Knitting calculations - Most suitable count for knitting machines

KNITTING CALCULATIONS . Most suitable count for knitting machines As a thumb rule knitting experts prefer to use such knitting machine whose gauges is near to count of yarn (English count) i.e. for 20-gauge machines most suitable yarn count is 20s. This rule is has certain limitations, like, for 28-gauge yarn of 26s to 30s is most suitable. But for very fine counts this rule is not applicable and also machines have maximum gauge 32. Normally fine counts are not used as such rather they are make double, like count 60s double, which means that net count is near to 30s. And this 60 double count is suitable for 30- gauge machine. To solve this problem some authors have suggested following formulas. For single Knitting Machine Suitable count = G*G/18 For Double knitting machine Suitable count= G*G/8.4 Where G is gauge of knitting machine Some knitting machine manufacturers suggest a range of yarn count for their machine. There is another way to solve this problem and that is to take help from old record. Every firm is producing many types of fabrics and on the basis of experience they develop a database for ready reference. One can get a ready reference from the table to produce fabric of certain grammage. We are also giving expected width of fabric after wet processing. This table can provide just a reference. Knitters have to decide by themselves after doing a trial production, since there are many more factors, which can affect yarn and gauge selection process. Knitting Machine Parameters Every knitting machine is made to fulfil certain demands of the customer. There are number of characteristics of machine which are intimated by the machine manufacturers while delivering the machine to customers/users. It is helpful for the user to be well aware about these parameters. Furthermore machine specifications are given in different unit. We will explain these parameters and will also give the conversion factors to convert parameters from one system to other. Machine Gauge As per Oxford Dictionary the word “gauge” is a noun and as well as verb. It is used to measure level of any thing or for an instrument to measure width, length or height of any thing. In knitting it is used to express the number of needle in a unit length of the needle bed. This needle bed may flat or circular. In double knit circular machine it is used for cylinder and as well as dial. Generally gauge is defined as number of needles per inch. According to German standard DIN 60917 (Iyer et al1995) alphabet “E “ is used to denote knitting machine gauge. E = Number of needles 1 inch (25.4 mm) Machine Pitch As per German DIN 62125 (Iyer et al1995) the notation “gauge” is to be avoided in the future. Rather they prefer to use notation “pitch” for comparison purpose. Machine Pitch means the distance between the centres of two neighbouring needles. It is denoted with small “t”. It is given in mm. Knitting Machine Production calculation Before explaining the method to calculate the nominal production capacity of the knitting machine it is imperative to be well aware of count and denier system and one should also be familiar with the conversion factors. Yarn is sold and purchased in the form of cones and bags. Cones and bags have certain weights. Still in the international market yarn is sold in pounds not in kilograms. Bags are of 100 pounds, which is equal to 45.3697 kgs. Previously there were 40 cones in a bag but now there are bags available of 25 cones. In other words cones are of 2.5 pounds and four pounds. Nominal Production of knitting machines One very simple way to calculate knitting machine production by weighing the total production of one hour or one shift or one day. The practical way calculating production of a machine is as follows. In this method following information for production calculation are required: • Machine Guage and Dia • RPM Knitting Machine • Yarn Count • Stitch Length From these figures we can calculate the length of yarn being used by the machine in one hour and then by converting this length into weight with the help of count given we can calculate the quantity of yarn being consumed by machine in one hour. This would be the optimum production of the machine. This optimum production can be converted into nominal production by multiplying it with efficiency. In the following pages we will explain this with few examples. In the following pages we will explain the method to calculate nominal production capacity of knitting machine. It is commonly believed that we can run knitting machine up to 85% efficiency. However, by creating most suitable environment one can increase machine efficiency. For this we need following figures: Machine speed RPM Machine guage Machine Dia Count/ denier of yarn being used Stitch length From the above-mentioned figures we can calculate the length of yarn being used in one revolution and if we know the length and count of yarn then it is quite easy to calculate weight of yarn (see Example: 03 for more details) Example 01 Calculate nominal production of a single jersey-knitting machine per hour from the data given: Machine Gauge 24 Machine Dia 30 inches Number of Feeders 90 Machine RPM 26 Yarn Count 24 Stitch length 4 mm Efficiency 85% Solution: Step one First we will calculate number of needles and number of stitches produced in one revolution. This would help us in calculating the total length of yarn consumed in one revolution. Number of needles = machine dia * gauge * π (3.14) = 30* 24*3.14 =2260 (exact 2260.8 but needles are always in even number so we will take nearest even figure) Number of stitches produced in revolution Every needle is making one stitch on every feeder because machine is producing single jersey fabric (full knit fabric). Number of stitches produced in one revolution = Number of needles * number of feeders = 2260*90 = 203400 This figure shows that machine is making 203400 stitches in one revolution. Step Two Length of stitch is 04 mm (stitch length is always calculated in metric system) From this figure we can calculate yarn consumption in yards in one hour Yarn Consumption (in yards) in one hour = number of stitches * length of (mm) * RPM *60 (minutes) 1000(to convert mm into meters) =203400 * 4 * 26 * 60 1000 = 1269216 meters or = 1388015 yards Step Three In previous step we calculated quantity of yarn consumed in yards. We can easily calculate weight of this yarn while its count is known (see example 03). Weight of cotton yarn = length of yarn Count * 840 = 1388015 840 * 24 = 68.85 pounds or = 31.23 Kilo grams Efficiency 85% = 26.55 Kilo grams Answer: this machine can produce 26.55 Kgs fabric in one hour at 85 % efficiency Example 02 For Filament yarn, Calculate nominal production of a single jersey-knitting machine per hour from the data given: Machine Gauge 28 Machine Dia 26 inches Number of Feeders 120 Machine RPM 30 Yarn Denier 75 Stitch length 4.5 mm Efficiency 85% Solution: Step one First we will calculate number of needles and number of stitches produced in one revolution. This would help us in calculating the total length of yarn consumed in one revolution. Number of needles = machine dia * gauge * π (3.14) = 26* 28*3.14 =2286 (exact 2285.92 but needles are always in even number so we will take nearest even figure) Number of stitches produced in revolution [...]... than one kind yarn Example 9 Calculate nominal production of a fleece -knitting machine per hour from the data given: Machine Gauge 18 Machine Dia 30 inches Number of Feeders for 60 Front yarn Number of feeders For loop yarn Machine RPM Yarn Count Yarn count for loop Stitch length of front yarn Stitch length of Loop yarn 30 28 26s for front 16s 4.5 mm 2.5 mm Efficiency 85% Solution: Step one First we... to elaborate the way to calculate the optimum production of a knitting machine The following formula is useful in every situation to calculate the optimum production capacity of a knitting machine at 85% efficiency For cotton count Production in one hour = Gauge * Dia * 3.14 * RPM *60 * Stitch length (mm) *1.0936 * 1 * 85 1000 *840 * yarn count * 100 Grammage Expressions Generally grammage is expressed... percentage with the help of examples Example Find exact composition of different fibres in fleece fabric from the following data: Yarn count front Yarn count for loop Consumption ratio 30s 100 cotton 20s 50:50 P/C Front: loop 2:1 (by weight) Suppose for front we need 2Kg yarn and for loop we will be requiring 1 Kg yarn Front yarn 2 KGS 100 % cotton Cotton 2000 grams Loop yarn 1 Kg 50:50 P/C Cotton 500 grams... calculate weight of this yarn while its count is known (see example 03) Weight of cotton yarn = length of yarn Count * 840 = 841312 840 * 30 Efficiency 85% = 38.52 pounds or = 17.43 Kilo grams = 14.85 Kilo grams Answer: this machine will consume 14.85 Kgs of yarn to knit front of the fleece fabric in one hour at 85 % efficiency Step Four Yarn consumed for loop knitting (back of the fabric) Every needle... of yarn consumed in yards We can easily calculate weight of this yarn while its count is known (see example 03) Weight of cotton yarn = length of yarn Count * 840 = 233696 840 * 16 = 17.39 pounds or = 7.89 Kilo grams Efficiency 85% = 6.70 Kilo grams Step Seven Now we can add both yarn consumed Yarn for front 14.85 Yarn for back 6.70 Total 21.55 This machine can produce 21.55 Kgs fabric in one hour... knitted with one kind of yarn but in some cases more than one type of yarn of different counts and combination (mixing of two different fibres) are used One very common example is knitting of fleece fabric, which is knitted by using fine and course yarns, and one yarn is made of polyester and cotton Another example is knitting of fabric by using spandex filament and cotton or pure polyester In such condition... number so we will take nearest even figure) In this example we will calculate consumption of yarn in Kgs of both yarns and then we will add them to get final production per hour Consumption of yarn for front knitting, Every needle is making one stitch on every feeder because machine is producing single jersey fabric (front of fleece) Number of stitches produced in one revolution = Number of needles *... produced in one revolution = Number of needles * number of feeders = 1696*30 = 50880 This figure shows that machine is making 50880 stitches in one revolution Note: that we have put 30 cones of course count for loops after every two feeders Step Five Length of stitch is 2.5 mm (stitch length is always calculated in metric system) From this figure we can calculate yarn consumption in yards in one hour Yarn... following lines we will explain relationship among these factors with examples Example 10 Calculate weight of fabric from the given data Grammage Width of fabric Length of fabric 300 GSM 35 inches (in tubular form) 20 meters First we will calculate area of the fabric Area of fabric = Fabric length * fabric width = 20 * 35*2 (since fabric is in tubular) 39.37 (one meter is equal to 39.37 inches) = 35.6 meter... And weight of 35.6 meter square = 300*35.6 = 10680 grams or 10.680 Kgs Example 13 Calculate GSM from the data given Total Weight of fabric = 15.5 Kgs Length of fabric = 35 meters Width of fabric in open form = 65 inches Solution: First we will calculate area of the fabric Fabric length Fabric width Fabric area = 35 meters = 65 inches or 1.65 meters = Length * width =35 * 1.65 =57.75 meters square Weight . KNITTING CALCULATIONS . Most suitable count for knitting machines As a thumb rule knitting experts prefer to use such knitting machine whose gauges is near to count of yarn (English count) . count) i.e. for 20-gauge machines most suitable yarn count is 20s. This rule is has certain limitations, like, for 28-gauge yarn of 26s to 30s is most suitable. But for very fine counts this. is suitable for 3 0- gauge machine. To solve this problem some authors have suggested following formulas. For single Knitting Machine Suitable count = G*G/18 For Double knitting machine Suitable