Value stream mapping as a mapping tool that is used to describe supply chain net
ID: 393435 • Letter: V
Question
Value stream mapping as a mapping tool that is used to describe supply chain networks. It maps not only material flows but also information flows that signal and control the material flows. The material flow path of the product is traced back from the final operation in its routing to the storage location for raw material. This visual representation facilitates the process of lean implementation by helping to identify the value-added steps in a value stream, and eliminating the non-value added steps / waste (muda).
Duggan (2006) has explained the application of value stream mapping and lean concepts to Mixed model production. Mixed Model production means producing a variety or mix of products or product variations through the same value stream at the pull of the customer. This means to build and deliver the right quantity of a specific product. In the Mixed model production, a group of products are determined to be a product family and are treated as one.
Ramesh et al (2008) et al mentions the value stream mapping as a technique which involves flowcharting steps, activities, material flows, communications and other process elements that are involved with process or transformation. Value stream mapping helps an organization to identify the non-value-adding elements in a target process and brings a product or a group of products that uses the same resources through main flows, from raw materials to the arms of the customer.
Martichenko and Grabe (2010) are of the opinion that a level flow show be created throughout the process. Level flow reduces variation in processes and tries to spread activities equally over working time. This minimizes the peaks and valleys in movement that creates unevenness and overburden, which result in waste. Use pull systems when level flow is not possible. A pull system is an inventoryreplenishment method in which each downstream activity signals its need to the next upstream activity. Pull system reduces wasteful complexity in planning and overproduction.
STEPS ADOPTED FOR THE STUDY As the company was manufacturing many products, our team in consultation with management decided to undertake a study in the molded circuit breaker unit. The following steps was adopted for carrying out value stream mapping in the company
A. Selection of the Product family The Product which we selected is called molded case Circuit Breaker also known as MCCB. We have taken two types of MCCB’s in our product family based on its current rating a) MCCB – Type A b) MCCB –Type B
Drawing the Current State This is an important step in Value Stream Mapping Process. The data is collected while walking along the shop floor and studying material and information flow. The data collection begins at the shipping end (Downstream end) and work towards the upstream.
Elimination of Waste After analyzing the current state map we found that there is a huge difference between production lead time and the actual processing time. So there are good opportunities to eliminate waste from the production line. We started our value stream mapping from the downstream process which is the Packing and finishing process and travelled upstream towards the Release assembly process. The following information of each process was collected.
Calculating the Work in process(WIP) at each work cell Calculate the Cycle time, Change over time and Utilization percentage of each process • Available time for production in each ft. Creating Current state based on the Data collected.
CREATION OF CURRENT STATE
After drawing the current state we could find out that the following observations
• The total processing time(production lead time) is 20.9 days and the value added time is 30.30 min.Which meant the total time required to produce one product took approximately 21 days which was relatively very high. • We could also find considerable amount of Inventory tied up between each process,which was also a great serious of concern.Which in turn prolonged the production process. • Further we could see the utilization rates of process Therm/magcalli,Reset force,mv/HV test were only 90%,95% and 95 % respectively.Our future goal was to increase it to 100 %.
This meant there were lot of scope to eliminate waste from the production line. In this scenario the authors decided to apply Lean principles and concepts to reduce the production lead time and increase the value added time.
VI ANALYSIS AND CREATION OF FUTURE STATE After analyzing the current state map we found that there is a huge difference between production lead time and the actual processing time. So there are good opportunities to eliminate waste from the production line. We have observed that Assembly 1, Assembly 2 and OT testing stations are having similar cycle times. So we can form continuous flow cell including these three processes. The Release assembly station cannot be included in the cell because of two reasons: a) High Cycle time
b) There is a break in flow due to Supplier 2. We will call this cell 1. Similarly we can make another continuous flow cell (cell 2) which includes Reset force testing, mv/HV testing and final finishing and Packing. We cannot include thermal magnetic calibration in our Flow cell because it has very high cycle time.
We propose to provide supermarkets in between processes where continuous flow is possible. We will also provide supermarkets for the raw materials to introduce the pull system.
A. Finished Goods Supermarket As we can see from the 4 months of the demand that there is considerable variation in the monthly demand. So we propose to provide finished goods supermarket before the shipment to take care of these variations. But our ultimate goal will be to eliminate this supermarket in future after the stabilization of internal processes.
Calculation of Takt time
“Takt time” is how often one product or part should be produced, based on the rate of sales, to meet customer requirements. Takt is a German word which means pace. Takt time is calculated by dividing customer demand rate per shift (in units), into the available working time per shift (in seconds). Available Working Time per shift = 25200 sec Daily demand = 140 units. Takt = Available Working Time per shift/ Daily
We started our value stream mapping from the downstream process which is the Packing and finishing process and travelled upstream towards the Release assembly process. The following information of each process was collected.
• Calculating the Work in process(WIP) at each work cell • Calculate the Cycle time, Change over time and Utilization percentage of each process • Available time for production in each shift. • Creating Current state based on the Data collected.
V. CREATION OF CURRENT STATE
After drawing the current state we could find out that the following observations
• The total processing time(production lead time) is 20.9 days and the value added time is 30.30 min.Which meant the total time required to produce one product took approximately 21 days which was relatively very high. • We could also find considerable amount of Inventory tied up between each process,which was also a great serious of concern.Which in turn prolonged the production process. • Further we could see the utilization rates of process Therm/magcalli,Reset force,mv/HV test were only 90%,95% and 95 % respectively.Our future goal was to increase it to 100 %.
This meant there were lot of scope to eliminate waste from the production line. In this scenario the authors decided to apply Lean principles and concepts to reduce the production lead time and increase the value added time.
VI ANALYSIS AND CREATION OF FUTURE STATE After analyzing the current state map we found that there is a huge difference between production lead time and the actual processing time. So there are good opportunities to eliminate waste from the production line. We have observed that Assembly 1, Assembly 2 and OT testing stations are having similar cycle times. So we can form continuous flow cell including these three processes. The Release assembly station cannot be included in the cell because of two reasons: a) High Cycle time
b) There is a break in flow due to Supplier 2. We will call this cell 1. Similarly we can make another continuous flow cell (cell 2) which includes Reset force testing, mv/HV testing and final finishing and Packing. We cannot include thermal magnetic calibration in our Flow cell because it has very high cycle time.
We propose to provide supermarkets in between processes where continuous flow is possible. We will also provide supermarkets for the raw materials to introduce the pull system.
Finished Goods Supermarket
As we can see from the 4 months of the demand that there is considerable variation in the monthly demand. So we propose to provide finished goods supermarket before the shipment to take care of these variations. But our ultimate goal will be to eliminate this supermarket in future after the stabilization of internal processes.
Calculation of Takt time
“Takt time” is how often one product or part should be produced, based on the rate of sales, to meet customer requirements. Takt is a German word which means pace. Takt time is calculated by dividing customer demand rate per shift (in units), into the available working time per shift (in seconds). Available Working Time per shift = 25200 sec Daily demand = 140 units. Takt = Available Working Time per shift/ Daily demand = 25200/140 = 180 sec = 3 min
1. Construct analysis of a Value stream map of the curent state and future state
a)define the activities and measure the time it takes from recieving raw material to shippng finished part to customer.
Explanation / Answer
1. Analysis value stream mapping of current state:
Production Lead time is increase due to increase in current WIP(work in process) on production floor. WIP increase the inventory on production line so that waiting or queue time is increased.
Our production process have lots of non value added activity so that resources are not fully utilized. So finished good delivery got delaying.
So the analysis found some gap in production process. A method of Lean Manufacturing is used to eleminate waste. Here waste considered as non value added activity in production process.
Analysis on Desired state Value stream mapping :
They have eleminate the waste from production line. First three process are aligned with similar cycle time. These procees are include Assembly 1, Assembly 2 and OT testing stations. Other process we can not consider in same manner because of different cycle time. These process included in Cell 1 & Cell 2 to reduce the WIP of line. They have introduce the Super market sytem to reduce WIP of production floor.
Activities:
Assembly 1
assembly 2
OT Testing
Reset force testing,
MV/HV testing
Final finishing and Packing.
Total Time for shipment= production lead Time + value activity
=20.9 days + 30.30 mint
= 20 days 9 Hour 30 mint 30 secs.
Thank You..
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