OCTOBER 19-20, 2012 - YMCA University of Science & Technology

II.
III.
IV.
Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
Pull-production – This is also called Just-in-Time (JIT) production, it aims to produce only what is
needed, when it is needed. Production is pulled by the downstream workstation so that each workstation
should only produce what is requested by the next workstation.
Quality at the Source – Lean Manufacturing calls for defect free production lines. It aims for first time
right approach. It aims for defects to be eliminated at the source and for quality inspection to be
performed by the workers as part of the in-line production process.
Continual improvement – Lean Manufacturing requires striving for perfection by continually removing
layers of waste as they are uncovered. This in turn requires a high level of worker involvement in the
continual improvement process.
2.2 Objectives of Lean Manufacturing:
The objectiveness of Lean Manufacturing is to enhance overall productivity lower cost of production, and
reduced lead times of production. Some of the objectives include:
I. Reduced work in progress (WIP) Inventory - Minimize inventory levels at all stages of production,
particularly works-in-progress between production stages. Lower inventories also mean lower working
capital requirements.
II. Lower Cycle Times - Reduce manufacturing lead times and production cycle times by reducing waiting
times between processing stages, as well as process preparation times and product/model conversion
times.
III. Improved Labor productivity - Improve labor productivity, both by reducing the idle time of workers
and ensuring that when workers are working, they are using their effort as productively as possible
(including not doing unnecessary tasks or unnecessary motions).
IV. Reduced Defects - Reduce defects and unnecessary physical wastage, including excess use of raw
material inputs, preventable defects, costs associated with reprocessing defective items, and
unnecessary product characteristics which are not required by customers.
V. Enhanced Output – Insofar as reduced cycle times, increased labor productivity and elimination of
bottlenecks and machine downtime can be achieved, companies can generally significantly increase
output from their existing facilities.
VI. Improved Flexibility - Have the ability to produce a more flexible range of products with minimum
changeover costs and changeover time.
VII. Better Utilization of equipment and space - Use equipment and manufacturing space more efficiently by
eliminating bottlenecks and maximizing the rate of production though existing equipment, while
minimizing machine downtime;
2.3 Implications of Lean Manufacturing
With the implementation of lean manufacturing in any industry several changes in manufacturing approach are
expected. The major change come with change from batch production with planning for every station or shop is
converted into smaller batch size production method tending to batch size of one piece or single piece flow line
with scheduling and planning at down most steam process where material is pulled from value stream based on
customer demand only. In new model of manufacturing work in process inventory is reduced as there is no or
very less material between work stations waiting for processing. Quality is not dependent on certification of line
inspector but it becomes sole responsibility of workman who manufactures the product and inspection is now an
integral part of manufacturing activities of operator. Some major implications of conventional manufacturing
model and lean model of manufacturing are discussed as follows:
Table 1. Implications of Lean Manufacturing
Scheduling
Lot size
Conventional manufacturing
Scheduling is done on whole value stream
based on production plan.
(Push production)
Bigger lot sizes
Lean Manufacturing
Scheduling is done at one place based on
customer demand. Processes are scheduled by
downstream processes.(Pull production)
Smaller lot size
(tends to single piece production)
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