The Revolving Flat Card(also known as the flat card with revolving flats) represents one of the most critical machines in the short-staple spinning preparation process, often referred to as the "heart" of the spinning line. This process transforms entangled fiber tufts into individual fibers, removes impurities and waste, reduces neps, extracts a portion of short fibers, and aligns the fibers to a high degree of parallelism and orientation. The output is a uniform, clean sliver that serves as the foundation for high-quality yarn production in ring spinning and rotor (open-end) spinning systems.

The revolving flat card is the predominant type used for short-staple fibers (typical staple length: 22–40 mm), such as cotton, viscose, short-cut polyester, and their blends. It features a high-speed main cylinder (typically 300–500 rpm or higher in modern models) combined with slowly moving revolving flats (approximately 8–20 cm/min), creating an extensive main carding zone that delivers superior cleaning, parallelization, and defect reduction. In contrast, roller cards are primarily employed for long-staple fibers (e.g., wool or long synthetic fibers) in nonwoven or worsted applications.

Virtually all modern cotton spinning mills worldwide (particularly in India, China, Turkey, Pakistan, Bangladesh, Vietnam, and Iran) utilize revolving flat cards. Leading manufacturers include Rieter (C70, C80, C77 series), Trützschler (TC 15, TC 19i), LMW, and Marzoli.

 Applications
- Production of 100% cotton yarns (both carded and combed)
- Blended yarns (cotton/polyester, cotton/viscose, etc.)
- High-quality yarns for home textiles, apparel, denim, and technical fabrics
- Predominantly used in ring spinning mills and a significant portion of rotor spinning for cotton processing

In advanced models such as the Trützschler TC 19i, features like the automatic T-GO Gap Optimizer and intelligent card systems can increase productivity by 30–50% while reducing waste.

 Flats in Revolving Flat Carding Machines
Revolving flats consist of T-section bars (typically cast iron or aluminum) fitted with flat tops clothing (needle wire). The effective clothing width is approximately 22–25 mm, with gaps between flats due to mounting clips.

Construction:
- T-shaped bar to prevent longitudinal bending
- Dense needle clothing (typically 140–640 points per square inch [PPSI] for revolving flats; similar for stationary flats)
- Mounting via steel clips or clip-less systems in newer models

Types of Flats:
1.Revolving Flats: Standard configuration; move in a circular path around the cylinder
2. Stationary Flats: Used in pre-carding and post-carding zones for initial opening and final parallelization (e.g., MAGNOTOP in Rieter or equivalent systems in Trützschler)

Flat Movement:
- Reverse direction (opposite to cylinder rotation): Provides higher quality; standard in modern Trützschler and Rieter machines
- Forward direction (same as cylinder): Easier flat cleaning but slightly lower quality

Here are some illustrative diagrams and images of revolving flat carding machines and their key zones (sourced from reputable textile machinery manufacturers and technical resources):

(Images: Schematic diagram of a revolving flat short-staple carding machine showing main components and zones [ResearchGate]; Detailed view of Rieter C70 high-performance card cross-section [Rieter technical documentation]; Trützschler TC 19i card with zones and intelligent features [Trützschler official brochure].)

Key Settings in Revolving Flat Carding Machines
Precise settings are essential for sliver quality, uniformity, waste minimization, and production efficiency. These must be regularly checked and adjusted based on fiber type, staple length, trash content, production targets, and machine condition. Settings are typically expressed in thousandths of an inch (Thou or 1/1000 inch).

1. Feed Plate to Licker-in: 0.009–0.012 inch  
   Purpose: Gentle separation of lap into small tufts without fiber damage.  
   Too close → Fiber breakage and increased waste; Too open → Large tufts and uneven distribution.

2. Licker-in to Mote Knives 
- Upper knife: 0.010 inch  
- Lower knife: 0.012–0.015 inch  
Purpose: Removal of vegetable matter (seed coat, leaf, stalk).  
Too close → Loss of good fiber; Too open → Reduced trash extraction.

3. Licker-in to Under Grid: 5/16 inch  
   Purpose: Retention of good fibers on licker-in while discharging dust, short fibers, and trash.

4. Licker-in to Cylinder: 0.007 inch (can be reduced to 0.005 inch with proper dynamic balancing)  
   Purpose: Efficient fiber transfer. Too open → Incomplete transfer and nep formation.

5. Back Plates
- Lower edge: 0.022 inch  
- Upper edge: 0.017 inch  
Purpose: Air current control and licker-in fringe management. Too open → Cloudy web and uneven fiber distribution.

6. Cylinder to Flats: 0.010 inch  
   Purpose: Effective carding and clean web formation. Closer settings yield cleaner web; wider increases neps.

7. Front Plate  
A. Top Plate  
- Upper edge: 0.010–0.060 inch  
 - Lower edge: 0.032 inch  
Purpose: Control of flat strip waste.  
B. Bottom Front Plate  
- Upper edge: 0.032 inch  
- Lower edge: 0.015 inch  
Purpose: Uniform fiber transfer to doffer.

8. Cylinder to Doffer: 0.005 inch (up to 0.007 inch for heavier laps)  
   Purpose: Complete removal of good fibers by doffer. Too open → Patchy or cloudy web.

9. Cylinder to Under Casing  
- Back: 0.012 inch  
- Middle: 0.032 inch  
- Front: 0.064 inch  
Purpose: Fiber retention on cylinder and discharge of dust/short fibers.

10. Doffer to Doffer Comb: 0.012–0.015 inch  
Purpose: Maximum fiber removal without contact damage (slightly wider for high production/heavy sliver).

11. Flats to Flat Stripping Comb: 0.032 inch  
Purpose: Effective removal of flat waste without contact.

Accurate and consistent settings in the revolving flat card are vital for achieving uniform sliver, high fiber alignment, low waste, and optimal mill economics. These should be verified periodically, considering raw material variations, production goals, and mechanical wear. Mastery of these adjustments by technicians ensures stable, cost-effective spinning operations.

For consultation on selecting or optimizing a carding machine, experienced textile specialists are available to provide technical guidance on machine choice, fiber-specific configurations, and optimal settings to enhance yarn quality and productivity.

♦ References 

►https://textilelearner.net

►https://onlinetextileacademy.com

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