Simpler setups: Supply Chain & Logistics

The Toyota Production System, lean manufacturing and associated concepts have become ubiquitous in modern manufacturing. Reducing or removing activities that do not add value for end customers is the foundation of lean manufacturing. Anything that does not add value is waste, or muda in Japanese. Eliminating muda lowers costs, which improves profitability and makes a company more competitive in the market.

A significant source of waste is setup time. In the 1950s, Toyota Motor Corp. started working to reduce the time needed to set up the large stamping presses used for making car bodies. After a while, the business was able to shorten changeover time from hours to minutes, improving efficiency and delivering substantial cost savings. Eventually, the primary pioneer of this concept named it “single-minute exchange of die,” or SMED.

Lean experts often speak conceptually about SMED and talk about muda, single-part flow, inventory turns and work in process. It is easy to glaze over when lean folks get started, but all machinists — regardless of whether they know the terms — understand that reducing setup time means an improved bottom line.

Reduced cost of setups at a machine is the most obvious positive impact from SMED. However, there are less obvious and possibly more meaningful ways that SMED impacts efficiency and shop performance.

Successfully implementing SMED means that a machine can be changed from producing product A to product B in a matter of minutes, which does not allow time for someone to chase dimensions and other quality requirements by adjusting the setup across multiple iterations. Achieving changeovers that can be done in minutes and delivering 100% first-pass yields require developing precise tooling, careful process planning and creative methods.

Setting up in minutes and producing a good first part with no adjustments demands precise workholding and toolholding that can be moved on the machine and located quickly. Many devices, such as quick-change chuck jaws, Capto toolholders and pallet changers, aid fast changeovers. A shop serious about SMED will commit to the expense of these tools and implement their use throughout the shop, thereby creating a standard method. Standard methods not only reduce costs of setup but create flexibility, which lowers lead times and inventory costs.

Discipline is the most significant hurdle to overcome when implementing SMED. Machining operations must be planned so that a system is developed. Workholding fixtures have to be designed to incorporate the quick-change features and built with precision to ensure accuracy and repeatability when loaded on the machine. Cutting tools need to be arranged and stored so they can be accessed and loaded quickly, and the dimensions of raw materials must be controlled to eliminate variation.