1. Introduction
Recently, there has been a lot of sales and marketing pushing the K-count of the face carbon as the main selling proposition for a racket. Rackets are advertised as 3k, 12k or 24k carbon fiber layups. The K-count terminology refers to the number of carbon filament strands in each carbon fiber. All manner of claims are made in the name of K-count, but when all is said and done, K-count has little direct influence on racket performance. It may give you a clue as to what performance is intended from a racket, but whether that is achieved or not can only be ascertained by measuring the actual property of the racket. The ingredients and the recipe are the means to an end, not the end itself. The choice of a K-count is more of a production process decision than a performance decision. Further, the bundling of filaments is only one small step in a complex carbon fiber production process. We will examine the entire process and K-count's role in it.
2. Filament, Fiber, Tow Production
K-count describes the number of carbon filaments bundled into a fiber, also known as a "tow."
- 3K = 3,000 filaments
- 12K = 12,000 filaments
- 24K = 24,000 filaments
But where do the filaments and tows come from? It all begins with a plastic called PAN (polyacrylonitrile), which is composed of carbon, hydrogen, and nitrogen atoms. The PAN is first dissolved or melted at approximately 100–350 °C, then extruded through a metal plate called a spinneret, which contains thousands of holes (e.g., 3K to 24K) roughly 5–25 microns in diameter. As the PAN exits the spinneret, it forms fine filaments that enter a 20–60 °C coagulation bath of water and solvents, where they solidify. These filaments are immediately bundled into a tow, then washed to remove residual solvents, stretched to align the polymer chains, dried, and wound onto spools.
To convert these polymer tows into carbon fiber, they undergo carbonization, where the PAN is heated to 1000–1600 °C in an inert (usually nitrogen) atmosphere. This process removes the non-carbon elements, leaving behind a fiber composed of 90–95% carbon with a disordered, graphite-like structure. For applications requiring extreme stiffness, an additional step called graphitization heats the fiber to 2500–3000 °C, which rearranges the carbon atoms into more perfect graphitic planes, resulting in 99–99.9% pure carbon. However, graphitized fibers are more brittle and far more expensive, so most sporting goods use carbonized (not graphitized) fiber.
3. From Tows To Fabric
Creating carbon tows is just the beginning. The tows must be assembled into unidirectional (UD) or woven sheets. The process begins with the rolled tow spools (bobbins). Depending on tow size (3K to 24K), the fiber length per bobbin can be from 5,000 to 100,000 meters, higher K-counts being shorter. These bobbins can weigh 3-20 kg (7-44 lbs) depending on fiber count.
Making UD sheets: A typical UD sheet is 1 meter wide and each tow is about 1mm (3K) to 2 mm (24K) wide. So, 500 - 1000 bobbins are required to cover the area. A wall of bobbins (a creel) is stacked vertically and horizontally and fibers are pulled over spreader bars, channeling and aligning them under constant and equal tension. For prepreg manufacture, which is predominately used in rackets, the target for these fibers is a moving conveyor belt carrying a release sheet with a thin film of partially cured resin. The tows are pulled and laid down on the resin film in perfectly parallel rows across the width. The ratio by weight of fiber to resin is about 35%. Pressure and mild heat is applied via rollers to spread the resin in and around the fibers to fully impregnate them (known as hot melt impregnation process). A second sheet of release film is laid on top to sandwich the fibers and resin and protect the sheets for handling, cutting, and rolling. The sheet is pulled and rolled onto large spools under controlled tension to avoid wrinkles and then stored in cold storage at around -18°C (0°F) to prevent premature curing. The finished roll is usually about 100 meters long.
Finally, in the factory where the sheet will be used, the UD rolls are unrolled, cut, stacked, and laid into molds, where heat and pressure is applied causing the resin to melt, flow, and fully surround the fibers, locking them into the final composite structure.
Making woven sheets: Preparing sheets of woven fabric is much more complicated. Just as with UD sheets, the process begins with carbon tow spools. In this case, there are two groups of spools — the warp tows (lenthwise fibers that stay stationary and in tension), and the weft tows (crosswise tows inserted row-by-row).
The warp tows are loaded onto a giant roller called a warp bean and then threaded through loops, called "heddles", mounted on vertical wires that will control whether that tow is lifted or lowered during weaving. Tows are also threaded through a comb-like guide, called a "reed", which spaces and packs down the weft.
The heddles are lifted or lowered to create space between warp tows known as the "shed". For a plain weave, the first row will be odd tows up and even tows down. Each row after that will be reversed. A weft tow is inserted into the shed and is pulled through. The reed then moves against the inserted weft tow to pack it against the previous row.
The finished fabric is drawn forward onto a take-up roll. The loom then advances the warp and sets up the next shed, and the process repeats, row-by-row. The finished fabric sheet is, unlike the UD sheet, rolled dry for later resin application.
As opposed to inline impregnation for UD production, impregnation of woven fabrics occurs in a separate hot melt process. Dry weaves are unrolled and then pulled through the impregnation line. Resin is applied in the form of thin resin films, which are laid on one or both sides of the fiber sheet to create a sandwich. This sandwich passes through heated nip rollers, which melt the resin and press it into the fiber network, evenly distributing and impregnating it around the fibers.
Once saturated, release sheets are laminated to the top and bottom surfaces to protect the prepreg and prevent sticking. The resulting prepreg sheet is then cooled and wound into rolls. These rolls are stored cold (to delay curing) and later cut into plies and laid-up according to the desired stacking sequence for the final product.
Weave types. Many weave types are created by this process, among them are plain, twill, satin, basket, spread tow, and others. Table 1 shows the structure and properties of common weave types.
| Table 1 Common Weaves | ||
|---|---|---|
| Weave Type | Structure | Properties |
| Plain Weave | Over 1, under 1 |
Tight, strong, less flexible |
| Twill Weave | Over 2, under 2 (diagonal) |
Smoother surface, better drape |
| Satin Weave | Over 4-8, under 1 |
Very smooth, best drape, less stability |
| Basket Weave | 2x2 or 4x4 over/under |
Uniform, good impact resistance |
| Spread Tow | Ultra-flat, minimal crimp |
Lightest, highest performance |
| Biaxial (Stitched) | 0°/+45° stitched |
Low crimp, easy formability |
| Triaxial | Three directions (0°, +60°, -60° |
Omnidirectional strength |
| Quadraxial | Four directions (0°, 90°, +45°, -45°) |
High stiffness and impact resistance |
Table 1 — Weave Types.
Not all tows are appropriate for all weaves. In theory, it can be done, but in practice certain weaves are better for certain K-counts. High-K tows are bulkier and harder to twist and bend tightly, while fine tows are more pliable and better for tight, crimped weaves. Therefore, usually only the outer surface layer is woven, typically with 3K or 12K fabric, and all inner layers will be larger unidirectional tow plies arranged at specific angles.
The hierarchy of material is filament to tow to fabric (Table 2).
| Table 2 Filament vs Tow vs Fabric | ||
|---|---|---|
| Term | What it is | Notes |
| Filament | A single carbon strand (5-7 microns wide) |
Very strong, very thin |
| Tow | A bundle of filaments |
Can be woven or laid up |
| Fabric | A woven sheet of tows |
Like 3k carbon fabric or 12k biaxial weave |
Table 2 — Filament vs Tow vs Fabric.
Choosing a fiber count fabric. From a manufacturing point of view, many factors are involved in choosing a fiber count (Table 3). The manufacturing choices don't necessarily dictate the racket face performance since it is more important how the tows are used instead of which tows are used, though tow type, in part, dictates its potential uses.
| Table 3 Considerations in Choosing Fiber Count | |||
|---|---|---|---|
| Category | 3K Fabric | 12K Fabric | 24K Fabric |
| Fiber cost (per kg) | Highest: fine tow, premium grade | Medium: common for sporting goods | Lower: industrial grade, bulk tow |
| Fiber volume (per area) | Less per ply, requires more layers | Moderate per ply | High: thick, fewer layers needed |
| Weaving complexity | High, many tows, tight weave | Moderate: balanced thread count | Low: fewer thick tows |
| Weaving labor time | High: more pick count, tight tension | Medium: manageable | Low: wide spacing, fast throughput |
| Layup flexibility | Excellent: can tune fiber angle, thickness precisely | Moderate | Limited: thick layers reduce design control |
| Ply count needed | High: must stack many plies | Fewer plys | Very low: 2-3 layers may suffice |
| Resin distribution | Better: even wet-out, less pooling | Average | Worse: resin pockets between large tows |
| Control forming over curves | Excellent: drapable, tight corners | Adequate | Poor: bridging and wrinkling likely |
| Waste during layup | Higher risk: many layers to trim | Moderate | Lower risk: fewer plies to manage |
| Typical cost per m2 (fabric only) | $40-$60 | $25-$35 | $15-$25 |
Table 3 — Key takeaways:
- 3K = High precision, excellent formability, high cost due to fine structure and high ply count. Best for fine-tuned performance.
- 12K = Middle ground — moderate cost, moderate stiffness, widely used in quality sport frames.
- 24K = Lowest cost, coarser structure, fewer plies needed. Best for fast layups and budget-friendly power-focused builds, but limited in design flexibility.
The cost of using various K-count tows is driven by both processing and, to a lesser extent, carbon quantity, as shown in Table 4.
| Table 4 Cost of Tow Choice | ||
|---|---|---|
| Cost Factor | 3K Tow | 24K Tow |
| Spinning and drawing precision | High (fine control) | Lower |
| Surface treatment and sizing | Slower, more uniform | Faster, bulk-applied |
| Weaving/draping complexity | More layers | Fewer simpler plies |
| Layup flexibility | Higher | Lower |
| Processing yield per kg | Lower | Higher |
Table 4 — Tow cost factors. With 3K tows you need many tows across the width, tightly woven. 24K requires fewer tows = less weaving time and loom complexity. So, 3K = more weaving, more stitching, more handling. 24K = fewer passes, thicker plies, faster throughput. 3K is premium and is engineered for precision. 24K isn't worse, it is just optimized for mass productions with less flexibility.
K-counts are often used in combination on a racket. Each K-count offers different processing and performance advantages depending on location (face vs edge vs handle), function (stiffness, durability, feel), forming difficulty (tight radius, curved edge, flat zone). The flat face outer layer is often 3K because of its better drape, surface finish, and feel. The inner face layers may be 12K or 24K for bulk stiffness with fewer plies and cost. The edge is usually +/-45° 12K or 24K for torsional stability and durability. Heavier K-counts usually go deeper in the laminate to avoid surface roughness. So, what is meant by a 3K, 12K, or 24K racket? Usually, unless otherwise specified with a full layup map, a K-specific racket is usually marketing shorthand for the most visible layer, not the entire stack.
4. Material Properties and Parameters
Beyond K-count, rackets are often marketed according to the specific fiber properties. In other words, what is the quality of carbon used and then bundled into fiber tows? Material properties and structural parameters are often mistakenly lumped under the "property" banner, but they are not the same. A property describes an intrinsic capability. A structural parameter refers to how a material is arranged or used. When speaking of carbon fiber, the properties most commonly referenced are stiffness (modulus) and strength. Associated structural parameters are fiber areal weight (FW) and fiber volume (Fv). We will examine each in turn.
Stiffness (Modulus)
Modulus is a measure of how stiff a fiber is, whereas K-count is how many of those fibers are in a bundle. Modulus, a.k.a. "Young's Modulus" or "modulus of elasticity", is a measure of tensile or compressive stiffness and is given by E = σ / ε where σ is stress (force per unit of area) and ε is strain (Δlength/length). It is measured in Pascals (Pa) or gigapascals (GPa, i.e., 109) for carbon or steel (Table 5).
| Table 5 Example Values of Young's Modulus | |
|---|---|
| Material | Approximate Young's Modulus E |
| Steel | 200 GPa |
| Carbon fiber (UD) (embedded in resin matrix) | 230-500 GPa (depends on grade) |
| Aluminum | 69 GPa |
| Fiberglass | 30-50 GPa |
| Epoxy resin | 2-5 GPa |
| EVA foam | 1-10 MPa |
| Human hair | 5 Gpa |
| Rubber | 0.01-0.1 GPa |
Table 5 — Comparative examples of Young's modulus.
Modulus has often been used to differentiate rackets (especially tennis racquets). Different grades of carbon fiber have different moduli (Table 6).
| Table 6 Modulus Grades of Carbon Fiber | ||
|---|---|---|
| Grade | Approx. Young's Modulus E | Description |
| Standard (SM) | 230-250 GPa | Most common; good stiffness, cost effective |
| Intermediate (IM) | 280-350 GPa | More stiffness, slightly more brittle |
| High (HM) | 350-450 GPa+ | Very stiff, lower elongation, expensive |
| Ultra High | 450-550 GPa+ | Rare, highly specialized, very brittle |
Table 6 — Comparative modulus grades of carbon fiber. The higher the grade, the stiffer, more expensive, and more brittle the fiber becomes.
Each grade will have characteristic properties besides stiffness. Table 7 shows a summary of properties associated with grades.
| Table 7: Grades and Properties | |||||
|---|---|---|---|---|---|
| Grade | Stiffness | Strength | Elongation | Cost | Brittleness |
| SM | Moderate | High | High | Low | Low |
| IM | High | Moderate | Moderate | Medium | Medium |
| HM | Very high | Lower | Low | High | High |
Table 7 — Comparative material properties by carbon fiber modulus grade.
Strength
In common usage, strength is usually referred to in its singular description as "tensile strength." This is the stress under which a material fails under pulling. There are other important strengths associated with rackets:
- Tensile: Stress at which a material fails under pulling
- Compressive: Stress at failure when material is pushed/squashed
- Shear: Stress at failure when layers slide past one another
- Flexural (bending): Maximum stress in bending before failure
- Impact (toughness): Ability to absorb energy and resist fracture during a sudden load
- Fatigue: Maximum stress a material can withstand for a given number of cycles before failure
- Torsional: Resistance to twisting failure
Although tensile strength is usually emphasized, all of these are important, and some are achieved or optimized at the expense of others. In the racket face, the main strengths are tensile and flexural. In the core, compressive and shear strength are most important. And the shear strength of the resin must be adequate to prevent delamination, both beween carbon layers and face and core. Failures, like face cracking or delamination, can occur because of a singular strength inadequacy, but usually will be due to a combination strength-type failures.
The headline "Made With High Modulus, High Strength Fibers", can hide the reality of how they are used and how that manifest in the final product. Modulus and strength numbers are of the raw, non-impregnated, carbon fibers. When you layup a racket, at every step the stiffness and strength of the carbon gets diluted when considering the racket as a whole. When engineers specify material, they start with fiber modulus but must work down to what actually matters: the final structure’s effective stiffness and strength. Table 8 shows how the effective strengths decay from raw material to finished product. These are all ball-park figures.
| Table 8: Strength Properties: From Fiber to Final Structure | |||||
|---|---|---|---|---|---|
| Structure | Tensile MPa |
Shear MPa |
Bending MPa |
Compressive MPa |
Notes MPa |
| Pure carbon fiber filament | 3,000–6,000 | N/A (fiber doesn’t shear internally) | N/A (single filament) | 1,000–2,500 | Filament is strong in tension, lower in compression (risk of buckling) |
| UD carbon-epoxy ply | 800–1,500 | ~60–100 | ~800–1,200 | ~500–1,000 | Shear = interlaminar matrix shear; tensile strength lowered by matrix |
| Woven carbon-epoxy ply | 500–1,000 | ~40–80 | ~500–900 | ~400–800 | Crimp reduces tensile, bending; matrix and angle reduce effective strength |
| Multi-angle layup (e.g. 0/90/±45) | 300–700 | ~30–70 | ~300–800 | ~300–600 | Off-axis plies dilute axial properties; better balance for shear and torsion |
| Final structure (e.g. racket face) | 100–400 effective | ~20–50 | ~200–500 | ~200–400 | Core and interfaces dominate; local failures often matrix- or bond-driven |
Table 8 — Decay in fiber strength properties from fiber to racket. The process diminishes the fiber strength but you gain other benefits in the process, like balance, toughness, and manufacturability. Even with the strength diminishment, failure usually starts in the matrix of along bondlines, not in the fibers themselves.
So, bottom line, when you see a big sign post number for modulus or strength, it doesn't really tell you much.
Fiber Areal Weight (FAW)
Fiber Areal Weight (FAW), expressed in grams per square meter (g/m2), measures the mass of dry fibers per unit area in a single ply. It is a critical parameter in composite design because it directly influences the thickness, weight, and stiffness of the laminate.
FAW is not a mechanical property but simply an expression of the quantity of material per unit area. It is a geometric/material quantity, similar to tows being a numerical fiber count, not a mechanical property. Each K-count has a typical FAW range. For example, a 3K plain weave has a typical FAW range of 180-220 g/m2 and a 12K twill weave about 300-450 g/m2. Unidirectional prepreg has a range of 100-300 g/m2. FAW is important in:
- Weight Control: Lower FAW (e.g., 100 g/m2 for 3K tow) allows finer ply stacking for thin, lightweight structures (e.g., padel racket faces). Higher FAW (e.g., 400 g/m2 for 24K tow) reduces ply counts but may compromise drapability.
- Thickness Prediction: FAW and fiber density determine ply thickness. For example, a 200 g/m2 ply at 60% fiber volume fraction with 1.78 g/cm3 fibers is approximately 0.19 mm thick.
- Manufacturing Efficiency: Thick tows (high FAW) speed up layup but risk resin-rich zones or dry spots.
Fiber Volume Fraction (Fv)
Fiber Volume Fraction (Fv) is the ratio of fiber volume to total composite volume, typically expressed as a percentage. The pre-cure target is usually 50–60%, depending on expected resin flow, compaction, and void content arising during cure. The theoretical maximum Fv is 78%. The pre-cure targets are also chosen based on tow K-count and on stiffness, weight, and strength goals. A 3K tow generally has greater resin content (35-45% by weight) than a 24K tow (30-40%). Odd, but true. A 3K tow has fewer fibers, less densely packed, more space between filaments, and thus more exposed surface area per tow. The filaments in a densely packed 24K tow shield each other and offer less surface area. Assuming 8 x 3K tows = 1 x 24K tow, it is obvious how this fiber resin wet-out is greater for 3K. As a result, and contrary to how it is commonly understood, 24K ends up with a higher fiber volume fraction, which one would think leads to more stiffness and strength. But the 3K more than makes up for it by better fiber-to-fiber stress transfer via the resin matrix, and also by being more flexible in use, optimizing layout layers and angles. The end result is greater effective stiffness and strength for the lower-Fv 3K compared to the higher-Fv 24K.
- Mechanical Performance: Higher Fv increases stiffness and strength (fibers carry most loads) but reduces impact resistance (less resin to absorb energy).
- Weight Efficiency: Maximizing Fv minimizes resin "dead weight," crucial for lightweight designs.
- Manufacturing Limits: Beyond ~60% Fv, resin cannot fully wet fibers, causing voids.
Fiber volume fraction is a post-cure measurement. This is because during curing, 5-15% of the resin is squeezed out. To make a measurement, the racket must be destroyed. A small cross-sectional sample size is cut from the face. It is heated or dissolved using acid to completely remove the resin. The remaining fiber mass is measured, divided by fiber density of 1.78 g/cm3, all divided by original sample volume.
5. Design and Layup Strategies
Choosing material, grade, and tow size is only the beginning. How fiber plies are layered (stacking strategy) ultimately defines how a racket flexes, twists, and rebounds. A typical face uses 6–12 plies of carbon fiber (often 3K, 12K, or 18K weaves), with the majority (60–80%) aligned at 0° (parallel to the face plane) to ensure consistent rebound and stiffness. ±45° fibers (20–30%) are interspersed to enhance torsional stability and spin generation, while a minimal 90° component (0–10%) may be added for shear resistance. Higher K-counts (e.g., 12K) improve impact resistance and reduce weight, while tighter weaves (e.g., 3K) offer finer surface control. The outer ply often features a toughened finish (e.g., textured carbon or protective coatings) to resist abrasion. Layup symmetry is critical—asymmetric designs risk unpredictable flex, while balanced constructions (e.g., 0°/±45° hybrid) ensure uniform response across the face. Advanced frames may integrate graded stiffness zones (softer edges, stiffer center) by varying ply angles or resin density.
Case Study: We want to build a 40 g, 1.5 mm, 256 cm2 face. Further we want to compare 3K, 12K, 24K tow layups. To do so, assume that we are given the following material and construction goals:
Design Goals & Assumptions
- Thickness = 1.5 mm
- Mass = 40–45 g (assume racket face area ≈ 0.025 m2, typical for paddles).
- Areal density = 40–45 g / 0.025 m2 = 1600–1800 g/m2 total.
Material Characteristics:
- Fiber density (ρf) = 1.78 g/cm3
- Resin density (ρr) ≈ 1.2 g/cm3 (epoxy)
- Fiber volume fraction (Fv) = 55–60%.
Tow Specs:
| Table 9: Tow-Specific FAW & Ply Thickness | ||
|---|---|---|
| Tow Size | Typical FAW (g/m2) | Ply Thickness (mm) |
| 3K | 100-125 | 0.01-0.12 |
| 12K | 200-250 | 0.20-0.25 |
| 24K | 350-400 | 0.35-0.40 |
Table 9 — Tow-Specific FAW & Ply Thickness
Given these design properties and specifications, possible layup configurations for each tow size appear in Table 10.
Laminate Design for Each Tow Size
| Table 10: Racket Face Layup Hypotheticals | |||||||
|---|---|---|---|---|---|---|---|
| Tow Size | Ply Thickness (mm) | # of Plies | FAW (g/m2 | Fiber Volume | Modulus/Strength | Thickness (mm) | Weight (g) |
| 3K | 0.12 | 1.5 / 0.12 = 13 | 125 | 60% | T700S (high) | 1.56 | 40.6 |
| 12K | 0.22 | 1.5 / 0.22 = 7 | 230 | 58% | T800 (intermediate) | 1.54 | 40.3 |
| 24K | 0.38 | 1.5 / 0.38 = 4 + 1 3K* | 375 | 55% | T300 (standard) | 1.52 | 40.6 |
Table 10 — Sample 3K, 12K, and 24K layups to achieve goal of 1.5 mm, 40g, 256 cm2 racket face. *Note: 4×24K + 1×3K. The modulus carbon examples are all Toray products.
Three further layup methods are used to fine tune the racket face response, especially near the edges: anchoring, floating, ply drop-offs.
- Anchoring: strong face-to-frame bonding and wrap-around to stiffen the face.
- Floating face: weak bonding to the frame allowing microscopic movement near the frame.
- Ply drop-offs: In a face layup, certain plies (usually middle stack plies) are cut short before the perimeter, adding softness around the periphery.
6. The Frame
The frame layup is not mentioned as often as the face. It too is carbon and usually dominated by +/- 45° and 0° plies for torsionally and compressive stiffness. The frame is usually an oval shaped tube filled with EVA foam. The frame will usually have more plies (~ 12-18) than the face (6-10) for impact resistance and its structural role.
7. Hole Drilling
Ironically, even if you get your layup angles all optimized, then you drill 60 holes in the face and destroy the results of all your efforts. Well, not really, because you plan for this in your layup, as much as you can.
Holes, drilled through the face plates and core, are used to optimize aerodynamics and to control weight and balance. But removing material also reduces strength and stiffness, breaks fiber paths, concentrates stresses, creates crack-inducing edges, and weakens the core.
Total mass lost due to drilling can be estimated. For the face, assuming hole diameter of 10 mm, 60 holes, 0.3 mm thickness, and carbon density (including resin) of 1.5 g/cm3, the for each face would be about 2.1 g or 4.2 g for both. Each face might be an average of 55 g, so total face mass lost is about 4%.
For the core, assuming hole diameter of 10 mm, core thickness of 30 mm, and foam density of 60 kg/m3 (EVA) or 100 kg/m3 (PU), then core weight loss will be 8-14 g, depending on material. So total drilling loss would be about 13-18 g.
Engineers design hole compensations into the layup. Layup is often reoriented around holes, +/- 45° plies or extra plies might be used to carry load between holes. Further, holes are strategically placed to minimize weakening fiber load paths, especially in the center and sides. Holes are often arranged in off-set rows to avoid creating continuous fracture lines. Fine 3K weaves might be used because they hold strength better due to their tighter bundle structure. Also, holes are drilled with radius edged bits to reduce creation of stress fracture points.
In the end, the resulting structure is no longer a clean laminate with uninterrupted load paths, but a fragmented network of fiber “islands” between voids. The more perforated the face, the more the racket behaves like a mesh rather than a plate, especially in bending and torsion. In this disrupted environment, the directional stiffness and theoretical optimization of ply angles lose much of their leverage — especially over longer distances. The face becomes a surface of local stiffness patches, each constrained by the nearby material and foam, but without a continuous pathway to distribute loads broadly across the structure.
As a result, the core — despite being softer — becomes the structural anchor. Its thickness gives it an outsized influence on flexural rigidity, especially under central impacts. According to theory, the bending stiffness of a composite structure scales with the cube of the distance between outer faces (i.e., the thickness). So while carbon fiber face layers are stiff but thin and fragmented, the foam core, being much thicker, dominates in resisting overall flex and rebound deformation. In this sense, even though the core may not feel like a “strong” material, it becomes the real backbone of racket structure once the faces are perforated. The face becomes more of a surface tension modulator and strike interface, while the core and local bonding behavior carry the structural burden. And that raises excellent questions about how meaningful it is to market fiber angle or K-count across a disrupted surface — unless we also account for how the core and perimeter framing are doing most of the structural work.
8. Final Performance Metrics That Matter
At the end of all the design and material choices, only one thing matters: measurable performance. Many separate claims are made about the performance benefits of each ingredient or process in racket design and manufacture, but at the end of the day, all that matters is what the racket does, and we can measure that with metrics such as ACOR, swingweight, twistweight, vibration frequency. These metrics measure how the racket actually performs and feels.
| Table 11 Performance Metrics | |||
|---|---|---|---|
| Metric | Why It Matters | ||
| ACOR | Real measure of energy return, ball speed |
||
| Swingweight | Swing speed, feel, and stability |
||
| Twistweight | Torsional and rotational resistance |
||
| Vibration Frequency | Comfort, feel |
||
| Effective Mass | Plow-through at contact, ball speed |
||
Table 11 — Performance Metrics.
9. Summary Timeline
Table 12 shows the complete timeline of tow processing.
| Table 12: Stage By Stage Carbon Fiber Timeline | ||
|---|---|---|
| Stage | Description | Happens Before/After |
| 1. Polymer Creation (PAN) | PAN fibers are chemically synthesized as long molecular chains | Starting material |
| 2. Spinning (forced through spinnerets) | The PAN is spun into fine filaments (~5–7 μm each) | Happens before tows are formed |
| 3. Tow Formation | Thousands of filaments (e.g., 3k, 12k, 24k) are grouped into bundles — these are your tows | Happens after spinning |
| 4. Stabilization (Oxidation) | Tows are heated in air (~200–300 °C) to stabilize them chemically | Still in tow form |
| 5. Carbonization | Tows are heated in inert gas (~1000–1600 °C) → hydrogen/oxygen removed, forming turbostratic carbon (disordered) | Tows now become carbon fiber |
| 6. (Optional) Graphitization | If higher stiffness is needed, tows are heated again at 2500–3000 °C to create graphitic carbon | Still in tow form — now very stiff, but brittle |
| 7. Surface Treatment & Sizing | Fiber surfaces are chemically treated & coated to improve resin bonding | Final prep for weaving or prepreg |
| 8. Weaving | Carbon tows are woven (or stitched) into fabric (e.g., 3k plain, 12k twill) | After all heat treatment |
| 9. Impregnation (Prepreg) | Fabrics or tows are impregnated with resin to become prepreg material | After weaving (or directly to tows) |
| 10. Layup / Molding / Curing | Prepreg or wet-layup fabrics are layered in molds and cured | Final part creation |
Table 12 — Stage by stage timeline of carbon fiber process.
10. Conclusion
The real story of a padel racket is a story of integration: materials, weaves, plies, cores, resins, and layups blending together into a unified, tuned composite. No single component defines it. Only the finished performance counts. And you can measure the performance. Metrics like ACOR, swingweight, twistweight, plowthrough, effective mass, and vibration frequency all tell you the end result of the ingredients. It is these that tell you about power, control, or comfort. Ultimately, you don't hit the ball with a "K-count." You hit it with a structure — a combination of fiber, resin, core, and layup — that determines rebound, control, vibration, and durability.
Racket core was not discussed in depth in this article. Core material, density, and face coupling is an equally important component in performance, and we will discuss that in a future article.
Acknowledgements
The author acknowledges the use of OpenAI's ChatGPT-4 (June 2025 version) for assistance in text editing, summarization, and concept refinement. All research and theoretical and conceptual development were provided by the author, and final interpretations, analyses, and conclusions were independently developed and verified by the author.