What is Value Stream Mapping?
The goal of value stream mapping is to visually map out the path of a product from start to finish. This includes showing which suppliers send in raw material, the individual manufacturing processes that create the product and the customers that receive the product. More importantly value stream mapping allows you to find the takt time, total production lead time, and total production cycle times. These KPIs help production teams understand the pace of their manufacturing processes. If a company is lacking in delivering products on time then understanding where the problems lie in their processes will help them get rid of waste.
Why is it Important?
Covid-19 is a prime example of how supply chains were disrupted. This event exposed companies weaknesses and caused them to rethink how they should structure their own supply chains. Now that companies are starting to get back on their feet the application of value stream mapping is a strong step towards understanding a companies current state and seeing where there can be improvements.
Value Stream Mapping Project
Value stream mapping can be used to map out processes in virtually any industry whether it is a company creating a physical product or a software company building an application. The company that my team and I worked with was Astronics. Astronics is an aerospace and defense manufacturer that provides innovative system technology including smart sensing, electrical power, and other aerospace products.
The task of this project was to create a current state map of Astronic’s Condor High Power Cell Line. The Condor Line is simply a product family. The products that come out of this line are a power conversion unit, dual frequency conversion unit, and electronic circuit breaker unit. These products help power the plane’s engine speed and in-flight entertainment.
Creating the Map
Here is the final draft of the the Astronic’s Value Stream Map. Lets break it down.
Starting out on the left we have two suppliers. These suppliers send raw material monthly and weekly to the first process. Then there are 9 more processes until the products are considered finished goods. On the right side we have 9 different customers that receive product daily. On the top middle section is “Production Control”. This shows how often Astronics is contacting their suppliers and customers, and the forecasted demand that they receive from their customers. Right below is the “Dispatch List”. Using an ERP system Astonics is able to coordinate and receive updates from all manufacturing processes. On the bottom right we have the blue box with three data points: takt time, total production lead time, total production cycle time. Takt time shows how long production should take to meet customer order demand. The lead time is the amount of time from a customer making an order to the customer receiving it. The cycle time is how long it takes a product to be produced from start to finished good. Cycle time can also be the amount of time for one individual process from start to finish.
When inputting the individual processes on the map it is important to get the necessary information because each process can vary. For example, the third process below has handling time, curing time, machine time, changeover time, and uptime. The process before it only has cycle time, changeover time, and uptime. The curing time takes 15 hours which is much longer the the cycle time of the previous process.
In-between each process there is a triangle with the letter “I”. This stands for the Work-In-Process Inventory. This represents the amount of inventory waiting to go onto the next process. In the first process in the white box there is a symbol with the number 2. This represents the number of workers per process. Three of the processes also have mechanics. The other data points including “C/O” represents change over time. Meaning the amount of time it takes a process to change over to another product. “Uptime” refers to the processes scheduled operating time divided by its actual operating time to see how efficient the process is. “C/T” stands for cycle time.
The final step of value stream mapping
Once you have all the processes filled out with their cycle time, changeover, uptime and any other data points you are then able to find the total production lead time and total production cycle time. On the bottom we have the ladder. The first process has a cycle time of 16.9 seconds. The next process has 118.1 seconds. Add up each cycle time from all the processes to get your TPCT. The same formula is used to find the total production lead time. Add 0 days, 5.1 days…
To find the takt time I was given the available working time per month and the monthly demand unit average. Divide the monthly demand unit average by the latter to get the takt time.
Reflection
Understanding how to do value stream mapping is currently a valuable skill. Companies are still trying to understand excess waste in their supply chain and production processes since Covid. They want to improve their efficiencies in their industry. I hope this article gave you a simple walkthrough of what value stream mapping is and how it can be applied to the aerospace industry. If you are in different industries like banking, software, service based, or other non-manufacturing businesses this is still applicable and I challenge you to try and create a value stream map of your own company to see what kind of value it can bring.
