Die changeover is just one area to bang out inefficiencies
February 7, 2006
Stampers face increasing pressure, from external and internal customers, every day. This, combined with increasing responsibilities, can cause production personnel to feel overwhelmed. Long die changeovers gobble up precious time that could be used for better purposes, leaving many production teams operating in a firefighting mode. Doing a thorough time study and using the results to eliminate time-wasting steps is the first step in implementing quick die change, freeing up some time for value-added activities, and getting control over your production processes.
Bang! Bang! Bang! If you stamp parts for a living, you hear this sound all day, every day. It could be the sound of a press stamping out parts, or it could be the throbbing in your head as you try to deal with a host of pressures. If you feel that the pressure in your head is nearly as great as the pressure in a stamping press, you're not alone.
Production workers are well aware that in today's manufacturing environment, demands are always increasing. New responsibilities add stress to the point that you may feel overwhelmed. These demands originate from both internal and external sources.
External customers require just-in-time deliveries, zero defects, price reductions, and ever-quicker responsiveness. You have to satisfy these demands and must have enough flexibility to turn on a dime whenever a customer calls with a revised production schedule.
Internal pressures include improved housekeeping, safety, identifying and eliminating non-value-added costs (also known as waste), and keeping up with tool and press maintenance. Other internal pressures are standardization, worker ergonomics, rules and regulations, corporate approval, budget, and finances. Demands for higher margins through lower costs require you to evaluate your efficiency continuously on the production floor.
These demands can be too much to manage. A common result is that you end up working continuously in a reactive mode, fighting fires and barely able, or unable, to keep up with the demands of both external and internal customers.
That banging in your head begins to generate a multitude of concerns and questions. How can we handle this? How can we remain competitive while meeting all these requirements? How can we increase the efficiency on the shop floor? Should we look at quick die change (QDC)? How can we be expected to fulfill daily responsibilities and at the same time try to improve shop efficiency? How can we gain control of this manufacturing environment? Where do we begin?
It is necessary to get control of the production processes—in other words, appropriately and proactively manage work processes and control the pressures before they control you. You can tell you're in control when processes become manageable, predictable, and repeatable.
You can't get control all in one leap. It takes several steps that you can do in two big phases. In the first phase, you need to take a look at what your company does and how it does it. In this phase you gather data. In the second phase you turn the data into information and then formulate a plan of action.
Look at Your Company, Your Vision, and Your Mission. Where do you begin?First, revisit your company's vision and mission. If you do not know what they are, find out. If your company does not have a vision and mission statement, create one. Get all the appropriate personnel together and determine what you do, how you do it, and what your company means to the world. This vision/mission statement will be your guide when making decisions about which future path to take. Be sure that all company departments participate in the process. All levels must share the ownership and accountability. Align all future goals, strategies, and action plans with the vision and mission. In today's manufacturing environment, your goals might include improving the quality of your products and services, reducing the amount of inventory on hand, improving customer responsiveness, and implementing lean manufacturing. Once you have the foundation in place, you can look at the future.
Identify the Largest Stress Intensifiers. Next, determine the chief sources of uncertainty and wasted time in your manufacturing process. Target these processes first by attacking the easy, simple, and inexpensive problems (low-hanging fruit). As time and budgets allow, start to address the long-term and more costly areas to continue to gain control of your operations.
If your operations are like most, your die changeovers add a significant amount of stress to your daily work load. Many production facilities have evolved over the years with little or no attention paid to commonality or optimum efficiency. Excessive changeover times steal precious hours from operations such as housekeeping and press maintenance. In addition, too little time for die maintenance can jeopardize part quality if you're forced to manufacture slightly inferior products rather than pull the die at the first sign of out-of-tolerance parts. Likewise, long and inconsistent changeovers make customer responsiveness and flexibility impossible. Finally, long die changeovers keep product cost unnecessarily high.
Take a Systematic Approach to Improvement. The first step in getting control of your die changeover operations is to perform a time study of the entire process from the last good part on one tool to the first good part on the next tool. It is critical that personnel from all areas of the company actively participate in the time study, define action items, and then work to implement solutions.
Set a Realistic Changeover Time Target. Before tearing into the improvement process, you must set realistic short-term and long-term changeover target times. You might desire five-minute die exchanges, but if the current changeover time is two to six hours, this goal is too ambitious. In other words, if you're crawling, learn to walk before you try to run. Set a short-range changeover time target that is near the current minimum time. After you consistently master the new target time, you can take it further. As with all improvement processes, initial time reductions will be inexpensive and quick to implement. Be aware of diminishing returns—after the first few improvements, later advances require more resources.
Planning and Performing a Time Study. You can perform the time study live and record it on video for subsequent follow-up. A video with a knowledgeable narrator identifying the steps as the process progresses can be helpful. You can view the video later with the changeover team to develop the time chart or to help answer any questions that arise. Another strategy, if you have a large enough staff, is to create several teams of observers and have each team generate an independent process and time chart.
Segment the chart into major sections, such as die retrieval and storage, die staging, delivery to and removal from the press, die unclamping and clamping, die exchange, material feed, verification, and start-up. Be sure to break the steps down to the most minute detail possible. For example, instead of simply stating a process as one step ("Unbolted lower die plate"), break it down into several steps ("Looked for and retrieved wrench from toolbox, loosened bolt No. 1, loosened bolt No. 2, removed and placed all front-side lower clamps on workshelf at right frame column"). The more detailed the information, the more thorough the discussion and analysis. For instance, threaded fasteners can account for significant die changeover time, and you may find that dedicating a toolbox with the correct tools for each press/die combination is a huge time saver and well worth the cost.
As you record the data, organize it in a table format. Identify every step of every process along with a minute-by-minute analysis of the changeover. Include in your chart the number of operators either working or idle throughout the entire changeover. Make notes about issues that can be harmful to the operator or other personnel in the area. Equally important, note any activities that can damage the die or the press. Take notes to identify steps completed either well above or well below normal time.
After gathering the data you need, the next phase involves turning the data into information and using the information to make a plan.
Make a Chart. Once you have listed all of the detailed process steps along with the time required for each, plot each activity to visualize where the staff spends its time during a changeover. Repeat this type of study for several changeovers to get an accurate picture of the various problems encountered during changeovers.
The narrated video can be helpful in answering any questions regarding a particular step or procedure.
Identify Solutions and Take Action. After the team completes the time chart, it begins to identify specific areas for improvement. Identify two or three items that can be corrected within a week (for example, organizing tools and prestaging dies and clamps), and then list one or two longer-term items to address. Set timelines for completing each goal and assign a lead person responsible for each task. Add the items to your task list, and make sure all superiors are aware of the added tasks and timelines. If you used several observation teams, compile the various improvement ideas.
Analyze the Results. Observe subsequent changeovers to ensure that the actions taken accomplished the desired results. If so, you continue with the process. If not, analyze the changeover performance further to develop additional actions until you achieve the desired results.
Repeat. After you complete the first series of improvements, you might consider running a new time study and creating a new time study chart and subsequent action items. This process can continue indefinitely.
Making certain that everyone in the production environment knows the importance of keeping costs low will help to ensure the changes are accepted and become the new way of doing business. Installing performance charts at each press is an ideal way to inform operators about daily production numbers, quality, recent changeover times, and other benchmarks.
The only banging you should hear is the banging from the press. Once the die changeover process is under control (that is, when the changeover time is repeatable and less than the targeted time), many of the other pressures will become easier to manage. Be aware that time studies are useful for more than just QDC—they are suitable for every other aspect of your production operation.
After making the first few sets of improvements, do not think for a minute that you are finished. This process never ends. It becomes a process of continuous improvement, which is required in today's global environment.
Michael P. Schollmeier is senior applications engineer at Green Valley Manufacturing Inc., 100 Green Valley Drive, Mt. Zion, IL 62549, 217-864-4125, fax 217-864-4275, email@example.com, www.greenvalleyinc.com.