A method for setup time reduction in high precision machine cells
This research focused on an important aspect of production, machine changeover, or setup time. Setup time is defined as the elapsed time between producing the last part from the most recent lot to the first part of an incoming lot. The research had four objectives. First, an existing method to reduce machine changeover time was evaluated in a high-precision machine cell (HPMC). Second, the causes and effects of setup problems in an HPMC were identified. Third, a method to reduce setup time was developed to more fully address some of the identified problems. Fourth, the developed method was evaluated in another HPMC.
After reviewing published setup reduction methodologies, the Single Minute Exchange of Dies (SMED) approach was selected for evaluation in machine cells. According to its developer, SMED can typically reduce setup time by 70 to 90%. The case study did not fully support this claim. Possible explanations for the mixed results were developed. Also, a number of setup problems were not fully corrected. These problems included machine and tooling failures, delays from tasks not completed at the machine area, and labor-related problems.
A method to reduce setup time was developed. The method applied the work simplification approach to reduce setup time. The developed setup reduction method consisted of five steps: (1) document the existing method, (2) simplify the current method while using the same tooling and procedures, (3) identify opportunities to reduce setup time, (4) prioritize the opportunities and (5) implement the prioritized projects. The method includes the basic setup reduction principles of SMED and addresses problems that were not fully corrected by SMED.
The developed method was tested in another high-precision machine cell. An additional 22% reduction in setup time occurred as a result of correcting problems not fully addressed by SMED. It was concluded that because the new method focused on the manpower, materials, and methodology used during a changeover, it reduced setup time further than existing methods.