Understanding the fleece sweatshirt manufacturing process is essential for any fashion brand. Walk into any wardrobe around the world, and you are likely to find at least one fleece sweatshirt or hoodie. It is the staple of modern comfort—universally loved for its warmth, softness, and durability. But for fashion brands, sourcing managers, and aspiring designers, simply knowing that people “love fleece” isn’t enough.
The "Black Box" of the Fleece Sweatshirt Manufacturing Process
Most people assume the manufacturing process starts when the fabric is cut on a table. This is a misconception. Based on our analysis of the current market information, most guides only tell you half the story: they either bore you with complex chemical formulas of polyester or skip straight to the sewing machine. This leaves a critical gap in understanding: How does a flat piece of fabric actually become “fleece”?
Why This Guide is Different
This article is your “end-to-end” blueprint. We are going to bridge the gap between the textile mill and the garment factory. Understanding the entire lifecycle—from the raw fiber selection to the mechanical brushing process that creates the fuzz, and finally to the assembly line—is not just academic trivia. It is a business necessity.
By mastering this process, you will learn how to:
- Control Quality: Spot the root causes of common defects like pilling and shrinkage before they ruin your production run.
- Optimize Costs: Understand where the real money goes (fabric vs. labor) to negotiate better prices.
- Innovate: Choose the right specific blends (CVC vs. TC) to fit your brand’s price point and quality standards.
Let’s dismantle the machinery and look inside. Here is how your fleece sweatshirt is really made.
Phase 1: The Foundation – Fleece Fabric Production
Before a single scissor touches the cloth, the “soul” of the sweatshirt—its texture and warmth—is created in the textile mill. Many brands make the mistake of treating fabric sourcing as a generic step. However, since fabric accounts for roughly 60-70% of the total garment cost, understanding this phase is crucial for budget control.
1. Raw Material Selection: The "DNA" of Your Sweatshirt
“Fleece” describes the fabric’s structure, not the fiber itself. While you can make fleece from various materials, the industry standard relies on specific blends to balance comfort, durability, and cost.
- Cotton: Provides breathability, moisture absorption, and a soft “hand-feel”.
- Polyester (PET): Provides strength, colorfastness, and—crucially—the ability to hold the “fluff” structure after brushing.
- Spandex/Elastane: Often added to the ribbing (cuffs/waistband) for stretch and recovery.
Choosing the Right Blend: Most suppliers will offer you acronyms like “CVC” or “TC”. Here is a cheat sheet to help you choose the right blend for your target market:
Blend Type | Composition (Approx.) | Pros | Cons | Best For |
100% Cotton | 100% Cotton | Premium soft feel; Breathable; Hypoallergenic. | Expensive; Prone to shrinkage; Fluff may flatten over time. | High-end streetwear; Luxury basics. |
CVC (Chief Value Cotton) | >50% Cotton (e.g., 60/40) | Best of both worlds: Soft like cotton, durable like poly. | Slightly more expensive than TC. | Mid-to-high range fashion brands. |
TC (Tetoron Cotton) | >50% Polyester (e.g., 35/65) | Very durable; Excellent color holding; Cheaper; Resists wrinkling. | Less breathable; Can feel “synthetic” or plastic-like. | Uniforms; Promotional merch; Budget lines. |
100% Polyester | 100% Polyester | Extremely warm; Moisture-wicking; Lightweight. | Traps odors; High static electricity; Pilling risk. | Performance/Sportswear. |
2. Knitting the Base Fabric
Once the yarn is spun, it is fed into Circular Knitting Machines. Unlike a standard t-shirt jersey, fleece is knitted using a technique often called “Plating” or “Two-End Knitting”.
- Face Yarn: This creates the smooth, vertical “V” shapes you see on the outside of a sweatshirt. It provides the structure and printing surface.
- Back Yarn (Loop Yarn): This yarn is knitted loosely to create distinct loops (Terry loops) on the inside. Crucially, these loops are the raw material for the fleece texture.
3. The "Magic" Step: Brushing & Napping
This is the step that transforms a “Terry” fabric into “Fleece.” It is a mechanical violence that creates softness.
How it works:
- Brushing: The fabric is run through a machine equipped with rotating cylinders covered in fine metal wires (resembling a pet brush).
- Loop Breaking: These wires physically catch and pull the “Back Yarn” loops we created in the knitting stage. The wires break the loops and pull the fibers upward.
- The Result: This process creates a thick layer of fuzzy, chaotic fibers.
Why does this make it warm? (The Physics) It’s not just about feeling soft. The chaotic, raised fibers create millions of tiny air pockets. These pockets trap your body heat and prevent it from escaping. This is why a brushed fleece sweatshirt is significantly warmer than an unbrushed French Terry sweatshirt of the same weight.
The Finishing Touches:
- Shearing: After brushing, the fuzz is uneven. A shearing machine cuts the raised fibers to a uniform height, creating that velvety, premium look.
- Anti-Pilling Treatment: To stop those broken fibers from tangling into annoying balls (pills), the fabric often undergoes a chemical wash or a “singeing” process (burning off loose microscopic hairs).
Phase 2: The Transformation – Garment Manufacturing Process
Once the fleece fabric is finished and passes the initial quality check, it moves to the garment factory. This is where engineering meets art. While many assume this phase is just “sewing pieces together,” for fleece sweatshirts, the challenge lies in managing the fabric’s thickness and elasticity without causing distortion.
1. Pattern Making & Grading (The Blueprint)
Before sweatshirt factory production begins, a “Master Pattern” is created—usually for a medium size (Size M).
- Digitization (CAD): Modern factories use CAD software to digitize these patterns.
- Grading: This is a mathematical step where the Master Pattern is scaled up or down to create other sizes (S, L, XL, XXL).
- Pro Tip: Good grading isn’t just making everything bigger; it maintains the specific fit ratios (e.g., ensuring the neck opening doesn’t become too wide on an XL hoodie).
2. Fabric Spreading & Cutting: The Hidden "Rest" Period
This is a critical step that many inexperienced manufacturers rush, leading to deformed garments.
- Relaxation (The 24-48 Hour Rule): Fleece is a knitted fabric with inherent tension. After being rolled tightly for shipping, the fabric is “stressed”.
- The Best Practice: We must unroll the fabric and let it “relax” on the spreading table for 24 to 48 hours before cutting.
- Why? If you cut tensioned fabric immediately, the pieces will shrink back to their natural state after cutting, resulting in panels that are smaller than the pattern. This is a primary cause of sizing inconsistencies.
- Cutting: Due to the thickness of fleece (especially heavy GSM), automated Laser Cutters or upright knives are preferred over manual scissors to ensure clean edges without fraying
3. Embellishment (Printing & Embroidery)
A common question is: “Why can’t I print over the pocket?”. The answer lies in the process sequence. Embellishment usually happens after cutting but before sewing.
- Cut Panels: Printing or embroidering is done on flat, cut fabric panels (e.g., just the front chest piece).
- Why? This ensures a perfectly flat surface. Once the hoodie is sewn, seams and pockets create uneven surfaces that ruin print quality.
4. Sewing & Assembly (The Construction Flow)
Fleece requires specific stitching techniques to handle its bulk and stretch.
- Overlock (Serging): Used for internal seams to join layers and prevent the raw edges from unraveling.
- Coverstitch: The visible double-needle stitch used on hems and cuffs. It stretches with the fabric, preventing thread breakage when you pull the sweatshirt on.
The Hoodie Assembly Line Flowchart: Instead of a confusing wall of text, here is the logical sequence of how a hoodie comes together:
- Pocket Attachment: The Kangaroo pocket is hemmed and attached to the Front Panel first.
- Shoulder Joining: The Front Panel is sewn to the Back Panel at the shoulders.
- Neck & Hood: The hood (constructed separately) is attached to the neck opening. Neck tape is added to cover the raw seam for comfort.
- Sleeves: The sleeves are sewn into the armholes (setting the sleeve).
- Side Seams: A long continuous stitch runs from the bottom of the waist, up the side, and down the sleeve to the wrist.
- Ribbing: Finally, the rib-knit cuffs and waistband are stretched and sewn onto the openings.
Phase 3: Quality Control (QC) & Finishing
You can have the best design and the most expensive cotton, but poor execution in the final stage can ruin the product. Because fleece is a thick, knitted fabric with a brushed surface, it is prone to specific defects that don’t occur in standard t-shirts or woven jackets.
A professional manufacturing process must include these specific checks:
1. Critical Inspection Points for Fleece
Standard QC checks for holes and loose threads are basic. But for fleece, we dig deeper:
- GSM Verification (Weight Check): Fleece is often sold by weight (e.g., “300 GSM Heavyweight Hoodie”). A variance of +/- 5% is acceptable. Anything more means the manufacturer may have over-stretched the fabric to save money. Always weigh the finished garment.
- Shade Variation (Body vs. Ribs): This is the most common amateur mistake. The body of the hoodie is Fleece, but the cuffs and waistband are Rib-Knit—two different fabrics often dyed in different vats. Under a standardized light box (D65 light source), ensure the color of the cuffs matches the body perfectly. A slight mismatch makes the garment look cheap instantly.
- Shrinkage Testing: Knitted fabrics shrink. A reputable factory will perform a steam test or a wash test before bulk cutting. If the shrinkage rate exceeds 5%, the patterns must be adjusted (enlarged) to compensate.
2. Common Defects to Watch Out For
When inspecting your samples or final shipment, look for these “Fleece Killers”:
- Pilling (The Fuzz Balls): Caused by short, weak fibers breaking and tangling on the surface. Ask your manufacturer if they use “Anti-Pilling Enzymes” during the dyeing process or request a Martindale Pilling Test report.
- Excessive Shedding (Linting): If the factory skips the vacuum/blowing finish, the inside of the hoodie will shed onto the customer’s t-shirt. Check this by rubbing a piece of white cloth vigorously against the inside; if it turns black, the shedding is unacceptable.
- Spirality (Torque/Twisting): If the side seam twists to the front after washing, that is spirality. It happens when the fabric tension isn’t balanced during knitting.
Conclusion
The journey of a fleece sweatshirt—from a plastic pellet or cotton boll to a cozy, brushed garment—is a complex interplay of chemistry, mechanics, and craftsmanship. Understanding this process empowers you to move from a passive buyer to an active partner.
You now know that:
- Warmth comes from the mechanical brushing process, not just the weight.
- Quality starts with the relaxation of the fabric before cutting.
- Durability depends on specific treatments like anti-pilling.
Final Actionable Advice: Never skip the Pre-Production (PP) Sample. Before you authorize the factory to cut thousands of yards of fabric, demand a fully finished sample made from the actual bulk fabric and accessories. This is your last line of defense. Use the checklist in “Phase 3” to audit this sample. If it passes, you are ready for production.
If you are ready to bring your designs to life with a manufacturer who understands every step of this process, contact us today to start your project.