A good factory layout is directly associated with good workflow, right from material receiving till the finished goods go out of the factory. Whatever type of plant layout a firm develops, it should be designed to optimise quality, throughput time and flexibility.
Experts differ in views on how and what constitutes a good layout. It is never easy to rate one layout over the other when both achieve the desired results. But at times, little changes bring wonders.
Suresh Dureja, in this article, defines the basic considerations while conceptualising and designing a factory layout.
Plant layout is the spatial arrangement and configuration of departments, work stations, machinery and equipment used in the conversion process. Layout of an apparel production plant directs the flow of materials and work-in-process from start till its completion and integrates material handling and equipment.
An efficient layout has the flexibility to be changed to meet requirements of the product line, delivery schedules, and anticipated volume. Safety is a major consideration in plant layout. Fire and safety codes, emergency and accessible exits, open traffic areas, etc. must all be a part of layout plans.
The following factors should be taken into consideration while planning a layout:
• Minimization of manufacturing cost,
• Feeding the materials and parts at highest possible speed and in one direction without any backtracking or overlapping flow of products,
• Minimization of work transfer among the processes from acceptance of raw materials till delivery of finished product with properly defined spaces for each process, and
• Provision of future expansion plans.
The layout planning should be done based on factory site selection and arrangement of building and machines.
Layout of the Plant
Layout of the plant is decided based on process sequence, building structure, shop floor transportation, type of layout (product or process based or a combination of both) and arrangement of machines. The aim of every layout is to maximize utilization of available space in order to speed up the material flow. Highly specialized machines and small parts assembly may be configured with a line arrangement for final assembly.
Factors to be considered for designing an effective layout include number of workers both male and female, number of machines (size, weight by models), entrance, exit and passages (size, width, position, number of each of them) for production as well as administrative wing, change room, lunch room, lavatories, medical emergency room and provision for those governed by local laws. Utilities like boiler, air compressor, vacuum pumps, generator, electric panel, air conditioning machine, underground water storage tanks for boiler and washing machines, water softening plant, waste water recycling plant, drainage system are also equally important.
General Steps for Making a Plant Layout
Make a scaled drawing of factory/shop floor
Make models of machines/equipments
Draw immovable facilities/equipments
• Entrances, exits/stairs
• Washrooms, corridors
• Pillars, partitions
• Air conditioning ducts, steam, air and vacuum lines
• Power outlets, electrical lines for feed to machines,
Arrange the main flow process in a straight line regardless
of available space
Arrange the main flow process in the available space
If it is necessary to change the direction of main flow process change it for worker who is in charge of an iron or a special purpose machine
Arrange the additional divisions in the remaining space
Make a final drawing based on completed machine layout
Other factors that need attention before laying out the factory plan include ceiling height (3-3.5 metres from floor), lighting (large windows of 2 or 3 stages) and illuminance levels (600 Lux for production and 800 Lux for inspection areas) besides ventilation. Also, the workplace should have sufficient number of men’s and women’s toilets and drinking water outlets in the vicinity.
Factors influENcing Machine layout
“Machine layout is the arrangement of available space based on conditions required by production system design and depends on various factors.” – Suresh Dureja, Director of Manufacturing, Canada Goose, Toronto, Canada
1. Types of products to be manufactured
The number of different types of product items, man hours, lot size, variation in garment design, degree of fluctuation in a year, etc.
2. Manufacturing system
According to sewing system being followed, like make through, PBU assembly line, sectional assembly line, UPS with overhead hanger, teamwork with stand up working (TSS).
3. Method of style changeover
Overall change or consecutive change.
(a) Overall change
All products/styles being manufactured are entirely different from each other and require major changes in operation sequence and in layout of machine with requirement of special purpose machines, for example shirts, trousers, jackets, ladies dresses, etc.
(b) Consecutive change
The products/styles being manufactured are with slight style variations only. That is most of the operations are similar and do not require major changes in layout of machines/operations, every time new style is introduced, for example in formal shirts, casual shirts, etc.
4. Material transfer system
Per bundle system or per piece system.
(a) Bundle system
The garment parts are made into bundles of 5, 10 and 15 pieces depending on kind of garment being made. The bundles are moved from one operation to another. Bundle size is important for selecting an appropriate handling method. Bundles can be in tied form, in plastic bags, in boxes and baskets, in bundle trucks, in clamps, on rails, etc.
(b) UPS overhead hanger system
The garment parts in single piece clipped in overhead hanger rails, where movement of rails can be manual (switchtrack/UHS) or motorized (ETON).
(c) Per piece
It means that garment parts are transferred piece by piece from one operation to another, for example in Toyota Sewing System, etc.
Number of cut components and half finished garments being maintained as WIP between operations.
6. Storage method of semi-finished products
Distribution of cut parts and temporary storage of semi-finished products in assemble tables, racks, shelves, bags, etc.
Special purpose machine, general purpose machine, semi automatic and automatic workstations (where machine to operator ratio is more than one).
8. Transfer equipment
(a) Manual humping
Bundles are picked up and carried by the operators to and from the workplace and storage area. Little capital is necessary for this method which is flexible. But its efficiency is restricted by the maximum load that can be carried by distance.
Bundles on racks are used between groups of operations. These facilitate visual balancing, reduce space requirements and improve the appearance of the shop floor. Bundle size is limited by the rack and box or basket size in which they are held. Garments are carried to and from the racks by hand.
(c) Trolleys or trucks
These permit the use of larger bundles or group of bundles, bulkier or heavier than those which can be moved by lifting or carrying, for example in the shirts, jackets and jeans factories.
(d) Unpowered conveyors
Chutes, roller conveyors and rails are all cheap and convenient means by which work can be stored or moved. They permit the use of bundles which are far heavier than would be possible by manual humping. Chutes must be set at a steeper angle. Gravity will only power one way systems.
(e) Powered conveyors
Belts and rails belong to this type. Suited for automatic routing, rails are run at head height and permit long garments to hang so that they crease little in transit.