Hartzell Fan Inc., based in Piqua, Ohio, manufactures fans for industrial applications. It has no difficulty when a customer chooses an item from stock. "The problem, " explains Marshall Miller, Hartzell's engineering manager, "is when a guy comes in and says, 'Yeah, that's what I want, but could you give me a larger motor?"

Filling special orders like this is an important part of Hartzell's business. But redesigning a fan is time-consuming and expensive, especially if the customer insists on seeing an exact drawing before deciding to buy. In the past, Hartzell would even pass up a chance to bid on such a job because it couldn't afford the time to do design work on speculation. That, however, was before it bought a computer-aided design (CAD) system.

CAD systems, which can be used by any company involved in designing, are to the designer and draftsperson what the word processor is to the typist. lnstead of working at a drawing board, users sit in front of a screen and, generally using a keyboard, tell the computer what they want drawn. A designer can command the computer to draw a line, say, from one sector of the screen to another, or to draw an arc beginning at one point, rising until it reaches a second point, and ending at a third point.

Hartzell bought its Hewlett-Packard CAD system last February for about $150,000. Hartzell hoped the system would help it speed up the design process so it could take on more work and provide more of its customers with precise drawings of the fans they requested. Miller found, however, that it takes almost as long, initially, to enter a design into the computer as it takes to draw it with pencil and paper. But, he adds, the pictures drawn by his plotter (the device that prints the picture after it is entered on the screen) are crisper and neater looking And once the overall dimensions of the fan are entered into the computer, the system will automatically calculate and label the measurements for motors, propellers, and other parts. This capacity alone eliminates frequent errors.

Since a CAD system can store component designs in its memory, the more Hartzell can collect these "standards" in the CAD database, the more it can accelerate the design stage. Now, if most of the components are in memory, a drawing that used to take eight hours takes only one. Because of the recession, Miller feels, Hartzell has not yet realized an increase in business from its investment. But the company is using this slow time to enter as many standards into the system as possible. "When business picks up," says Miller, "we will be ready for it."

A CAD system has other benefits besides its capacity to remember standards. If a designer makes a mistake, or wants to try out an idea and then remove it, one command will eliminate any unwanted material. Another command will rearrange a design -- and, with some systems, flip the whole drawing over so it can be examined from the back.

When a design is final, systems with computer-aided manufacturing (CAM) capability help plan the manufacturing process. These systems will determine, for example, the best way to lay out patterns for cutting pieces from large sheets of material. Or, if automated tooling is involved, they will calculate the most efficient movements for such instruments as cutters, drills, and punches.

Higher costs of CAD/CAM systems -- as much as three times that of CAD-only systems -- have so far kept them out of the reach of most small businesses. But recent price trends should soon make them more affordable. A few small companies have taken the plunge, buying a system while prices are still high. Jackson Jordan lnc., a $30 million-a-year manufacturer of railroad maintenance equipment, bought an lBM Corp unit last January for $500,000.

"We had to gulp hard to swallow that price," says Bruce Bradshaw, vice-president of engineering at the Ludington, Mich.-based company, "but we are committed to automate as many of our operations as possible." Like most new users of CAD or CAD/CAM, Jackson Jordan has been loading designs into the system. Already, using just the CAD system, the company's design productivity has increased 2 to 10 times. Bradshaw says the company is waiting for the economy to improve before it starts using CAM. He expects, however, that CAM will eventually allow Jackson Jordan to slash the number of hours it takes to program its computer-controlled machinery for making each design. With 25,000 designs on file, the company foresees an excellent return on its investment.

"Four years ago, CAD/CAM systems cost a quarter of a million and up and were used primarily by large companies," says Sam Holland, a CAD/CAM industry consultant now working for Calma Co., a CAD/CAM manufacturer based in Sunnyvale, Calif. "In two to four years they will cost from $20,000 to $60,000, and those who don't have one will be at a distinct competitive disadvantage. "

CAD systems are still relatively rare. Only about 9,000 units are in use in the United States, and fewer than 1,000 of these have been bought by small companies CAD units range in price from $55,000 to $200,000, while CAD/CAM systems range from $200,000 to $750,000. This year, a few manufacturers will market CAD/CAM units for a little more than $100,000, although these "stand-alone" systems won't allow the addition of extra terminals.

Although systems are expensive, a company could make back its investment in three years, says Eric Teicholz, president of Graphics Systems Inc., a CAD and CAD/CAM consulting firm based in Cambridge, Mass. If a company pays its designers $25 an hour in salary and benefits, he explains, and saves only 15 hours a week in designing time -- a conservative estimate: some eight-hour jobs are reduced to one -- it is pocketing $20,000 a year. Add the time saved from fewer errors and the tax advantages of a capital expenditure, and cost-justification becomes easy. But, says Teicholz, payback time isn't as important as the increased business possible from higher productivity, better-quality drawings, and greater creativity.

Mark Deardorff, president of Deardorff & Deardorff, an 18-employee civil and structural engineering firm in San Diego, was less interested in payback time than in competing successfully in a shrinking market. All engineering firms, he says, occasionally make expensive errors. Before the CAD system, he recalls, it could happen that, "after we added up the dimensions of the doors, windows, elevator shafts, and other details, they wouldn't equal the outside dimensions of the structure. A mistake of a quarter of an inch might equal thousands of dollars in construction costs."

At first Deardorff didn't notice a surge in fees after buying his CAD system. He says, "We had a $150,000 investment and no increased business to show for it.' But in the past six months, in the middle of a building industry depression, business has tripled. Deardorff is convinced that the increase is due to the system.

His company needed a full year before CAD paid off, Deardorff thinks, because it took that long to enter standards -- in this case, details of buildings -- into the computer's memory. It took only six weeks for his draftspeople to develop skills at their terminals, but it took longer for Deardorff to learn the most efficient way to use the system. By having draftspeople do rough work on paper, for example, and enter only the finished product into the computer, he felt he could free up the terminal for better use.

But Joel Orr, a CAD/CAM consultant and author of a user's newsletter, CAD/ CAM Alert (822 Boylston St., Chestnut Hill, MA 02 167), thinks that design engineers can greatly improve their work by creating at a terminal. Because they no longer need to juggle complicated ideas mentally or try them out on paper, they can easily experiment with designs. The greater freedom, Orr says, should bring about a new wave of innovation.

Jim Lewis, president of J.J. Lewis Inc., a four-employee steel detailing and drafting company in Lacrosse, Wis., hasn't noticed a rash of innovations, but he does feel CAD makes his designers more effective. Working at the terminal does take getting used to, though, he points out. For example, the designer can see only part of the design -- as much as will fit on the screen -- at a time. And skill at typing in commands improves only with practice. Lewis bought his CAD system from Itasca, Ill.-based Bruning for $75,000 last March.

About 40 manufacturers now make low-cost turnkey CAD systems. Because the units come with such a confusing array of optional and standard features, choosing the right system can be very difficult. Some questions to ask: What is the quality of the graphics? How easy is it to move components on the screen or merge designs? Can the system produce a list of materials used in the design? Will it calculate automatically the centers of lines and arcs? Are the graphics twoor three-dimensional? Is the database protected against unauthorized use? Can it be hooked up to a central data bank?

To choose a system, explains consultant Teicholz, author of Low-Cost CAD Systems for Design and Drafting (McGraw-Hill, New York; $195), use trade shows and product literature to discover the various options available in your price range. Then analyze your business's operations. Next, list those options that you want most. A construction company or architectural firm might want a machine capable of producing a list of materials and their specifications; a research company might be concerned with system security.

And, warns Orr, be sure you know what the price includes. Some price decreases are illusory. "It is as if you were offered a car very inexpensively, " he says, "but when you tried to buy it, the salesman says, -Oh, you want a steering wheel? That will be another $4,000.' " Cascade Graphics Development, in Santa Ana, Calif., for example, offers a CAD system for about $20,000. But the plotter costs about $15,000 more.

Still, there is no question prices are rapidly tumbling. And that makes it tempting for prospective buyers to wait. But Sam Holland, for one, thinks that delaying purchase is a mistake. "If a company waits too long," he says, "it might find itself in such a poor competitive and financial position in a few years, it won't be able to afford to modernize."