Chapter 18

1. Chapter 18 Process Characteristics

2. Objectives • Identify the process variables and evaluate their relationship. • Evaluate process flow and utilization to identify waste and constraints. • Analyze processes

3. Input and Output Variables • A process is a step or a sequence of steps that uses inputs and produces a product or service as a output. • Every process has inputs such as material, machines, methods, manpower, and management. • Processes are often made up of smaller sub processes. • When defining a process it is important to identify start and end points.

4. Study of Processes • Elements of a process - SIPOC: • Suppliers – The internal and external providers of resources, materials, knowledge, and services that the process requires. • Inputs – The elements that feed the process. • Process – The steps or sequence of steps that is being improved. • Outputs – The measurable end product or services produced by the process. • Customers – People who receive the final product.

5. Process Flow Metrics • 1. Work in progress (WIP): It is the material that has been input into the process but has not reached the output stage. • 2. Work in queue (WIQ): It is material waiting to be processed by some step in the process. It helps identify process bottlenecks or constraints. • 3. Touch time: It is the time that the material is actually being processed by one of the steps. • 4. Takt time: It is the rate at which the process must output completed items = Time available / Number of units to be processed.

6. Process Flow Metrics • 5. Cycle Time: Average time for a particular step to complete one item. • 6. Throughput: It is the number of items or amount of material output from the process in a given period of time. • 7. Value added time: It is the amount of time used for activities that a customer is willing to pay. • 8. Setup time: It is the time required to convert from producing one product to producing a different one.

7. Process maps and flowcharts • Flowcharts show each step in the process, decision points, inputs, and outputs. • Process maps usually contain additional information about the steps including cost, set up time, cycle time, inventory, types of defects that can occur, probability of defects, and other appropriate information. • Process maps and flowcharts enable a broader perspective for process improvement.

8. Written Procedures • Almost every process can be improved by reducing variations. • The best way to ensure that things are done the same way is to have written procedures and work instructions. • The procedures are generic often covering several processes and products. • The work instructions are usually product specific and often include graphics showing discrete steps including defects to avoid, safety hazards, tooling requirements, and other information to ensure that the job is done in a standard way.

9. Value Stream Map • Value stream mapping is a technique for following the production path for a product or service from beginning to end while drawing a visual representation of every process in the material and information flows.

10. Steps to develop and analyze a value stream map • 1. Produce a value stream map (fig 18.7, page 87 shows some symbols that are used in value stream maps. • 2. Analyze all inventory notes with an eye towards reduction or elimination. Inventory increases costs. • 3. Analyze the entire value stream map for unneeded steps (fig 18.8, page 87). Notice the information about timing and inventory is provided for each process. • 4. Production decisions should be based on the pull of customer demand. • 5. Extend the value stream map upstream into supplier plants. • The flow of information, material, knowledge, and money are all potential targets for lean improvements.

11. Spaghetti and Circle Diagrams • Spaghetti diagrams are helpful in reducing waste and streamlining product flow. • Spaghetti diagrams refer to product flow paths in an organization (fig 18.9, page 88). • A circle diagram ( hand off map) is used to show linkages between various items (fig 18.10, page 89).

12. Summary • A process is a step or a sequence of steps that uses inputs and produces a product or service as a output. • The elements of a process are Suppliers, Inputs, Process, Outputs, and Customers. • Work in progress (WIP) is the material that has been input into the process but has not reached the output stage. • Flowcharts show each step in the process, decision points, inputs, and outputs. • The best way to ensure that things are done the same way is to have written procedures and work instructions. • Value stream mapping is a technique for following the production path for a product or service from beginning to end while drawing a visual representation of every process in the material and information flows. • The flow of information, material, knowledge, and money are all potential targets for lean improvements.

13. Home Work • 1. What is a process? • 2. Name the 5 elements of a process? • 3. What is throughput? • 4. What do flowcharts show us? • 5. What is the best way to ensure that things are done the same way? • 6. What are work instructions? • 7. What are potential targets for lean improvements?