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Lean, theory of constraints (ToC), quick response manufacturing (QRM), cross training, and SPC are powerful, tried and true methodologies for process improvement. However, these tools are rooted in high-volume manufacturing environments and don't always play nice in a high-mix, low-volume (HMLV) operation. The new WORK manufacturing strategy was specifically developed to overcome these shortcomings while capitalizing on their strengths.
Limitations of the Current Toolset
Lean is a collection of tools and methods designed to eliminate waste, reduce delays, improve performance and reduce costs. Lean focuses on eliminating non-value-added activities, as opposed to more traditional improvement efforts, which focus on reducing the time in value-added steps. The problem with lean is that many of the tools work best in a high-volume process that has very little variation in product mix.
ToC is a methodology that focuses on removing bottlenecks from a process through a series of five steps:
1. Identify the constraint
2. Exploit (improve) the constraint
3. Subordinate (align all activities)
4. Elevate (additional actions)
The problem with ToC is that, by definition, eliminating one bottleneck creates another, and in a high-mix process the bottlenecks can change with the mix.
Quick Response Manufacturing
Quick response manufacturing (QRM), a cell-based strategy closely related to focus factories that was developed specifically for HMLV, has been gaining popularity over the past few years. The problem with QRM is that it works best when equipment sets from a number of sequential departments can be physically organized into small cells. This becomes problematic in operations that have processes requiring capital intensive environments like plating, clean room imaging, etc., where setting up a single machine in a cell is prohibitive.
Editor's Note: This article originally appeared in the October 2015 issue of SMT Magazine.