Most people have heard of “lean manufacturing,” but they think of it in terms of mass production. Does it apply to digital printing? Well, no and yes.
“No,” because some lean manufacturing techniques are focused on repetitive manufacturing processes, such as those of an assembly line. That type of process is not a good match for the “job shop” nature of much of digital printing. In particular, most digital print runs are not long enough to benefit greatly from statistical process control during the course of the run.
But the question can also be answered “yes” to some degree. Let’s take a look at the Toyota Production System (TPS), the philosophy that was the source of much of what we call “lean manufacturing.” In TPS, problems are put into three categories which carry the Japanese names “muda,” “mura,” and “muri.”
Muda. Muda means “waste,” and this has been the focus of much lean manufacturing activity in the US. Printers have tried to address this by reducing the number of sheets required to get an offset press up to color, for example. This analysis would not apply to a digital press, with little or no start-up waste.
But muda has a broader interpretation that includes problems that digital printers need to work on. For example, waiting for a proof to be approved is a form of waste—a waste of time rather than materials. Techniques like color-managed virtual proofing could address this waste. In some cases, providing higher quality than required for the application could be muda. Does your company strive to provide “offset quality” in products where the customer clearly isn’t interested in it? That is a type of muda.
Mura. Mura means unevenness. In the manufacturing context, it means a steady production flow and just-in-time receipt of raw materials. These concepts are harder to fit into many digital shops, but they can provide some useful insight. Look around your shop: what equipment and supplies do you see that are sitting around not being used? That’s a sign of mura. Do you have press checks, where a customer can delay or cancel a press run at the last minute? Mura again. Is there a resource in your shop which is often a bottleneck for getting jobs out? That’s mura too. A certain amount of mura may be inevitable in some printing environments, but some reduction is almost always possible.
Muri. Muri means “overburdening.” It occurs when a machine or a person is required to do more than is reasonable in a given time period. For example, a press operator who receives a file that does not print correctly may spend time trying to salvage the job instead of spending that time printing, thus putting subsequent steps (and subsequent jobs) behind schedule. Muri can often be addressed by setting a standard for the result of each process and making it the basis for beginning the step that follows.
We hope these examples make it clear that there is indeed a role for lean manufacturing principles in digital printing. We can’t get into the details in this post, but those of you attending PODi’s Application Forum (January 28-30, 2008, in Las Vegas) will be able to hear more in Rab Govil’s keynote presentation. Here’s a link for information about the conference: https://www.podi.org/events/index.php?mode=events_regcontent&menuid=3.1&direct=events_regcontent&eventid=59