Count Selection Equations for Textile Operations
This document provides a set of empirical equations for selecting yarn count based on the desired GSM (Grams per Square Meter) for various common knitted fabric structures. These equations serve as a quick reference for textile professionals involved in fabric design, production planning, and quality control. It is important to note that these are approximate values and actual yarn count selection may require adjustments based on specific machine parameters, yarn properties, and desired fabric characteristics.
Equations for Count Selection
The following equations can be used as a starting point for selecting yarn count based on the desired GSM for different knitted fabric structures:
1. Single Jersey
Equation:
COUNT = 4400 / GSM
Explanation: This equation is applicable for single jersey fabrics, a basic weft knitted structure known for its simplicity and versatility. The constant 4400 is an empirically derived value that relates GSM to yarn count for this specific structure.
2. 1x1 Normal Rib
Equation:
COUNT = 6100 / GSM
Explanation: This equation is used for 1x1 rib fabrics, characterized by alternating knit and purl stitches in each course, resulting in a fabric with good elasticity and recovery. The constant 6100 reflects the higher yarn consumption per unit area compared to single jersey due to the rib structure.
3. 2x1 Normal Rib
Equation:
COUNT = 6700 / GSM
Explanation: This equation applies to 2x1 rib fabrics, where two knit stitches alternate with one purl stitch in each course. This structure offers even greater elasticity and recovery than 1x1 rib, leading to a further increase in yarn consumption, as reflected in the constant 6700.
4. Interlock
Equation:
COUNT = 7700 / GSM
Explanation: This equation is for interlock fabrics, a double-knit structure that produces a smooth, stable fabric with good drape and opacity. The interlock structure involves two layers of fabric knitted simultaneously, resulting in significantly higher yarn consumption, hence the larger constant of 7700.
5. STBPQ (Stripe Pique)
Equation:
COUNT = 5300 / GSM
Explanation: This equation is used for Stripe Pique fabrics. Pique fabrics are characterized by a textured surface created by a combination of knit and tuck stitches. The stripe pique variation incorporates colored stripes into the design. The constant 5300 reflects the yarn consumption associated with this specific structure.
6. Polo Pique
Equation:
COUNT = 5400 / GSM
Explanation: This equation is applicable for Polo Pique fabrics, a type of pique fabric commonly used for polo shirts. It has a slightly different structure than the stripe pique, hence the constant 5400.
Important Considerations
While these equations provide a useful starting point, it's crucial to consider the following factors:
Yarn Type: The equations are based on the assumption of using a standard cotton yarn. Different yarn types (e.g., polyester, viscose, blends) will have different densities and properties, which can affect the relationship between count and GSM.
Machine Gauge: The gauge of the knitting machine (needles per inch) influences the fabric density and, consequently, the required yarn count. These equations are based on common machine gauges. Significant deviations from these gauges may require adjustments.
Loop Length: Loop length is a critical parameter that affects fabric GSM. Shorter loop lengths result in denser fabrics with higher GSM, while longer loop lengths produce looser fabrics with lower GSM. These equations assume a standard loop length for each fabric structure.
Finishing Processes: Finishing processes such as washing, dyeing, and calendaring can affect fabric shrinkage and GSM. It's essential to account for these effects when selecting yarn count.
Desired Fabric Properties: The desired fabric properties, such as drape, hand feel, and dimensional stability, can influence the optimal yarn count selection.
Practical Application
To use these equations, simply divide the constant value for the specific fabric structure by the desired GSM. The result will be the approximate yarn count required. For example, if you want to produce a single jersey fabric with a GSM of 150, the calculated yarn count would be:
COUNT = 4400 / 150 = 29.33
This suggests that a yarn count of approximately 30 Ne (English Cotton Count) would be a suitable starting point.
Disclaimer
The equations provided in this document are intended as guidelines only. Actual yarn count selection may require experimentation and adjustments based on specific production conditions and desired fabric characteristics. It is recommended to conduct trials and fine-tune the yarn count to achieve the optimal results.
Equation For Count Selection:
1. SINGLE JERSEY
COUNT=4400/GSM
2. 1X1
NORMAL RIB
COUNT=6100/GSM
3. 2X1 NORMAL RIB
COUNT=6700/GSM
4. INTERLOCK
COUNT=7700/GSM
5.
STBPQ
COUNT=5300/GSM
6. POLO PIQUE
COUNT=5400/GSM