The Ideal Value Stream

Guidelines

Producing to takt time: Takt time is a calculation based on the daily production number required to meet on-hand orders divided into the total number of work hours in a day. Compare cycle times to your takt time. If cycle times exceed takt time remedy by increasing work shifts, eliminating more waste, or using faster equipment to keep pace.

Developing continuous flow: This is the act of producing one piece at a time with each piece passed immediately from one process to the next without encountering any delay. Group processes that complement each other as well as increase the flow of the product. As you combine your processes you can figure out the amount of workers needed for your new station. Do this by combining the cycle times for each individual process, as they were before combining them, then divide it by the takt time.

Controlling production: When continuous flow isn't attainable, you must produce only as much product as downstream processes need. Use a "supermarket" system as a temporary storage pit-stop for your product. Gradually, release product as downstream stations demand it. Causes for using a supermarket system: long changeover times, transportation times, and excessive lead times.

Setting a pace: One of your processes must be the "pacemaker" process. The pacemaker process sets the pace of production for all upstream processes. The main rule for the placement of the pacemaker process is that all downstream processes must have continuous flow. If a supermarket reserve system is in place (because flow is disrupted), the pacemaker process is usually in the same place. If a supermarket reserve system doesn't exist, the pacemaker process is higher in the production process to facilitate custom orders.

Leveling the production mix: You must distribute your production evenly over a specified amount of time to avoid building up too much inventory or clogging up any supermarkets you have in your map. Making all your products at once forces you to have a large finished product inventory to satisfy customer needs. Alternating your products can give customers what they want on short notice. This is how you serve the customer.

Leveling the production volume: This means leveling the production load on the pacemaker process. To do this you must create an initial pull consisting of small work loads that are produced and then distribute the workloads at the same time. By its nature leveling the production mix advises you of problems within your value stream so you can take quick corrective action. This guideline also creates a predictable production flow eliminating uneven work volume and effort and problems monitoring the stream. As you complete a small consistent amount of product at the pacemaker process, you remove the same number of finished product from the end of the production line. This effort counters shuffling work around the floor and smoothes out the response time for product changes.