Wednesday, July 4, 2018

Planning of Garments Pattern Making

Planning of pattern making:
Planning of pattern making is the first stage in clothing production planning. This stage includes all activities from garment pattern design, grading and preparation of markers to material requirements.

Constructing garment patterns:
Constructing garment patterns is a very complex process that is performed, for particular types of garments, on the basis of

  • Additional measurements
  • Back and chest widths
  • Body measurements
  • Body proportions
  • Construction measurements and
  • Garment-sizing systems and size designation of clothes
  • Main body measurements
  • Pictograms
A pattern is a diagrammatic representation of the way a garment part is constructed, which forms the working plan for its manufacture. As garments are generally composed of the basic fabric, lining, and interlining, they require a pattern for the basic fabric, which will then form the basis of the pattern for the linings. Lining patterns should always include what is known as ‘ease’. The lining should never pull the clothing out of shape or cause wrinkles. The ease may have to be increased, depending on the spread or stretch in the clothing fabric.
Jacket's pattern pieces for lining pattern
Fig: Jacket's pattern pieces for lining pattern (Image courtesy: https://www.threadsmagazine.com)
Industrial pattern making has two basic stages,
  1. The block pattern. The block pattern can be created by two ways: a) Flat Method b) Modeling
  2. The garment pattern.
Garment Patterns Constructions are done by ways, Manual or conventional method and by computer (CAD). Basic pattern construction and modeling can be performed either in the conventional manner or by using a computer aided designed (CAD) for the purpose. In the conventional manner, the construction, modeling and modification of garment pattern-pieces are done manually, whilst grading (i.e. stepwise increase or decrease pattern-pieces) can be done manually or using appropriate computerized systems. When garment patterns are constructed using a computer (with such systems offering construction, modeling and modifications of the basic pattern, as well as simultaneous grading of individual pattern-pieces into target sizes), it is necessary to do the following:
  • Systemize the pattern-pieces and models
  • Prepare the pattern-pieces
  • Determine the type of material to be used and
  • Define the cutting marker parameters.
Contrary to the above, in conventional construction preparation, which includes the construction, modeling, and modifications of garment pattern-pieces manually, it is necessary to prepare the pattern-pieces in advance, which can be used later during computerized processing.

Instruction of garments pattern making:
To enable the garment to be made up correctly, following instruction must be marked on apparel pattern:

  • Balance Mark: Used to ensure patterns are sewn together at the correct points.
  • Construction Lines: These include button holes, pocket placing etc.
  • Grain Line: All patterns must have grain lines. It indicates the length direction of fabrics, i.e. during marker making all patterns must be placed to the length direction.
  • Name of the part
  • Size ( it will show you how to find your size on a pattern finished garment measurements)
  • Style Number.
Pattern Pieces and Their Preparation:
A pattern-piece can be defined as a component of a garment pattern constructed on the basis of technological-construction requirements, or a component of a garment part cut from a particular template. A pattern-piece should contain a designation (code), size designation, marks for the positions of darts, folds, pockets and control incisions, as well as an indication of yarn direction (warp yarns or loop column in the case of knitted fabrics). Pattern-piece designation should be composed so as to indicate the type of fabric used (or other sheet material, such as leather, fur, etc.) for the pattern-piece in question and the model to be manufactured, the designation of the appropriate grading table, the name of the model, and the identification code that indicates particular model pattern-pieces. A nine-digit designation is often used (although contemporary systems enable larger designations to be used, up to 13 digits), where the first six digits indicate the model, whilst the last three describe the pattern-piece. The pattern-piece designation therefore assumes the following form:

1. Adding seam and hem allowances:
The seam allowance, which is defined as the distance between the seam line and the cut edge, should be determined for individual pattern-pieces, with respect to their clothing models. Within the seam allowance is a defined measure, which varies from enterprise to enterprise but should be defined uniformly in every production. The seam allowance can be, depending on the production programme and the seam position, between 7.5 and 15 mm. The standard seam allowance measurement is 10 mm, but high quality garments (e.g., a jacket) may have 15 mm seams on the back and side seams. Intricate seams, such as welt seams, will also vary in size. The hem allowances are also different. For example, hem allowances on the body and sleeve of a coat are approximately 40 mm.

2. Preparation of pattern-pieces for digitizing and grading:
Garment pattern-pieces are generally formed of particular geometrical shapes that cannot be easily stored in a computer memory but have to be converted into a form appropriate for computer notation, that is, an electronic form that is appropriate for further computerized processing. There are various actions to be taken in the preparation of pattern-pieces, their storage and computerized grading. An important step is the systematization of those pattern-pieces and model names necessary for computerized pattern-piece grading and cutting-marker planning; all the data necessary for these two actions should be systematically included in adequate databases, which involve:

  • Basic pattern-pieces;
  • Grading rules;
  • Garment models; and
  • Cutting-markers.
Pattern-piece preparation for digitizing involves:
  • Defining pattern-piece contours, being composed of a number of different lines, each starting with one and ending with another main point;
  • Decomposing pattern-piece contours;
  • Determining segment types, where those with straight lines are defined by their first and second main points, whilst those with curved lines are defined by their starting and ending points, as well as those with auxiliary points, which further define the shape of a particular curve.
  • Determining auxiliary points in the areas of curved segments;
  • Defining those border garment sizes for which grading is to be performed.
  • Defining those types of garment sizes for which grading will be performed within the border areas previously determined;
  • Designating the main and auxiliary points on the pattern-pieces contour, as well as inner points;
  • Determining the types (TIPs) and manner of moving (COD) the main points, where the main point TIPs define various designations, warp yarn direction, darts, pockets, folds, etc. Inner contours and inner points can be distinguished from the point of view of main point TIPs whilst COD describes the interval of size deviation from the basic pattern-piece of the basic size, towards particular measurement sizes.
Types of point TIPs on a jacket basic pattern-piece
Fig: Types of point TIPs on a jacket basic pattern-piece.
Pattern-pieces are digitized using a digitizer, which physically transforms geometrical shapes of pattern-pieces into a series of numbers that are appropriate for computerized processing. In order to perform this process, the pattern-piece is attached to the digitizing tablet and the position of each marked pattern-piece contour point is recorded, in a clockwise direction. The digitizer is linked to a microcomputer, which records data on the position of each point.
Fig: Schematic diagram of a digitizer used for recording and reading-off
Pattern-pieces can be digitized in three ways:

A. Digitizing is done on a previously prepared grid of basic size pattern-pieces, highlighting the biggest and the smallest.The coordinates of the main and auxiliary points, as well as the grading values, are stored by the computer.

B. Digitizing with the simultaneous formation of a grading database. Digitizing is again performed from the previously prepared pattern-piece contour grid. However, grading data are shaped during digitizing and are stored in the database containing this type of information.

C. Digitizing referring to the designation of the memorized grading rule values. The basic size is digitized for this purpose.

Pattern pieces digitizing with Gerber technology system
Fig: Pattern pieces digitizing with Gerber technology system
The pattern-pieces are graded when the digitizing and control processes are complete, by employing previously determined grade rules (also called grading rules). Grading means the stepwise increase or decrease of a master pattern-piece to create larger or smaller sizes. The direction and values of the shift for each main point position during grading are defined at each main point of each segment. When digitizing is over, modifications and digitizing control have been performed successfully and the grading rules are stored, the digitized pattern-pieces are stored as well.

3. Preparation of pattern-pieces for model definition:
Garment model defining is started when the preparation of pattern-pieces has been completed, that is, digitizing, confirmation of variable data on the pattern-pieces main points for basic fabric, and modifications for the other pattern-pieces, such as pattern-pieces for the lining and interlining. The garment model includes all the pattern-pieces necessary for manufacturing an article of clothing. These are:

  • Pattern-pieces for the basic fabric;
  • Pattern-pieces for the lining;
  • Pattern-pieces for the fusible interlining;
  • Pattern-pieces for the auxiliary fabrics (pockets, etc.); and
  • Templates to be used when marking the positions of pockets, buttonholes, etc.
A model is defined by its name and the list of pertaining pattern-pieces, by the number of repeated pattern-pieces, and by the type of fabric used. Apart from those requirements that define the basic characteristics of a particular pattern-piece, each pattern-piece should also contain symbols that clearly determine its position within the cutting-marker. For example, the quality of a finished article of clothing is affected significantly by the position (direction and orientation) of a pattern-piece into a cutting-marker. The symbols are used to arrange pattern-pieces into a cutting-marker. The symbol charts are in below:

When preparing model pattern-pieces from patterned fabrics, that is, fabrics with checks, stripes or other patterns, it is necessary to determine the requirements for matching pattern repeats. The quality of a product is affected significantly by the accuracy of pattern matching, and the positions of the components during matching pattern repeats in a finished article of clothing can be:
  • Transversal pattern match related to seam symmetry;
  • Repeat of the pattern match related to seam symmetry;
  • Transversal pattern match regardless of seam symmetry; or
  • Repeat of the pattern match unrelated to seam symmetry.
The following symbols in figure can be used to designate pattern match, or pattern-repeat match, for pattern-pieces in the area of the seam. During spreading it is necessary to match the pattern exactly at each end of the lay and in every ply.
Types of pattern matching
Fig: Types of pattern matching
References:
  1. Design of Clothing Manufacturing Processes by Jelka Gersak
  2. http://textilelearner.blogspot.com/2011/05/description-of-apparel-garment-patterns_3015.html
  3. https://www.slideshare.net