Reducing Die Changeover Time without Capital Expenditures
One of the cornerstones of an efficient stamping operation is its ability to perform die changes in less than 10 minutes. Retrofitting an entire stamping operation for quick die change can require a very costly investment. Justifying such a large amount of money in a short payback scenario can be impossible.
Knowing what needs to be done is one thing; providing the cost justification in today's tough economic environment is another major issue. The first priority is to maximize existing resources as much as possible before spending any money. Take all opportunities to resolve productivity bottlenecks without making a major capital investment.
Addressing out-of-press Setup Time
One logical starting point for a quick die change program is a blitz strategy, which uses a team concept to reduce changeover time by addressing out-of-press setup time. The main goal is to reduce changeover time by at least 50 percent over a period of three to four days.
This strategy provides plant management with the following information:
- Instant feedback detailing potential time and money savings on a press or press line with minimum investment.
- The expected degree of success based on the company's available resources and expertise.
- A viable plan of action detailing how to proceed with a custom die change reduction program for the remaining presses.
One Step at a Time
Identifying pockets of time is the first step toward reducing die changeover time. This chart shows pockets of time for a 300-ton coil-fed press.
To be successful, the program requires taking specific steps in a logical sequence.
Step 1—Identify Pockets of Time. Before implementing any changes, a company must break down the existing changeover time into "pockets of time" (see Figure 1). Pockets of time refer to individual tasks in a die changeover from the last hit to the first good hit. The most effective tool for this process is a videocassette recorder. Videotaping a representative changeover from last good part to first good part can help identify frequently occurring pockets of time.
Step 2—Select the Team. Before training can begin, an established team must be in place. Be sure to incorporate shop expertise in your team. Include the production supervisor of the area being affected, as well as production operators; setup people; and industrial, process, and tool engineers. In addition, be sure to include representatives from the various support departments, such as the toolroom, tool crib, die storage, maintenance, material handling, and scheduling.
Step 3—Implement Program Techniques Using the Team Concept. The first day of the program involves a full day of training for the team, providing the basic principles and techniques needed to analyze current changeover procedures and address out-of-press setup.
The second day builds on the training of the first day and develops a plan of action to direct the work effort. Team members analyze the videotaped changeover and break it down into pockets of time. Although a single session is not enough to make them experts, team members will become familiar enough with quick die change principles to develop a realistic plan for making short-term improvements.
Planned improvements to eliminate walking and go-fetch-find include:
- Identify specific duties for the external work elements.
- Preplan job assignments.
- Standardize clamp pieces and store them with the die.
- Build carts to prestage tools and stock chutes.
- Prestage containers, stock tubs, dies, and fork truck.
- Prestage coil on the coil car and feed coils to the die during die exchange.
- Hang signs identifying setup and prestage areas.
- Identify two die sets to be used in the program to demonstrate all possible setup combinations.
The third day begins with practice runs to perfect changeovers and videotaping of a new representative changeover. The day culminates with a presentation to management that includes "before" and "after" changeover videos, identification of changeover time savings, and identification of short- and long-range strategies for completing planned press improvements.
Textron Turf-Care, a lawn and garden equipment manufacturer in Lincoln, Neb., recently implemented a three-day blitz program to identify short-term improvements that would reduce die changeover time on an 80-ton press with a 50- by 33-inch bolster.
Based on the urgency of the program, the team outlined some parameters. Mainly, it wanted to keep the program simple and low in cost, involving no new buildings or facility additions and no major capital expenditures.
The program was implemented in the following steps:
- Perform time study of several changeovers.
- Identify present pockets of time.
- Divide pockets of time into internal (work that occurs while the press is down) and external (work that occurs while the press is running) elements.
- Modify as many internal elements as possible into external elements.
- Identify method changes to improve external elements and reduce out-of-press setup time:
- Go-fetch-find of material, clamps,and tools
Upon review of the video, the team identified several problems:
- Too many wrenches, no socket wrench on open-back inclinable presses
- No preplanning
- Too many turns to tighten bolts
- Too much time spent on go-fetch-find
- Operator has to get off fork truck to load and unload die
- No prestaging of die or material
- Carts filled with odd-sized T bolts at each press
- Lack of labeling on die storage racks
- Clamping strap used instead of one-piece clamp
- Congested layout
- No standardized wheeled baskets
In three days of work, the team was able to reduce the average 33-minute changeover to less than 10 minutes without spending money or purchasing new equipment.
Work With What You Have
As this concept illustrates, you must address the basics of quick die change before adding sophistication. And it can be achieved without all the bells and whistles.
Sean McDermott, an operations manager at a stamping plant in California that implemented this concept, said, "We had invested heavily in the equipment required to perform quick die change but had not realized many of its benefits. With no additional investment, the simple concepts of prestaging, team setups, and ownership enabled us to achieve an 80 percent reduction in setup time within two weeks. Our input has increased by more than 40 percent, and the setup team is eager to apply these same concepts through the rest of the plant."
These same results can be attained in your factory. Success is a matter of planning, training, and practice.
Gary Zunker is president of Lightning Time Savers Inc., 103 Steeplechase Court, Nicholasville, KY 40356, 859-223-9277, fax 859-223-1066, firstname.lastname@example.org, www.lightningtimesavers.com. Lightning Time Savers Inc. specializes in all areas of quick die change engineering, consulting, and hardware.
STAMPING Journal is the only industrial publication dedicated solely to serving the needs of the metal stamping market. In 1987 the American Metal Stamping Association broadened its horizons and renamed itself and its publication, known then as Metal Stamping.