Manufacturing

Simulation screen image shows storage of totes in AS/R system (center) and totes loaded with components moving via conveyor (yellow) to the factory floor. Pallet loads of totes with lower-volume parts are on the pallet conveyor (green, at left).

By Staff -- Modern Materials Handling, 4/1/1998

conveyor rollers: Interroll

When Hewlett-Packard's Inkjet Business Unit (IJBU) took on a highly complex project to automate materials handling at its Corvalis, Ore. production plant, the company wanted to maximize what it would get from a new system, and maintain its leadership position in the market.

Recognizing that comprehensive computer modeling would be necessary to prove out the design, IJBU chose a systems integrator and supplier that had experience with the simulation software.

IJBU wanted a system capable of delivering components for building inkjet printer cartridges to assembly line stations within a 30-minute JIT "window" from the time a work station placed an electronic order.

Earlier, because production had expanded to meet large increases in demand, aisles were seriously overcrowded. Forklifts and pallet jacks delivered components to assembly.

IJBU and systems integrator personnel developed a design concept using an overhead conveyor located above the plant's drop ceiling and below its reinforced roof. This conveyor transports components in 20 x 24 in. totes to four main drop points. Automatic guided vehicles then pick up totes and deliver them to individual assembly stations on the shop floor.

IJBU wanted to "see" the system run in a true-scale 3-D simulation before finalizing the design. AutoMod simulation software accurately portrays engineering details. The system, which depicts distances to an accuracy of 0.01 inch, uses actual order data to create "true" demand on the system model.

Through simulation, engineers at the company determined what would happen if either the line or the pallet load AS/RS went down. The model produced a specific requirement for buffering capability within the line to compensate for an AS/RS shutdown.

The model also highlighted several design issues that had to be solved: More AGVs would be needed than anticipated. Changes would also have to be made to the design of the drop points, the buffering capability of the conveyor line, and the speed of the conveyor. IJBU also would also have to install a high-speed, tote-based AS/RS.

Fully operational, the system meets all requirements, including the 30 minute maximum between electronic transmittal of an order to the pallet load AS/RS or tote AS/RS. Significantly, the system can handle outages of up to 30 minutes in the AS/RS without causing an assembly line stoppage.

The simulation provided as much as a 20% performance boost by allowing Hewlett-Packard engineers to provide vital input into the design. Furthermore, according to Bruce Johnson, project manager, the software's animation capability "made it possible to involve many more people in the design process, including individuals not accustomed to dealing with engineering drawings."