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Maybe you CAM, maybe you CANC: time to get serious about using low-end, low-cost CAM to off-line program your growing army of NC machines.

Maybe you CAM, maybe you CANC

Time to get serious about using low-end, low-cost CAM to off-line program your growing army of NC machines.

Computer-aided manufacturing (CAM), the shop-floor mate for computer-aided design (CAD), is a popular acronym defining the dream of major manufacturers for over a decade--the paperless factory where the definition of everything from initial part concept to final part inspection exists only in the bowels of a massive computer system. As we enter the '90s, it remains a dream for all but the largest shops.

But a funny thing happened on the way to realizing that dream--CANC, computer-assisted NC programming--a low-cost solution for the little guy who more often needs to program parts drawn on the back of an envelope than translate electronic part geometry from somebody's fancy CAD system. When the lowly microcomputer suddenly developed a massive memory a few years back, smart software people quickly found ways for it to think CAM thoughts. Since then, a plethora of CAM products have mushroomed to offer solutions so inexpensive they belong in any shop that has more than one NC machine.

If CAM proponents can be believed, two NC machines plus off-line CAM equals the productivity of three NC machines; i.e., programming-related improvements (faster and better programs, fewer errors, quicker prove-outs, and faster machining times) equal the output you would get from adding a third machine. So, instead of spending $150,000 for that extra machine, you get the same payback from a good off-line CAM system selling for $20,000 or less. Is that a bargain, or what?

The evolution of CANC has been rapid. Low-end, formerly low-tech, PC-based CAM packages are now high-tech, high value, and hard to distinguish from high-end CAM. They walk like CAM and talk like CAM (and even talk to CAD/CAM), so they deserve to be called CAM. (So let's drop the CANC acronym from here on.)

Who needs CAD?

The ideal CAM software user is somebody doing a lot of short-run parts, or mold work; i.e., writing medium to long programs with lots of trig. Just as CNC is not for those with 50,000-part runs, neither is CAM.

Part of the image problem for low-end CAM is that people are hung up on CAD--the concept that all part designs must occur in the CAD area. The part is drawn on the tube, electronically transferred to CAM software, tool paths are added, and the program downloaded to the shop. But that's not yet commonplace for the small to medium-sized shop. A lot of shops still work from their customer's prints, or if they get part data electronically, it's not the norm. They do a lot of "flying by the seat of their pants," and what they want is a CAM system that will enable them to do all the drawing they may need to create a program that will run on their wild menagerie of NC tools.

It takes time to go through CAD to CAM to a usable NC program. It's much better to have a CAM system that doesn't require a CAD front end (or wait on it). A lot of people use CAD front ends simply because they are not sophisticated enough to do their drawing on CAM.

"Yes, CAD came first," laments Tom Gabore, national sales manager, Anilam Corp, "and it's ten times easier to make a guy part with $30,000 for a CAD system for a small shop than it is to get him to spend $15,000 on a CAM system. I don't know why this is so. Maybe it's the flashy colors. They'll go for the CAD system in a heartbeat, but when it comes to CAM, they question whether they need it."

Evolution to CAM

Recognize this typical scenario? Five years ago, a shop owner with eight Bridgeport knee mills takes a chance and puts an experimental digital readout on one of them. Initially, everyone avoids that mill like it has AIDS, but eventually one brave soul tries it out, and discovers to his amazement that it makes his job easier. He can position significantly faster, he doesn't lose track of handwheel turns, and he makes fewer mistakes. His success is noted by the others, and they line up behind him to use that machine. Soon, it's in constant use.

Six months later, his good judgment vindicated by this experience, the shop owner adds more DROs. Soon, all eight machines have DROs, and he's upgrading to more complex features like single-button reset, instant metric/English conversion, absolute-zero positioning, etc.

Then, in another two years or so, with some readouts now almost as complex as an NC control, the shop starts thinking seriously about going to CNC for repetitive work. The owner takes the plunge, orders a $20,000 retrofit control because he can't afford $40,000 to $50,000 for a new NC machine tool. He chooses his best mill--the one with the best stability and repeatability.

While waiting for delivery, and knowing what this will enable him to do, the owner starts bidding on more complex work, and some of this arrives before the new machine is retrofitted.

This puts the shop in a bind, so they break out the easiest parts and do them on their manual machines. By the time that NC machine is ready to go, only the toughest, most complex parts remain. Their first parts are the worst possible parts to learn on, and their designated programmer goes berserk and quits!

Programming teams

How to avoid this trial by fire? Says Anilam's Gabore, "We try to sit down with management and plead that NC operator's case. We can guarantee that that first part he makes will take much longer than it would have to do it manually. You can spend two hours showing a group of guys how to drill a simple pattern of four holes. Invariably, there will be an old timer in the back mumbling, `Hell, I could have done that in five minutes!'

"You must give these people enough space to come up to speed on these machines. We try to train at least two people, preferably three, just in case the company has made a mistake in picking the right people for this job. Two or three chances to win are far better than only one.

"Another reason is that they will be able to talk to each other and work out problems themselves. Although we're always willing to help, we encourage them to try and figure things out themselves because the operators are far better off this way, they remember much more."

Scene two

So once again, after this initial team has shown some success, others want to get involved, and in matter of a year or so, the second or third CNC is ordered. And that's when the programming problems begin to get serious.

With that first CNC, the owner was quite content to have the programming done manually at the machine. He didn't have a lot of work for it, he couldn't keep it busy all the time, yet he was already getting benefits. Using this machine for repetitive parts, he found that he could hire a lower skilled person to run that machine, and with NC precision and repeatability, parts fit much better and fewer people are needed downstream in assembly.

But on the more complex cuts that require complex trig, there's a tendency for the programmer to fall back on manual methods to avoid dealing with the required math. Also, no matter how sophisticated your NC controls or how good your programmer, when you add machines and start using them heavily, you create waste--your machine is down for programming and your programmer is out there dodging chips. This is not the best use of these two highly valuable resources.

At this point, the need for off-line programming should become apparent. You want to be able to put your best programmer off somewhere in a quiet room to tackle the toughest programs in peace and quiet.

CAM's benefits

Enter off-line programming. Here's a summary of CAM's key benefits: Eliminate dry runs. Off-line programming allows graphic inspection and verification of the tool path before the program goes to the shop floor. There's no need to tie up the machine for dry runs. Although some machine controls now have this capability to various degrees, few have the isometric capabilities of CAM software--to view the tool and part from a variety of angles (preferably with orthogonal, rotatable, and zoom views). Some CNCs can approach this with three simple planar views, but most just have readouts to tell you where you are in the program, and thus require some degree of machine run-through. Handle increasing complexity. Even with advanced machine controls, the guy on the floor will have some problems programming trig calculations and cutter compensation at the machine. These are much easier handled off-line on a CAM system. Also, unlike the machine control focused only on real-time cutter position, the CAM system has the capability to look ahead in a program to anticipate other problems such as gouging, internal keyholes, or interferences with clamps. Reduce errors. Another benefit is reducing key-in errors. A guy can go through all the trig calculations correctly, then go out and make a mistake or two keying it in to the machine. Leave out one period, for example, and you have a serious problem. He will often need significant time to correct key-in errors, make dry runs, change the program, rekeys, etc. Save time. That first jump from manual controls to DROs can show a 70-percent positioning-time improvement. Then, moving up from DROs to CNC can mean making parts in one third the time over manual DRO methods (once, of course, the NC program is proven). Then, the more time you're spending on NC programming, the more you will benefit from CAM. To a lesser extent, the better you are at programming (and/or the better your software), the faster you can turn around parts, including significant improvements in machining time. Bigger, cheaper memories. Most machine-control memories are relatively small and expensive to expand, whereas most CAM systems have much larger and relatively inexpensive memories. They're also faster. Better bids. With fast CAM programming capability, users are realizing they can program prospective parts to fine-tune bids. They can bid much more accurately when they know ahead of time exactly how long the part will take to cut. This can not only make the difference between getting the job or not getting it, but--more importantly--between making a profit and losing your shirt. Secretive outsourcing. When your machines are all tied up and you're in a bind, you can download to a friendly competitor in the neighborhood. You simply ask him to bid on running a known part (and known machine time) from a program and stock that you supply ready to run on his specific machine. Your customer and his print remain secret--nothing proprietary is disclosed. And when you buddy's in a bind, you can do the same for him.

Selection tips

So, convinced by these benefits, how do you sort through dozens of CAM software systems to find the one that's right for you? Here are some hints and basic features to expect: Expertise: "Where's your expertise?" is a good first question to ask. In too many cases, good CAD software is matched with a poor CAM, or vice versa, because no vendor really knows both sides of the CAD/CAM equation equally well. So, if your emphasis is primarily on the manufacturing side, you should select a CAM vendor whose software is also coming from that area of expertise. Speed: Because most low-end CAM is based on the DOS environment, future improvements in speed will be minimal. The 286 machines have been pushed out by the 386s, and although 486 machines are twice as fast as 386 computers, there aren't enough 486s out there to make CAM vendors rewrite their software. Even if they did, the 386 machine is fast enough for most applications--few users are wasting time waiting on their hardware. At one time, software had to be throttled to wait on the slower DOS computers, but that's no longer the case.

(So why should vendors rewrite software to gain a minimal hardware-speed advantage and lock themselves out of a major chunk of the market? Super-fast workstations are available, of course, and the latest leading-edge CNC controls have leaped to 32-bit technology. This will permit machining at higher feed rates, finer resolutions, and sexier contours; and eventually up the ante for off-line CAM systems. But for the moment, the premise for this aricle is that you are among the majority trying to supplement the shop-floor programming of more conventional NC controls.) Memory capacity: You will need to know whether the typical 640K CAM memory is sufficient for the complexity of parts you intend to program. As a rule of thumb, this translates into a part with something like 400 elements. Going beyond this level of complexity--to wireframe models that require a lofted surface to intersect with another surface, or a really complex plastic-injection mold--entails one of two approaches: expanded memory or extended memory.

Expanded memory uses protocol to page memory in and out of your 640K memory board, and is relatively clumsy. With memory extenders, on the other hand, you can directly access up to 16 Megabytes of direct RAM. This means that when you get into complex parts, you can run very quickly because you're running in real-time RAM. Otherwise, when part complexity expands, paging to a hard disc bogs down--you're continually going to the hard disc, looking for information, and bringing it back.

Paging is really an interim solution. In the future, everyone will be using 16-Meg RAM, whether in DOS or Unix. Talk to me: Menu-based, interactive graphics is now dominating over older (harder-to-learn, say its detractors) language-based systems. Some CAM systems are bilingual and let you have it either way (i.e., if you don't want to master a language-based system, you don't have to).

But what's "interactive graphics?" A widely misused term says Point Control's Carl Watkins, claiming few systems (his own, SmartCAM, of course) actually interact: "The language-base people put a graphics front end on their system and claim `interactive' graphics. What they really are is `re-active graphics.' Their graphics reacts to something that the system has done. This is not interacting with the system as you make your programming specifications of tool path, but reacting after you've generated code." Canned expertise: Some built-in basic database of machining expertise should be provided--recommended speeds and feeds--for your programmer to supplement with his own level of experience (or inexperience). Of course, if the vendor goes overboard on this aspect--a highly touted AI expert system, for example--expect to pay a whole lot more for his software (and maybe, a little less for your programmer). Canned cycles: Part of the basic package, these should be ready to tackle an array of the more common problems--machining islands, pockets, sharp angles; avoiding tool collisions or gouging of the part; and clearing common clamps and fixtures. Special situations, like gears and parametric spines, should be available as options. Reposting: Enough (a hundred or so) standard postprocessing programs (and/or some help on customizing existing posts) should be provided to enable you to repost-process a program and quickly jump from a tied-up machine tool to an available one. Most post-processors leave the original tool-path numbers alone so that shop-floor people can do this themselves. Cutting air: In many 3-D systems, the tool spends a lot of time cutting air because the software is overly cautious about the tool hitting or gouging the part--routines are written to keep the tool away from the part, and you have difficulty changing them. This is something you don't realize watching their initial demo of how the tool-path graphic is generated, but only after you've used their system for a while. Much better is software that allows you to deal directly with tool path and streamline it for the most productive cutting time. CAD access: Options should be readily available to input part graphics from most common CAD systems, or to network to higher-level hardware for more sophisticated processing, if either of those needs arises later (i.e., you don't want to dead-end yourself with software that can't communicate).

A good CAM system should allow you to draw the part, write the program, shoot it out to the floor, and be cutting the part while you send (via translators) that same part definition electronically back into your own CAD system or somebody else's to document the program while the part is being machined. This can cut in half the time it would take to generate that part first in CAD. Cost: Generally, for 3-D software that can do these things, expect to pay something in the $20,000 area. Some 2-D packages go for as little as $995, and 2-1/2D systems are in the $6000 to $10,000 area. There are plenty of choices--these price ranges are where the key software-vendor battles are being fought (primarily because nobody wants to pay more for software than hardware). Of course, special options are extra, but shop around, you may still get everything you need for not much more than this.

An important cost corollary: you don't have to marry your software vendor. Expect to throw away today's package in a few years in favor of something newer, better, and even more productive at an equal or lesser cost. Adds Smart-CAM's Watkins, "When you buy a CAM system, you bet your business--your ability to compete with others and their CAM system. If you're stuck with a CAM system that's not working for you, you have no choice, you must change to something better. Yet, some people will just about go out of business before they will make that change." Discount derby: When software is sold through a dealer network, that dealer cannot discount and still provide service. He must have a profit to pay for the support that is usually required to get you up and running. So don't expect something for nothing--a low-ball price will mean hands-off service. With as little as $500 profit per sale, a distributer can't make a living doing three demonstrations, installing it, working out the hardware details, and holding your hand until you get the hang of it and make good parts. Define your needs: A key selection factor is to define beforehand just how much programming you expect to be doing in the near future. In some cases, if it's not a whole lot and you have a clever programmer you can count on, maybe you don't need CAM at all.

Says Anilam's Gabore, "We try to sit down with a customer, establish his present and near-term potential needs, and match that to a particular software package. The alternative approach is to tell people `I have a package to sell, and I will find some way to make it look like what you need.' That, in fact, is what many in the industry are doing."

People angles

Don't neglect the people side of CAM, Gabore warns. "People come to us for a variety of reasons: They've seen an ad for CAM, they think it's high tech, they want to be a leader in their industry, they want to impress their friends, etc. Or the worst case: they're in a panic because their programmer just quit--that's a great CAM incentive!" (When you relegate all your programming responsibilities to one guy, you're really vulnerable.)

And don't neglect the guy on the other end, he adds. "It's dangerous to rely solely on the programmer's skills and let anyone hired off the street run the machine. No matter how good your software, someone has to occasionally iron little kinks out of it. They don't need to be an expert programmer, but they should be comfortable with the machine and able to resolve these little problems when they occur.

"A good CAM system can turn out programs that cover 95 percent of your machining problems, but you still need someone to trouble-shoot on the floor--to let you know when the feeds and speeds are not right based on how the machine is actually running. The reason CAM software is relying more and more on feed-and-speed tables is because that programmer is often not a machinist. All modern machine controls have override buttons to increase or decrease keyed-in feed rates by 5 percent or so to make these corrections in real time on the floor."

Just sign here

Okay, fellows, lets hear your closing sales pitch. Says SmartCAM's Watkins, "Today's CAM software choices should be viewed as opportunity generaters. In the past, programming systems were viewed as a hassle--a major obstacle to getting the code you need to make a part. Today, the software buyer will find that CAM can expand their business because of the new capabilities it provides, the flexibility to do lots of different kinds of parts.

"So this is what it is all coming down to: who's able to use CAM effectively. That's where the competition is. Everyone can buy the same machining capabilities. The payoff is in how quickly and how well you use them."

Adds Anilam's Gabore, "When GM (and others) send programs and prints out for bids (where they also provide the stock and the tooling), they're asking you only to provide space, a machine tool, and manpower. Low bid gets it. That's scary because what's left for you? Where's your profit?

"I sincerely feel that CAM is something that will really help American industry. I've done a lot of seminars and am continually surprised at all the people who don't have the foggiest notion of what CAM can provide. I tell them, `I don't care what CAM system you buy (I do, but I don't), but darn it, GET ONE! If you have an NC machine and are doing any significant work on it at all (which you darn well better be to make the payments on it), you better have somebody programming off-line.

"Payback periods will range from three to six months, depending on whether you're buying both hardware and software. What machine tool will pay back this quickly? Where else is a relatively inexpensive software purchase equivalent to buying a third machine?"

But, it's also a case of use it or lose it, he warns. "As with any equipment, you must apply yourself. You can't buy CAM, and tuck it away in the corner, or save it for the toughest programs and scare your programmer half to death. The secret to CAM success is three-fold: Use it, use it, use it. Your commitment and mental attitude transcend the capability of whatever CAM system you purchase."

PHOTO : Base building. Concept software from PMX talks shop language and builds a knowledge

PHOTO : base--yours and theirs--via automated programming functions, pulldown menus, and mouse

PHOTO : entry of geometry. Tool path, curve fairings, and feeds and speeds can be selected

PHOTO : automatically or overriden. Information contained in a single move includes not only 3-D

PHOTO : coordinates, but also depth component, tool normals, and vectors.

PHOTO : Big little box. General Numeric's PG Mark II is an off-line, desk-top microcomputer for

PHOTO : programming all types of NC machines (not just those with Fanuc controls) in FAPT

PHOTO : language or symbolic FAPT, a menu-driven conversational version. Features include

PHOTO : full-color graphics, CADKEY interface, 3-D sculpting of 2-D section curves, and automatic

PHOTO : reading of drawings with a digitizing tablet.

PHOTO : Model magic. Manufacturing-process modeling is the key to SmartCAM's approach to NC-code

PHOTO : generation. As you develop tool path, the software generates a manufacturing model with

PHOTO : built-in part geometry, manufacturing sequence, and machining properties (tool geometry,

PHOTO : offset, etc) with which the user can interact freely and directly, and (it's hoped)

PHOTO : imaginatively and productively.

PHOTO : Space wrap. To quickly wrap a surface and create a tool path for 3-D milling, Master-CAM

PHOTO : uses lofted, swept, or coons surfaces and blends up to 100 cross sections using linear,

PHOTO : parabolic, or cubic options. Subsequent modifications can include surface trimming,

PHOTO : projections, filleting, intersections, reversals, roughing, and cutter compensation.

PHOTO : Burn routes. I/BURN thermal-cutting option from Intergraph enhances their I/NC software

PHOTO : with interactive and automatic tool-path generation for flame, plasma-arc, laser, and

PHOTO : waterjet cutting. It employs a combination of graphic depiction, close-ups, and program

PHOTO : editing in a single screen.

PHOTO : Holey CAM. Fabrivision optical scanning system from Metalsoft digitizes templates or flat

PHOTO : parts and, when combined with their FabriCAM software, produces "instant" NC part

PHOTO : programs.
COPYRIGHT 1990 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1990 Gale, Cengage Learning. All rights reserved.

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Title Annotation:computer-aided manufacturing; computer-assisted numerical control
Author:Sprow, Eugene
Publication:Tooling & Production
Date:Mar 1, 1990
Words:4115
Previous Article:Selecting a laser cutter.
Next Article:CMM cuts measurement time by 24:1 ratio.
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