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Automation swings to cells.

The pendulum swings back from the concept of the fully automated factory to the more-realistic goal of individual manufacturing cells. Computers and software tie components and cells together, but hardware is basic.

Manufacturers demand increased machine profitability and flexibility, and many shops are finding that automated material-handling systems are important elements in achieving these goals. For example, Hans Geppert, general manager, Eimeldingen Corp, Indianapolis, IN, says, While most manufacturers can't afford to automate a shop from the ground up, palletizing a machining cell can be practical and cost effective. "Pallets enable operators to maximize spindle time. It follows that pallets applied to a machining cell maximize the spindles of several machining functions. In that way, a cell becomes a profit center.

"By integrating standalone machines into machining cells, manufacturers can create fully automated systems one cell at a time and palletize them to create a flow of parts across a shop. Starting small offers manufacturers a gradual, well-planned approach to automation and integration." Well, that sounds like the automated factory after all, but you don't have to go that far! Even if you just palletize one machine with two pallets, the machine can process one part while the operator sets up the next part on the other pallet. After the first part is complete, an automated pallet exchange takes place in which the finished pallet is removed from the machine and the second pallet moves into position at the spindle. That's the beginning of a cell.

"A palletized cell is born when a two-pallet, single-machine process is linked via the pallets to other machine spindles," says Mr Geppert, "so it's possible to maximize turning, drilling, and washing in one cell."

Before selecting a supplier for an automated material-handling system for a cell, it's important to evaluate the shop needs. Mr Geppert says you should ask the following questions, and they apply to most areas of automation, not just material-handling:

* What shop areas generate bottlenecks during production?

* Which spindles show the weakest uptime numbers?

* What areas of the shop need greater efficiency between operator and machine?

* Which machining areas are due for improvements and tool upgrades?

* How do plans for shop expansion fit into the need for automation?

* What automation is already in place, such as pallet-shuttle systems and CNC interfaces?

* How adaptable is current automation to new machines?

* What are specific productivity-improvement goals for each machine or available manufacturing cell?

Mr Geppert notes, "Productivity at the spindle is the truest measure for automated systems, whether a manufacturer is palletizing one machine or integrating several machines into a cell ... A palletized cell should maximize the time that machine spindles are working by establishing an automated flow of parts."

Software, centers, and pallets

By integrating the technology of today's advanced CAD/CAM systems, CNC machine tools, and machine-tool attachments, Bijur Lubricating Corp, Bennington, VT, recently experienced a Quantum Leap" in production efficiency of lubrication mist heads. For example, an 18-operation production step that took 90 days and required 10 operators is now a one-operation step with a 27-min cycle time, managed by one operator. Also, the new technologies have reduced scrap to zero, according to Bijur.

Bijur invested in an Okuma & Howa machining center, and two Mori Seiki CNC machining centers-all in 1988 and 1989. The machine tools use Fanuc hardware and software, as well as automatic tool changers (ATCs) with up to 40-tool magazines. "With these new machining centers, our toolmakers and manufacturing engineers can really roll up their sleeves and get creative," says Bijur plant superintendent Bruce MacDougall.

Bijur designed and produced custom hydraulic fixtures for the machining of several mist-head models. These heavy-duty fixtures, made of cold-rolled steel and weighing up to 400 lb, can hold six mist heads securely in place, using hydraulic pressure up to 2500 psi. To take advantage of the new CNC vertical machining centers and custom hydraulic fixtures, the company created a geometry file using MASTERCAM from CNC Software on an Epson Equity III+ microcomputer. The geometry file runs through a post processor for the Okuma & Howa and Mori Seiki VMCs, while the NC program runs directly to an NEC laptop computer. The information is then downloaded on the laptop to the VMC Fanuc controls.

"Compared to handwritten programming, MASTERCAM really is a productivity booster. It's like a word processor or a desktop publisher for manufacturing engineers," says Steve Latif, Bijur's supervisor of manufacturing engineering.

In 1989, MacDougall chose to retrofit Koma PCH shuttle-type manual pallet changers on all three CNC VMCs. "It was the finishing touch to the whole process. Installation took about 4 1/2 hr per pallet changer. We now have one operator who manages these three machines simultaneously. It's a very efficient manufacturing cell," says Mr MacDougall.

He adds, "With the pallet changers, the operator can easily set up and move the 800-lb loads. The manual pallet changers also add flexibility, because the mist-head fixtures can be kept on two pallet-changer pallets while allowing access to the VMCs for other work."

David VanSickle, VP of manufacturing at Bijur, notes, "If US industry is to compete effectively in domestic and world markets, creative integration of these new technologies is a must. Everything-from computers and machines to accessories, software engineering, and operator performance-must be high quality."

One-unit cells

Sometimes you can get integration in a single package. For example, Mazak Corp, Florence, KY, still offers full factory-automation systems, but the firm is willing to settle for something smaller. At IMTS-90, Mazak demonstrated the Multiplex series of six-axis and four-axis turning centers, each with varying levels of automation from automatic jaw changing, tool setting, and work measurement to full parts-handling and transfer.

The Multiplex is virtually a machining cell in itself, because it's based on a symmetrical design with headstocks located at right and left ends-with independent turrets servicing each. It can transfer workpieces from spindle to spindle, turn long shafts coordinated between spindles without workrests, and perform secondary operations with rotary tooling.

Cincinnati Milacron, Cincinnati, OH, also has much to offer in cell technology. Just one example is the new Chronos series of flexible manufacturing cells. Chris Edwall, division manager, Advanced Manufacturing Systems Div, says "In recent years there has been a trend away from large, dedicated systems and machines-and an evolution toward lower-risk, more-affordable modular components.

"Our Chronos FMC and Synchron cell controller offer advantages for both the traditional large manufacturer searching for an expandable standard platform, and the medium-sized to small shop that can't afford customized cell technology."

Mr Edwall believes that standardization of the Chronos and Synchron components can provide 25% to 40% cost savings for the users, while providing flexibility for system expansion. Components include rail-guided pallet-handling systems for palletized and fixtured parts, and gantry workpiece-handling systems for untended batch processing of low-variety, high-volume prismatic parts with short cycle times.

The Werner FMS 400 flexible manufacturing system has a special tool-cassette concept, providing automatic supply of workpieces and tools through a common transport system. The design allows use of inexpensive system peripherals, yet is NC controlled. The system provides high transport performance at 90 m/min, and pallet-transfer time is 7 sec. The modular cell, from Fritz Werner Machine Tool Corp, Carol Stream, IL, boasts a machining center with 12,000-rpm spindles, 30kW drive power, and torque of 300 Nm at 1000 rpm.

Rotary cells

Rotary-transfer machines were called manufacturing cells long before the expressions FMS and cell technology became buzzwords. How are they doing today? The D/DR-12 and DICO-18 rotary-transfer machines from Mikron Corp, Monroe, CT, are used to produce fuel-injection parts automatically with consistent quality. All the things FMS cells can do.

The rotaries allow deep-hole drilling in successive stages, simultaneously. The result is a short cycle time and high output level in a single cycle. A special workholding system rotates the part for high concentricity, and indexes the workpiece to a fixed position for drilling off-center holes or boring with live tools.

Another firm, Hydromat" Inc, St Louis, MO, likes to talk about the VM-16 trunnion machine. This rotary-transfer unit competes with automatic screw machines in making small connectors and fittings. It has 16 chucking fixtures with 1/2"-dia capacity and uses a 14"-dia indexing drum with 0.3-sec table-indexing time.

In one application, making an antenna part out of 303 stainless steel, it worked at 90% efficiency to make the part in 4.5 sec. A competing automatic screw machine made the part in about the same time, but granted only 60% efficiency, requiring the use of more than one machine. Yes, there are ways to compete, and cell technology may turn out to be the simplest way to do it. Cells can be as big or nearly as small as you like.
COPYRIGHT 1991 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1991 Gale, Cengage Learning. All rights reserved.

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Title Annotation:individual manufacturing cells
Author:Miller, Paul C.
Publication:Tooling & Production
Date:Feb 1, 1991
Words:1452
Previous Article:AC drives boost press throughputs.
Next Article:Workholding - the key to changeover in turning.
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