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Flexible manufacturing expands its envelope.

Advances in control technology and a more realistic approach to application are making flexible manufacturing an alternative even in job shops.

In the 25 years or so that flexible manufacturing has been around, the concept has taken more than its share of criticism. Many would say that has been justified; numerous flexible manufacturing systems (FMSs) have never met expectations in either productivity or on the bottom line.

John Fletcher, manager of special products at Ex-Cell-O Machine Tools Inc, a Novi, MI, supplier of both flexible and dedicated machining equipment, can cite multiple examples of FMSs that were too big, too complex, and expected to do too much. But one of the most famous, he says, was a major automaker's attempt at flexible, lights-out manufacturing of families of drivetrain components. "It was lights-out, all right," he says. "They turned the lights out and walked away from it. The cost of doing that must have been tremendous. If they'd just thrown a few more people in there and had less complexity, it would probably have been a lot more successful."

That comment seems to point up the current thinking in flexible manufacturing: smaller and less complex is often better. The point is echoed by those involved in flexible manufacturing at other machinery suppliers.

"The failures have been on the most ambitious projects," says Pete Lechtanski, manager of software development at Toyoda Machinery USA Inc, Arlington Heights, IL. "The most successful units are where the problem is kept relatively simple."

The modular approach

One way users can maintain that simplicity and get their feet wet in flexible manufacturing without excessive risk is to combine modular components into a manufacturing cell. The simplest cells might consist of a single machine, such as a horizontal machining center, with half-a-dozen pallets. More commonly, a cell will consist of three or four machines linked by a more sophisticated material handling system, such as a rail guided vehicle, and a control system that coordinates machining and material handling.

Cincinnati Milacron, Cincinnati, OH, has been teaming its horizontal machining center modules with standardized material handling and control packages for several years.

"We've learned a lot about the types of software and control features that are required for FMS," says Tim Chapman, manager of Milacron's cell and system group. "Over the years, we've built those requirements into a set of pre-engineered software modules" that can be tailored to meet customer needs, he says.

Other suppliers taking this kind of approach include Mazak Corp, Florence, KY, and Toyoda. "Our system is modular from the standpoint that you can start with a machine prepared for future integration into a cell," says Mazak factory automation specialist Steve Campbell. "You can add the FMS features, and none of those need to be engineered."

Suppliers of more complex, engineered systems also are incorporating at least some aspects of modularity in system design. Ex-Cell-O prefers to think of large systems as groupings of cells. The cells themselves can be operated separately, so they're not dependent on the throughput of the rest of the system. "Each machine in that respect is going to be self-contained, and the operation is not dependent on the machine down the line or sequential manufacture," says sales manager Malcolm Mason. "One of the main reasons for that philosophy is up-time. Any time you get sequential machining in a line, no matter how long or short, if one of those machines goes down for whatever reason, you affect the efficiency of the line. Self-contained machines that operate independently are the way things are going."

Even Giddings & Lewis, a company that, as vice president Rick Pierce says, "has always been looked at as a provider of intensively engineered products," is building more modularity into its systems. "If we know the ultimate design goal is five machines, then the software would be set up to handle five machines," Mr Pierce says. "It would just be a matter of turning on an additional module as you install equipment."

The modular approach to flexible manufacturing also lends itself to expansion in increments as small as a couple of pallets or a single machine. This advantage is making the technology practical--and affordable--even in some job shops. Mr Chapman says Milacron has implemented cells in shops as small as 40 persons, and Mr Campbell concurs. "We're starting to see the job shop industry take a keen interest in four-machine-and-under cells," he says.

In control

The role of improved control technology in making flexible manufacturing work is hard to overemphasize. Since the days of the first FMSs, control systems have undergone a sort of de-evolution from minicomputers running custom software to workstations or even PC-based systems using out-of-the-box software packages.

A good example of the current thinking in cell control is Milacron's Cincron, which is based on a DEC workstation platform. "When a customer requires a very straightforward cell with minimal communication, we can offer him a basic unit," says Mr Chapman. "When a customer has a high-variety, low-volume application, tool management software might be an option. We can add that tool management package to the cell just like you'd add Lotus 1-2-3 to your PC."

Mr Lechtanski says Toyoda's standard control software has been developed along similar lines over the past 20 years or so, with many features being the result of customer requests or requirements. "The thing about standard software is, it's relatively inexpensive compared to custom software. For custom software, you're easily talking $1 million. Then, you add hardware," he says. Toyoda's standard hardware platform is an IBM-compatible PC, or multiple PCs depending on system complexity.

To illustrate the cost differential that's possible between modular and custom control hardware and software, Mr Lechtanski cites a job Toyoda is installing for the US Navy. Development of custom software was farmed out to a sub-contractor, and the cost of the minicomputer and terminals used was more than $250,000.

"Then you've got maintenance," he adds. "If a PC fails, you go down to the store and buy one. The minicomputer takes another level of maintenance and maintenance contracts and that sort of thing."

What's in it for me?

Some advantages of flexible manufacturing are easily measurable: increased throughput, reduced setup, and improved part quality. But, like other types of factory automation, flexible equipment can be difficult to justify using just traditional return-on-investment calculations.

"Any factory automation system is going to help people realize a return on their investment. That's not the whole picture. What we really try to teach people is that with flexible manufacturing or any type of automation, you're actually able to build more profit into your part cost," says Mr Campbell.

"The driver is part cost," concurs Mr Pierce. "What approach can provide me a finished product least expensively? I might wind up paying more for a system, but if it's more productive and cost-effective than one that's lower priced, it's certainly justified."

Other system suppliers urge potential customers to try to quantify things like work in process and inventory turns. Milacron's Mr Chapman "challenges" manufacturers to look at their in-process inventory, calculate its value, work with Milacron to determine how much of it can be eliminated, "then see if the net difference isn't enough to pay for the cell and put money in the bank. On a few occasions, it is. They've already invested the money. They've just got it lying around in inventory," he says.

"The other thing to look at is inventory turns," he adds. "Most people in this business are doing 2.5 or 3.5 turns a year. We can see where a lot of people can get to 25, maybe even 50 turns a year."

The benefits you'll derive from flexible manufacturing depend on where you're starting from. Says Giddings & Lewis's Mr Pierce: "A lot depends on how the part is currently processed. If you have a well-integrated facility and you can put a part on a machine and process it complete, unless you're looking at significant direct labor savings, you're not going to see much improvement.

"On the other hand, if you've got a part like a motor frame, and you're boring, drilling, and turning, and you're doing that with six machines, you can probably put that in a cell or system and do it with two different types of machines and have a much better quality part because you've eliminated all these setups," he says. "It's also going to be more productive, with less work in process, because you're going to fixture that part once and process it complete, and it'll be on its way to assembly."

All things considered

There are many steps a potential FMS user can take to maximize an investment in flexible manufacturing technology. This includes analyzing tooling to reduce the number of total tools required, as well as looking at designing products for manufacturability.

"If a user can, for example, reduce the number of total tap sizes on a part and standardize on that, he's reduced several tools, reduced tool setup time, reduced costs, and probably reduced total cycle time because he doesn't have a lot of tool changes," says Mr Campbell.

The cooperation of customers in doing that sort of thing varies tremendously, but Mr Chapman says Milacron has corporate agreements with some large customers that amount almost to partnerships. "We meet every couple of months, and we look together at long-range plans, both in terms of what new machine tools we are planning and as to what new products they intend to put into the market, how they should be designed for manufacture, and how they can be designed to take full advantage of future machine tool products," he says.

Still another point to consider is how--or if--the system will be integrated with all the other operations performed in the factory. "The problem I see is, we sell machining centers, lathes, and grinders. But to make whatever you're making, you'll have assembly, heat treating, and all kinds of different processes," says Mr Lechtanski.

"You can buy a group of machines and have the greatest cell controller technology, but that controller is only going to control that group of machines. It has no knowledge of what's going on before or after that. If you're going for a work flow, you're still stuck with all these disconnected islands," he adds.

But will it work?

The suppliers of modular flexible manufacturing equipment emphasize that the building block approach to FMS can minimize the risks of trying the technology. And it's generally true that off-the-shelf components are less expensive than custom engineered hardware and software--often about half the price, according to Mr Chapman.

But suppliers of more sophisticated, highly engineered systems also are trying to increase the comfort factor for skittish potential users. Mr Pierce describes a factory simulation model Giddings & Lewis uses to evaluate the performance of various system designs based on the process, cycle times, number of machines, type of material handling system, and other variables.

"We worked jointly with someone who had experience in developing systems to produce this software that lets us look at the operation in more detail, rather than making global assumptions," he says.

To illustrate how the simulation software works, Mr Pierce described a recent experience. "A customer came in with a system pretty much spec'd out as far as number of machines. He had four of one kind of machine, three of another, and two of another. Once we started working on it, we found out that because of the interrelationships between cycle times and the process, you're not going to be able to burden those machines at the time you think you are. If you're looking at systems with large numbers of machines, inter-dependencies of one machine on another, material handling, pallet shuttle time, and transport time, all have to come into play. Things get very complex very quickly," he says.

In the end, however, implementing flexible manufacturing may not be as great a risk as deciding against trying it. "You almost have to get into it because it's where things are going," says Mr Lechtanski. "If you look at it long term, instead of talking about machines, you're talking about technology. You have to get your engineers up to speed using it and thinking about how to use it. Maybe you can figure out a better way to use it than a competitor, and you'll be ahead in the long run."

Cell or system? You decide.

You may have noticed the terms "cell" and "system" being used pretty much interchangeably throughout this article. That's no accident.

Many do use the terms interchangeably. Some define the difference in terms of the number of machines in the system, classifying any grouping of more than four major machine tools as a system. "But if a customer takes a four-machine cell and adds things like tool transportation, gaging, wash stations, and things like that, then it gets into the realm of full-blown FMS," says Mazak's Mr Campbell.

Others make the distinction based on the sophistication of the material handling and control systems used--a judgment call at best.

But the bottom line is, as usual, the bottom line. Most of the supplier representatives interviewed for this article echoed the opinion of Milacron's Mr Chapman: "The answer is, it's whatever the customer says it is."
COPYRIGHT 1993 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1993 Gale, Cengage Learning. All rights reserved.

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Title Annotation:includes related article
Author:Destefani, James D.
Publication:Tooling & Production
Date:May 1, 1993
Previous Article:Stamp it out in software.
Next Article:Anatomy of a machine tool.

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