Case study: Using process mapping to schedule a production system.
A team was formed, comprised of associates from different shifts as well as the shop scheduling personnel, to analyze and recommend a new operational strategy for a whiteboard communication system between the different shifts of an electronics factory using process mapping. Team members were quickly able to establish how the different shifts and scheduling departments in their plant carry out their tasks, and interact with other departments. The team elected to formulate the challenge of improving the system in the following three steps.
1. Problem statement: Establish a dispatching system for shop floor scheduling using whiteboards.
2. Establish a set of rules and guidelines.
• Work the plan: Do not expedite from the next production period and do not start more parts than scheduled.
• Do not start a job before materials are scheduled or physically in-house.
• Identify and follow schedule control points or whiteboards.
• Reduce inventory by developing flexible catch-up plans.
• Schedule all whiteboards on the floor at the same time.
3. Goals of the scheduling system using whiteboards:
• Visibility and communication of the plan
• Track performance to plan
• Prioritize jobs
• Recovery plan from problems
• Improve work flow
• Communications with upstream and downstream processes
• Production associates assume responsibility to execute the plan
Using the tools of process and data flow diagrams，the team members collectively produced the context diagram and the top-level data flow diagram, as shown in Figure 1.7. The charts were helpful for team members to understand the overall manufacturing processes and their interactions, and were used as the basis for formulating a new strategy for the production function of the company.
The DFM diagram in Figure 1.7 contains data stores, which are name y acronyms particular to this manufacturing operation. Their intent was to document the manufacturing process flows in general, and not to specifically detail every existing operation and process. Although no data dictionaries or process specifications were provided for the current process, the reader can follow the information and data flows through the different departments, and understand the complexity and interconnection of the different systems involved in scheduling and manufacturing the product. When designing new manufacturing processes, it is advisable to create the data dictionaries and process specifications to identify each procedure in as detailed a manner as possible.
The data flow diagrams can be used as a quick reference to understand and follow the manufacturing system procedures and requirements. They can lead to better management of the manufacturing function and the data structure needed to support it. They provide a visual representation of the connectivity of the different departments, databases, and functions to be performed. The results of using process mapping are well-managed and efficient operations made possible by:
• Eliminating redundant operations, which will become apparent once the total process is visualized.
• Improving the efficiency of existing operations by clearly identifying the responsibilities of each and its relationship to other operations, as well as by providing the information necessary for correctly performing its functions.
• Better integration with outside activities and sharing of existing resources rather than developing new ones, based on the description of the procedures and documentation of the current process.
• Increasing data integrity by eliminating excess operations. More accuracy will result when databases are well connected, consulted more frequently, and used in more applications. With more focused attention, data has a greater chance of being maintained correctly.
Process mapping methodologies could be very useful when new processes and products are designed or improved to six sigma levels. A good understanding of the system components and their interactions is very beneficial in successfully achieving the goal of six sigma quality for the entire enterprise.