Material handling in spinning mill

Material handling involves the movement of materials, manually or mechanically in batches or one item at a time within the plant. The movement may be horizontal, vertical or the combination of these two, says R Senthilkumar.

Material handling can be defined as: “art and science of conveying, elevating, positioning, transporting, packaging and storing of materials”. Material handling plays a vital role in any manufacturing industry by easily transporting the material from one place to another place. A material may be handled even 50 times or more before it conversion to finished product. It has been estimated that average material handling cost is roughly 10 to 30 per cent of the total production cost depending upon product to process. The cost of the production can be reduced considerably by saving the material handling cost.

Material handling involves the movement of materials, manually or mechanically in batches or one item at a time within the plant. The movement may be horizontal, vertical or the combination of these two. Material movement adds to the cost but not to the product value. The ideal manufacturing plant would have an absolute minimum of materials handling and more use of mechanical material handling equipment. The multiple benefits associated with effective material handling in a manufacturing industry are listed in table 1.1.

Principles of material handling

• Reduce the unnecessary movements (manual and mechanical) involved in a production process.
• Adopt possible shortest routes for transporting materials.
• Employ mechanical trolleys and fork lifts wherever essential instead of manual labor for material handling in order to accelerate the material movements.
• Adopt principle of containerisation or palletisation to transport bulk number of materials in single unit (bobbins, cones).
• Overloading of material in the material handling equipment should be avoided in order to prevent any material quality deterioration.
• Appropriate, standard, efficient, effective, flexible, safe and proper sized material handling equipments should be selected.
• Utilize gravity for assisting material movements wherever possible.
• Design trolleys, containers in such a way that material transported should not get damage during handling.
• Design material handling equipment in such a way that it economises the material handling process.
• The movement of material handling equipments should not interfere with neighbouring machine operations.
• The maintenance of material handling equipment is vital in preventing any interruption in handling.

Factors governing selection of material handling equipment:

• Dimensions and parameters of the materials being transported: The dimensions of the material being transported such as length, width diameter and material parameters such as weight, surface characteristics, delicacy and its chances of getting damaged during handling etc. should be considered
• Layout of Department: The path of material transportation, door dimensions, equality in floor levels between departments, height of the ceiling, strength of floor and walls, columns and pillars influence to a great extent the choice of a material handling equipment.
• Machine production: The machines may have different production rate per unit time. The material handling equipment should be able to handle the maximum output.
• Type of material flow pattern: A horizontal flow pattern may need trucks, overheads bridge cranes, conveyors etc, whereas a vertical flow pattern will require elevators, conveyors, pipes etc…
• Production type: The selection of the material handling equipment depends on type of production such as mass production and batch production. Conveyors are more suitable for mass production on fixed routes and powered trucks and trolleys for batch production.
• Other factors: Some other factors also considered during selection of material handling cost such as cost of material handling equipment, handling costs, life of the equipment and amount of care and maintenance required for the equipment.

Material handling equipment
in spinning mills

In spinning mill, there are many departments, which involve handling of raw material, intermediate products, wastes, finished goods, stores and maintenance tool equipment. During fibre to yarn conversion, materials (raw material, laps, sliver, roving, yarn, finished goods and wastes) are stored at different places and transported between departments. The selection of appropriate production machinery and proper lay-out of spinning mill eliminate as far as possible the need of material handling. In a spinning mill, the chute feed system, and automatic material transportation (ribbon lap, roving bobbin, ring bobbin, cone) reduces the material handling activities to a greater extent which significantly contributes to productivity enhancement. The selection of appropriate material handling equipment for performing a particular task is crucial in terms of safety and cost minimisation. The various material handling equipments used in different departments of spinning mill are summarised in table 1.2.

Spinning mills receive cotton fibres in the form of bales in lorries or trucks. Cotton bales usually weigh around 170 kg. In conventional mills, bales are transported with the help of 2, 3 or 4-wheeled industrial trolleys for storing in bale godown one by one which consumes time and requires more workers. Modern mills normally handling large number of bales can use forklifts exclusively for unloading bales from lorry and transporting them to the godown and stackers can be used to stack the bales.

• Mixing and Blow room department: In a conventional blow room line, cotton from the mixing to the mixing bale opener is transported by means of a mixing trolley. Use of lift-able spring type pedal operated mixing trolley eliminates spilling of the fibre tufts on the floor leading to poor housekeeping and more waste. This type of trolley can transport up to 30 kg of material at a time. In a conventional blow room line, blow room laps are transported manually by the workers keeping one lap at a time on the shoulder. Some modern mills having lap feed system are using lap trolley that can transport 4 to 6 laps at a time. The vertical stacking of laps closer together in the lap trolley may lead to damage the lap surface. Lap produced from blow room must be covered with synthetic cover cloth in order to correct the above problem.
• Trolleys used in carding, drawing and comber: Sliver cans (full and empty) are to be transported between cards, draw frames, comber preparatory machines, combers and fly frames. The cans in which sliver get deposited are of various diameter such as 14-inch, 16-inch, 42-inch and 48-inch that are provided with or without castor wheels. Cans that are transported manually by dragging them on the floor would not only spoil the floor but also damage the can and result in wastage of sliver. To overcome the above problem, the slivercan is normally transported by means of can trolley.
• Roving bobbins trolley: The doffed roving bobbins are normally placed on the top arm frames and the doffers then carry 8 to 10 bobbins by hand to the storage place. This practice affects the package quality and sometime may also cause injury to the worker. Roving bobbin trolley can be moved in between fly frames and up to 60 bobbins (30 on each side) can be stacked easily. After doffing, roving bobbins are usually kept in racks and transported to the ring frame by open type trolley or automatic roving bobbin transporting system. In another model of roving bobbin trolley, the spring-loaded bottom keeps the bobbins at an almost constant height and thus avoids physical strain on the workers and protects the yarn when loading and unloading the trolley.
• Ring bobbin trolley: In conventional mills, doffed cops are transferred to baskets or big containers and they are transported to post spinning departments in trolleys. This practice results damage to some cops and entanglements leading to yarn waste. Today, the ring bobbin trolley is used which has two compartments such as one for carrying empty cops and another for keeping doffed cops. Plastic crates can be fitted in the compartments. Each doffer must be given one trolley. Modern mills are equipped with automatic doffing and ring bobbin transportation which drastically reduces the yarn waste and labor requirements and improves yarn and package quality.

• Winding and packing: Cone/cheese trolleys are used to transport the cone from winding machine to packing section. Packed cone bags or cartons are transported to cone bag godown by carrying them manually. This reduces the capacity of material handling and some time it may cause yarn damage. Platform truck can be used to overcome the above problem.

Automation in roving bobbin transportation

Automation is about improving quality, because frequent contact with the bobbins, which damages the material and impairs quality, is avoided, and many working processes can be simplified and designed to be less labour-intensive. The bobbin transport system provides economic advantage to package handling in ring spinning. It ensures the protection of roving wound around the bobbin, which is highly liable to damage during manual transportation. The train of bobbins is automatically transported from speed frame to the storage area and respective ring frame by selecting the appropriate program in the PLC. Empty bobbins in the ring frame are manually interchanged with full bobbins.

Automation in Ring bobbin transportation

The maximum level of automation on the winding process is achieved by a direct link of the ring spinning frames to the winder. The advantage is continuous automatic transfer of the ring bobbins from one machine to the other. The main advantages are:

• Yarn quality of the wound package is preserved as bobbins are prepared and automatically doffed on the ringframes, without any operator handling or loading into separate boxes
• Higher efficiency on winder
• Production output flow consistency and timed as a single machine
• Minimisation of winding room personnel

The article is authored by R Senthilkumar from Yarn R&D of Super Sales India LTD-Textile Division, 34A, Kamaraj Road, Coimbatore – 641018, Tamil Nadu. He can be contacted on: 9677468590.