Circular knitting machines have revolutionized the knitting industry, significantly boosting production rates and finding application in almost every knitting factory. Let's delve deeper into understanding these machines and how their production is calculated.

Types of Weft Knitting Machines

Weft knitting machinery can be broadly classified into three main groups based on their frame design and needle bed arrangement:

Straight Bar Frames: These machines have a straightforward design with straight bars.
Flat Machines: Flat machines have a flat needle bed arrangement.
V-Bed Flat Machines: This category includes machines with a V-bed needle arrangement, which is the most common type.
Flat-Bed Purl Machines: These machines utilize double-headed needles.

Circular knitting machines encompass all weft knitting machines with needle beds arranged in a circular cylinder or a combination of a circular cylinder and dial. These machines can employ various needle types like latch, bearded, or compound needles and are utilized for knitting a wide range of fabric structures, garments, hosiery, and other articles across different diameters.

Circular knitting machines come in various types, including:

(1). Single Jersey Circular Knitting Machine
(2). Terry Single Jersey Machine
(3). Auto Striper
(4). Jacquard Single Jersey Machine
(5). Double Jersey Circular Knitting Machine
(6). Interlock Double Jersey Machine
(7). Rib Double Jersey Machine

Dissection of Circular Knitting Machine Components:

Stop Motion: These are yarn supports equipped with springs that pivot downward in case of yarn breakage or increased tension. This action releases excess yarn to the feeder, preventing press-offs. Simultaneously, it activates a circuit that halts the machine and triggers a warning light indicator.

Spring-Loaded Detector Points: Strategically positioned around the cylinder, these detector points are designed to detect faults or malfunctions such as yarn slubs, fabric lumps, needle heads, or latch spoons. When triggered, they stop the machine to prevent further issues.

Tape Positive Feed (4A): This component provides three different speeds (course lengths) and is driven and adjustable from the drive arrangement (4B).

Cylinder Needle Cam System: Each feed is contained in a replaceable section with an exterior adjustment for the stitch cam slide. This system is responsible for forming stitches.

Automatic Lubrication System: This system ensures the smooth operation of the machine by lubricating its components.

Start, Stop, and Inching Buttons: These buttons control the machine's operation, allowing it to start, stop, or inch forward as needed.

Cam-Driven Fabric Winding Down Mechanism: This mechanism revolves with the fabric tube, facilitating the winding down of fabric.

Revolution Counters: Utilized for each of the three shifts, these counters keep track of the machine's revolutions. Additionally, there's a pre-set counter used for stopping the machine upon completing a specific fabric length in courses.

Side Creel: This component holds yarn cones for feeding into the machine.

Lint Blower: The lint blower reduces the occurrence of knitted-in lint slubs, particularly beneficial when using open-end spun yarns. It also helps in minimizing cross-contamination by fibers from other machines, thereby improving overall fabric quality.

The evolving market demands for smaller orders and shorter production runs have spurred machine builders to devise rapid-response techniques, aiming to cut costs and minimize downtime during machine changes, especially on large diameter multi-feeder machines. Some key areas addressed in this endeavor include:

Centralized Stitch Control: This feature streamlines the process of resetting all cylinder stitch cams collectively, eliminating the need for individual cam adjustments. It operates within a specific cam track, saving valuable time during machine setup.

Monarch/Fukuhara Rotary Drop Cam System: This innovative system offers a swift and convenient method of altering cam set-outs without requiring the replacement of cams or needles. Positioned on the outside of the dial and cylinder cam system at each feed and needle track, a disc can be rotated to various positions (up to 180 degrees), each corresponding to a specific needle height setting. This enables adjustments for knit timing, tucking, missing, and fabric support, facilitating efficient knitting operations.

Three-Leg Portal Frame for Diameter/Gauge Changes: The design of the three-leg portal frame provides ample space between pillars, allowing for the horizontal removal of the dial and cylinder during changes in diameter or gauge. While gauge changes on machines like single-jersey jacquard or double-jersey machines can be time-consuming (ranging from a few hours to a couple of days), this setup minimizes downtime. Gauge changes typically incur costs ranging from 20 to 25 percent of the machine's cost price, while diameter changes can range from 30 to 40 percent.

Compatibility of Modules: Ensuring compatibility between machine types facilitates quicker conversions and changes in knitted structures at a reduced cost in additional parts. Conversion kits, such as those offered by Monarch/Fukuhara, allow for seamless transitions between different knitting techniques, like rib, interlock, or eight-lock knitting. This capability significantly reduces the time required for gauge adjustments, enabling changes in minutes rather than hours.

Industrial Frames and Automatic Doffing: Machines equipped with industrial frames can accommodate larger cylinders, up to 38 inches for single-jersey and 42 inches for double-jersey machines. Additionally, advancements in automatic doffing systems have been developed up to the prototype stage, aiming to streamline the process of fabric roll removal and ejection from the machine, further enhancing operational efficiency.

Circular knitting machines can be measured in three different ways to express their speed:

Machine Revolutions per Minute (RPM): This measurement is specific to each individual machine and its diameter. Generally, larger-diameter machines or those with more advanced patterning capabilities are expected to operate at lower RPMs.

Circumferential Speed in Meters per Second: This speed, measured in meters per second, remains constant across a range of machine diameters within the same model. It provides a standardized metric for calculating the RPM required for a particular machine diameter.

In summary, circular knitting machines play a vital role in the knitting industry, with high-quality options now readily available thanks to advancements in technology.