Fabric cutting

Cutting is a preproduction process of separating a
spread into garment parts that are of precise size and
shape of pattern pieces on a marker.
Cutting Quality:
Cutting contributes to the quality, efficiency and cost of
subsequent operations, including handling, fusing and
sewing.
It can be judged by the accuracy and condition of cut
edges and precision of cut garment parts.

Accurate cutting facilitate sewing and improve cutting
quality. Inaccurate cutting may cause sewing operator
to compensate by stretching or easing to make
adjoining parts the same length.
Factors that cause cutting inaccuracies are
Wide or vague lines on the marker
Imprecise following of lines on the marker
Variation in cutting pitch
Shifting of the spread
Fabric bunching up or pushing ahead of the knife
Improper equipment
Improper cutting sequence as parts are cut.

Cutting pitch:
It is the angle at which the cutting device contacts the spread.
Maintaining the cutting device at vertical position with pitch
of 90 degree create uniformity.
Condition of cutting edges:
Smooth edges and precise corners are easier to align and
position during the sewing operations. Edges that are frayed,
jagged, scratched and fused are difficult for operators to pick
up, align and sew accurately.
The condition of edges is affected by
Appropriateness of cutting equipment
The shape being cut
Condition of the equipment

Cutting Equipments:
There are two major types of cutting equipments:
Operator controlled cutting systems
Automatic, Numerically controlled cutting systems

Operator controlled cutting systems
Hand Shears
Portable cutting machine
Vertical straight knife
Rotary knife
End cutter
Stationary cutting machines
Band knife
Die Cutter
Servo cutting machine
Specialized cutting machine
Stripe cutting machine
Automatic cutting systems
Automatic blade cutting
Laser cutting
Water jet cutting
Plasma jet cutting

Operator controlled cutting systems
Manually operated systems depend on the skills of operator
to position, manipulate and guide the fabric or cutting
device. Operator controlled equipment may be portable or
stationary.
Hand shear:
It is used normally for cutting of single or double plies
The lower blade passes under the plies and distortion of
fabric might be occur.
Both left handed and right handed shears are available
Disadvantage of method is time consumption and
consequent high labor cost per garment so not used at mass
level
It is useful for made to measure garments

Portable Cutting Machines:
Portable knives can move to and through a spread by an
operator.
There are two types
Vertical reciprocating straight knives
Round knives
Structurally and mechanically the two types of the machine
share many similarities
Both types have the base plate, power system, operating
handle, cutting blade, sharpening device and blade guard.

Vertical straight knife cutting machine:
It is used where the quantities for cutting does not justify
purchase of computer controlled system.
It is versatile and blade has a vertical cutting action.
The element of knife are base plate usually on rollers for
ease of movement, an upright or stand carrying a straight
or vertical blade and an electric motor, a handle and a
sharpening device.
The cutting blades are available with different edge
characteristics like straight edge blades, wavy edge blades,
saw type and coated blades.

The base plate slides under the bottom most layer of fabric.
Various types and sizes of base plates are available such as
small, medium and large.
Blade height vary from 4 to 14 inches.
The 90° angle of blade to the cutting surface make it
suitable for accurately cutting sharp corners, angles and
curves.
The greater the blade movement, the faster the blade cuts
the fabric and more rapidly and easily the operator can push
the machine

Rotary or Round Knife Cutting Machine:
It can be identified by round blade that cuts with a downward turn
at leading edge.
The element of machine are base plate, electric motor, a handle
and a circular blade.
The cutting capacity is determined by the radius of blade, motor
size and speed.
Blade diameter vary from 2.25 to 8 inches.

It can not be used around tight curves and sharp edges. May be
used for large radius curves.
This is not suitable for cutting curved lines in high lays because the
blade does not strike all the plies simultaneously at the same point
as the vertical point does. Therefore it is used only to cut straight
lines.

Rotary or Round Knife Cutting Machine (End Cutter):
The element of end cutter are same as round knife
machine except base plate including a rail onto which the
cutting head moves back and forth on the cutting table,
lifting mechanism to lift the rail after cutting each ply.
This is used to cut single ply during spreading process.
Used only for straight cuts.

Operator Controlled Cutting Systems:
Stationary Cutting Machines:
Stationary cutters are those cutting machines that have
blades that remain in fixed position
The two types of stationary cutters are band knife and die
cutters
Operator must move the fabric to the machine for cutting
action

Band Knife Machine:
It comprises a series of three or more pulleys, an electric
motor with a continuously rotating steel blade mounted on
them.
One edge of the blade is sharpened.
The band knife passes through a slot in the cutting table
in a fixed position and the section of the lay to be cut is
moved pass it.
The operator position and guide the fabric around the
knife.

Pieces to be cut are first cut on a block and then cut
exactly on band knife.
Heavy cardboard may be placed on top of a section block
to provide a guide for cutting specific shapes.
Band knives are used for highly accurate cutting.
Band knife blade is finer and narrower than reciprocating
blades so they can be used to cut tight curves.

Die Cutting:
Dies are preshaped metal outlines with one cutting edge.
Die cutting involves uses of a die to cut out a specific
garment part or trim from a single piece or small block of
fabric.
Die cutting involves placement of fabric, positioning the
die on the fabric and engaging the machine to press the die
on the fabric.
Dies can also be used to cut parts from centre of fabric
Die cutting is labor intensive when dies placed manually.
Only a small area of fabric cut at one time and die must
be repositioned each time.

Servo cutting machine:
It is between manual and automatic cutting machines.
This machine has servo motor with adjustable speed and a
system that supports the knife perpendicular to cutting
table.
It can combine vertical cutting and band knife cutting in
one machine.

Specialized Cutting Machines:
Stripe cutter:
Stripe cutter may cut or cut and roll stripes or bindings
from knit tubular yardage, cut bias stripes from woven.
Stripe cutter is used to measure and cut lengths of
material as ribbon, tape, elastic and strapping.

Automatic Cutting Machines:
Automatic blade cutting:
These are used to cut large number of plies with great
accuracy and speed.
Information can be sent directly to the cutting machine.
The central control unit operates the components such as
cutting head, cutter carriage, knife sharpening and
conveyorized cutting table.
Automatic knife sharpening is done at intervals during
cutting.
The reciprocating blade can be adjusted to the height and
density of fabric

Laser Cutting:
Laser cutting focuses a powerful beam of light projected onto a
minute area to cut fabric. The fine V shaped beam is only 0.004 of
an inch. The beam cuts without pressure on the fabric which is a
major advantage for some types of fabrics. The fabric remain
immobile during cutting.
Laser cut with high speed, accuracy and multidirectional ability
but with some heat emission.
The heat produce can seal fabric edges which can be advantage
for fabric that ravels and disadvantage for cutting multiple plies
as edges fuse together.
The handling operation of laser cutting is labor intensive as well
as parts must be handled individually.

Water Jet cutting:
It is computer operated multidirectional cutting method.
Water jet cutting is done by propelling a tiny jet of
water(0.0010-0.0015 inch) through the fabric at very high
pressure (70,000 pounds per square inch)
The forward edge of the jet stream shears the fabric as it
moves along the cutting line but does not wet the fabric .
It can cut multiple plies without fusing but it can fray and
tangle the yarns of some fabrics.
It is used when heat build up is avoided but water
absorption is not important.
At present time its uses are limited to cut leather and vinyl
fabrics.

Plasma Jet Cutting:
It is computer operated, high speed, single ply cutting
device that offers same features as laser cutting but at lower
price.
ATV camera reads the fabric on the conveyor and a digital
image processor decides the best way to match and lay out
the pieces based on predetermined matching rules.

Cut parts identification:
It involves identifying and marking parts for further
operations. Through out the sewing operation it is essential
that each garment be assembled from the parts that have
been cut from the same ply of the fabric, which is ensured
by shade marking each piece in the lay.
Ticketing:
Each piece or garment part is ticked with a style number,
size and ply number. Plies are numbered sequentially.
Garment parts are grouped and bundled for the specific
production system to be used.

Fabric cutting

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Fabric cutting