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

Proceedings of the National Conference on
Trends and Advances in Mechanical Engineering,
YMCA University of Science & Technology, Faridabad, Haryana, Oct 19-20, 2012
ENHANCING PRODUCTIVITY BY STRATEGIC IMPROVEMENT IN
THROUGHPUT-TIME ON ASSEMBLY LINE: A CASE STUDY
S.K. Gupta 1 , Dr. V.K. Mahna 2 , Dr. R.V. Singh 3 , Rajender Kumar 4
1 Research Scholar, Department of Mechanical Engineering, FET, MRIU, Faridabad
2 Dean Academics and Executive Director, MRIU, Faridabad
3 Prof. & Head, Department of Mechanical Engineering, FET, MRIU, Faridabad;
4
Asst. Prof., Department of Mechanical Engineering, FET, MRIU, Faridabad
e-mail:
1 gupta.sarojkumar@gmail.com, 2 rajender629@yahoo.com
Abstract
The targets of an increased productivity, operational availability and better overall efficiency, on the production
lines are the most important goals for almost all manufacturing organizations. The specific objectives of this
case study are firstly to reduce setup time and secondly, reduction in waiting time on the line with focuses on
economic lot size and buffer stock. Design for production (DFP) is a tool to identify the losses in the line and
iron out these losses in a systematic way to achieve improved throughput time, higher efficiency, higher
productivity and improved manufacturing cost. The reduction in throughput time gives a base of 44% increase in
production (Refer Sec. 4.0) i.e. present average production quantity of 37805 Nos. gets increased to 54440 Nos.
with defining buffer stock and optimal lot size.
Keywords: Setup Time, Buffer Stock, Waiting time, Throughput Time, Economic Lot Size.
1. Introduction
All production units aim at utilizing existing resources and enhancing the output to achieve cost oriented
product. The design for production (DFP) is a powerful tool to curtail the inputs in terms of time & cost. The
assembly line, by and large, are manual in nature therefore, need a close control on the performance of manual
labour. In manufacturing industries, the throughput time is identified as the length of time between the release of
a production order to the factory floor and its receipt into finished goods inventory or its shipment to the
customer.
The throughput time comprises of setup time, waiting time, cycle time, inspection time, and move time. The
activities of movement can be cut down to some extent by mechanizing the process of moving the material (if
possible). The inspection time is very much part of the cycle time and can be brought down again to a lesser
level by introducing digital/air gauging systems. The amount of time spent on setup and also waiting for material
is a general phenomenon on any assembly line particularly in case the product is multi model mix. The amount
of time setting up the line for a particular model may vary between 10-20% and waiting for material 20-30%.
The waiting for material is directly associated with prevalent lot size and availability of buffer stock being
followed and bigger the lot size higher is the waiting time. Therefore, these two areas need a thorough study and
investigation to reduce the through put time and enhancing the process performance in terms of productivity
without utilizing any extra resources i.e. over time to compensate for the system inefficiencies.
In an Assembly Line, the cycle time is also an essential part of the throughput time that means it needs to
investigate the allocation of tasks to workstations. This study itself is a complete subject within itself to establish
the no. of workstations as per existing production requirements under the heading of assembly line balancing.
2. Literature Review
At present manufacturers must be able to manufacture a wide variety of highly differentiated and high quality
products in a cost-effective manner, and respond quickly to changes in the product designs and volumes in order
to compete effectively [1].
Recently most of the manufacturing units have focused on market demand and customers responsiveness. This
has led to the implementation and adoption of lean manufacturing techniques in the automotive industry. Due to
the complexity and demand behavior from customers, the role of better change over or setup time reduction and
minimizing the waiting time (through better scheduling and also optimizing the lot size). It can help better
response in small batch manufacturing [3]. In the past two decades, setup time reduction and quality
improvement programs have become prevalent in manufacturing industry. Applying lean principles represents a
systematic method for identifying all the activities which contribute in the value stream of the decision making
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