APPAREL MANUFACTURING - I 3(1+2)

Lesson 7 : Pattern Grading

System Description

A typical system usually contains of five hardware units operating in conjunction with a central processing unit and these units are:

1. Central Processing Unit: This is the unit of the computer which includes the circuits controlling the interpretation and execution of instructions. The CPU is generally referred to as main frame.

2. Disc Drive Unit: This includes the magnetic disc which is a mass storage device with real time recall and interfaces directly with the CPU. This unit primarily provides data storage for on-going operations and information can be transferred from the disc to a magnetic tape or floppy disc for temporary or permanent storage.

3. Graphic Display Terminal: This is the basic work station of the system and provides the means to implement and visually monitor functions relating to pattern grading and marker planning. The unit itself consists of :

   1. The cathode ray tube display screen on which the operator can view the contents of files and the graphic display of stored pattern pieces and markers. Most systems have the option of regular or coloured displays.
   2. The keyboard which interfaces with CPU and through which the operator is enabled to input commands for data processing and manipulation routines.
   3. The terminal’s data tablet and pen which are used to position pattern pieces during the marker planning process or for manipulatory routines when creating patterns via the system.
   4. The graphic display terminal can also be configured with an on-line printer which prints out commands and system responses.
4. The Digitiser : This unit consists of digitising work table and a free floating cursor which are used to convert pattern shapes into a format understood by the computer system. This format is basically a description of the lines of the pattern according to sets of X and Y coordinates. The cursor has two hair lines engraved onto the viewing glass and the intersection of these lines is used as the registering point. The cursor is placed on a line and when a button is pressed, the X and Y coordinates of the location of the cursor register point is inputed to the system. This process is repeated on a number of points on a line segment so that the computer can then determine the curve to be used which would precisely represent the original pattern line segment for grading. Apart from the entry of grading instructions, the cursor’s buttons are used to input other information which has positional characteristics such as notches and drill holes.


5. The plotter: This generates system output in the form of pattern pieces and / or markers. The plotter users the same type of information as that recorded by the digitizer, namely X and Y coordinate values. These coordinates define the position of the pen on the paper and successive commands provide the necessary instructions to the plotter for the definition of the required line.

The plotter has its own CRT terminal which controls the plotting function. In addition, the plotter can be equipped with a knife for cutting out patterns, or alternatively, a laser cutter can be used for this purpose.

Software

These are the programmes and procedures which control and co-ordinate the tasks associated with all of the functions of the system.