How to Effectively Use Value Stream Mapping in Camshaft Manufacturing: A Case Study
Value Stream Mapping (VSM) is a powerful process for understanding, improving and optimizing processes in business. It is a methodology that helps you understand and predict the flow of a company’s products and services. This paper presents the application of Value Stream Mapping in the Indian Camshaft Manufacturing Industry.
The basic premise of Value Stream Mapping is to identify the processes that make up a business, and then apply the concept of flow charts to these processes. Value Stream Mapping allows you to map out where value is lost and gained, and how this affects the company’s overall performance. It also helps you visualize the flow of a process, and identify bottlenecks and potential improvements to your current processes. The entire manufacturing process can be broken down into its most basic components.
This case study is a practical application of Value Stream Mapping in an Indian auto-manufacturer company. It discusses how the approach helped improve the quality of the product and accelerate the production process of the manufacturer.
In this case study presented by S. Vinodh, K.R. Arvind & M. Somanaathan (See Journal of Manufacturing Technology Management (2010) Vol. 21, No. 7, pp. 888-900. Emerald Group Publishing Limited), about the CeeYes Metal Reclamations, stiffer camshaft (hereafter referred to as “shaft”) was chosen as the candidate product since it is more in-demand, approximately 320 shafts/month, compared to other products.
The Current State Map in producing shafts was developed. The orders are being received from the customers on a monthly basis. The customer demands are stable throughout the year without any fluctuations; approximately 320 shafts/month. The production control department transmits the instructions daily to the production supervisor. The production supervisor then transmits the instructions to various personnel on a daily basis. A total of 12 processes are involved in manufacturing the stiffer shaft.
In the 12-step manufacturing process, the first step is cutting, with one operator, 24-minute cycle time, and 10-minute Changeover Time between the successive products. The company operates on 3 shifts per day (each shift of 8-hour duration with 30-minute lunch break (inclusive)).
The Available Production Time is calculated as follows:
Available Time = Total Production Time – Planned Down Time
Available Time = (60 x 8 x 3) – (30 x 3)
= 1,350 minutes
Uptime is calculated by dividing the Actual Operating Time by Available Time:
Uptime = Actual Operating Time
= Available Time – Changeover Time x 100
Uptime = 1,350 – 10 x 100
The inventory carried over between cutting and rough turning is 10 units. The Changeover Time between cutting and rough turning is 0 minute since the same operator performs both operations. The computation was carried out for all the remaining processes.
The total cycle time for manufacturing the shafts is 539 minutes while the total idle time is 19,660 minutes. The shafts are being delivered to the customers on a monthly basis. CeeYes maintains a high finished products inventory of 320 units because of the monthly delivery scheme.
After identifying the wastes in the manufacturing process of shaft, various proposals for waste elimination were developed in consultation with the executives of CeeYes, including:
- 5S – the concept of 5S was found vital at the following stages of operations: cutting, rough turning, cam milling, cam grinding, heat treatment and packing.
- Introduction of stage inspection – stage inspection after the following operations: cutting, length and outer diameter (OD) correction, boring, drilling and forming, flange hole drilling, heat treatment, OD and length correction and super finishing.
- Reduction of Work In Process (WIP) – WIP between super finishing and inspection stages was decreased as a result of implementing the stage inspection.
- Utilization of jigs and fixtures with adequate mistake-proofing at the co-boring, drilling and forming and flange hole-drilling stages.
- Automation in storage and retrieval system to be implemented at co-boring, drilling and forming, flange hole-drilling operations.
- Introduction of information technology (IT)-enabled logistic system.
The Future State Map depicting the various modifications incorporated in the manufacturing process of shaft at CeeYes (below), was developed.
The modifications included in the Future State Map achieved the following:
- For the current cluttered system prevailing during operation, deployment of 5S ensured the clean maintenance of the shop floor.
- Currently, inspection is being carried out at the final stage; with 2 operators and 14-minute cycle time. Final inspection was transferred to stage inspection. Since the final inspection transfer, the process had significantly eliminated the final inspection.
- With final inspection eliminated, WIP was reduced by 50 units in the value stream of the product line.
- For jigs and fixtures without effective mistake-proofing, steps taken ensured the inclusion of adequate mistake-proofing measures, an important concept of Lean production system.
- In certain operations with longer handling time and demanding more efforts spent by operators, the introduction of automation of storage and retrieval system shortened the process.
- For the electronic tracking of various activities associated with logistics and supply chains and to save CeeYes from outsourcing the process, the IT-enabled logistics system established the operations.
The improvement in various performance measures as a result of the case study includes:
- Decrease in idle time from 19,660 to 19,449 minutes.
- Reduction of total cycle time from 539 to 525 minutes.
- Reduction of Work-In-Progress inventory from 4,660 to 4,610 units.
- On-time delivery improvement from 70 to 85%
- Reduction (4%) in defects.
- Increase (1.72%) in uptime.
To determine the practical feasibility of deploying Value Stream Mapping to enable reconfiguration of the manufacturing process, a validation was conducted among the executives of CeeYes using a questionnaire.
The analysis of the responses indicated the practical receptivity of deploying Value Stream Mapping process to improve the leanness at CeeYes.
Value Stream Mapping helped the managers of CeeYes to visualize the wastes occurring in their organization and the future possibility of reducing/eliminating them.
Thus, it can be concluded that Value Stream Mapping is an effective Lean manufacturing technique, which could be deployed in industrial scenario to improve leanness, consequently, helping organizations achieve competitiveness.