Pattern Grading in Garment Manufacturing
Pattern Grading is the process whereby patterns of different sizes are produced from the original master pattern. This process can be performed manually or automatically by a computerized system. Patterns are graded according to size charts which present the sizes and the average measurements of the population group for which the garments are intended.
When the fabric is cut for making garments, it is important to ensure that fabric is fully relaxed and is not subjected to any additional tension or strain during rolling or unrolling while layering for cutting. So fabrics are often relaxed prior to cutting to ensure that the shrinkage is minimized in a garment. Garments which are unwashed and can shrink while laundering at customers end are made with measurements with shrinkage tolerance included.
Woven fabric garments typically shrink just a little. This will usually be about 2-3% which is fairly unnoticeable. Knits that are not garment dyed will be more affected by washing and drying. Shrinkage for knit fabrics can be anywhere from 1-8% and 95% of this shrinkage will take place the first time it is laundered. In these cases, shrinkage is incorporated in all the patterns of a garment. This shrinkage incorporated in patterns could be lengthwise or widthwise depending on the type of fabric.
Shrinkage adjustments should not distort the original shape and balance of the patterns. When shrinkage is applied to a panel in garment all corresponding patterns must also be applied with shrinkage adjustments.
What is Pattern Grading?
Patterns initially are made in only one size. In order to produce clothing that fits various body types and sizes, the pattern pieces must be increased or decreased geometrically to create a complete range of sizes. The process of resizing the initial pattern is called “grading.” Each company determines its own grade specifications for each size, and size specifications vary slightly from manufacturer to manufacturer.
Grading is the method used to increase or decrease the sample size production pattern to make up a complete size range. For example, the sample size 10 patterns must be made larger to accommodate sizes 12, 14 and 16 and smaller for sizes 8 and 6. Each company sets predetermined grade specifications, or rules. For example, a missy manufacturer’s grade rules might call for increments of one and a half inches in width and a quarter inch in length for each size.
Today most manufacturers grade pattern on CAD systems. The pattern maker guides a cursor around the edges of the sample pattern on a digitized table. At each of the key points, he or she pushes a button to record a grade point. Each point is cross-referenced by a grade-rule table stored in the computer, which enlarges or reduces the pattern automatically according to the predetermined direction.If the pattern was originally made by computer, data are already in the computer and can be enlarged or reduced automatically.
Pre-programmed grade rules for increase or decrease are automatically applied to the pieces of each grading location. Then the computer can print out the pattern in each new size. Manufacturers often use an outside service to make patterns, grade patterns and make the marker.
Although many small firms still use traditional grading methods, grading, like patternmaking, is becoming increasingly computerized. Using a CAD system, the pattern can be resized according to a predetermined table of sizing increments (or “grade rules”). The computerized plotter can then print out the pattern in each size. Because the productivity gains are so great, small to medium-sized manufacturers are beginning to acquire their own CAD systems for grading.
Alternatively, they may use an outside grading service to perform this function.
Shrinkage Incorporation in Pattern Grading
Grading and shrinkage incorporation in a pattern is very important and plays a big role in not only getting correct fit and drape of a garment but also measurements as graded specs. Pattern grading is a technique of scaling a pattern to reproduce a pattern in other sizes. It must be done accurately. To properly fit a pattern to a range of sizes, each pattern piece needed to be graded, or systematically increased or decreased.
The purpose of grading is to proportionally increase or decrease the size of a pattern, while maintaining shape, fit, balance and scale of style details. It’s important to remember that grading only makes a shape larger or smaller and isn’t intended to change a shape. Grading also reflects the fact that individuals of different sized are proportionately different, not uniformly different.
Stacking or “0” point for grading
For grading it is important to have stack point which will define the “x” or “y” grading of pattern. It is defined as “0” point located at the centre of the pattern of a Front, back or sleeve panel. For centre front it is perpendicular to the centre of check line. For sleeve the “0” point is centre of sleeve at the bicep line.
- Front and back neck drop is applied to shoulder neck point. Shoulder line should remain parallel between sizes.
- Body length is distributed between the shoulder neck point and the bottom. Grading is divided between shoulder/beck point, neck drop, armhole, waist, hip and bottom. Body length combined grading is total of centre front length and neck drop.
- Neck width is applied at the shoulder neck point it is always parallel to check line.
- Armhole curve is combined measurement of armhole width and armhole height grade
- Sleeve armhole is combined measurement of sleeve cap height grade and sleeve bicep grade along the armhole curve.
- Sleeve length from shoulder is distributed between the sleeve cap and bottom sleeve edge. Sleeve cap grade is applied above bicep line and sleeve cap while balance length is divided between bicep line and sleeve cuff.