Darron Peddle is the Principal Engineer at WishBone Medical, a company that manufactures pediatric orthopedic products. He is an experienced seal industry veteran engineer with over 20 years of experience in the seal design field. Before joining WishBone, Darron was the Product and Engineering Manager at Parker Hannifin’s Engineered Materials Group and the Senior Engineer at DePuy Synthes Companies.
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New to seals? Engineered elastomer (rubber) can behave in surprisingly non-intuitive ways. Learn how one expert has achieved mastery using an analytical methods-based approach.
Darron Peddle is a skilled engineer and expert in the seal industry. His carefully honed design approach has led to diverse engineering positions and participation in multiple influential design projects. No matter where you are in your career, Darron will educate you on the complexities of working with rubber so you can create a functional design to meet your product performance goals.
In this episode of Makers of Our Future, Bill Sharratt is joined by Darron Peddle, Principal Engineer at WishBone Medical, to discuss the best design methods for elastomer seals. Darron shares his tips and tricks on designing with rubber, his crucial role in overcoming a hardware design flaw, and his advice to engineers engaging with seals for the first time.
This show is brought to you by Darcoid. We're building this podcast as a searchable store of knowledge, something you can reference if you’re new to seal design. And if you’re starting out on your career in engineering you’ll learn what others have done to achieve career success. Learn more at www.darcoid.com.
Intro 0:03
Behind every great product is a great seal. Join us at the crossroads of preeminence product design, engineering, seal mastery and supply chain excellence, and to learn from the makers of our future.
Bill Sharratt 0:21
Hello, welcome to Makers of Our Future. I'm excited you're here to join us for conversations with the people behind the products that are changing the world. We put this podcast together to form a searchable store of knowledge to help out up and coming designers working with seals get to grips with what they need to do. Okay, let's get started. My name is Bill Sharratt, and I'm your host for today. I am Senior Vice President of Business Development at Darcoid and my guest Darron Peddle. Darron is an experienced seal industry veteran with over 20 years in engineering before moving, training the level of product and engineering manager at a prestigious division of Parker Hannifin before moving on to the medical products field. So welcome, Darron.
Darron Peddle 1:13
Thanks. It's great to be here
Bill Sharratt 1:15
Yeah, it's good to have you. I enjoyed working with you. In the past. I was a little sad when you left, Parker, but I'm delighted you could join the show today. So it's excellent. I'm gonna call my first question at you. So you got your How did you get? How did you get into the steel industry? It's kind of not on everyone's career wish list? I think when they're going through school, what was what's your
Darron Peddle 1:40
story? So probably no different than most people. I wasn't looking to get into rubber industry either. In fact, when I joined. So I started in some automotive products in southern Ontario and a little company called yo rubber. And after a few years there, I had an opportunity to move to Friedenberg NOK, in New Hampshire,. Friedenberg, I had the option of working on either plastic or rubber components. I selected plastics. And then within a week or so the rubber engineer quit, and they had an urgent need. And guess who fell into the Rubber Products? Okay. Right, and then proceeded to spend about the next 20 years there. So, with with Yo, I had experience in both plastic and rubber, so the Friedenberg decided that they had the greater need on the rubber side. So that's where I ended up. Okay, excellent. So
Bill Sharratt 2:41
what got you? What, how about your education? Where did you go to school
Darron Peddle 2:47
University of Waterloo, it's about an hour west of Toronto, mechanical engineering back in the early 90s. Okay.
Bill Sharratt 2:57
And so they taught you a lot of seal knowledge, or
Darron Peddle 3:01
I seem to recall, there was maybe 45 minutes set of mine that was spent.
Bill Sharratt 3:12
So that's, I think, typical. That's something that we hear about all the time. Another reason that we're putting this podcast together. What was it that you learned about rubber? First, that really gave you a good a good grounding in the subject.
Darron Peddle 3:33
Hmm. It doesn't behave like anything you've ever any other of the engineering materials that you've ever worked with? Hmm. So a lot of things, even intuitive engineers could look at and say it's going to do this or it's going to do that. And with rubber. You just throw that out the window? Yeah, one of one of the things I learned very early on, is finite element analysis is a phenomenal tool for hoping to dispel what you think it's going to do, and show you what it's actually going to do. A week,
Bill Sharratt 4:07
that's interesting, we've used FEA in many of our successful designs. It's a great tool in predicting performance, it has some limitations. But if you know modulus, say its its tensile strength and so on, can you when you're just sketching out a seal and and theoretically, applying pressure you sent intuitively understand what's going on? Where do you get surprised with FEA?
Darron Peddle 4:38
So it's when rubber is loaded. You know, if you had a steel structure and you're loaded a certain way you can you can kind of anticipate how it's going to move under those loads. Whereas with rubber, it's got so much for more flexibility built into it that things just happen. and a little bit differently finite element analysis as I mean not simple shapes, obviously, when you squeezing over, you know what the ordering is going to do, it's pretty, pretty obvious what when you got some complex seal shapes, especially ones that may be deformed rather than or flex rather than deforming or compressing, reflecting that there can be some big surprises and just where they move how they move. Sometimes it's just not intuitive at all, when you look at a cross section. What's what's really great about FEA, though, is it enables you to look at iterations very quickly. Whereas you might have to prototype something, kind of to make parts, test them, you can turn around some very quick concepts and discard ideas that don't go anywhere, very quickly, and see those those movements in the rubber that you couldn't otherwise anticipate unless you spent all the time and money to make those prototypes. Yeah, indeed,
Bill Sharratt 6:04
I remember working with you a while back. We looked we wouldn't. we visited the customer. And we really got our hands on their application, it was an LED light bulb. Designer and early days of LED mass produce light bulbs, and they had a requirement for a volume compensating diaphragm. And I remember you looked at it, and all the inputs that you needed to work with, and you kind of said, you know, I'm going to I'm going to kind of model this tonight, my hotel room. And lo and behold, we came up with a very successful design. How much do you remember that one? How much modeling did you do on that to get comfortable when
Darron Peddle 6:49
I do remember that one, and that one had some really tight constraints, because the packaging on it was so confining. And there was quite a bit of volume that we had to compensate for. We really had very little space to do it. And so yeah, that one that one does stand out in my mind as a particular challenge. And the other one that was challenging, and that was the material that we had to use, if I remember correctly, because of what the fluids we were containing and the temperatures and all that kind of good stuff. We had to use a material that doesn't like to be molded on severe undercuts and that type of thing. So the traditional expanding bellows wasn't going to happen. Yep. So yeah, I recall that one, even the concept that we came up with on that one was pretty unique. Yeah, we turned the convoluted and the the bellows 90 degrees. So it didn't find out. And that one seems to me there was a tried, three and four and five different conference, not different convoluted, but the just the number of convoluted needed. And looking at trying to manage the stress as the as the diaphragmexpanded to accommodate the volume. Yeah, FEA was really helpful for that. And you could also calculate exactly how much movement you're allowing, which online compensation you're aligned with, with each of the designs. So yeah, that was a I was actually rough on one. And fortunately turned it in pretty quick and work right out of the gate. Yep, no, that
Bill Sharratt 8:26
was it was good. It tested really, really well. And tricky. Material doesn't like to move normally. Not real good for flexing, and so on. But your design was outstanding. Limitations on FEA, though, I mean, I know. It can be difficult under dynamic when you got dynamic, dynamically moving surfaces, for example that the seal might be working against, do you find you have limitations there or all bets are off at some point?
Darron Peddle 8:26
Yeah, there's several limitations, dynamics is definitely a whole different animal that I really didn't get into very, very much the vast majority of what I was involved with was static sealing. So that was a challenge for some other engineers to deal with. One thing I did find was, no matter how good your material properties were, you could still only get it was far better at doing relative comparisons between designs. That was an outright prediction of performance. So for example, predicting the exact loads that you were going to see from a seal, it was okay, it wasn't great. If it gets you in the ballpark. But if you were looking to dial something in, it wasn't fantastic for that. But if you were looking at stresses, for example, in two different designs, and it said that you were going to have 20% Less stress or 50% Less stress in this design versus in to resign, or you're going to have twice the load something to that effect. Now, those are great as far as determining the direction and design should take. But at the end of the day, I didn't trust the results as an outright predictor of exactly how much force that seals is going to require that type of thing.
Bill Sharratt 10:19
Yeah, we always have to test in in the real world to make that final determination, I guess. But the, the fact that you can use that iterative process before cutting steel is tremendously helpful. We've seen the benefit time and time again. Also, I guess, the more accurate the FEA is, relies on how well characterized your material is, you've really got to understand the unique properties. So many times we're asked to design a rubber component, and there are so many families within the engineered elastomer realm. And they all need to be within the families, there's different properties as well. So each of those has to be categorized before you can put them in the model. Is that
Darron Peddle 11:11
correct? Oh, absolutely. And even more so than that. It's a 70, durometer, EPDM, one versus the next, or nitrile, or whatever the case may be. You can't even substitute compounds, if you're trying to get some sort of accurate representation in it one, one 70 durometer nitrile. For another, for example, they're not the same. You know, we use durometer, very loosely in the rubber industry. It's one of the worst predictors of how a part is actually going to behave or worse representations. It's not really, it's very roughly related to the modulus of the partner. And the materials are so nonlinear that it's, it's almost like a point on a wavy curve, right? You pick the one and compare that to to another. Compounds are so different, they're they're individually compounded. Each manufacturer has their own end, even within a manufacturer, there'll be a lot of variation between the compound that's, say a 70 EP versus another. Yeah, that is,
Bill Sharratt 12:23
we found that critical. FEA without the adequate characterization is we just miss it pretty quickly. On the you talk to modulus, I think that's a it's often shown on on on a datasheet. People want to understand the material, they look at a physical property datasheet and modulus is in there. And I think a lot of people overlook modulus. Can I put you on the spot and talk to how modulus predicts seal performance, say under a pressure situation? And we're talking extrusion and seal failure? Where do you look to modulus there to inform your prediction, regardless of FEA?
Darron Peddle 13:14
That's that's a tough one. Because even on a date, datasheet, you got a single point representing the modulus. Modulus is a variable with an elastomer depends on how much you're deforming it. So yeah, even looking at even looking at as a single point, actually called modulus is tough. But obviously, the higher the modulus, within reason, you're going to have more extrusion resistance. But even that, by itself is not a great predictor.
Bill Sharratt 13:46
Yeah, you know, like you said, it's a complicated material, no complicated engineering challenge. So I'm sure you have over your career in the seall industry had a lot of people come to you who've got into into a problem, they've got too far down their product design path, and they realize the seal that they hadn't really thought much about, is proving to be a big problem. Can you think about a time where you really saved someone's bacon or got a project back on track? By late stage emergency engagement?
Darron Peddle 14:35
Yeah, I could probably come up with one or two of those. Yeah, the vast majority of the products we worked on naturally engineered seals. And occasionally you'd have a customer come to you early in the project, recognizing that, you know, they needed assistance with that. But an awful lot of the projects we worked on, you described you know, somebody thought they were going to use an O ring here. or something simpler, and really didn't plan for proper sealing parameters seal height, and enough space to accommodate that seal. So very, very often that was the case. But one in particular, and I'm not going to name names, but there was a company that was producing a fuel tank. For for an automotive OEM and expensive vehicles, and customers were coming home after filling up their fuel tank, parking in the garage coming out a few hours later in the garage floors covered and gasoline. So yeah, they weren't very happy, obviously. So I recall working on that one pretty hard to try. And then it wasn't our seal, by the way, we hadn’t gotten involved with creating the original seal. But they did bring us in to try and help resolve the issue. And we did some analysis work and some tolerance stacks, and realized that what they had done, at least on paper, was created a fuel sender that didn't overlap fully with the ceiling land and the fuel tank. So it can be offset enough that there was no direct compression line of compression on the ceiling. So they were actually seeing this in practice, the sales were just kind of rotating, dropping into the fuel tank a little bit, and there was no crush on the seal whatsoever to create the former seal. So when we realized that there wasn't even a line of the compression seal, kind of sat back and scratched our heads and thought, Well, what in the world are we going to do here? It's not like we can tell them, you know, you need to redesign the tank and redesign the senders so that there's overlap, there's cars out in the field, they need to repair these things. And they really didn't want to replace entire fuel systems in order to accomplish this and be an extremely expensive recall. So we came up with a design that we ended up patenting with him, uses a Belleville washer essentially molded inside a rubber seal. So an a Belleville washer is essentially a conical spring. So it's a flat conical spring the washer, but it's got a little bit of a pitch to it. So on the inside edge, we had a seal bead, and then the load would be transferred out to the outside edge through the washer, press the seal bead further outboard on the bottom side on the fuel tank, leveraging the load across that. Okay, yep. So that worked even better than we expected it with. The customer had some of our prototypes, put them in, and we drove up to visit them and see see them testing. And they said, Yeah, this will work just perfectly fine. And of course they had been leaking before. They took it apart and showed me the sealling land. And I said, had you showed me this in the first place? I would have said there's nothing we can do to help you replace the tenants? Yeah. Wow. So it worked really well. And it had a side benefit that it took materials for carbon materials that are high flooring materials that typically don't work well at low temperature. And it actually extended the low temperature ceiling capability because the spring was still improving force where the rubber itself had become solid.
Bill Sharratt 14:35
Okay. Did you know all that was going to happen when you when you design?
Darron Peddle 15:15
No, that was the benefit that we accidentally discovered after the fact.
Bill Sharratt 18:45
Fantastic that there's so much to bear in mind. Designing seals and and you talk to the land or the meeting surface, the hardware. You’ve gotta get that right too it sounded like you got lucky on this one. But there's theoretical surface finish. And then there's actually manufactured surface finish. So you got to got to pay attention to all the details, right? Yep, absolutely. Excellent. Good story. Well, well done. That was a check so many boxes. Love it. So how would you talk to your design approach when you look at or when you were looking at a new seal? And maybe this is a universal approach that you've used later in your career, but what's what path do you take when you you figure it out and you design?
Darron Peddle 19:39
Typically, the first thing I would look at was a tolerance stack up was everything, the size of the seal that you need. So look at the meeting components, figure out what what they're made of. Which gives you an idea of durability, how much they're gonna move over time, and kind of tolerances that you can expect to be holding if you were to give explicit tolerances to begin with. But yeah, we're getting that initial size of the seal. Mechanically, that's one of the first things you do. Of course, you got to look at the temperatures and the fluids in and understand what material you're going to be working with, probably as the next step. Yeah.
Bill Sharratt 20:17
Yeah. So how often do you get a surprise? I mean, I think sometimes customers get a little frustrated, because we keep asking questions, and asking more questions. And then kind of sometimes have to circle back and make sure that the answer the first question is still the same? Because we've had those late stage surprises like you talk to the surface finish on that fuel application. So how often do you get surprised at the last minute?
Darron Peddle 20:51
I would say it's the exception. Okay. There are some oddballs, though, I can recall the an engine manufacturer or an automotive manufacturer producing engines. And they're complaining of a leak that they were seeing, I believe was a valve cover gasket. And we couldn't understand for the life of us why this thing was leaking. So visited the plant and coming to find out they were using sandpaper to clean up a step on the machining process. And sanding across the seal face
Bill Sharratt 21:29
Oh, perfectly the wrong direction.
Darron Peddle 21:32
Yeah, so you can imagine sandpaper it's got the sharpest tip you can imagine on the cutting hinges. So it's creating a perfect V shape across your ceiling surface. rubbers pretty good at conforming, but it can only do so much. Yeah, so those are leaking at a pretty good clip.
Bill Sharratt 21:49
Yeah. Yeah. As always a surprise. So 20 years, we use 20 years with Freudenberg before moving to Parker or how did them you may be 20
Darron Peddle 22:05
years in the ceiling industry overall.
Bill Sharratt 22:09
So did you join Parker through an acquisition and find yourself in the family or did you do another album?
Darron Peddle 22:17
I joined let's see I joined wins precision I was there for a couple years and left and went to Goshen rubber. Okay. Then Goshen rubber was acquired by winds precision six months later.
Bill Sharratt 22:30
Was that a bit awkward? I mean, that. Yeah. I'll be left Windsor on good terms. It was
Darron Peddle 22:35
it was okay. It was a little weird. Yeah. But I don't think anybody at wins was terribly concerned because a few months later, we were acquired by Parker. Okay. And I suspect that was kind of the plan all along. Winds and Parker I'm sorry, winds and Goshen. We're not quite big enough. Parker to acquire. But combined, they were exactly what they're looking for. Okay. Yep. Makes sense. There was a bigger plan in motion. Then you’re
Bill Sharratt 23:06
working out of Syracuse. And at what point did you work through the management hierarchy to to the position you achieved?
Darron Peddle 23:17
Actually, that was in North Carolina. And I'm still working as well. Through that series of acquisitions. I was still in North Carolina. And when the engineering sealsdivision was formed, I was the number one first engineer for that division. And then I think, you know, Tillman King Yep. He started working as an engineer as well, for engineering sales division, added the volume or became more than I could handle by myself. And Tillman was working at Syracuse, I was working at North Carolina. And I believe I was there for roughly six years. And they asked me to move to the headquarters here in Syracuse, Indiana, to become the engineering manager and run around the group. Yep. Excellent.
Bill Sharratt 24:07
Congratulations. I mean, they had a lot of faith in you. I mean, you did really good work. How do you what advice do you give to up and coming engineers getting to grips with a seal application for the first time? What do they really need to know that that would benefit them as they engage on that project?
Darron Peddle 24:30
Listen to engineers have been working on it for a month and if you have the the opportunity bend theirr ears as much as you can, don't assume you know what you're doing because of your engineering degree. Because when it comes to rubber, you probably don't. Okay. I can run Remember running into younger engineers, generally customers that thought they knew what they were doing would get in over their heads, and even when you told them what, you know what you needed to do in order to solve the problem, there were still some skeptics that thought they knew better. Yep. Yep. Yeah, wrong intuition. Yeah.
Bill Sharratt 25:15
So I mean that again, that kind of speaks to why we're doing this, why are we having this conversation because having the luxury of joining a company where there is that, that knowledge and experience and kind of tribal knowledge, if you will, on rubber, and seals and how to make them, that's pretty rare, unless you're actually in a rubber manufacturer manufacturing company, we see it in some obviously, some larger companies, where rubber is a very important part of the product, but so often, that knowledge is not there, or it it is retired out and not replaced at the rate that it should be, or people are moving job hopping so fast that those centers of excellence can't build up. Yeah, so hopefully, following your advice, find someone who who knows, there are resources out there on the web.
Darron Peddle 26:11
Well, and honestly, if if I was giving advice to young me, and I wasn't working in the rubber interesting, somewhere else, and I needed rubber parts, and it was critical my application, I'd be calling somebody like you guys, thank you. Because you really do need somebody who knows their way around rubber, you're not going to figure it out on your own. I mean, unless you're doing something extremely simple, and you're looking through the Parker o-ring handbook, and you can follow exactly what's in there. But even after my career in the rubber industry, I've gone into places where somebody's been working on a river park, and intelligent people, good engineers, and they have been struggling with something for months, if not a year. And you go working on and, you know, ask a few questions, you know, try this right here. And I actually had that experience last summer, with employer walking on something they have been working on developing at least six months. And I took that was a flat rubber gasket. I took it over or workbench with an exacto knife and a ruler and I cut it up and put it back in the application. And it did exactly what they needed it to do in the span of about 10 minutes. Like I said, intelligent guys, but you just don't know, rubber. And it's all of all the tips and tricks and techniques that you'll learn over the years. You only get that working in the rubber industry working with materials. It's not something you're going to pick up out of a textbook.
Bill Sharratt 27:58
Yeah, when I when I started my mentor in the industry, he said it. I need I need to know you're going to be with us for five years, because it's going to take at least two years to get halfway knowledgeable and asking the right questions, let alone with coming up with solutions. So and he was right. And I'm still learning and we see new applications every day that make it a really exciting industry to be in. We get to look at every technology out there. It's super. I know we're kind of running out of time a little bit but I like to say talking to you know the depth of knowledge that's built up. We kind of stand on the shoulders of giants in this industry. Who gave you your best advice? What was it and does it still? Does it still ring true today?
Darron Peddle 28:57
I think probably Len Barnes. I'm sure you know when I know him. Yeah. And Len was in the rubber industry for years and years. I'm not sure if he's retired yet. I haven't spoken to him in quite a while. But he was a mentor to me for sure. And I don't know if there's any one thing that stands up my mind as as advice but the way he treated people was probably I mean that really stuck in my mind. They use the Southern gentleman for sure. Really, really enjoyed working with dignity and respect. Yeah. Excellent. It is.
Bill Sharratt 29:47
Talking about brain drain the rubber industry lost a great brain when you moved on but you moved out into the medical device field. How was that transition? What could you take with you From the rubber industry, and in terms of your approach, and style, and management, and so on, congratulations on making the jump and even got a lot out of it. How's it been?
Darron Peddle 30:11
It's been excellent. I've been fortunate to be involved with some really cool product developments and actually launch some stuff some things, which is not easy to do all the time in medical device career, because some of the products do take quite a long time. From, from concept to product launch. I joined DePuy Synthes in 2012, as project manager, and the reason I joined as a project manager and not a product engineer, was I recognized that I had a lot to learn about that product line before I started, you know, getting my hands into any kind of product development.
Bill Sharratt 30:55
We're talking orthopedics . Yeah, joints and so on.
Darron Peddle 31:00
Yet, specifically hip implants. Okay. And we ended up launching one of the most successful, hip femoral implants in the history of the company. Fastest Growing. I'm not sure it's number one in sales, but I believe it is in the US. So, and it's clinically superior, proven clinically superior to what's what's out there now today. So that's pretty weird as well. Normally you get clinically equal to, but apparently, what I'm what I'm hearing, not firsthand, because I'm not with DePuy anymore, but when I hear is it's actually been proven superior. So it was pretty exciting to be involved with that project.
Bill Sharratt 31:49
Yeah, something, something that goes on to impact people's lives in a positive way. And it's got your fingerprints on it. And he said to you, and that that's fantastic. Congratulations.
Darron Peddle 32:01
Thank you. And,
Bill Sharratt 32:03
and then you move ultimately, to where you're at now is WishBone
Darron Peddle 32:09
WishBone Medical,
Bill Sharratt 32:10
which is more of a I guess addresses specific sizing for orthopedic stuff, right?
Darron Peddle 32:18
As it's pediatric orthopedics. Okay, so you were saying before how, you get to impact people's lives with medical devices. It's absolutely true. With WishBone, we're actually able to impact kids lives. And it's it's even more that much more rewarding. Right? I think that the energy in the building every day is just phenomenal, because people are there not because they have to be there. They they're there because they want to help kids. It's just an amazing environment to work in. Fantastic.
Bill Sharratt 32:51
Congratulations. I'm delighted that you're you're getting so much out of it and continue to make an impact. So hats off to you, sir. Well, then. Good. This has been a great chat. I would. Would you like to shout out how to contact you. Is there anything that your current position that that would benefit from some exposure?
Darron Peddle 33:17
Yeah, absolutely. WishBone is growing. I'm not a spokesman for the company. This is completely me making these statements. But there are openings available. We're actively recruiting for people. So WishBonemedicalemployee.com medical I think I've been with the company, four months now. So don't slam me too hard for the website address. But yeah, if there's there's some great engineering opportunities there, as well as others. So anybody watching is interested, please apply. Fantastic.
Bill Sharratt 33:55
All right. Well, thanks again for your time. Darron, we'll wrap here and again, thank you for making a difference. And thank you for making such an impact and contribution to the rubber industry. Appreciate it. Thanks very much.
Outro 34:12
Thanks for listening to the Makers of Our Future Podcast. Behind every great product is a great seal. Learn more about how we can help at www.darcoid.com That's darcoid.com. The best seal on time zero defects darcoid
You need to get your best product designed, validated, specified, ramped and released. We’ve got your back, from concept through zero defect supply programs. It starts with understanding what you need the seal to do. We’re ready to get started.
