Generation 2

The full use of thermoforming defines the Generation 2 paddle. The Legacy Pro paddle was the first to be approved on September 20, 2022. In this section, we will cover how Generation 2 paddles are made, as well as one of the biggest pickleball controversies that happened as a result.

Thermoforming

The term thermoforming has been popularized by the pickleball paddle industry to generally refer to the manufacturing process of Generation 2 paddles. But in fact, thermoforming technically only includes processes where a plastic is heated up and formed into a desired shape. The foamed edge from Generation 1.5, which Generation 2 paddles also use, is thus thermoformed. More accurately, the manufacturing process that creates a Generation 2 paddle is hot press molding. All RCF paddles use hot press molding in their facesheet fabrication, Generation 1.5 paddles use hot press molding a second time for the foamed edge, but only Generation 2 paddles use hot press molding for the entire process. However, hot press molding is not unique to pickleball paddle fabrication; it has been a standard composite material manufacturing process for many decades. 

Generation 2 paddles largely use the same materials and structure as previous generation paddles. However, because each paddle is thermoformed, the facesheets and PP honeycomb core are first separately cut into paddle shapes. This contrasts with the previous generations’ method of using epoxy glue to fully attach entire 500 mm x 600 mm sheets together before cutting into paddle blanks. Then, as shown in Figure 6, the facesheets and PP honeycomb core are attached together in a three-layer structure. A carbon seam foam edge is then placed around the edge. 

Figure 6. Lay-up of facesheets and PP honeycomb core into three-layer structure.

Finally, this entire structure is placed into a mold (Figure 7), which is then placed into the hot press molding machine. The thermoforming process bonds the paddle layers together and forms the Generation 2 paddle. The application of heat and pressure during the thermoforming process enables the epoxy resin to flow and fully disperse between all layers of the paddle (facesheets, PP honeycomb core, carbon seam foam edge). This creates a unibody paddle that is significantly stronger than before. Figure 8 shows how the resulting edge is fully attached to the body of the paddle.

Figure 7. Thermoforming mold. Paddles are placed into the lower half of the mold before the top half of the mold is closed.

Figure 8. Generation 2 paddle after the thermoforming process. The carbon seam edge is fully attached to the rest of the paddle, creating a unibody structure.

Delamination, Disbonding, and Crushed Core

Generation 2 paddles were incredibly popular soon after their release. However, a few months in, many players started noticing an abnormal popping sound and high levels of power in these paddles. After cutting the paddles open, it was revealed that these paddles had lost their structural integrity. This problem has come to be known as a combination of the phrases delamination, disbonding, and crushed core. Chris Olson from Pickleball Studio has examined the issue, as has JohnKew Pickleball. 

First, we define what each of the three terms mean. Delamination refers to the issue of the carbon fiber plies coming apart in the facesheet. Disbonding refers to the issue of the separation of the facesheet from the PP honeycomb core. Crushed core refers to the issue of the PP honeycomb core being crushed and losing its structural integrity. Although the three are often used interchangeably, delamination itself is quite rare. Disbonding and crushed core are far more common.

The root cause behind the problem lies in the structure of the Generation 2 paddle and its thermoforming fabrication process. Although the PP honeycomb core looks perfectly flat and smooth to the naked eye, there are unavoidable variations in the thickness of the core at the microscopic level. This results in space for air in between the facesheet and the PP honeycomb core. Furthermore, the carbon seam foamed edge around the paddle creates a fully enclosed unibody structure. With the use of high temperatures and pressures, the air from the imperfection in the PP honeycomb core expands and creates intense internal pressure. Thus, parts of the PP honeycomb core could be crushed. After a certain amount of play, the constant force of the ball hitting the paddle leads to more areas of the core being crushed (Figure 9). The increased power players experience when using such a paddle can be explained by these unintentionally created pockets. Rather than the ball coming into contact with a solid paddle surface, the crushed core paddle’s pockets create a trampoline effect. 

Figure 9. Comparison of a regular PP honeycomb core with a crushed core. (source)