Mass production is wrongly equated with heavy production
meant for teeming millions. However mass production is
a concept. It believes in break up of task into its simplest
possible elements. These elements are then grouped as
per production norms.
Concept of assembly line is used for mass production. On
assembly line, the material moves continuously at a
uniform speed. It reaches the various work stations,
where a portion of work is done.
Mass production: suitability
Mass production refers to a large quantity of production
with standardized products having less variety. Ideally, it
should be a single standard product manufactured on a
continuous basis over a period of time.
There is a smooth flow of material
There are small WIP
Production time as a whole is short
Closely spaced WS’s reduce material handling
No expertise necessary to operate the system.
Less training cost
PPC is simple
Less storage space is required
One machine failure results in a stoppage of whole line following it.
Maintenance is challenging
Assembly lines are not flexible
Great changes in layout are necessary when product line changed
Production speed is determined by slowest machine.
It requires general rather than specific supervision
More capital required because of duplication of machines
Line balancing method: Kilbridge
and wester method
(i) Draw the precedence diagram of work elements. Draw
columns taking the starting elements first and then the
(ii) Select CT which is feasible
(iii) Assign work elements to WS. Sum of elemental times
should not exceed CT while doing so. Proceed from col.i
to col. ii and so on. Break intra column tie by using the
norm of minimum number of predecessors.
(iv) Deduct assigned work elements from the total number
of elements. Repeat step 3.
(v) If WS time is more than CT, identify the work element
due to which this happens and carry forward to next WS.
(vi) Repeat steps 3 to 5 till all elements are fully assigned.
Now we want to balance line with CT=8
WORK ELEMENT NO. OF PREDECESSORS TIME
1 0 4
2 1 2
3 2 3
4 1 2
5 2 5
6 5 4
Station Element T Station sum Idle time
I 1 4 4
2 2 2 2
II 4 2 2
5 5 5 1
III 3 3 3
6 5 5 0
Line efficiency= total station time
CT x No. of WS’s
8 x 3
Balance delay= idle time of all stations x 100
available working time of all stations
= 3/21 x 100= 14.29%
Problems and prospects of mass
Variable work element times
Break down at WS’s
Multi product lines
Batch production is resorted to when a variety of
products are to be made and the volumes are not large
enough to demand a separate line for each product. In
this method, general machines are used to turn to
different products. Here the rate of production exceeds
rate of demand. Hence many products are produced
Fewer machines are necessary
Specialized supervision is possible
Not so capital intensive
Low investment in machines
Job satisfaction for the operatives
Material handling is costlier since the flow is longer and irregular
PPC is elaborate
Production time is longer generally
WIP ties up large capital and space.
Skills of a higher order are necessary considering the variety.
Economic lot size
There are two types of cost involved
(i) Carrying cost: The cost which we need to bear in case
we have purchased raw material in big lots. E.g.
insurance, storage, godown rent, interest on money
(ii) Buying cost: The cost which we need to incur
whenever we place an order. E.g. transportation cost,
and we also do not get the benefit of bulk discount
now economic lot size is that size where our cost is
minimum with a specific combination of two. We
calculate the specified qty using formula and that
combination proves the cheapest out of all combination.
Hence our cost is reduced.
Set up cost
Batch production involves a set up cost, each time a batch
is produced. Set up cost is roughly equivalent to the
ordering cost per order. It consists of engineering cost of
setting up the production lines or machines.