March 20, 2014 / customer delivery, lean manufacturing, production planning
There is no question that lean techniques have changed the face of manufacturing. Kaizen programs, 5S, value-stream mapping, and other lean strategies have rendered impressive results in high-volume manufacturing plants around the world. However, not every lean principle is an off-the-shelf solution for operational efficiency. This is especially true for high-mix, low-volume manufacturing environments.
Machine shops that cut metal are often juggling multiple jobs—many of them custom and almost none of them the same. Production requirements, lead times, and due dates can vary, which makes forecasting and traditional lean concepts difficult to apply. That’s not to say, however, that high-mix operations can’t get lean. As the following examples demonstrate, lean and other improvement techniques can be modified to increase efficiency in even the most customized job and machine shops.
- Improve where you can. According to the book, Made-to-Order Lean by Greg Lane, the primary focus for high-mix, low-volume operations should be “eliminating non-value-added activities and instituting improvements on the most repetitive jobs, a strategy that gives you more time to produce your low-volume work.” In other words, get lean where you can and as much as you can. This video posted by Modern Machine Shop describes the lean journey of a job shop that only produces hundreds of parts per month. While it wasn’t able to apply the entire lean philosophy to its operation, it was still able to implement some principles and has seen significant results, including increased sales.
- Identify patterns to optimize flow. At first glance, most high-mix machine shops appear very complex. However, as the job shop owner quoted in this Modern Machine Shop article discovered, almost every operation can be broken down into a few standardized processes. With the help of a software tool called the Production Flow Analysis and Simplification Toolkit (PFAST), the shop owner was able to evaluate and simplify material flows in order to develop part families and machine grouping. As a result, the shop was able to organize parts into process families and implement hybrid cells to streamline routings, fundamentally transforming the shop’s business.
- Reduce work-in-process. As described in this white paper from the LENOX Institute of Technology, a common workflow pitfall of a high-mix operation is cumbersome production planning and variability, which can cause machine shops to scramble day-to-day, minute-to-minute and just barely meet order deadlines. An in-depth article from The Fabricator describes how two managers addressed this issue by adapting another improvement principle called the Theory of Constraints (TOC). Using the drum-buffer-rope concept and a tool called the Velocity Scheduling System, the companies featured in the article were able to reduce the amount of work in process (WIP) on the floor and, as a result, improved productivity, delivery time, and cash flow. You can read the entire article here.
While high-mix, low-volume operations certainly present a unique set of production challenges, these case studies reveal that there are several strategies managers can put in place to reduce waste, optimize flow, and improve productivity. It may take a little research and some creativity, but leading-edge machine shops are finding that in today’s competitive market, the benefits are well worth the investment.