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voices A Quick-Start Approach for Implementing Lean in Job Shops Dr. Shahrukh Irani, Director, IE Research, at Hoerbiger Corporation of America In the August issue of Gear Technology, we examined the lean tools that will and will not work in high-mix, low-volume manufacturing facilities. Now, we will examine how to implement the tools that will work in the job shop with an approach that expands the capabilities of value stream mapping. A Quick-Start Approach for Implementing Lean in Job Shops Figure 1 presents a flowchart for a “Quick-Start” (Q-S) approach for implementing lean in job shops. Perhaps the biggest departure from value stream mapping is the use of productprocess matrix analysis of the entire product mix to find a clearcut, significant and stable part family. Using a sample of routings from this particular part family, several industrial engineering analyses are done: (1) a spaghetti diagram to understand the flow disruptions due to the layout and building architecture, (2) a process flow chart to break down the product flow into activity elements and delays that are not captured in a value stream map, (3) a material handling analysis chart to understand the flow disruptions due to the material handling equipment and containers being used, (4) absence of Line-Of-Sight between key workcenters, (5) communications and logistics that support schedule execution, etc. The use of a video camera to make a live video recording of a “gemba walk” of the entire value network for the routings that were selected is strongly recommended. Another unique feature of this approach is that in a job shop, where batch-and-queue flow is often the norm, it is advisable to use Theory of Constraints (TOC) to focus the initial Continuous Improvement events (kaizens) on the bottleneck work center used by this family of parts. There is a good chance that the bottleneck for this single part family could very well be the bottleneck for the entire facility. In which case, efforts to improve process yield, standardize tools and fixtures, error-proof machine settings, apply 5S, improve Figure 1 Collect Sales data from the past fiscal year: - Revenue - Quantity PFAST Obtain all Routings/ Bill of Routings Create Part Families Pick a Part Family with Highest Contribution From this Part Family, pick a Part (or Parts) with same Routing Obtain the layout of the facility and locate: - Receiving - Shipping - Value-added workcenters featured in the routing/s Generate the Flow Diagram for the Part (or Parts) Evaluate the Flow Diagram to identify: - Flow Delays - Eight Types of Wastes - Violations of the Principles of Design For Flow - Absence of Line of Sight - Crossflows and Backtracking in Flow Paths - Large (>10ft) travel distances between consecutive operations, - etc. materials delivery schedules, reduce setup times, etc. on this workcenter will have widespread benefits. The bottleneck splits the value stream (or network, if the part routings are not identical) and helps to break up the material flow logistics into two parts: [Receiving → Bottleneck] and [Bottleneck → Shipping]. These two portions of the value network for the part family can be controlled using multi-product multi-machine pull scheduling mechanisms like CONWIP (CONstant WIP), drum-bufferrope and finite capacity scheduling (my favorite method). By integrating the part family concept and TOC, the Q-S approach has always been an effective investment for evey job shop that has hired a student intern to implement JobshopLean during a three-month appointment. A Comprehensive Approach for Implementing Lean in Job Shops The real challenge is to implement JobshopLean in a comprehensive manner, unlike the quick-start approach. Figure 2 presents a flowchart for a comprehensive approach for implementing lean in job shops. At the core of this iterative approach is the expectation that (1) a job shop will utilize production flow analysis and/or group technology to identify the stable part families A Quick-Start Approach for Implementing JobshopLean. Create a Flow Process Chart to identify Flow Delays and Eight Types of Waste Create the Value Stream Map for Detailed Evaluation of the Flow Diagram TEST ABRASIVE STOCK SAW 1 1 1 1 Number of shift: Number of shift: 1 951 760 C/T= 1 day/ht # C/T= 20/hr C/O= C/O= 10 min S/U= S/U= 15 min Compute: - Value Added Ratio (VAR) - Makespan (C) - Weighted Makespan (Cw) Help to identify the Bottleneck Perform TOC Analysis at Bottleneck Identify and Prioritize Strategies for Improvements Project Schedule to Implement Recommendations in Order of Priority Conduct a detailed analysis of material handling and shopfloor control using a Material Handling Planning Chart Conduct a timeline analysis and develop a cashflow diagram using records for one or more past orders for this part Stages in the analysis when a facility walkthrough and taking photos would be valuable: 1. At each machine 2. Between pairs of machines 10 GEAR TECHNOLOGY | October 2012 [www.geartechnology.com]
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