Various types of rib and interlock fabrics found in the market depend on their structure such as 1 × 1 rib, 2 × 1 rib, 2 × 2 rib, 3 × 1 rib, 3 × 2 rib, 4 × 1 rib, 4 × 4 rib and 1 × 1 interlock, 2 × 2 interlock etc. These all types of fabric can be possible to knit in circular knitting machine after machine setting. When these fabrics are knit on the machine, some needles are needed to drop or withdrawn from needle groove according to their design such as 1 × 1, 2 × 1, 2 × 2 etc. Due to needle dropping or withdrawing production per hour will changed as production per hour directly depends on the No. of active needle. No. of needle or active needle depends on machine gauge. This paper gives a new approach for machine gauge which is somewhat different from other thinking. This paper also shows the production calculation formula with their machine setting for various rib and interlock fabric with their derivation. By this paper, one can easily understood about machine gauge and calculated production of any type of rib and interlock knitted structure. Complexity of calculating production can be reduced by this paper.
Knitting is the second most popular technique of fabric or garment formation by inter-looping one or one set of yarns. Continuous length of yarn is converted into vertically intermeshed loops either by hand or by machine in knitted fabric [
Machine gauge: The machine gauge of knitting machines is a measure expressing the number of needles per a unit (normally 1 inch) of the needle bed width or circumference [
Machine diameter: The diameter of knitting machines is measured at the bottoms of the two opposite needle grooves in a cylinder or at the top of the two opposite needles in a circular bar and is usually expressed in inches [
Number of feed system or feeder: On the circumference of a circular knitting machine up to 120 knitting cam sets can be mounted, each cam set fed with a separate yarn. This results in obtaining 120 knitted loop courses in one machine revolution [
Stitch length: The length of yarn knitted into one stitch in a weft knitted fabric [
Rib circular latch needle machine: There are two circular needle beds on this type knitting machine such as cylinder bed and dial bed. Latch needle cylinder dial revolve through the stationary cam system. In this machine, there is one set of needles on the circumference of a vertical cylinder and a second set of needles, arranged perpendicular to the first set and mounted on a horizontal dial [
Interlock circular latch needle machine: In case of conventional interlock machine, both the needle bed contains one short butt and one long butt needles once after another. But in modern machine the needles are of the same length [
Machine setting for 2 × 1 rib machine: A 1 × 1 rib gating in which each cylinder needle is neighbored by a dial needle and they are offset with respect to each other such that when both sets move forward to catch yarn, each cylinder needle passes through the gap between two neighboring dial needles. When this 1 × 1 rib machine is converted for 2 × 1 rib fabric, one needle is dropped after every two needles from both of the needle bed. Needle can be dropped by using miss cam or withdrawn of needle from the needle groove.
Machine setting for 2 × 2 rib fabric: When 1 × 1 rib machines is converted for 2 × 2 rib machine, two needles are dropped after every two needles from both of the needle bed.
Machine setting for 3 × 2 rib fabric: For 3 × 2 rib fabric machine setting, two needles are dropped after every three needle from both of the needle bed.
Machine setting for 3 × 3 rib fabric: When 1 × 1 rib machines is converted into 3 × 3 rib machines, three needles are dropped after three needle from both of the needle bed.
Machine setting for 4 × 1 rib fabric: For 4 × 1 rib fabric machines, one needle is dropped after every four needle from both of the needle bed.
Machine setting for 4 × 4 rib fabric: For 4 × 4 rib fabric machines, four needles are dropped after every four needle from both cylinder and dial bed.
Machine setting for x × y rib fabric: Here x denoted the no. of face loop and y denoted the no. of back loop. y no. of needles is needed to dropped or withdrawn after x no. of needles for this type of fabric.
Machine setting for 1 × 1 interlock fabric: In this case, needles of both beds operate consecutively and then after a certain delay on the passive needle bed. The active needle bed is that which receives the yarn for forming loops from the yarn carrier. That means the time of knitting operation fifty percent needles are active and rest fifty percent are inactive. In next knitting cycle previously inactive needles are active and previously actives are inactive.
Machine setting for 2 × 2 interlock fabric: When 1 × 1 interlock machines are converted for 2 × 2 interlock machines, two needles are dropped after every two needle. Needles can be dropped by using miss cam or withdrawn of needle from the needle groove. 2 × 2 interlock machine runs by maintaining same principle of 1 × 1 interlock machines.
Machine setting for x × y interlock fabric: Here x and y denoted no. of face and back loop respectively. When any interlock machine converted for this type of structure y no. of needles are needed to dropped or withdrawn after x No. of needle. Operating principle is same as any other interlock fabric.
New Approach for Machine Gauge: Appropriately machine gauge is the total number of needle grooves of tricks per unit length (normally 1 inch). It can be also defined as the capacity of carrying total no. of number of needles per inch. It is somewhat same to the old concept. For an example, A 30 gauge circular knitting machine is running with 1 × 1 rib fabric machine setting. That means the machine has 30 needles in 1 inch and also 30 needle grooves. When this machine is converted for 2 × 1 rib fabric, it has been needed to drop or withdrawn 1 needle after every 2 needle from both of the needle bed. In this case, no. of needle is 20 in 1 inch length where needle grooves remains 30. But the machine is 30 gauges for all time and for all of the structures.
Production Calculation: If all needle grooves are filled by needle,
So the formula of production will be,
For 2 × 1 rib fabric: In 2 × 1 rib machines one needle is dropped after every two needles so that two third of total needles are active in the machine.
For 2 × 2 rib fabric: During machine setting of 2 × 2 ribs gating two needles are dropped after every two needle. So t hat, two fourth or half of total needles are active.
For 3 × 2 rib fabric: In 3 × 2 rib gating two needles are dropped after every three needle so that three fifth of total needles are active and rest are inactive.
For 3 × 3 rib fabric: Three needles are dropped after every three needle for 3 × 3 rib gating. So that three sixth or half of total needles are active in the machine.
For 4 × 1 rib fabric: During the time of 4 × 1 rib machine setting one needle is dropped after every four needle. So that four fifth of total needles are active.
For 4 × 4 rib fabric: For 4 × 4 rib fabric machine setting, four needles are dropped after every four needles. So, half of total needles are active in the machine.
For x × y rib fabric: For x × y rib fabric machine setting, y no. of needles is dropped after every x no. of needles. So, x off 1/x + y No. needles is active and rest is inactive.
For 1 × 1 interlock machine: During interlock fabric production at a time fifty percent needles are active and rest fifty percent are inactive. There is no need to drop any needle for 1 × 1 interlock fabric.
For 2 × 2 interlock fabric: For the machine setting of 2 × 2 interlock fabric 2 needles are needed to drop after every two needle from both of the bed. For this reason half of total needles are present in the machine and acting as working needle. Again fifty percent or half of total present needles are working at a time.
For x × y interlock fabric: For x × y interlock fabric machine setting, y no. of needles is dropped after every x No. of needles from both of the needle bed. So, x off 1/x + y No. needles is active and rest is inactive. In one knitting cycle fifty percent of total active needles are working. In second knitting cycle rest fifty percent needles are working. So, in every knitting cycle fifty percent of total active needles are working.
No. of active needles present in the machine directly influence the production per hour of knitting machine. Increasing the No. of active needle in the machine increases the production of this machine. According to this and also according to the formula 1 × 1 interlock fabric production is half of 1 × 1 rib production. But in practically 1 × 1 interlock fabric productions are slightly decreases than 1 × 1 rib fabric. Because in case of interlock fabric production higher machine speed (RPM) than rib fabric can be achieve. Machine speed (RPM) depend on various factors such as type of fabric, fabric quality, yarn quality, machine condition etc. If RPM are constant for all types of fabric than production are decreases with the design variability of fabric.
Machine gauge is an important factor for any particular structure and also for calculation of production. Appropriate approach of machine gauge may need to be use for calculation of production mathematically. The values which are used in the production calculation have influences on the production of knit fabric. On the other hand, yarn quality and fabric quality also influenced the knit fabric production. All the values can be constant without total No. of active needle present in the machine. If design of fabric needed to be changed, No. of needles must be dropped and production fabric decreases. Production of fabric has directly influenced the cost of fabric. Higher the fabric production means lower of cost and vice versa. In those cases, cost of fabric will be changed with the design variability of fabric such as 2 × 1, 2 × 2, 3 × 1 etc. Knitting price per kg also changed as production per hour decreases. However, it is important for the knitter to calculate the production per hour in weight to deliver the products according to buyers lead time. Knitting charge also depends on the production of fabric. Lower the production means per kg production takes higher time. So, knitting charge will be changed as the changing of production per hour. This paper helps to give a new thinking about machine gauge of a knitting machine. By this paper, knitted fabric production in weight can be calculated easily. Although knitted fabric production can be calculated in length but knitted fabric is sold in market by means of weight. So calculation of knitted fabric production in weight is most important for the knitter and also for the person who are related to this sector.
The author thanks to Mr. Abul Kalam Azad, Technical Knitting Manager, AST Knitwear Ltd., Gazipur, Bangladesh for his technical support and allow the author in the industry.
Ripon Kumar Prasad, (2016) A New Approach for Machine Gauge & Production Calculation of Various Kinds of Rib and Interlock Knitted Fabric Structure. Journal of Textile Science and Technology,02,31-36. doi: 10.4236/jtst.2016.22005