Material Handling
Monday | 18 August, 2008 | 4:25 am

Solving inventory problems

By Lauren Duensing

August 2008 - The goal: Double sales volume. Starline Windows, Langley, British Columbia, made this intention known back in 2005; however, at that time its production equipment wasn't up to the challenge. The company is a major North American manufacturer of windows and doors, and its Langley facility produces windows for multi-unit residential structures. The aluminum-framed windows are available in a variety of styles and custom colors, and, prior to 2006, the company ordered custom extrusions from aluminum suppliers. Because aluminum extruders have automated high-volume paint lines, Starline was obligated to order and receive large batches of custom-colored aluminum. The inventory would then be stored in its facility for many months while a project was under construction.

Two million pounds in storage
Because its customers requisitioned windows one floor at a time, Starline could be working on as many as 30 different projects at once and would be storing as much as 2 million pounds of painted aluminum extrusions, comprising as many as 1,500 unique inventory types.

. To complicate the situation, each of these inventory items had to be accessible for fabrication in small quantities so the painted bundles from the extruders had to be opened and racked vertically inside the plant. The extrusions occupied more than 30,000 square feet of floorspace, as well as one acre of outside space for sorting and staging. In addition to the painted inventory, Starline also maintained 200 types of mill finish (unpainted inventory) to satisfy the small orders of some customers.

With all this inventory, Starline found it hard to keep up. Ed Lindahl, vice president and general manager, says that the inventory was unmanageable, the factory was exhausting, and the available space for operations and sales was being hurt because of the difficulty in responding to changing job-site requirements. Exacerbating the problem was the fact that Starline often found itself either in a short or long position with inventory. A large overage of custom-colored material at the end of a job is enough to drive anyone over the edge.

Managing the inventory was just one of the problems. The aluminum extrusions Starline uses can be more than 20 feet long and weigh 50 pounds to 100 pounds so they can be difficult to handle. Plus, the product was being stored in vertical racks so the ends were susceptible to damage while in storage.

Step one
The decision was made to inventory only mill-finish aluminum and set up an in-house paint line to paint batches of extrusions as they were required. The problem with this change was that a great many batches are needed, with exact quantities of extrusions in the batch, and they're needed in a short time to maintain production speeds.

As a result, Starline required an automated storage and retrieval system capable of storing and dispensing the requisite number of extrusions, and the system needed to be linked to the existing inventory management program. The company also wanted the capability of loading 1,000-pound bundles of extrusions into the system from the receiving yard and delivering the exact number of extrusions from inside the building near the new paint line.

To find an automated storage and retrieval system that would meet the company's requirements, Lindahl turned to the Internet. He found the German company Remmert GmbH and learned that DoAll Sawing Products was the company's North American representative. Remmert has installed more than 500 automated storage and retrieval systems worldwide for companies such as Daimler-Chrysler, Reynolds Aluminum, Volkswagen and John Deere.

After a comprehensive review of Starline's needs, DoAll and Remmert provided Starline with a rack-type system that holds storage cassettes containing the mill-finish extruded lengths. It was fitted with a storage and retrieval machine and three shuttle cars to transport the material. The rack has openings to the outside receiving yard so it can be directly loaded without bringing product through the factory. The storage system measured 23.5 feet high by 66 feet long by 25 feet deep. The storage and retrieval machine that transports the product within the tower sits on top of the rack frame and adds another 2 feet to the height. The system proved to be so successful that a year later a second storage rack was ordered and integrated with the initial assembly.

The way it works
When extrusions are retrieved, the operator selects the needed material from a menu displayed on a central control console. The cassette selected on the screen is then lifted from the storage system via the storage and retrieval machine and transferred to one of the shuttle cars automatically. For safety's sake, the operator must hold down the control button while the shuttle car is moving, otherwise it stops immediately. The opposite path is followed when the cassette is returned to the storage rack.

There's a weighing unit installed in the storage and retrieval machine that measures the loading and unloading weight of each cassette with an accuracy of 4.5 pounds. The weight is transmitted to the computer system so the number of extrusions added or removed from the cassette can be calculated, enhancing real-time inventory control.

Control of the entire system uses Remmert's proprietary software PRO WMS, which uses the Windows NT/2000 operating system. PRO WMS can be operated as a stand-alone system or can be integrated into a customer's host computer system. It's a complete management system controlling the inventory, job and batch and can be customized for specific storage strategies, such as ABC classification or FIFO, as well as dynamic allocation of storage locations and job optimization. It can also prepare numerous customized analysis and statistical breakdowns using Microsoft Excel or Microsoft Access.

Because the technology is changing so quickly, the computer used to operate the system was the last item ordered, ensuring that it was fitted with the most up-to-date technology.

Goal reached
With the DoAll/Remmert automated storage and retrieval system, control of the aluminum extrusion inventory is now manageable. The aluminum extrusion inventory was reduced by more than 50 percent. Floor and yard space was freed up for other uses. Production turnaround time was reduced. Overstock sent for scrap was virtually eliminated. And inventory status is shown in real-time, improving accuracy.

As a result, Starline has met its sales goal. In 2007, production volume at the Langley facility was double what it was two years ago with a one-third reduction in personnel. And with the increased flexibility provided by the DoAll/Remmert system, the company can now easily meet its customers' varying needs.MM


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