Material Handling

11/15/2002


Conveyor system enhances production line agility, cuts costs

"In this business, you've got to be fast on your feet," says Bruce Wakefield, manufacturing engineer for Mann+Hummel Automotive, South Bend, IN, which develops and produces injection-molded plastic manifolds for the automobile industry. Using lost core and multishell technology, the Mann+Hummel unit is a Tier One producer of plastic manifolds, primarily for U.S. OEM customers.

The South Bend operation produces three-part manifolds for 4-cylinder General Motors engines, and a four-part assembly for 8-cylinder Chrysler engines. Plastic manifold components are friction welded on the production line, eliminating the need for later assembly on the vehicle engine production line.

The manifold production lines include conveyors that feed three 1750-ton presses located in three cells. Work in process goes from the presses to a collect chute, where operators put parts in totes and continue on to workstations where automatic welding takes place.

The original conveyor system installed when the plant was built in 1989 was a typical, fixed, steel design, with runs varying up to approximately 80 ft. Although the conveyors performed reliably, there were circumstances when they did not offer the flexibility or ability to "tweak" a configuration that would have helped production flow. When manifold designs changed, the molding cells needed to be reconfigured, sometimes requiring the ordering of new conveyors, which also meant waiting weeks for them to be delivered.

In early 2000 Mann+Hummel replaced the conventional steel conveyors on a secondary line with a DynaCon modular plastic conveyor system manufactured by Dynamic Conveyor Corp., Muskegon, MI.

The trial system proved to be reliable and offered the ultimate in flexibility with a wide range of module designs. So, Mann+Hummel decided to apply the system to the line feeding one of its primary manifold molding cells.

"We had a tight arrangement in one cell, and the modular system made it a lot easier to bring the parts in on the conveyor," Wakefield says. "We put an angle on the end of the conveyor to be more ergonomic with the positioning of the parts to the operator. With the flexibility of the system we were able to try a 30 or 45-deg angle to the conveyor as we were laying out the cell on paper. It gave us a lot of flexibility in our floor plan layout. Plus, the system gives us a lot of flexibility down the road if we want to move some gear, reconfigure the cell, add a piece of equipment or take one out. And it's easy to reconfigure the conveyor. That's a big advantage, because with automotive programs that have a definite life, your cell is eventually going to be obsolete."

Whether doing a complete reconfiguration or simply tweaking the system, Wakefield is confident he can handle the task without assistance from Dynamic Conveyor.

In addition, Wakefield is impressed with the advantages of carrying an inventory of standard parts for reconfiguring or replacing the system. "With our modular system we can often work with modules and components we have on hand." Dynamic Conveyor Corp. 866-249-2641 DynamicConveyor.com .

Retrofittng AGVs is low-cost alternative to new vehicles

Reasons to consider changing/upgrading existing AGV systems include changing system requirements, desired utilization or productivity increases, rising maintenance costs, availability of replacement parts, or growing safety concerns.

The choices are not always simple. But often, the retrofitting option gives new life to an old investment and will provide an additional 5 to 10 yr of service life.

A retrofit — one of the more cost-effective remedies to an aging AGV system — may return the system to its original performance level or exceed it. Just as important, the cost of a typical retrofit can be as low as 20% to 60% the cost of a new system.

Also, the extent of the retrofit project may weigh heavily in the decision-making process. For example, some retrofits are as simple as rewiring or new software, whereas others can be as extensive as a complete overhaul — from the chassis on up. And special, one-of-a-kind vehicles are prime candidates for retrofit due to the phenomenal cost of engineering and replacement.

There are many telltale signs that a retrofit may be for you. Age of the installation is a place to start, but it should not be the sole reason to retrofit. Every 7 to 10 yr you should evaluate the performance of your system (see accompanying list).

Every retrofit is a custom project. Managing a retrofit project with the least amount of disruption requires close coordination between your project team, which should include members from all affected departments, and the vendor doing the work. Retrofit veterans recommend development of two plans for rerouting materials and information in order to minimize interruptions.

After a retrofit is completed, an AGV system looks much the same as it did before. Certain discrete operations and procedures within the system may change, but most of that is transparent to the people on the shop or warehouse floor — except in one important regard. They now receive materials in a timelier manner. In a nutshell, that's what a retrofit is all about.

Jim Jarvis, project manager for Boeing's Frederickson, WA, composites manufacturing facility discusses a major retrofitting project. "We use three types of AGVs in our facility and we literally stripped the vehicles down to the frame and rebuilt them. The entire process took us nearly 15 months to complete. Vehicles were sent out for rebuilding one at a time to maintain production. Some movements were supplemented using forklifts until the new system software was brought online. We replaced the transmissions, the motor controllers, all onboard communications and control equipment, and rewired the entire vehicle.

"The Fredrickson facility builds the empennage sections for the Boeing 777 tail, and the AGVs are used to move various sized tooling around — from staging area to lay-up and bagging to autoclaving to unwrap to assembly. Three unique vehicles handle the moves from step to step. All of the vehicles are radio controlled and wire guided by one host computer system. Reliability problems got to the point that we were continually making repairs and changes to the vehicles, but we could not keep up. The existing computer system was slow, cumbersome to operate, and its tool data was unreliable. The retrofit had to be done.

"In fact, the reliability problem got to a point where the uptime on some of the vehicles was an extremely low 20%. This resulted in movement control issues and a huge increase in manual handling that caused damage to tooling.

"The retrofitted AGVs are more flexible and efficient. We actually have one area where a single AGV does the work that three previously performed. Therefore, we are able to take the other two vehicles out of service to conduct preventive maintenance without losing a production beat. We have implemented a more efficient tool management program using the AGV computer system to help us achieve true 'Lean Manufacturing'."

Ten signs an AGV retrofit may be justified

  1. Decrease in system throughput of more than 10%.

  2. Downtime exceeds 5% and is continuing to increase.

  3. Software cannot be modified to meet changing needs.

  4. Mechanical components show wear or structural damage.

  5. Flow of materials in the system is no longer efficient or logical.

  6. Service and support are not readily available.

  7. Additional people must be put on staff to address maintenance issues.

  8. Diagnosing problems with the system is becoming increasingly difficult.

  9. Speed of the system must be reduced to keep it running properly.

  10. AGV cannot be integrated with other material handling operations.

    1. AGV Products, Inc. agvproducts.com

      Nissan ends seat retrofit program

      Nissan Forklift Corp., North America has announced that it will be ending its long-running Operator Restraint System (ORS) Program. The program, started almost 10 yr ago, was set up to offer owners of pre-1988 Datsun and Nissan forklifts an operator restraint system seat for their trucks. Since 1988 Nissan has supplied an ORS seat with every new forklift manufactured for use in the U.S.

      The ORS program provided a free operator restraint seat kit to all qualified owners and a voucher for free installation by a Nissan Forklift dealer. To date, over 9000 ORS kits have been provided to end users.

      The program will conclude on December 31, 2002. After that date, owners will have to pay for costs associated with these retrofits.

      Nissan Forklift Corp. , North America 815-568-0061 nissanforklift.com



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