Systems of Cutting

  1. Hand Shears   :   Hand shears are normally used when cutting only single or double plies. The method is flexible enough to accommodate any fabric construction and pattern shapes. It is appropriate for made-to-measure garments. But it consumes a lot of time and the consequent high labour cost per garment.

Straight Knife

It consists of a base plate, usually on roller for ease of movement, a stand carrying a straight vertical blade with varying edge characteristics and an electric motor above it, a handle for the cutter to direct the blade and a sharpening device. The base plate on its roller slider under the glazed paper which is spread below the bottom ply of fabric in the lay.

Two kinds of power are required to operate a straight knife. Motor power drives the reciprocating blade and operator power drives the knife through the lay.

Advantages: It is most common means of cutting lays because it is versatile, portable, cheaper then a bent knife, more accurate on curves than a round knife, relatively reliable and easy to maintain.

Round Knife

Blade diameter vary between 6 cm to 30 cm

Advantage: It is a fast machine , excellent for cutting straight lines or gradual curves.

Disadvantages: It is difficult for a circular blade to negotiate a tight curve, such as an arm hole

Bend Knife

It consists of an electric motor with a continuously rotating steel blade. The blade knife passes through a slot in the cutting table in a fixed position, and the section of lay to be cut is moved past it.

Advantages: Bend knifs are used when a higher standard of cutting accuracy is required. They are used more in mens wear than in women’s wear as they are often used to cut large garment parts, such as large panels of jackets and overcoats.

Computer Controlled cutting

The input for this operation comes from the markers generated on computerized marker planning systems. The marker planning is transferred to the cutting unit by means of tapes or floppy discs etc.

Advantages: Computerised cutting is six to eight times faster than any manual method and produces cut components with a consistent level of accuracy.

Disadvantages: Requires a substantial initial investment.

Methods of cutting

The following points should be taken care of while cutting:
1. The blades must present very thin edge to the fibres so that high pressure may be presented to the fibres enough to shear them without stretching or deforming them. 
2. All fibres must be severed to allow the blade to pass through the fabric and produce free standing cut parts
3. the Act of cutting dulls the blade, so blade must be regularly sharpened to renew the thin sharp edge. 
4. The methods of cutting must not remove any material between the cut parts
5. Fabrics should return to their original shape after cutting
                                                                                      

The Cutting of the Fabric

The objective of Cutting

The objective of cutting is to separate fabric parts as replicas of the pattern pieces in the marker. In achieving this objective, certain requirements must be fulfilled.

1. Precision of the Cut

The garments must be cut with as much precision as possible.

2. Clean Edges

The raw edges of the fabric should not show fraying or snagging. Such defects come from an imperfectly sharpened knife

3. Unscorched, unfused Edges

The built up of heat in the knife blade comes from the friction of the blade passing through the fabrics. Solutions to this problems lie in well sharpened blade, the use of antifusion paper, spraying the blade with silicon lubricant, slowing down the speed of the cutting blade and reducing the height of the lay.

4. Support of the Lay

The cutting system must provide not only to support the fabric but also to allow the blade to penetrate the lowest ply of a spread and sever all the fibres

5. Consistent Cutting

The cutting system must cut accurately irrespective of the height of the pile.

The Cutting of the Fabric