Welcome to Six, Sigma black belt Course 4, Module 1, Process Characteristics. Before we can discuss the process flow and the associated analysis tools with process flows, we first need to define a series of Lean terms. Some of these Lean terms will receive a more in-depth treatment in other modules. For now, we simply wish to raise awareness as we framed the content of this module. Let's start with some common Lean measures. A process on a product consists of several steps that must be completed before the product is moved to the next process. Cycle time is the amount of time needed to complete one cycle of the process. When we produce, we consume inventory. The number of times inventory is consumed in a given time frame is the inventory turn. Sometimes product must wait for the next process. This waiting time is referred to the queue time. A skills matrix is a visual aid that shows wort steps and helps operators come up to speed on a job. It is not a measure, but it is included in this area since it does convey information. During a shift, we have an amount of available production time in which a certain amount of product must be produced. Looking beyond our immediate needs, we can frame this needed product in terms of a rate of customer demand. Takt time is the ratio of production time divided by the rate of customer demand. Touch time is the amount of time the product is being handled during the process step. Another way of thinking of this as in terms of the amount of time that value is added to the product. Waste is defined as one of the eight wastes of Lean. Further into this specialization, we will discuss these eight wastes. Now let's introduce a number of common Lean systems. Kanban is a triggering system for inventory flow and control. As product is consumed, a Kanban trigger initiates replenishment. Single minute exchange of dies or SMED is a method for facilitating rapid changeover of dies and equipment. While we aim for zero set-up time, it is common to start with a more realistic goal and increment from there. When we wish to visualize the sequence and interaction of events in a process, we use a process flow chart. A single product proceeding through the entire process without interruptions, back flows or scrap is called single piece flow. This is in contrast to batch runs that consists of multiple products moving to each point in the process as a group. Just-in-time delivers the right items at the right time and the right amounts. We use just-in-time to facilitate single piece flow. Continuous flow manufacturing is a type of one-piece flow. It is dictated by the demand of the customer. It is continuous and requires no work-in-process. 5S is a system of organization and standardization used to remove clutter and normalized processes in work areas. A good way to showcase the state of the production system and raise awareness of emerging problems is to use an Andon board. Poka-yoke is mistake proofing. This could be through a device, a process, or an instruction designed to prevent or detect an error. We have all heard of a pull system. In a pull system, the signal goes from downstream to upstream. The downstream supplier signals a need to the upstream supplier. The product is pulled as the need is identified. This is the opposite of a push system. Now let's discuss some key terms within the Lean lexicon. When inventory is delivered directly from the location where it will be used, it is called point of use inventory. The hidden factory is essentially a factory inside another factory. Activities are performed that reduce the efficiency of the manufacturing operation. They are performed on an ad-hoc basis and most are not documented or even known to management. These activities generate material and labor costs that the organization is not tracking or addressing. Additionally, value is added to the product that the customer will not pay for. This brings us to a non-value-added activity. These will be any activities that do not add value to the product. Believe it or not, as essential as inspection is within some organizations, these activities are considered non-value-added. Because of entities like the hidden factory and the presence of non-value-added activities, we need ways to continually reduce waste in all areas and in all forms, what we call Lean manufacturing. Two ways that we advanced the aims of Lean manufacturing is through standard work and the elimination of muda or waste. Standard work entails a precise description of each work activity. Parameters such as cycle time, takt time, material, and the work sequence are included. Lean systems promote the reduction of the lot size to as close to as one as possible. This is known as the small lot principle. Visual control involves the placement of tools, material, and performance indicators in plain view, such that the operator can quickly assess the state of the system and adjust as needed. A work cell is conducive toward the use of visual controls by putting all the elements required for the operation within arm's reach. This minimizes movement and flexible deployment of human effort. Within each work cell is a group of works centers. Work in queue is the material that is at the workstation waiting to be processed. Lean thinking requires a different spin on how we describe waste and work to continually improve the organization. Some key points to consider include; identifying the value byproduct, identifying the value of each product, understanding the value added and non-value-added components of the flow, allowing the customer to pull value from the producer, and striving for perfection. This slide is dedicated to a number of elementary, yet important Lean metrics. These will be very useful as the Lean professional seeks to understand the current state of the process as well as measure and track improvement. Throughput rate is the reciprocal of cycle time. Work-in-process inventory is the product of throughput and flow time. Combining these two gives a relationship for flow time based on work-in-process and cycle time. Process cycle efficiency, PCE, is the ratio of value-added time to the flow time. Let's consider this example. We have 50,000 units scheduled for production. Our throughput is 2,500 units per day. The value-added time is 4.5 days over the flow time interval. The flow time is the ratio of the work in process and the throughput, or 20 days. The process cycle efficiency is the ratio of the value-added time and the flow time, which is 22.5 percent.
