BIAS CUTTERS

The calendered fabric cut to specified width and
angle, using the machine commonly known as ‘Bias
Cutter’ , is called a ‘PLY’.
· It gives strength to the tire to contain the inflation
pressure.
· The number of layers is decided based on the
inflation pressure, bias angle, optimum modulus
gradation etc.
· From inner plies to outer plies to the breaker and
then to the tread there shall be a gradual reduction in
the modulus.




There are two types of bias cutters according to
the plane of movement of the fabric during
cutting.
1.Vertical bias cutter
2.Horizontal bias cutter

There are two principal types of tires in use today,
namely
1. Bias tire
2. Radial tire
The bias-ply tire is also called the cross-ply or
conventional tire. In this tire the cords in adjacent
plies cross the circumferential centerline of the
tire at opposite and approximately equal angles.

· In the radial tire, the ply cords extend radially from
the beads and are normal to the meridian of the tire.
· A high modulus cord-belt constrains the radial
carcass in the tread region

Bias angle

· The angle which the cords in the tire makes with respect to
the centerline of the tire is one of the most important
parameters in a bias tire.
· It is the equilibrium angle between radial force of inflation
pressure and circumferential forces of traction / braking,
directional control and centrifugal force.
· The performance of a bias carcass depends on the Bias
Angle.
· The higher the angle better the load carrying capacity.
· The lower the angle the better the speed capabilities and the
handling characteristics.

· Thus if the requirement is weighed more towards load the
angle will be in the range of 38°to 40°and the angle drops as
the emphasis shift to speed and directional stability like in
racing tires, where the angle is as low as 30°.
· This angle corresponds to a cutting angle in the range of 50 –60°.
· In the case of radial tires, the cured ply angles are in the
range of 85 –90°and belt angles range from 16 –25°.




Bias angle is decided so as to get the desired cured angle

Cured angle for different Bias tires:
Passenger : 32-38°
Light Truck : 35-40°
Truck : 35-40°
Rear Farm : 32-38°
OTR : 31-40°

Types of bias cutters

· Bias cutters are basically classified in to two types
depending on the plane of movement of the fabric
during cutting.
1. High table or Vertical bias cutter where the fabric
moves vertically during cutting operation.
2. Low table or Horizontal bias cutter where the fabric
moves horizontally during cutting operation.