Nexa3D/Wilson Sporting Goods
The ball game. Peanuts and Cracker Jack. The Great American Pastime. Baseball has been an integral part of American culture for over a century.
In Major League Baseball (MLB), the manufacturing process for bats has largely stayed the same since the late 1870s, but the design has changed numerous times, with the first major change coming in 1885 when a rule was introduced that allowed a flat side to the bats. This rule was later rescinded in 1893.
The first metal baseball bat was patented by William Shroyer in 1924, but would bend and dent if solid contact was made. Aluminium bats were not effective enough for mass production until 1970. In fact, MLB has never used metal bats, despite their popularity in lower levels of the sport such as Little League and college baseball, and still requires all MLB players to use wooden bats.
In 2023, however, Nexa3D and Wilson Sporting Goods are collaborating to bring further innovation to the baseball bat using additive manufacturing (AM). Wilson's R&D team, which recently caused a stir with its 3D printed airless basketball prototype, was seeking a more effective means to produce tooling for plastic injection mould prototypes, historically made with subtractive manufacturing technologies.
With a large print envelope and ultrafast LSPc process offered by Nexa3D’s NXE400 system, Wilson says it can now create a prototype in one working day, a process which could have previously taken months, and produce multiple design iterations in a single print batch. Wilson says the benefit of using 3D printing is that its R&D team can “afford to be wrong.”
Nexa3D/Wilson Sporting Goods
In baseball, the part of the bat that hits the ball, the barrel, is a tube, normally manufactured from a metal, or sometimes a composite such as carbon fibre. The handle is manufactured with a different material. According to Wilson, this is to tune the performance and feel of the bat. The plastic pieces of the bat include the end cap, a knob, a separate handle piece that goes inside the tube, and some internal technology to manage the performance. Some cosmetic elements, such as a grip that goes on the bat, can also be plastic.
Director of Advanced Manufacturing at Wilson Sporting Goods Glen Mason said: “It’s really interesting seeing the variety of technology that’s out there. And players have a preference, right? Because we do a lot of moulded parts, and we’re in a very high mix, low volume environment, meaning we might make millions of parts a year, but its thousands of this and hundreds of this and then 5,000 of this. We can tune each one of those components for the player. So, even though the bat that the college players are swinging and the 12-year-old players are swinging look very similar, and may even be branded similarly, they’re actually more than just a shorter version of the adult bat. We have tuned it specifically for that player to make it the best possible experience for them, and plastics allow us to do that.”
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Mason told TCT that he doesn’t ever see wooden bats disappearing from MLB, partly due to baseball being a very traditional sport, but also due to the fact that the implementation of metal bats in MLB would change the game “significantly.” Mason added: “It would be easy to make a bat that hit the ball over the fence every time, that would not be the challenge. The challenge is making the game more fair, making more parity across the game.”
The standard in 2023 for the coefficient of restitution of a baseball bat is 0.5. Coefficient of restitution is the ratio of final velocity to the initial velocity between two objects after collision, or more simply put, the percentage of speed a ball retains after hitting another object, such as a basketball hitting the ground, a tennis ball hitting a tennis racquet, or a baseball hitting a baseball bat.
Collisions in which there is no loss of overall kinetic energy is known as a “perfectly elastic collision". This collision has the maximum coefficient of restitution of e = 1. Collision where maximum kinetic energy is lost, is known as a “perfectly inelastic collision”, and has a coefficient of restitution of e = 0. If a ball was dropped from 10ft, and bounced back to 5ft, that would be a 50% coefficient of restitution, so would be measured as 0.5. Every baseball bat in the MLB has a stamp stating that it is BBCOR certified, meaning that the ball bar coefficient of restitution is 50%.
Mason told TCT: “Every manufacturer has to be at 50%. There’s no opportunity to be better, except there’s so much more to a bat than the energy. There’s the experience for the player, the way that the ball interacts with the bat, adding spin to the ball etc. If you’re hitting the ball faster or slower, you can have a different performance.
“We have a box, we have to play inside the box, but there’s a lot of room there, and I feel like its actually more than we even know because it’s constrained by the cost of tooling. Why don’t we have thousands of different models out there? Because they’re expensive to produce. If we really can zero in on these opportunities faster at lower costs, and can really identify some competitive advantage, which we’ve been doing since 1987 when DiMarini started, and we’re still doing it. This [3D printing] is just one tool along the way, but I’m personally really excited because in this advanced manufacturing role this is something I want to take advantage of.”
Nexa3D/Wilson Sporting Goods
When Wilson first began using AM, it was to complement the use of injection moulding, with the brand liking the combination of the ease and the digital workflow of 3D printing, while still having access to the injection moulding feedstock that a lot of data had been built around.
Mason said: “In the early days I said, 'okay, this is just going to get me to digital tooling right? To faster moulds?' That was my walk in the door. I then realised quickly that it was far more than that because we have a different type of workflow where we can go from a CAD design to a moulded part with relatively low inputs. The time is so low that even if it just has the remote chance of being successful, why don’t we just try that? What’s the downside, right? We’re investing hundreds of dollars, and days, versus tens of thousands of dollars and potentially months. So, as the cost drops and the speed drops, all of a sudden, we are able to explore things that we weren’t able to look at before. So, initially, it was all about getting to a faster mould and now I’m realising it’s really more about a better workflow.”
Lasse Staal, Director of Business Development at Nexa3D told TCT: “I think what we’ve done in collaboration with Wilson is that the performance achievable with 3D printing has taken a leap forward. I’ve also been in touch with people interested in golf, and we’ve been making stuff for athletes in the Paralympics. One of the prohibitive costs associated with injection moulding used to be the tooling. To help people understand what is now possible, we need forward looking companies like Wilson who are able to and willing to take a chance with the technology. It may be only a little thing we are changing with this approach, but it does a world of difference to the workflow.
“What injection moulding is, first and foremost, is an incredible amount of tried and true materials that have been available for many years. It’s a lot of highly skilled suppliers who are used to working with those materials. We are on a mission to connect those manufacturers with a novel way of using injection moulding. I think the Wilson case is so powerful because it highlights exactly that. We are now changing the frame around injection moulding, moving it from having been a high volume to becoming a batch of one technology. With AM as the enabler, lets call it.”
