Primary Motions of Weaving Loom Mechanism | Shedding Mechanism | Picking Mechanism | Beating Mechanism

Primary Motions:
These are fundamental or essential mechanisms. Without these mechanisms, it is practically impossible to produce a fabric. It is for this reason that these mechanisms are called ‘primary’ mechanisms. The primary mechanisms are three in number.
a. Shedding mechanism
b. Picking mechanism
c. Beat-up mechanism

(a) Shedding Mechanism
The shedding mechanism separates the warp threads into two layers or divisions to form a tunnel known as ‘shed’. The shed provides room for passage of the shuttle. A shed may be formed by means of tappets, dobby and jacquard.

Fig: Shedding motions.

 

Types of Tappet Shedding Mechanism:
Generally there are two types of shedding
1. Negative tappet shedding
2. Positive tappet shedding

Negative Tappet Shedding:
In a tappet shedding mechanism, if the tappet controls only one movement, either an upward or downward movement of the healed shafts, then the shedding is known as “negative tappet shedding”. The healed shafts are returned by some external devices like springs, dead weights, rollers, etc.

Positive Tappet Shedding:
In a tappet shedding mechanism, if the tappet controls both upward and downward movements of the healed shafts, then the shedding is known as positive tappet shedding.

(b) Picking Mechanism
The picking mechanism passes weft thread from one selvedge of the fabric to the other through the shed by means of a shuttle, a projectile, a rapier, a needle, an air-jet or a water-jet. The inserted weft thread is known as “pick”.

Picture: Picking Mechanism

 

(C) Beat-up Mechanism
The beat-up mechanism beats or pushes the newly inserted length of weft thread (pick) into the already woven fabric at a point known as “fell of the cloth”. These three mechanisms namely shedding, picking and then beat-up are done in sequence. 

Picture: Beating mechanism with sley