Avoiding Pitfalls to Lean
Certain common hazards can interfere with your attempts at making your operation better and more efficient.
Executive Director, Center for Manufacturing Systems, New Jersey Institute of Technology
With time and effort, most of us would agree that much can be done to make our operations better. As a “lean guy,” I believe this, and I have seen companies transform themselves using simple, yet powerful lean techniques. On the other hand, I also have encountered instances where companies mishandle the introduction of lean techniques, or simply do not follow through with implementation and are disappointed with the results. There are certainly some pitfalls that can hinder the effectiveness of tried-and-true lean techniques, and I would like to point out just a few.
The 5S system of workplace organization. This is probably the most commonly used lean technique and is based on the idea of having “a place for everything and everything in its place.” 5S stands for sort, set in order, shine, standardize and sustain, and if these steps are followed in sequence they should lead to an organized workplace. The main pitfall of this system comes with the failure to audit the workplace once it has been introduced. Quite simply, if the organizational effectiveness of the workplace is not being checked, conditions will backslide.
For example, a shadow board can be a very effective means of keeping tools organized because it is highly visual, showing both where tools belong and whether they are missing. Some people do not like shadow boards, however, believing they cause all tools to eventually go missing. In these cases, the shadow board’s strengths of visibility and easy access are also viewed as weaknesses. To be effective, shadow boards need to be checked regularly (such as at the end of each shift), and corrective action should be taken if needed.
Another pitfall for 5S is a lack of standardization in workplace organization. Ideally, workbenches that perform similar tasks should be uniformly organized so that anyone can work at any workbench. Uniformity (or standardization) eliminates confusion and delays associated with searching for needed items.
Quick change-over techniques to reduce machine setup time. As a standardized process for converting a machine from producing one part to producing another, quick change-over is key to getting the most out of equipment. Consistent, short-duration change-overs reduce machine downtime, improve product quality and provide increased flexibility. One common constraint to quick change-over is not having the tools or supplies needed to perform the change-over when it is required. This can result in a less-than-ideal change-over with unpredictable results that negate the benefits of a standardized approach. Another pitfall to this lean technique is a constantly changing schedule. As quick change-over relies on advance preparation for the next job before the current job finishes, it is critical that everyone involved knows what that next job will be.
Pull systems using supermarkets. Pull systems advocate buying or producing parts only when they are needed. Typically, a “pull signal” of some type conveys the need to replenish a part. A supermarket is the area in which the parts are stored and from where such a pull signal originates. Although a relatively simple concept for effectively managing inventory (one that has worked well in food supermarkets for years), such a system relies on action being taken in response to the signal. The biggest pitfall of this system can be seen when this action is not taken in a timely manner. Signals may be missed and orders not generated when required; part lead times may increase suddenly, resulting in stock-outs; or cash-flow management may cause orders to be consciously delayed.
In addition to delayed execution, another pitfall is from not reviewing the supermarket’s fundamentals, including the inventory level at which reordering is required and the amount to reorder (both of which may be impacted by some of the other pitfalls described earlier). These fundamentals need to be reviewed on a predetermined schedule to ensure the pull system is working the way it was intended.
Total productive maintenance (TPM). This technique, which relies on machine operators also being involved in the machine maintenance process, has proven to keep equipment running better, longer. Once again, a pitfall of such a system is not taking appropriate action when needed. If it is determined that an operator must complete certain tasks during machine startup, these tasks must be completed and documented. The operator being too busy is a common excuse, but not a valid reason to circumvent the TPM process. An effective TPM program will also identify the right spare parts that should be on hand. Not committing to keeping these spare parts in inventory or being able to readily obtain them also will hinder TPM effectiveness.
Don’t let these pitfalls cause you to miss the improvement opportunities that lean techniques can deliver to your operations.