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Taking a chance on teams.

Teamwork results in a successful and creative alternative to true flexible manufacturing--and an empowered workforce.

What started out as a "dare" by management to find ways to improve a manufacturing process has turned into a lesson in empowerment at Tol-O-Matic Inc, a Minneapolis, MN, manufacturer of linear motion products. A rapidly growing, medium-sized company, Tol-O-Matic makes more than 1200 different products ranging from custom rodless cylinders to rotary actuators. It has been meeting a 10-day delivery commitment and a warranty return rate of less than 0.3% for over 10 years.

Looking for ways to improve productivity and customer service, Tol-O-Matic began to research a flexible manufacturing cell (FMC). The cell under consideration consisted of a horizontal machining center with 120-tool changer, touch probe for part inspection, random-access 20 pallet system with load/unload station, and all required cutting tools resident in the tool magazine. Separate pallets would be permanently fixtured to allow a family of parts to be machined complete on one pallet.

Computer simulation revealed three problems with this approach: shortage of floor space, shortage of bench space for drawings and gages to monitor part quality, and the likelihood of operator errors due to the many different parts and the fast pace. Tol-O-Matic's manufacturing engineering group and the shop supervisor began informally discussing alternatives to the automated FMC. The less automated cell they settled on required manually loading the pallets onto the machine and accessing the proper CNC program. Two distinct parts could be run simultaneously, minimizing space problems and allowing pallet changing while the other pallet is in the machining center.

The team's the thing

The new cell concept, however, would require a completely different view of how to operate in the plant, and thus a high level of support and commitment from shop personnel.

Tol-O-Matic formed a cross-functional acquisition team made up of one representative each from quality assurance and manufacturing engineering, the plant manager, first and second shift shop supervisors, a setup man, and a machine operator chosen by peers. The team was chaired by the manufacturing engineering manager, who functioned as team facilitator but had no vote in the decision-making process.

The team met weekly for one hour for the first four weeks. The objective was to install a new horizontal machining center by the end of January 1991 with the machine operating on "zero" setup time and performing in-machine inspection of critical part features.

All team members agreed that the manual FMC concept was feasible. They identified several concerns that had to be resolved to ensure project objectives were met, including a method to move pallets to and from the machine

in 15 minutes or less, and a system to ensure access of the correct CNC program.

Machine options

The team limited its machine selection to four major manufacturers. Initial screening was based on the quality of technical support and service of the local distributor and the manufacturer's reputation and support of quality. The team eventually chose the Mazak H400N. It was ordered the last week of June 1990, leaving the team six months to finalize all operating procedures, design and obtain fixtures for the first parts, and prepare CNC programs.

The manufacturing engineering department began the fixture design with periodic review by the team, while the team set out to finalize the pallet moving method. The main concerns were quickly and accurately locating the pallet over the machine and the ability to gently set down the pallet to prevent part damage.

After considering alternatives ranging from fork trucks to hydraulically actuated lifting arms, the team selected a wire rope overhead hoist. The hoist had two speeds up and down and a creep feed in both directions to ensure a gentle landing as the pallet was loaded into the machine.

Wooden pallet boxes designed by the team protect the fixtures during storage. The box bottoms safely support the pallets, and allow them to be moved from the staging table to the pallet racks by standard forklift trucks. The sides are designed to allow complete access to the fixture with the cover removed.

The team also selected Renishaw probe software and standard EIA programming to maintain a common format with existing CNC equipment. All programs are stored in the control.

In operation, the machine operator places the pallet/fixture in the change station and enters an eight-digit part number; the control takes over from there to verify the part number and select the proper program. The Renishaw probe inspects critical features and checks the results against programmed allowances. Out-of-tolerance features stop the machine and notify the operator of the problem.

Installation was completed in mid-January 1991, and the cell was manufacturing product by the end of the month. After more than a year of operation, the manual FMC has attained all of the original goals.

Success breeds success

The team concept seemed slow at first, but Tol-O-Matic believes the time saved at the end of the FMC project more than made up for the slow start. Because team members from all functions had up-front input on the project, startup problems were minimized. Team members took ownership of the project from the beginning and continue to solve any problems associated with the cell with minimal input from management.

New teams are being discussed to further improve operations. One team will work on an SPC program using data downloaded from the Mazak. Another is working on a complete, just-in-time production system.
COPYRIGHT 1992 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1992 Gale, Cengage Learning. All rights reserved.

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Title Annotation:Tol-O-Matic Inc.'s flexible manufacturing cells
Author:Thrun, Jeffrey A.
Publication:Tooling & Production
Date:Dec 1, 1992
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