Jacquard Loom Calculation for Fabric Weaving

Jacquard Shedding Mechanism

• Single Lift Single Cylinder (SLSC) Jacquards have one operating cylinder, whereas Double Cylinder Jacquards have two cylinders, one for odd picks and one for even picks.

SLSC Jacquard Mechanism

• The mechanism completes its cycle once in every pick, being single lift and negative in action.
• Lifting of harness is achieved through jacquard hooks, while lowering is done by dead weights attached to the harness.
• Each hook is connected to a harness after passing through a grate.
• A double roller or pulley system is used to move the harness up and down.

Operating Cycle

• The initial position has hook (b) and its knife (f) in the uppermost position, while hook (c) and its knife (g) are in the lowermost position.
• The harness is at the bottom position at the initial stage.
• To remain lowered in the next pick, the right-hand solenoid is energized, and the retaining hook (d) does not catch hook (b).
• The knife (g) will then go up, taking hook (c) up, and the knife (f) will go down, taking hook (b) down.

Jacquard Capacity and Utilization

• Jacquard capacity = 10 x 40 = 400
• Total ends = 60 x 50 = 3000
• Number of repeats handled by jacquard = Jacquard capacity / (Ends per repeat) = 400 / 150 = 2.66 or 2
• Utilized jacquard capacity = Number of repeats handled by jacquard x Ends per repeat = 2 x 150 = 300
• Harnesses per hook = Total ends / Utilized jacquard capacity = 3000 / 300 = 10
• Width of repeat = (Ends per repeat) / (Ends per inch) = 150 / 60 = 2.5"
• Height of repeat = (Picks per repeat) / (Picks per inch) = 300 / 60 = 5"

Casting Out

• Warp thread density can be controlled by changing the reed count and reed plan in shedding mechanisms other than jacquard.
• However, every jacquard has a specific harness density, and the maximum ends per inch achievable on the loom is equal to the harness density.
• Casting out is used to achieve warp thread density less than harness density.

DLSC and DLDC Jacquards

• In Double Lift, Single Cylinder (DLSC) jacquard, the cylinder turns once, but the knives reciprocate (rise and fall) half the time.
• This is an advantage of DLSC jacquard over SLSC jacquard.
• DLSC jacquard produces a semi-open shed.
• Double Lift, Double Cylinder (DLDC) jacquard has two cylinders, one for odd picks and one for even picks, each carrying a pattern card.
• A 400 capacity machine will have 800 hooks and 800 needles.

This quiz tests your understanding of jacquard loom calculations, including total ends, repeats, and harnesses per hook. It's an essential concept in textile engineering and fabric weaving.