Stamper Designs New Plant Layout for JIT

Hit-to-hit time is reduced significantly thanks to a closed-loop die change and storage/retrieval system that serves three presses at Volunteer Engineering's new automotive stamping facility in Manchester, TN.

This closed-loop die change and storage/retrieval system includes a multi-tier rack for die storage (left). Located along the back wall of the new facility, the rack can be accessed by an elevating die cart, which brings selected dies to any one of three different presses. Atlas Technologies, Fenton, MI, designed and built the system.

Just a few years ago, manufacturers might have cringed at the thought of having to supply high-production parts to its customer with a one-day turnaround. However, just-in-time (JIT) delivery now has gone beyond being just a theory. Today, it is a critical practice for many manufacturing companies.

Such is the case for Volunteer Engineering, a division of Davis Industries, Detroit, MI. In order to serve its customer -- Nissan Motor Company -- Volunteer needed to open a plant operating on a JIT basis. "Quite simply, if you can't provide product on a just-in-time basis, you may not survive in today's highly competitive marketplace," observes John Felice, president of Volunteer Engineering.

To meet Nissan's stringent delivery requirements, Volunteer strategized on how to design the most cost-efficient stamping facility possible. The first priority, of course, was how to design a plant capable of practicing JIT principles. This resulted in determining how to best maximize uptime and productivity while minimizing the time it took for die changeover. One of Volunteer's strategies was to implement a JIT-approach first used by Toyota called Kanban, which "pulls" the necessary units in the necessary quantities at the necessary time (as opposed to "pushing" inventory based on speculation of market demand). In other words, under the Kanban Visual Management/Pull System for inventory control, part production initiated when inventories reach predetermined levels. Kanban cards are used to trigger raw material orders and production runs, and in some cases, raw material becomes a stamping within 24 hours.

Under the visual management inventory control system, Volunteer allows high-volume products to decrease until two-days worth of inventory is remaining. At that time, a new lot (five-days worth of inventory) is run. According to Felice, a lot of components may be as many as 8000 parts. Quick response also allows Volunteer to ship Nissan its various stamped components instantaneously. This approach has made inventory paperwork and material requirement planning (MRP) things of the past.

"Everything about the way we manufacture components in Manchester -- from die changeover to restocking inventory -- is based on JIT principles," notes Felice, who has implemented much of the JIT philosophy and expertise he gained after eight years of studying JIT concepts and six years as an engineering manager at Nissan's Georgetown, KY, facility. Even the decision on where to build the 62,400 sq. ft. Manchester facility was based on proximity. Manchester is just 15 miles away from Nissan's engine and transmission plant in Decker, TN.

Quick Die Change with Control
In order to properly operate a JIT facility, Volunteer needed a quick and consistent way to reduce downtime and increase output. The solution was an integral, automatic die change and storage/retrieval system, designed and built by Atlas Technologies, Fenton, MI. This system uses a powered elevating die cart that travels between three presses and a multi-tier rack storage area. Die changes are staggered so the cart can serve all three presses.

This elevating die cart from Atlas Technologies uses a push/pull module to select dies off a storage rack and accurately place them in the appropriate press. Die changes are staggered so the cart can serve all three presses.

The die cart has the ability to pull a die onto the cart from the storage racks. Then it can push the die out the other side and accurately position it in the press. Die size can range from as little as five tons up to 20 tons or more. Actually, Atlas' automated die storage/retrieval systems are not limited to small, lightweight dies. The heaviest automotive body panel dies can be accommodated in multi-tier racks for easy storage and retrieval. Total die retrieval and change-over time at Volunteer Engineering is less than five minutes per press. Hit-to-hit time, including die clamping time (hydraulic) and coil change on dual-mandrel quick-change coil feeders, is 12 minutes.

"In the past, many manufacturers with 300- to 600-ton presses might be satisfied with a changeover that took an hour," Felice points out, "But when you consider a stamping facility with five changeovers per day on each of three different presses, time is of the utmost importance. This is why we made the strategic decision to implement an automatic die change system with storage/retrieval capabilities.

Looking through the press, the Atlas elevating die cart (in orange) demonstrates its capability to pull dies off multi-tier racks and place them accurately in the appropriate press. Typical die retrieval and changeover time is less than five minutes per press.

"Minimizing response time is critical to meet our customer's requirements," Felice reports. "Fast predictable die change is mandatory since up to five different parts are produced on each of the three presses every day. When you consider the fact that up to 25 different part numbers are cycled through each press, it's easy to see why quick and reliable die change is important to us."

An interesting aspect of Volunteer's die change and storage/retrieval system is that it does not require the use of a die table or separate die cart. Die sets are retrieved with the elevating die cart and placed directly into the press. By eliminating the die table or cart, plant floor space is maximized. In addition, nearby storage racks allow the dies to be stored in close proximity to the presses.

The die change and storage/retrieval system was totally integrated into the plant design. Multi-tier racks are positioned along the back wall in order to neatly store and retrieve die sets in an efficient manner. These racks allow a maximum number of dies to be stored using a minimum amount of floor space.

The elevating die cart (center of photo), rides on floor tracks. It does not require a die table or separate die cart. Die sets are retrieved and placed directly into the press.

This space savings also gives Volunteer the flexibility to add storage capacity or presses without expanding existing floor space. Felice notes that a fourth press is scheduled to be added later this year. When Phase II is completed, Felice anticipates there will be 75 dies working on four presses in 7500 sq. ft. of floor space -- about half the floor space typically required for that many dies and presses.

Another benefit of the automated die cart is that it allows pressroom personnel to pre-stage dies before an upcoming production run. At that time, tooling setup or maintenance can be completed and verified. This is part of Volunteer's philosophy of a very strict die maintenance program. To ensure high reliability and eliminate special die adjustments, every aspect of the production process is standardized, including subplates, pass-lines and die shut-heights. Through standardization, multi-tier storage units, storage/retrieval die casts and a JIT-focused philosophy, Volunteer has put a new spin on the terms quick die change and agile manufacturing. MF

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