Five to six decades ago, Toyota quickly realized they had a problem on their hands: Their car body molding process was being bottlenecked. Somewhere along the way, one stage of production was running slower than the others, and couldn’t keep up. Not only did this mean a slower production rate for Toyota’s factories, it meant less efficiency for the effort put in, and therefore less return on investment.
In response, Toyota tasked its engineers and employees with figuring out how to reduce “changeover” times, or the time it takes for a machine or team to move from one process to being ready to begin on the next. In a modern, mechanized world, many machines and assembly lines are capable of completing multiple steps in a production process, but the time spent on changeover can kill your efficiency.
Changeover Times Discussion
Recently, a LinkedIn user (Chris Harris) asked questions akin to the ones that Toyota asked 50+ years ago. He said that he had been tasked by his employer to reduce the changeover times a particular machine, and was looking to the community for some help. Many of the responses that he received, while modified and updated for a modern-day work environment, have their roots in the lean principles that companies like Toyota have already been using for decades. Let’s take a look at a few of the suggestions he received and talk about how they work.
One of the best ways to start out in any changeover time reduction process is to take a look at all of the components and steps involved and then categorize them. In general, all tools and steps will fall into one of the three following categories: cleanup, set up, and start up. Cleanup involves any actions that take away remnants of the original process and that are required to clear the way for the second job. Setup will involve placing new molds, adapters, or setting up other relevant and necessary components of the second job. Finally, startup involves the last tasks needed in order to actually start working on a new step.
SMED and Changeover Times
In general, setup is the most time-consuming one of the three. In order to address this, you can implement an SMED regimen to help streamline your setup. SMED is a lean acronym that stands for single minute exchange of dies. Unsurprisingly, it was one of the first suggestions given to the LinkedIn user.
One of the most common and illustrative examples used to show what SMED is all about is that of a race car driver at the pitstop. Shaving even just tenths of a second off of the pitstop time can be the difference between one team winning or losing a race. For this reason everyone involved in the process is extremely well-versed in their specific tasks, nearly to the point of perfection. While you don’t have to actually get changeover down to one minute, as the name implies, keeping the minutes dedicated to changeover in the single digits should be your goal whenever possible. To achieve this, visual markers or notches that show where new pieces of equipment go during changeover can help reduce the amount of time it takes for your workers to get things in place.
Organization and Changeover Times
Organization is also a huge part of reducing your changeover times, as one user (Hasmukh Desai) pointed out in his reply:
Before starting change over keep required tools and spares ready. Largely time is lost in searching such items. Say washing/cleaning material, change over spares, lubricants, required tools and tackles, skilled workmen & supervisors etc. Also keep cross functional people ready like electrical, instrumentation etc. If past records of such change overs showing time taken are available then before starting work, discuss with your personnel as to how to imrove the time and take it as challenge for the whole team. We have done this exercise and improved by 1%.
Note the focus on organization. Can you think of any other lean tools that might be associated with organizing the workplace? 5S certainly comes to mind. Using various tools and strategies such as a 5s shadow board tape or a foam tool organizer (which you can find here) can help keep a workplace organized and clean can certainly be key to shaving off extra minutes in changeover. In some workplaces, tools may be shared between stations which can cause them to not always be in the same place when an employee is looking for them. In some cases, changeover can be improved by ensuring that each station has its own set of tools. This might mean having to buy some new equipment, but the gains in long-term efficiency from eliminating a bottleneck and improving changeover times can easily make up for these immediate costs.
Training and Changeover Times
Training is also going to be one of the biggest factors to reducing the changeover times. Ensure that you make the most of each worker by training them to be independent, so that they don’t need the help of third-party engineers or machine operators in order to make changeovers, for example. Just like with the pit crew idea, you will also want to make sure that each individual worker, in any job that involves a team, has a specific, assigned role. This will reduce confusion among coworkers and increase efficiency when it’s time to make a changeover.
Of course, it’s important to know which steps of your work process really need to have their changeover times reduced before you implement any of these ideas. This is because you may be actually wasting time and effort if you go through the process of streamlining a machine that isn’t an actual bottleneck. Before beginning, be certain you’ve identified the actual processes that are limiting your business before moving forward. Once you’ve implemented initial changeover time reducing-strategies, keep using worker feedback and your own observations, along with numbers and data, to shave seconds off until the process is either no longer the bottleneck in your production cycle, and/or is being executed with pit crew-like precision.
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- Lean Manufacturing in a Nutshell