'We now have much better control over tool inventory'
Using five vertical lift modules and nine tool dispensers, Sikorsky reduced storage requirements by 90% in one tool crib and cut inventory levels 50% elsewhere.
By Gary Forger -- Modern Materials Handling, 3/1/1998
At first glance, storage efficiency of production tools doesn't seem likely to be much of a priority when the shop floor covers 5 million sq ft. But as Sikorsky Aircraft managers Steve Schuman and Fred Kendrick have proven, improved storage efficiency can have a very positive domino effect.The key at Sikorsky's Stratford, Conn., helicopter facility was changing the way that 30,000 reusable template tools and 32,000 disposable cutter insert tools were stored and dispensed.
Floor storage space for the reusable templates used to make sheet metal parts was slashed 90% by making better use of the cube with vertical lift modules (VLMs). That opened up enough floor space to store an additional 300 pallet loads of oversized tools previously stored at an off-site location 30 min distant.
Retrieval time for a tool is now only 45 sec compared to 3-5 min with the old mezzanine and racks.
Meanwhile, inventory on hand of the cutter insert tools was cut in half by removing them from a centralized tool crib and storing them in seven point-of-use tool dispensers. With access to dispensers in their work areas, workers no longer waste time walking back and forth to the central crib. They can also pick up only the exact number of tools they need, eliminating an age-old problem of hoarding tools. In addition, inventory control software tracks the who, what, when, and where of each tool transaction.
"We now have much better control over tool inventory on the shop floor," says Kendrick, manager of tool services.
And as Schuman, the project engineer who wrote the capital appropriation for the project, explains, payback for the VLMs and tool dispensers is less than 3 yrs.
Tools move to people
Sikorsky's reusable templates are primarily aluminum tools used as a pattern for the production of helicopter sheet metal parts. The tools range in length from 3 in. to 6 ft.
Before the VLMs arrived, the templates were stored in a central crib either on shelves on a 9 ft. high mezzanine or hanging on hooks from racks at various intervals up to the 32 ft. high ceiling.
In an average day, nearly 300 templates were requested from or returned to the crib. About 75% of the template transactions involved the mezzanine with the balance from the racks.
Template requests were made on paper and turned into crib personnel, six people for each of two shifts. Someone would then go and retrieve the tool. It typically took 3 min. if the template was on the mezzanine but 5 min. if hanging from the racks. To access tools in the racks required a Sikorsky worker to ride a scissor lift up to the storage position.
The mezzanine and racks, which required a total of 3,100 sq ft, have both been removed since installation of the five VLMs (Remstar) in just 270 sq ft of floor space. In fact, the VLMs store a total of 35,000 tools, a 5,000 template increase from before, with the additional tools coming from other areas of the plant.
The VLMs are 32 ft tall and each have a maximum capacity of 44,000 lbs. Two of the units have 72 in. wide trays and three have 48 in. wide trays. Each tray can hold up to 550 lbs and is subdivided as needed. Because most of the tools are aluminum, maximum tool weight in any of the trays is only about 250 lbs. The VLMs also keep the templates much cleaner than was previously possible.
Tools are now ordered electronically from the manufacturing workstation where they are needed. A printout at the VLMs directs personnel who work in the crib to the appropriate storage unit.
When the location is input to a keypad at the front of the VLM, the retrieval process begins. Trays of parts are stored on both sides of an open central column. The retrieval mechanism rides up and down a spine in that column. When the retrieval mechanism arrives at the designated tray, it stops, pulls the tray out of its storage location, and delivers it to the picking window at the base of the VLM.
A typical retrieval takes about 15 sec. Removal of the part from the tray typically takes 30 sec. Then the tray is placed back on the retrieval mechanism for return to its storage location. The retrieved tool is either picked up by the person requesting it or delivered to the appropriate workstation.
"In the old scheme, people went up and down to get the tools. Now the tools move up and down to the people," says Schuman.
The additional floor space freed up by the VLMs is now filled with 30 ft high racks. These will store the 3,000 tools that did not fit into the VLMs and an additional 300 pallet loads of less-often requested tools that were previously stored off site, significantly improving access to those tools when they are needed.
Cutter insert use cut 56%
Meanwhile, Schuman and Kendrick realized that the centralized crib approach to storing disposable cutter insert tools had room for improvement.
To start, the centralized location of the crib meant some of the areas of the machining center had no point-of-use access to tools. It was always a hike to get them.
In addition, most of the cutter inserts were packaged in sets of 10 or 12. That combined with the distance to the crib and a habit of hoarding tools meant workers typically took a full pack even if they needed only three or four tools.
During a pilot test, three dispensers were loaded with cutter inserts and efficiencies measured. Schuman and Kendrick found that cutter insert consumption actually dropped 56% when access was at the point-of-use and workers could pick up only the precise number needed. With tool costs ranging from $6-40 a piece, that added up to a cost savings of nearly $100,000 a year.
As a result, the decision was made to move the cutter inserts out of the centralized crib and place them in seven tool dispensers (Remstar) on the shop floor. The seven units dispense a total of nearly 15,000 items, down from the 32,000 that were previously given out.
Now workers walk up to the tool dispenser in their area (see drawing) and pass their personnel identification card through a reader on the front of the unit. A display then requests the part number and quantity required. Once that information is keyed in, the dispen-ser's carousel rotates the bin with the requested item and dispenses it to the worker.
"This procedure gives us all of the details about who is ordering disposable tools. It also helps to expedite accurate replenishment of cutter inserts when they are needed," says Kendrick.
While the gains with the tool dispensers are significant, Schuman is already looking into ways to improve efficiency. One is to build an information network for the dispensers.
Today, each unit's inventory information is self contained. A network with one of the dispensers acting as a central server would allow personnel to access inventory status for all units from a single location, ending the dispenser by dispenser routine now required. This would also expedite replenishment of the units.
In addition, the VLMs and tool dispensers have been so beneficial to Sikorsky that additional units are being considered for use elsewhere in the facility.
"We're in the process of putting together a series of machines that meet our requirements in other departments," says Schuman. "We're sure there is the potential to lower costs elsewhere in this facility."
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