Stop wasting time!

Figure 1Refurbished die carts are in the standby position by the press, ready for the automatic changeover sequence.

Staying competitive in today's manufacturing environment is a challenge that all stampers are trying to manage. Running lean is a way of life, and most successful companies are embracing this concept and eliminating waste associated with handling dies.

Every minute a press is not making parts, it's costing you money. Increasing press uptime should be every press shop manager's goal. From a die handling standpoint, this means keeping dies in good condition and minimizing changeover times.

Minimizing changeover times is accomplished with effective die change procedures and equipment. Applying quick die change basics is a necessity, such as standardizing die parameters and clamping, prestaging dies, and using proper tools and personnel.

Handling dies in a controlled manner also means less damage. Dedicated die handling equipment is designed for the task, unlike fork trucks and cranes. When dies are handled properly, it translates into fewer repairs, longer life, better and more consistent part quality, and less general maintenance.

Time Killers

When it comes to die handling, most stampers don't apply lean principles—an important piece of the puzzle. Most die handling time is consumed, away from the press, in the storage and retrieval process.

Die storage and retrieval is a major waste of time and resources. This handling process is non-value-added, and the cost can be significant with respect to manpower, floor space, die damage, part quality, and safety issues.

In the typical stamping operation, dies are moved between the press and storage area via cranes or fork trucks (equipment not specifically designed to handle dies in a controlled manner). In the storage area, most stampers tend to stack dies on top of each other on the floor or use a fork truck to place them in racks. Both are rough on the dies and can cause major damage.

To help eliminate these time and resource killers, world-class stampers have integrated quick die change and die storage and retrieval to minimize waste throughout the process. The following real-world applications show how three U.S. stampers implemented integrated die handling systems.

Case Study 1: Retrofitting an Existing Tandem Press Line

A North American HVAC company needed to increase the output of an existing tandem line to meet growing production needs. Automation was added to increase parts per minute, but the key to an effective cell involved quick changeovers and integrated die storage and retrieval.

The line had a manually operated die cart changeover system. However, because of new product requirements, batch sizes were getting smaller, and changeover times had to be reduced to improve productivity.

Figure 2For a tandem press line, an HVAC stamper opted for an integrated quick die change and die storage and retrieval system.

The existing die carts were refurbished and retrofitted with controls to create a fully automated system. Because the number of parts produced was relatively small, all dies could be stored adjacent to the line on single-level storage racks. The carts used for changeovers also were used to store and retrieve the cell's dies.

Now while the line is running, the operator keys in the next part to be run on the line supervisor control panel. The automated die carts move to the designated racks; retrieve the next dies to be run; and move them to a standby position next to the presses (see Figure 1).

When a part run is complete, the operator initiates the changeover at the control panel. Part transfer equipment automatically moves offline to make room for the die carts. While this is taking place, the presses close, dies are automatically unclamped, and the ram is raised to a clear position. The carts automatically move inline with the presses and remove the old dies while simultaneously inserting the new ones. The carts then move back offline with the old dies.

Once the dies are in place, the rams are lowered, dies are clamped, utilities to the dies are automatically connected, part transfer equipment moves back into position, and production starts anew in a matter of minutes.

When the press line is back in production, die carts automatically store the old dies and retrieve new dies for the next part run. The dies are handled throughout the process in a controlled manner, reducing or eliminating die damage. Good first parts are produced, uptime is high, and the line's productivity is meeting the manufacturer's requirements.

Case Study 2: Designing a New Integrated Tandem Press Line

Another HVAC company was planning to manufacture a new product that would require building an addition to house a new tandem press line. Because numerous parts would be run on this line, die storage was a major consideration.

The stamper opted for an integrated tandem press line that included quick die changeover and an adjacent high-rise automatic storage and retrieval system (see Figure 2). Storing dies vertically in multilevel racks allowed them to use building space more effectively and reduce the overall square footage of the new addition.

Robots are used for part transfer in this line and are floor-mounted between the presses. The presses are designed with large windows to allow dies to be changed through the windows.

A two-position, quick-change die table is attached to each press. New dies for the upcoming part run are prestaged on the tables during production. At changeover, an operator initiates a die change from the control panel. Dies are automatically pulled from the press onto the table. The table then shifts to align the new die with the bolster, and the new die is inserted. This is an automatic process that includes die clamping and utility connection.

When the line is back in production, an elevating storage and retrieval cart removes old dies from each table and stores them in designated locations in multilevel racks. The operator prioritizes upcoming part runs in the control system, so the storage and retrieval cart is directed to which dies to retrieve and prestage on the die change tables for subsequent production runs.

Figure 3An elevating die storage and retrieval cart is designed to change out dies from multiple presses.

The integrated die handling system allowed this stamper to reduce initial capital expenditures, and also gave it a manufacturing cell that is efficient and flexible.

Case Study 3: Implementing Integrated Die Handling on Stand-alone Presses

A contract stamper in the South learned the benefits of controlled die handling. Because the job shop never knew which parts it would be running from year to year, it needed a highly flexible system.

The stamper developed an integrated die handling system that uses an elevating die storage and retrieval cart (see Figure 3). It changes dies from numerous, stand-alone progressive-die presses, as well as stores and retrieves dies in multilevel racks near the presses.

For changeovers, the cart is moved to a press and located via floor bushings. The die is removed from the press and inserted into an empty rack directly behind the cart. The cart's elevating platen is raised to the next rack level and retrieves a prestaged die for a new part run. The elevating platen then is lowered to the height of the press bolster and the new die is inserted (see Figure 4).

Once the die is clamped and back in production, the operator moves the old die to its designated storage rack and prestages the new die for the upcoming production run.

Cut Your Waste

As you can see, die handling and storage can be a major source of waste in stamping operations. Paying attention to this area can net significant cost savings and help you become more competitive and profitable.