Unit 1: Loom fundamentals
Introduction to Weaving notes · PTU syllabus (BSTD 102-20)
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Unit summary
Weaving interlaces two sets of yarns at right angles to make fabric. This unit explains what a loom does, the motions of weaving and the parts of a table loom.
After this unit you can
- Define a loom and list its three primary motions
- Name the parts of a table loom and state their functions
- Classify looms by drive and by method of weft insertion
- Explain why shuttleless looms replaced shuttle looms in industry
PTU syllabus topics
Basic types and functions of a loom, parts and functions of a table loom
Warp beam
Holds the warp at the back
Heddles and shafts
Lift groups of warp threads
Reed (beater)
Spaces warp and beats in weft
Cloth beam
Winds up the woven fabric
Levers
Raise the shafts
Topic 1
What a loom does
A loom is a machine or frame that holds the warp (lengthwise yarns) under tension so that the weft (crosswise yarn) can be interlaced to form woven fabric. Every loom, from a simple frame to a high-speed air-jet machine, performs the same basic work.
- 1Shedding
Warp ends are separated into two layers to form a shed
- 2Picking
The weft is passed through the shed
- 3Beating-up
The reed pushes the new pick into the fell of the cloth
- 4Let-off and take-up
Warp is released and cloth is wound on
| Motion | Purpose | Mechanism on a table loom |
|---|---|---|
| Shedding | Raise some warp ends and lower others | Shafts (harnesses) lifted by levers or treadles |
| Picking | Insert the weft across the shed | Shuttle or stick shuttle thrown by hand |
| Beating-up | Push the pick into the cloth | Reed fixed in the beater (batten) |
| Let-off | Release warp from the warp beam | Ratchet and pawl, hand controlled |
| Take-up | Wind woven cloth on the cloth beam | Ratchet and pawl, hand controlled |
Shedding, picking and beating-up are primary motions; let-off and take-up are secondary motions; stop motions that protect the loom are auxiliary motions.
Topic 2
Parts of a table loom and their functions
Warp yarns run from the warp beam over the back beam, through the heddles and reed, over the breast beam and are wound as cloth on the cloth beam
- Frame
- Rigid structure that supports every part
- Warp beam
- Roller that carries the warp sheet
- Back beam
- Guides warp from the warp beam to the shafts
- Shafts (harnesses)
- Frames that hold heddles; lifting a shaft raises its warp ends
- Heddles
- Wire or string loops with an eye through which each warp end passes
- Reed
- Metal comb with dents (spaces) that spaces the ends and beats up the weft
- Beater (batten)
- Swinging frame holding the reed
- Breast beam
- Front beam over which cloth passes
- Cloth beam
- Roller on which woven cloth is wound
- Levers or treadles
- Raise the shafts in the order of the lifting plan
- Shuttle
- Carrier that holds the weft yarn
Topic 3
Types of looms
Handlooms
Frame, pit, table and floor looms operated by hand and foot
Power looms
Driven by electric motors
Shuttle looms
Weft carried by a shuttle across the shed
Shuttleless looms
Projectile, rapier, air-jet and water-jet looms
| Loom | How the weft is inserted | Notes |
|---|---|---|
| Table loom | Hand-thrown shuttle | Used in design studios for sampling |
| Pit or floor loom | Hand-thrown or fly shuttle, treadles | Traditional handloom clusters |
| Power loom (shuttle) | Shuttle propelled by picking sticks | Noisy, about 150–200 picks per minute |
| Projectile loom | Small gripper carries the weft | Wide fabrics, high speed |
| Rapier loom | Flexible or rigid rapiers carry the weft | Versatile for many weft colours |
| Air-jet loom | Compressed air blows the weft | Very high speed, fine yarns |
| Water-jet loom | Jet of water carries the weft | Fast, for hydrophobic filament yarns |
Values are indicative; shuttleless looms are faster, quieter and use less floor space per metre of cloth
Key terms
- Loom
- Machine or frame that holds the warp so the weft can be interlaced
- Warp
- Lengthwise yarns; Weft: crosswise yarn
- Shed
- Opening between raised and lowered warp ends
- Reed
- Comb that spaces ends and beats up the weft
- Heddle
- Loop that lifts an individual warp end
- Fell
- Edge of the woven cloth where beating-up occurs
Quick revision
- Primary motions: shedding, picking, beating-up; secondary: let-off, take-up.
- Table loom parts: warp beam, back beam, shafts and heddles, reed, beater, breast beam, cloth beam, levers.
- Shuttleless looms: projectile, rapier, air-jet, water-jet.
- The reed spaces the warp and beats up the weft.
Important exam questions
Practice questions written to the PTU exam pattern for this unit's syllabus: short answers (Section A style) and long answers (Sections B and C style).
Short-answer questions
- Q1.Define a loom.
- Q2.Name the three primary motions of weaving.
- Q3.What is the function of the reed?
- Q4.What is a heddle?
- Q5.Differentiate between let-off and take-up.
- Q6.Name two shuttleless looms.
Long-answer questions
- Q1.Explain the primary, secondary and auxiliary motions of a loom with a labelled sketch.
- Q2.Describe the parts of a table loom and the function of each.
- Q3.Classify looms and compare shuttle and shuttleless weft insertion.
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