Operation sequence, material flow pattern, stages of material flow at receiving, in process and at shipping, flow planning criteria & design of flow pattern.

1. Unit 04: Material Flow
Understanding Material Flow
We heard this word while studying the principles of material handling i.e. material flow. A
material (material means raw material, supplies or parts, goods in a ware house, paper or file
in an office or bank, medicines in a hospital) flow principle looks after planning an
operation sequence and equipment arrangement to optimize material flow. The material
flow should be based on layout or operation sequence. The material is required to be moved
from the beginning i.e. from receiving to end shipping over the most efficient paths.
Although the material flow in industries occurs prior to receiving that is from source
of supply to the plant and, after the shipping i.e., in distribution and service to the customers.
By providing orderly flow of materials the productivity can be improved. The most
common error in material flow is back hauling or the back tracking, which means that
once the material has passed through an operation it must maintain its direction and
does not retrace its path.
The material flow could be optimized by eliminating the obstacles in material flow, by
planning material movement in a direct path; and by avoiding backtracking, zig-zag
movements, by using product layout whenever possible, Keeping related work areas close
together, or by combining operations to reduce material movement. There should be
minimum movement between the floors and the bulky or weighty materials should be moved
the least distance, further the processing of heavy and bulky materials should be done close
to receiving.
Operation Sequence:
Production Planning and Control: It is an organized activity of converting raw materials
into useful products. But before starting the actual production, production planning is done

2. to anticipate possible difficulties and to decide in advance as to how the production process
should be carried out in a best and economical way to satisfy customers. Since only planning
of production is not sufficient, hence management takes all possible steps to see that plans
chalked out by planning department are properly adhered to and the standard set are
attained. In order to achieve it, control over production is exercised. The ultimate aim of
production planning and control (PPC) is to produce the products of right quality in right
quantity at the right time by using the best and least expensive methods.
Sequencing
The order in which jobs pass through the machines or work stations is called sequencing.
The relative priorities are based on certain rules as discussed in the following:
 First Come, First Served (FCFS) rule: This is a fair approach particularly applicable
to people. In case of inventory management, it is First In First Out (FIFO). That
means the 1st piece of inventory at a storage area is the 1st one to be used.
 The shortest processing time (SPT) rule: SPT rule sequences jobs in increasing order
of their processing times (including set up).
The flow of part is the path which that part takes while moving through the plant. We can
improve the flow by developing product or parts classes with similar flow. We can try to get
each part to take a similar path, and we can try to move the parts automatically. The
movement of men and materials is the most important aspect which should be critically
examined. The graphical techniques are more common for analyzing the move. The most
commonly used such techniques are Operation process chart.
Operation process chart: These are useful to show operation performed on each component,
sequence of operations, sequence of component production and assembly, accurate material
flow pattern. Or
Operation process chart is a graphic representation of the sequence of all operations and
inspections involved in the process. This provides a compact view of the whole system of
operations involved in the manufacture of a product.
Sample Operation Process Chart

3. Operation Process Chart for an electrical bulb
In the figure above the horizontal lines indicates all components or materials entry points,
whereas the vertical lines shows processing of these materials.
Material Flow Pattern: For Production :
Flow Pattern: flow pattern means the system to be adopted for the movement of raw
materials, from the beginning and up to the end of manufacturing. The overall objective of
the flow pattern is to plan for the economical movement of the raw material throughout the
plant.
Classification of flow pattern: the flow system can be classified into horizontal and vertical.
The horizontal flow system is adopted on a shop floor while vertical flow is adopted where
material has to move in a multi-story building.
Horizontal Flow Lines:
I flow or line flow, L-flow, U-flow, S-flow, O-flow
I flow or line flow is the simplest form of flow. The materials are fed at one end and
components leave line at the other end, may be preferred for automobile industries. L-flow, is
used where I flow cannot be accommodated in the available space. In the U-flow, both
feeding and output takes place at the same end. This method is easier for supervision, and can
be adopted in manufacture of electric motor. S-flow, is used if production line is very long, as

4. it provides sufficient use of space. O-flow, is used where operations are performed on a
rotary table or rotary handling systems, such as in manufacture of electric bulbs.
U-Flow S-Flow
O-Flow I-flow L-flow
Vertical Flow Lines: following are the types
Processing downward or upward, centralized or decentralized elevation, unidirectional and
retractional flow, vertical and inclined flow, single or multi-flow.
In the unidirectional flow the material is passed from one station to another without having to
pass along the same path again. Whereas in retractional type, the flow is repeated i.e. two or
more non-consecutive operations are performed on the same machine.
Unidirectional and Repeated flow

5. In the downward processing the materials are fed from the top floor and in upward processing
the materials are fed from the bottom floor while the finished product is received at the top
floor. Downward are economical since gravity principle can be used.
In the centralized elevation all the material handling devices are installed at one central place
of the building. Therefore this system is economical in supervision and maintenance. A
decentralized elevation method is more costly in installation, maintenance and space but by
this method handling on each floor can be greatly reduced and more flexibility in design on
flow lines is possible.
Vertical Flow Systems
Vertical type of low is more economical and carried on with material handling devices such
as elevators, chutes and buckets. Inclined flow may also be carried out by conveyor belts
such as in coal mines, and chain system to move boiler grates.
In a single flow, there is only one flow line of materials while in multi-flow there will be
several flow lines and all these feed one assembly line.

6. Material Flow Pattern: For Assembly
These are used in establishing the general shape of assembly lines. Commonly used flow
patterns are
Comb pattern, tree pattern, dendritic pattern, overhead flow pattern.
In the comb pattern the main assembly line is fed from a series of subassembly. In tree
type, the main line is fed by subassembly or parts lines from both sides. The tree pattern is
used when the main assembly line is located near the center of an area. In dendritic pattern,
each part progresses along its product line until production is completed to the point of
assembly at which time it is combined with other parts to form a sub-assembly or assembly.
Assembly Flow Patterns

7. Stages of Material flow at receiving, in process and at shipping:
1. Receiving: In every manufacturing or physical distribution system material flow
begins with the receipt of the material. Since prior to this time the material had to be
purchased.
The quickness with which material moves from the carrier, across the receiving dock, and
out of the receiving department is a measure of its efficiency. Does the material on the
receiving floor moves out within 4 hours, 24 hours or 3 days or week, is generally an
indication of the pace of the overall plant operation. Product mix of items to be handled and
method of transportation, that is whether the material arrives by over-the-road carriers, city
delivery trucks, rail or a combination of these methods, needs to pay, special attention in
working on receiving area material flow. Material should be moved within four hours from
the receiving floor that should be target.
There should be provision in receiving area for truck wells (Concrete truck wells are
special type of concrete structure that provides a bay area for large trucks to back into. They
provide a strong stable platform for trucks being loaded with goods as well as the surface for
the equipment loading the trucks) and it is better to provide more space than congestion.
Truck Well and Overhead Bridge Crane
Further, an overhead bridge crane should be situated over the truck well so that flat bed or
open vans may be unloaded. Truck dock levelers need to be permanently installed as a part of
the layout, concerning safety and better utilization of space.

8. Truck Dock Levelers
The receiving space should be intelligently designed. We should consider the over the road
carrier truck door sizes, dock aprons (Apron space is the space between the loading platform
and the nearest obstruction. Apron space includes the parking area where the truck parks at
the dock and the maneuvering area, which is the area the truck uses to maneuver in and out of
the parking area.
Apron Space
For modern and progressive receiving department one can think of implementing in
floor, drag chain conveyors, and tow conveyors. Tow Conveyor could be used widely owing
to its versatility. It does not require an operator. The tow conveyors should be used for the
movement of material from shipping to receiving. Since, we can use the empty pallets
coming from shipping in receiving floor, where they can be used to load incoming materials.
Again if tractor trailer trains are used in the receiving department, the flow of material should
be from shipping to receiving, in order to supply pallets for the receiving function, obtained
after offloading and depalletizing.
Railcars are preferred than trucks as they carry 40 to 70 more tons of merchandise.
Skate wheel and gravity roller conveyors are used widely to increase the productivity of
receiving department.

9. The provision of walking beam can be used to unload the truck within minutes. Also powered
conveyors can be used effectively.
Many types of materials can be conveniently stored out of doors, like steel, castings, that is
called as outdoor storage or yard storage.
If receiving department knows where to send each incoming material, a large amount of
double handling can be avoided.
Tow Conveyors
Drag chain conveyors

10. Railcars

11. 2. In process handling: Material Flow
The movement of materials as they proceed from point to point within the production or
order selection cycle is considered as in process handling material flow. In the production or
fabrication cycle, raw or purchased finished material is received and then transported to
one of four destinations. There should be standardization of containers used in the in process
handling systems.
The material can be held in temporary storage awaiting inspection, the material can be
placed in short or long term storage to be held until needed, the material can be transported
directly to the assembly line to become part of the complete product or a subassembly, as is
sometimes the case with purchased finished materials, or the raw material can proceed to a
fabrication line where it may be cut, turned, drilled or so.
Further there should be control of the in process materials. It may be controlled by placing
the material in high rise, high density stacker crane retrieval system and use either a
punch card or tape controlling means with a process controlling computer.
High Rise, High Density Stacker Crane Retrieval System

12. 3. Shipping : Material flow
Shipping is the one single area in the plant where collusion for theft is most predominant.
Thus systematic organization of the shipping department is absolutely essential to maintain
the highest degree of accountability for the material flow across the shipping floor.
Design the shipping area to provide easy access to it from all parts of the plant. Further, as
loads are built up on the shipping floor, there should be a direct flow of this material to the
carrier.
Further the shipping department is usually larger than the receiving department in square feet
of the floor space. The reason for this is loads must be accumulated to await a carrier and the
materials may move in to the shipping department at a relatively slow rate.
It will be a wise decision to package a product directly as a last operation on a fabrication line
than to put it in a temporary container prior to packaging and then have to remove it from the
temporary container.
Product mix plays a vital role, if numbers of small containers are to be merged with larger
unit loads, then it is necessary to provide pallet storage racks or bin shelving at convenient
places on the shipping floor.
Pallet Storage Racks

13. Bin Shelving
Boxing and crating like dusty operations should be separately carried away from shipping
floor.
Boxing and Crating

14. The effectiveness of out loading operations should be improved by using mechanization.
Out Loading Operations
Most carriers should be out loaded by forklift truck, which saves travel distance and time,
further it eliminates cross traffic that would occur on the shipping dock.
Weight distribution in an over the road carrier is very critical, since putting the heaviest
load/items in the tail end of the truck could prove disastrous.
Weight Distribution

15. Use of conveyors, tractor-trains, driverless tractors and tow conveyors: In Shipping
Floor conveyors, skate wheel conveyors, roller conveyors, should be used for optimum
utilization of floor space.
Floor Conveyors
Skate Wheel Conveyors

16. Roller Conveyors
It is better to use tractor train to transport material from other departments within the plant in
to the shipping area.
Tractors
Tow conveyors should be preferred for large volume movements, driverless tractors for small
to moderate movements, whereas for both small and large movement’s tractor trains could be
used.

17. Design of Flow Pattern:
While designing for flow pattern, many factors are required to be considered some of them
are,
1. Factors related to materials or products
2. Factors related to movements
3. Factors related to handling methods
4. Factors related to process manufacture
5. Factors related to building
6. Factors related to site
7. Factors related to personnel
Materials/Products : Quantity of materials to be processed and its effect on production
processes, characteristics of materials, number of parts or products, no of operations on each
part. A part requiring large number of operations, machines, tools, gauges, or fixtures, will
require a more complex flow pattern and shall require more space and more people to
produce the part.
Movements: frequency of movement, speed, distance to be moved. Interrelated work places
should be close together.
Handling: characteristics of material, possible use of gravity, equipment’s required, possible
alternatives.
Manufacture process: type of processing activities, sequence of operations, specific
requirement like, provision for ventilation, fire protection, air-conditioning, number and size
of machineries required for manufacturing.
Building: building size, shape, number of columns, aisles, number of floors, location of
doors, height.
Site: topographical aspects, such as contour, shape and size of land available, subsoil
condition, modes of transportation desired, as per economy and feasibility, any expansion
possibilities.
Personnel: movement of personnel and their number, frequency, distance, safety aspects,
working conditions, like heat, light, ventilation, temperature, noise and vibration, ease in
supervision and control.

18. Criteria for Designing or Planning Material Flow:
1. There should be uninterrupted flow of materials.
2. No back tracing should be allowed.
3. There should be minimum possible handling distance between the activities.
4. Heavy and occurred material should be moved to lesser distance.
5. Minimum material should be kept in work area, minimum rehandling should be
target.
6. There should not be violation of health and safety requirements.
7. There should be provision to take care of scrap flow.
8. There should be provision for expansion.
9. Location of receiving and shipping should be at convenient place of transportation to
have economy.
10. Aisles should be kept to be straight, and minimum in number.
11. There should be optimum flow of personnel, as regards to number frequency and
distance.
Advantages of Planned Material Flow:
1. Better utilization of floor space, manpower, and machineries.
2. Reduced processing time, the in process inventory, and chances of accidents.
3. Reduction in material, manpower movements and traffic congestion.
4. Simplified material handling and production control.
5. Minimized back tracking and better housekeeping.