomes especially important when you're working with certain types of plastics or if you know that the mold is going to be exposed to some pretty harsh environments.
Right. So if you're designing a mold for a part that's going to be exposed to chemicals or something.
Yeah.
Then you need to factor that into the steel selection.
Exactly. In a case like that, you might consider S136 Steel. We talked about it earlier, remember?
Yeah.
It's not only known for wear resistance, it's also got excellent corrosion resistance that's going to help prevent damage to the mold, and it'll help the mold last longer, even in those challenging environments.
It's all starting to make sense now. Yeah. So we've talked about wear resistance, hardness, and corrosion resistance. Those seem like the three big properties to consider when you're choosing a steel for a mold. But I'm wondering if there are other things that can influence the decision too. I mean, we've really only just started talking about all of this.
Yeah. We've only just scratched the surface. There's still a lot more to uncover. Like, one crucial factor we haven't even touched on yet. The production batch size. Basically how many parts you need to make that can have a big impact on what kind of steel you should choose.
That makes sense. If you're only making a few hundred parts, the mold probably doesn't need to be as tough as a mold that's going to be making millions of parts.
Exactly. For those smaller batches, a more cost effective steel like P20 might be the best way to go. It's readily available and it gets the job done. But if you're going to be doing some large scale production runs, you know where that mold's going to be. Under constant stress and wear, you're going to need to go with something tougher, like maybe NAK 80 steel. It's specifically designed for those high volume production runs, so you can be sure that the mold can handle the demands of running all the time.
So it's like Choosing the right kind of car for a trip. If you're just driving around town, a small car might be all you need. But if you're going to drive across the country, you're going to want something a lot more durable and reliable.
I like that analogy. It's a good one. It really shows how important it is to choose a material that's going to be able to handle the demands of the project. Oh, and speaking of important choices, there's another factor that we need to talk about, one that people often overlook, but it can be just as important as the material properties themselves.
Okay, I'm all ears. What is this overlooked factor that's so important?
Well, we've talked a lot about the steel itself, but what about the company that supplies the steel? Their reputation can make a big difference. You want to make sure you're getting high quality material and that you're going to get the support you need throughout the whole process.
That's true. I hadn't really thought about that. You're right. I wouldn't just buy mold steel from anybody.
Exactly. A supplier with a good reputation will have strict quality control measures in place. They want to make sure that their materials are consistently good and they're reliable. They're also going to be able to give you technical expertise and guidance on things like processing the steel, and they'll be there to support you if you have any problems. All of that can be really valuable, especially if you're working on a complex project or if you run into any challenges along the way.
So it's not just about finding the right steel on paper. It's also about finding a supplier you can trust, someone who can help you through the process and make sure the project is a success.
You got it. It's about building a relationship, you know, a relationship built on trust and expertise. You both need to be committed to quality. And when you're dealing with something as important as mold steel, having that strong foundation can make all the difference in the world.
Absolutely. Wow. So we've covered so much ground already.
Yeah.
From wear resistance to supplier relationships. It's a lot. But I'm realizing we haven't even talked about, like, the actual mold itself, the design. I mean, it can't just be about the steel.
No, you're absolutely right. It's like, oh, imagine you've got all these amazing ingredients for this incredible meal, like the best ingredients you can possibly find. But if you don't know how to put those ingredients together, you know, in the right way, you're not going to End up with that delicious meal. Meal. It's the same with mold steel. You can have the best steel in the world, but if the mold's poorly designed, it's not going to perform well.
Yeah, that makes sense. So how does mold design actually play into this whole material selection process?
Well, it's all about making sure everything works together. The design of the mold needs to, like, complement the properties of the steel. So, for example, let's say you're working with H13 Steel. It's got that high hardness we were talking about. Well, the mold design has to be able to handle that.
Okay.
You know, if the mold has, like, sharp corners or if there are big changes in the thickness, those can turn into stress points. And those stress points can cause cracks or even make the mold fail, especially during the heat treatment.
So even if you pick the perfect steel, if the mold design isn't made for that specific steel, you can still run into problems.
Yeah, you could. You've got to think about how the molten plastic is going to flow through the mold, you know, where the cooling channels should be and how they're designed, and even where you put the ejector pins. All that stuff can impact how well the mold performs. And ultimately, that's going to determine the quality of the parts you make.
That reminds me of what we talked about earlier with hardness and toughness, how you have to find that balance. If the steel's too hard, it can become brittle, and if it's too tough, it can wear down more easily. So is it the same with mold design?
Yeah, it is. A really good mold design is going to distribute the stress evenly so that there's less chance of cracking or warping. Think of a bridge. It's got all these arches and supports that are specifically placed to handle the weight of the bridge and prevent weak points.
Right. So it's like the form and structure of the mold are just as important as the material itself.
Exactly. And just like an architect has to think about the materials they're using when they're designing a building, a mold designer needs to understand the steel they're working with so they can design a mold that's going to perform reliably and produce those high quality parts.
It sounds like this requires a lot of collaboration. The people choosing the steel and the designers and the engineers, they all have to be on the same page.
Oh, absolutely. Communication is key. Everyone needs to understand what the goals of the project are. The choice of steel should help to inform the design process, and vice versa. It's an ongoing back and Forth with everyone working together.
Okay, so now I'm thinking about the manufacturing process. Does the type of steel affect how the mold is actually made?
Yeah, for sure it can. Some steels are easier to machine than others, like 718H Steel. Steel, it's known for being really machinable. So it's pretty easy to cut and shape and polish, which can make the mold making process a lot smoother and save money, too. But some other steels are a lot harder to machine, especially those with really high hardness. Right.
So that's where something like EDM comes in. Right. I keep seeing that in the research I'm doing.
Oh.
But I don't really know what it is.
Yeah, EDM stands for Electrical Discharge Machining. It's basically a process that uses electrical discharges to, like, erode the metal.
Okay.
And that allows you to create some really intricate shapes and features. So it's off often used for those really hard to machine materials or when you're trying to create complex mold geometries, you know, that would be super hard or even impossible to make using traditional machining.
So it's kind of like using a tiny little controlled lightning bolt to sculpt the metal.
Yeah, that's a good way to think about it. EDM is really precise. You can create features with really tight tolerances. But it is a slower process and more expensive than traditional machining. So usually the choice of whether or not to use EDM comes down to a few things. How complex the design is and how much it costs and how long it's going to take to make the mold.
It seems like every decision you make when you're making a mold involves a lot of compromise. Weighing the pros and cons and figuring out the best solution.
Yeah, that's pretty much engineering in a nutshell. And with mold making, there's no one perfect way to do things. Every project is different, and you have to think about the material properties and the design and the manufacturing and then make sure everything's going to work together. Together to get the final product you want.
Right. And speaking of the final product, what happens when things don't go right? Like, what if the mold breaks too soon? Or what if the parts don't meet the specs? I imagine trying to figure out what went wrong can get pretty complicated.
Yeah, it can be like trying to solve a mystery. You have to look at all the evidence and gather information and then use your expertise to figure out the root of the problem.
So what are some of the most common reasons why moles fail Is it usually a problem with the steel itself or the design or the manufacturing process?
It could be any of those things, or sometimes it's a combination of factors. Sometimes it's a simple fix, like there was a defect in the material, or someone made a mistake during machining. But other times it's a more complex issue, like maybe the heat treatment wasn't done right, or there was a flaw in the design that didn't show up until the mold was actually being used.
So how do you actually figure out what went wrong? Do you just look at the mold, or are there other more high tech methods you can use?
Usually you start by just looking at the mold, see if you can spot any obvious damage or wear or deformation. We might also use a microscope to look at the microstructure of the steel. That can give us some clues about how it was processed and whether there are any signs of stress or fatigue.
So you're looking for tiny little clues that can tell you what went wrong?
Exactly. And sometimes we even do a chemical analysis to make sure the steel is actually the right type of steel. Sometimes the problem isn't the design or the manufacturing, it's that the material itself is wrong.
Wow. It's amazing how much science and technology goes into making a mold. But with all this talk about high performance steels and advanced manufacturing, I can't help but think about the environmental impact of all of this. Is sustainability something that people in this industry are thinking about?
Yeah, that's a really important question, especially now. We all want to create a more sustainable future, right? And yeah, the traditional mold making process can use a lot of energy. And then there's a problem of what to do with old molds. You know, when they wear out, it can be an environmental challenge.
So what are some ways that the industry is trying to address this? Are there any new approaches or materials that are being explored, you know, to try to make mold making less harmful to the environment?
Yeah, absolutely. One thing people are doing is trying to optimize the design and manufacturing process so that they use less material and less energy. They're using computer simulations to create more efficient mold designs. And they're also exploring new molding processes that don't need as much heat or pressure.
Okay, that makes sense. Are there any materials that are more eco friendly than traditional mold steel?
There are some really cool things are being developed. Researchers are looking into bio based polymers and composites that could potentially replace some of the metal components in molds. And those materials are renewable and biodegradable. So that's a big plus for the environment, you know, when the mold's life is over.
That's incredible. It sounds like mold making is really changing. Yeah, with technology getting better and people caring more about the environment.
Yeah, it's an exciting time to be in this industry. Yes, it's amazing to see all this innovation and efficiency and sustainability all coming together.
Oh, and speaking of innovation, there's one more thing we should talk about. The future of mold making.
Okay, now I'm really intrigued. What's coming next for mold making? What new trends and innovations are going to change everything? The future of mold making, huh? That sounds pretty exciting. What kind of advancement are we talking about here? Are we going to be making molds with flying cars and robots soon? Huh? Well, maybe not flying cars just yet, but there are some really amazing things happening in the field, like additive manufacturing. You probably know it better as 3D printing.
3D printing? I thought that was mostly used for, like, making prototypes and small batches of things. I can't imagine how you'd use that to make a whole mold.
Well, you're right. 3D printing isn't quite ready to take over for traditional mold making, at least not for those big production runs. But the technology is getting better all the time, and it's already being used to make prototypes and mold inserts and even some small production molds.
So for someone like me who's still trying to understand how traditional mold making works, what are the advantages of using 3D printing to make molds?
Well, one of the biggest advantages is that you have a lot more freedom with the design. With 3D printing, you can make some really complex shapes, and you can even put features inside the mold, stuff that would be super hard or even impossible to do with traditional machining.
So it's like you have this magic tool that can make any shape you want with all these tiny details and channels inside.
Yeah, kind of like that. And another good thing about 3D printing is that it's an additive process. You're building the mold layer by layer, so there's not as much waste material compared to traditional manufacturing, which is better for the environment.
That makes sense. Yeah, but 3D printing is still pretty slow and expensive, right? Yeah, especially if you're trying to make a big mold. So how realistic is it that it'll become the standard way to make molds in the future?
Well, it's already happening, really. The technology is improving so fast. The printing speeds are getting faster, the machines can make bigger molds, and there are more and more materials you can use. So, yeah, it's definitely becoming more and more viable to use 3D printing for larger production runs, especially for products that need to be customized or specialized. That's where 3D printing really shines, because you have so much flexibility with the design.
So it's not really a question of if 3D printing will become the main way to make molds. It's just a matter of when.
Yeah, pretty much. And it's not just 3D printing that's changing the industry. There's also this whole movement towards Industry 4.0, which is basically about using digital technologies in manufacturing things like artificial intelligence and the Internet of things and big data.
Okay, I've heard people talking about Industry 4.0.
Yeah.
But I'm not sure what it means for mold making.
Well, imagine if you had sensors in your mold that could measure the temperature and pressure and all sorts of other things, and all that data could be sent to a computer, and then artificial intelligence could be used to analyze that data and make changes to the molding process in real time so that you're always making the best quality parts and you're being as efficient as possible.
So it's like having a robot expert watching over the whole process.
Yeah, exactly. And not only can it improve efficiency, it can also help prevent problems. The system can analyze the data from the sensors and look for any signs of wear and tear or any other issues that could cause the mold to fail. So you can do preventative maintenance. And that means the molds will last longer and you won't have as much downtime.
Wow, that's amazing. So the future of mold making is all about using data and technology.
It's definitely a big part of it.
So it's not just about being a good craftsman anymore. It's also about knowing how to use all this technology.
Yeah, you need both.
It's really incredible to think about how much the industry has changed.
Yeah. And there's even more exciting stuff on the horizon, like self healing material.
Wait, what self healing materials? Is that even real?
It sounds like science fiction. I know, but researchers are actually making a lot of progress. Imagine having a mold that could fix itself. Like if it got a small scratch or a crack, it could just heal itself. That would mean the molds would last a lot longer, and you wouldn't have to spend as much money repairing them or replacing them.
Wow, that would be incredible.
It would be a game changer for sure. Especially in those tough environments where the molds are getting beat up all the time. Yeah, and that's just one example of the cool things that are coming in the future. The world of mold making is constantly changing and improving.
Well, this has been an amazing deep dive. I feel like I've learned so much about injection mold steel. It's not just about the steel itself. It's about the whole process, the design and the manufacturing and all the innovations that are happening.
Yeah. It's a whole ecosystem, and it's clear.
That people in this industry are really passionate about what they do.
Oh, yeah, we're definitely passionate about it.
It's a fascinating field.
Yeah.
And I'm really excited to see what the future holds for mold making.
Me too.
Thanks for taking the time to talk with me today. I've learned a ton.
It was my pleasure. Remember, the world of materials science is always changing. So stay curious and keep learning. You never know what amazing new things are just around the