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Question and Answer

Die Lockup Methods

by Jeff Peterson

February-March, 2000
What are my choices for locking up dies?

There are two basic ways hot stamping dies are locked-up on press-either with a honeycomb mounting system utilizing toggle hooks or with a bunter post system that uses a bunter front plate and bunter posts to position the die. A third basic method for die lock-up is using die-mount tape that is activated by the heat and pressure of the press to hold the die in place. This is a very messy and antiquated and method for die lock-up that is used very rarely in foil stamping operations today.

Utilizing toggle hooks with a honeycomb chase is probably the most common method of locking up dies. This is accomplished by first positioning the dies in place with a master transparent positive, demonstrating where the foil stamped images are to be stamped on the sheet. The foil stamping press operator then inserts the toggle hooks into the nearest holes on the honeycomb chase and tightens them so the jaws of the hook are locked securely against the die. Adjustments can be made very easily by loosening or tightening each toggle hook until precise registration is achieved.

For an approximate 4" x 4" die, it is recommended to utilize between 6 to 8 toggles, depending on the application and the weight of the die. As one can imagine, a sculptured brass embossing die will need more support than a lightweight flat stamp magnesium die.

Tightening the toggle hooks too tightly around the die can sometimes cause the hooks to break or snap. This can be avoided by securing the toggle, but not so tight as to cause unneeded pressure between the toggle and die. In addition, a new toggle is now on the market developed by Eagle Systems that is constructed of a special grade of stainless steel to help withstand the heat and pressure of the foil stamping process without breaking.

Another common method for securing hot stamping dies is a bunter post system. This is a cost-effective solution when a die cutting press has been converted to a foil stamping press. The bunter post system consists of four key components: a heated chase, a temperature control, bunter front plates, and the bunter posts. It is a dual-purpose system to provide controlled heat to the press and provide an easy way to lock-up foil stamping and embossing dies into position.

The heated chase provides the source of heat to the press and is fastened in the same manner as a die cutting chase. The temperature control maintains the desired temperature and is connected to a power supply and the heated chase. The bunter front plate is a heat-treated precision-ground plate with a grid of tapped holes that can be easily attached and removed from the heated chase. This enables the press operator to lock-up dies off press and eliminates the time of disconnecting and connecting electrical wires, which is necessary if the operator is working with a heated honeycomb chase. Once the bunter front plate is in place, small rectangular bunter posts are attached to the front plate around the perimeter of the die. The operator can then tighten adjusting screws to position and lock the die in place. Additional bunter front plates are available to lock-up jobs while one is running or to leave repeat jobs locked-up for future runs.

Is there anything new on the market for die lock-up?

During the recent Foil Stamping & Embossing Association Conference in Las Vegas, TDI Magneticx P/L of Arcadia, Australia, introduced a new process that the company has developed and patented utilizing a magnetic plate and steel-backed engravings. The magnetic plate can be manufactured in a variety of sizes and can be easily mounted to a honeycomb chase with standard toggles. The dies are a water-soluble photo-sensitive thermo-plastic that are hardened in a special machine and manufactured with a thin steel backing. Once the magnetic plate is mounted, the steel-backed dies can be easily placed in position on press. Adjustments are quick and simple, eliminating the repositioning of toggles or bunter posts. The new system is said to be an excellent alternative for short runs and quick changeover applications. TDI is currently setting up distribution channels in North America to make this product available to trade finishers from coast to coast.

What are my choices for choosing the right type of chase? Honeycomb chases and bases are available in many different sizes for a variety of presses and are commonly manufactured of steel. However, high strength aluminum chases and chases made of other alloys are available on the market. Steel chases are extremely durable and wear-resistant to withstand the constant pounding and heat of a foil stamping press. The disadvantage of steel is that it weighs up to three times that of aluminum or the alloy material used by Chase Engineering's Lightweight chases. Steel chases can be a problem for smaller operators to handle, including women operators, which are becoming more and more prevalent in the industry. Lighter chases allow the operator to easily move the chase in and out for setting up jobs off press.

Sterling Toggle Inc. commonly manufactures aluminum honeycomb chases to fit inside an existing die cutting chase for cold embossing. The small honeycombs can be fastened inside a die cutting die board to enable the customer to emboss and die cut in one pass on press. Small aluminum honeycomb bases can be manufactured in a variety of custom sizes to fit the specific application.

Referenced Chase and Die Lock-up System Manufacturers and Suppliers:

Chase Engineering (Lightweight chases for Kluge presses) 800-452-4423

Eagle Systems, Inc. (Steel chases and Eagle Claw toggles) 800-6EAGLE9

Sterling Toggle Inc. (Steel and aluminum chases, toggle and bunter post mounting systems) 516-491-0500

TDI Magneticx P/L (Magnetic mounting plates and steel- backed thermo-plastic dies) +61 2 9653 2148