How Does a Rib Circular Knitting Machine Work?

A rib circular knitting machine is a specialized piece of equipment used in the textile industry to produce fabrics with a ribbed structure, known for its elasticity and texture. Rib structures are characterized by alternating face and back loops along a course, with the loops of each wale remaining identical. The versatility and productivity of rib circular knitting machines make them essential for manufacturing various knitwear products such as sweaters, cuffs, collars, and stretch fabrics. This article explores the working principle, processes, and applications of rib circular knitting machines.

Understanding Rib Structure in Knitting

A ribbed fabric is one where the structure consists of alternating face (front) and back (reverse) loops in the knitting process. The distinguishing feature of ribbed fabric is that the loops within a wale are the same, making the fabric stretchier and more flexible compared to plain knit fabrics. Ribbed structures can vary in terms of patterns, such as 1x1, 2x2, and 3x1 ribs, depending on how the face and back stitches are arranged.

In a rib circular knitting machine, these ribbed structures are produced by alternating two sets of yarns—one for the face side and another for the back side of the fabric. The interaction between these yarns and the machine's needles creates the distinct rib effect.

Key Processes in Rib Circular Knitting Machines

1. Clearing:

The process begins with the clearing action, where the cylinder and dial needles move outward to clear the previous loop formations (plain and rib loops) from the previous knitting cycle. This ensures that the needles are in position to form new stitches in the next cycle.

2. Yarn Feeding:

The yarns are fed into the rib knitting machine through a yarn feeding system. Typically, two sets of yarns are used in a rib circular knitting machine. One set is dedicated to knitting the face (front) side of the fabric, and the other is used for the back (reverse) side. The yarn is delivered to the needles via yarn guides that direct it to the right position.

3. Needle Selection:

Rib circular knitting machines feature specialized needles that are arranged in a circular configuration around the cylinder or dial. These needles are equipped with latch mechanisms that open and close to catch the yarns and form stitches. The needles move in a continuous circular motion, interlocking the yarns to create the fabric.

The needles are arranged alternately in two sets: one set for knitting the face stitches and another set for the back stitches. This arrangement ensures that the fabric produced has a ribbed structure.

4. Stitch Formation:

As the cylinder or dial rotates, the needles move up and down, pulling the yarns through each loop to form the stitches. The interaction between the needles and the yarns creates loops that interlock to form the fabric. In rib knitting, the needles on the cylinder create face stitches while the needles on the dial create back stitches.

This alternating needle arrangement allows for the formation of different rib patterns, such as the 1x1 rib (one face stitch followed by one back stitch), 2x2 rib (two face stitches followed by two back stitches), and others. The number of face and back stitches in a given combination determines the texture and appearance of the ribbed fabric.

5. Rib Structure Formation:

As the rib knitting machine operates, the needles work in tandem to form the desired rib pattern. The key feature of ribbed fabrics is their elasticity, which is a result of the alternating face and back stitches. The ribbed structure can vary in thickness, stretch, and texture depending on the machine's settings.

For example, in a 1x1 rib, each face stitch is immediately followed by a back stitch, creating a smooth, consistent texture. In a 2x2 rib, two face stitches are followed by two back stitches, resulting in a thicker, more pronounced rib.

6. Fabric Tube Formation:

As the knitting process progresses, the ribbed fabric is formed into a continuous tube that wraps around the cylinder or dial. The size of the tube corresponds to the circumference of the machine's cylinder or dial. This tube formation allows for continuous fabric production, which can later be cut into various lengths or rolled into fabric rolls for further processing.

7. Fabric Take-down:

Once the desired length of ribbed fabric is knitted, it is taken down from the machine. This process can be done manually or automatically using a fabric take-down system. The fabric is then inspected for quality, defects, and any inconsistencies. The take-down mechanism ensures that the fabric is properly collected and is ready for further processing.

8. Finishing:

After the fabric is removed from the knitting machine, it may undergo additional finishing processes. These processes include washing, dyeing, pressing, and heat-setting to improve the fabric’s appearance, texture, and overall performance. The finishing process can also include additional treatments such as softening or adding special coatings to enhance the fabric's properties, such as moisture-wicking or anti-wrinkle features.

Advantages of Rib Circular Knitting Machines

Rib circular knitting machines offer a range of benefits to textile manufacturers, including:

High Productivity

Versatility

Elasticity and Comfort

Minimal Waste

Cost-Effective

Applications of Rib Circular Knitting Machines

Fashion Apparel

Sportswear and Activewear

Hosiery and Underwear

Interior Textiles

Medical Textiles

Conclusion