How to use 4 Point System for Knits Fabric Inspection?

4 point system for fabric inspection is a standard method that is widely used in Textile and Apparel Industries. In this system, fabric quality is evaluated by penalty points per 100 square yards.
Formula: Points / 100 sq. yd. = (Total points in roll * 36 * 100)/ (Total length in yards * width in inches) 
So, to evaluate fabric quality you need to know fabric width and length of the inspected roll or thān.  In case of woven fabric, length of the fabric roll is written on the Fabric roll tags. But knits fabrics are sourced in weight and supplier does not mention length.

That's why when it comes to use 4 point system in knits fabric, inspector finds it difficult to use given formula for calculating penalty points. To use the 4 point system for fabric inspection you need to calculate length of the fabric in a roll/thān. 

Follow standard method of 4 point system to mark defects, calculate total penalty points in a than according standard method explained in How to 4 point system in Fabric Inspection?

Evaluate fabric quality of Knits in 4 point system:

Step#1: Measure fabric length in a roll /thān
Generally you will get following specification in knitted fabric roll or find these
  • Weight of the Than (in Kgs) 
  • Fabric weight Grams per square meter (GSM) and 
  • Fabric width (inches) Note: always take open width for knit fabric
For example, fabric weight of a than is 50 kgs, fabric GSM 250 and fabric width (W) 46 inches (open width).

Use following formula to know approx length of the roll/thān with above information. 

Fabric length (in meters) = Fabric weight * 1000 /(Fabric GSM *Fabric Width * 0.0254)

Using data from above example

Fabric length (L) = (50*1000)/(250*46*0.0254) = 171.17 Meters

Step#2: Convert fabric length into yards. 
Multiplying factor is 1.09361
Fabric length in yards = 171.17* 1.09361 = 187.2

Step#3: Calculate total penalty points.
Suppose you have given total 34 penalty points to the above roll. Once you find the length of each fabric roll/ than use the above formula to calculate points per 100 square yards.

Point /100 square yards = (Total penalty points * 36 * 100)/(roll length * Width in inches)
= (34*36*100)/(187.2 * 46)
= 14.21
You are done.

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