Programming for MTM
As multitasking machine tools become more affordable, users are getting serious about programming for MTM
By Patrick Waurzyniak
Programming complexity for multitasking machines (MTM) with multiple spindles and turrets poses a challenge for manufacturers deploying machine tools capable of performing simultaneous milling and turning operations. With these machines becoming more affordable, CAM software developers recently have begun offering more widespread support of MTM, with advanced solutions allowing manufacturers to more easily undertake highly complex programming tasks.
Machine simulation also has become much more common, with many CAD/CAM developers and NC simulation/verification software suppliers offering manufacturers more sophisticated simulation capabilities. These packages help synchronize MTM operations that often involve simultaneous machining with multiple spindles or turrets operating in synch with each other.
"The number one focus for us recently has been multitasking/multifunction machining, doing a better job of integrating the programming necessary for machines where we're doing milling and turning on the same machine tool," says Chuck Mathews, vice president, DP Technology Corp. (Camarillo, CA), developer of Esprit CAM software. "This is where you machine the front of the workpiece, move it to another holding device, and then machine the back.
"In that area, you've got machining cycles that have become really important," Mathews adds. "One of the newest machining cycles would be using the B-axis on one of these machines while you're doing traditional turning operations. You're actually changing the orientation of the cutting tool during the cutting process, so that's a unique machining cycle to a B-axis class machine tool. You wouldn't have that available on a traditional lathe."
Working with machine tool partners including Mori Seiki, Mazak, Nakamura, and Citizen, DP Technology has developed software to better utilize such machines, Mathews notes. The latest Esprit CAM software includes prepackaged solutions for programming mill-turn machines, including real-time simulations that verify machining processes without the need to take machines off-line. "It has been a focus for a couple of years, and it continues to be a very important focus of ours," Mathews says. "It's just improving machining cycles to allow the shop to run high cutting speeds to maximize tool life, which are the main two priorities in improving machining cycles, including optimizing feeds and speeds."
Machine simulation added to the latest FeatureCAM software benefits all users, particularly those working with five-axis and multiturret systems, notes Tom McCollough, vice president, software development, Engineering Geometry Systems (EGS, Salt Lake City). "It is going to be useful on all of the different products we sell; the two-axis milling, three-axis, five-axis positioning, and turning, but the ones that are really going to benefit from it are the ones that target complex machines. For example, our five-axis positioning product is going to be used by customers on a machine that has several different degrees of freedom, lots of things moving around and opportunity for things to hit each other, and that's when the full machine simulation really comes in handy."
With machine simulation in FeatureCAM 2006, EGS customers will be able to use the simulation on a wide range of applications including five-axis positioning, complex turning, turn-mill machines, and multiple-turret systems, McCollough notes. "At the same time, we're releasing a multiaxis turning product, so we've wanted to do the full machine simulation.
"Our latest product addresses more multiturret programming, and that gives customers the ability to reduce cycle time," he adds. "What you want to be able to do is get these parts made, you want to make a thousand of them in as little time as possible, so it's production turning. Those kinds of machines will also have dual spindles, but more importantly they'll have multiple turrets--some of them have as many as four turrets--so you can have several different kinds of turning/boring going on all at once, some on the main spindle, some on the sub-spindle, and so every few seconds you're parting off another workpiece."
In addition to machine simulation, the next FeatureCAM release also will include synchronized turning for production machining. The EGS package will incorporate four-axis, twin-turret machining capability into its existing turning programs which, combined with machine simulation, allow production machinists full program control and cycle-time reduction. This new feature supports synchronization, follow turning, and pinch turning, and can program machines with dual spindles and as many as four turrets. The simulation allows programmers to set up attributes for each type of machine, including horsepower and preferred feeds and speeds.
Cutting parts more efficiently with reduced setups and shorter cycle times is crucial for manufacturers to remain competitive. "We want to make our customers able to cut parts faster, and that's taking a priority over just being faster to write the program, because we like to step back, and we like to look at where our customers spend their money," notes Bill Gibbs, president of Gibbs and Associates (Moorpark, CA), developer of GibbsCAM. "Our job is to see how we can help customers be more competitive, more profitable, and if we can correlate what we're selling to them making money, it makes it an easier sale. The most expensive thing most of these shops have is machine time. We want to save them machine time, and we can start this with physically creating a program that will cut faster. That's where high-speed machining, feed-rate optimization, optimal toolpaths, and not cutting air but material only, come into play as a first priority.
"A big waste of machine time also occurs during setup and anytime a mistake gets to the CNC machine," Gibbs adds. "So after we've got the part theoretically cutting as fast as a program could be written, we want to make sure that we're catching all the mistakes, we want to make sure that we're not telling people to go out and use them as programming tools. We have a relatively new simulation that allows you to completely test out your setup dimensions before going out to the machine."
GibbsCAM's machine simulation, which has been shipping since IMTS last fall, allows for users of more expensive machines, including MTM systems, to perform setups without wasting valuable machine time. "It's very useful for people that have expensive machines," Gibbs says. "Typically, the problem is that you're going to spend so much time setting up a machine before you run the part. If your machine is easy to set up and it's an inexpensive machine, there's no problem just doing that for the first time at the machine.
"But at the other end of the spectrum, when you run into very large horizontals, big tombstones, or MTM machines, you have very high hourly rates, very high costs, very high-complexity setups, and the opportunity to do this on a computer first is a real time-saver, a real low-risk money-saver," Gibbs says. "You're not going to crash your tool into the table or index a tool through something."
Multifunction machine support and five-axis machining elements were added to the NX 3 Machining package released by UGS (Plano, TX) at IMTS, and the company also is focusing on die/mold and hard milling markets, notes UGS' Vynce Paradise. "Multifunction machine support is a big interest to manufacturers today, being that that class of machines has come down relatively in price, compared to what it had been. With NX 3, we added the Synchronization Manager, which helps the customer actually put the sync codes in, and we're getting a lot of interest in those across a range of machines--Mori Seiki, Mazak, Okuma, Nakamura--and what we're finding is that we must provide a complete solution because of the complexity of some of the machines."
With its latest NX 3 software, UGS also added machine simulation of toolpaths and full machine simulations, which helps users eliminate any chance of machine tool collisions, Paradise adds. "For the complex multifunction machines and some five-axis equipment, it's really very useful," he notes. "Machine tool simulation has a lot of value, especially with more complex cases. We're working on that as differentiators. We push full solids with simulation including very detailed 3-D models."
Along with new cutting techniques, "smart" functions, and surface machining features, the latest Mastercam X package from CNC Software Inc. (Tolland, CT) offers a new streamlined user interface. The updated Mastercam features new high-speed machining improvements and changes to its surface machining techniques, according to Mark Summers, CNC Software president.
An enhanced machining model in Mastercam X ensures precision toolpaths and dramatically speeds programming changes, including Z-level toolpaths that can be processed up to 400% faster. "It's kind of like a machining model, but it's going to help calculate toolpaths quicker, especially when you have to re-do the toolpath and change your step-over or cutting angle."
The updated Mastercam also features improvements in multiaxis machining. "That's been a bigger and bigger part of our business," Summers says, "and one of the reasons is that five-axis machines are a lot more affordable and that's creating a demand. People buy them and then they realize they don't know how to program them, because they are a lot more complicated than a three-axis machine."
Besides its new streamlined interface, Mastercam X also allows users to customize the toolbars and menus that can be tailored to their specific work, so multiple users can save their custom interface. "You've probably seen interfaces where you've got 200 buttons on the screen, and it's just a cluttered mess," Summers says. "So we try to set it up so that you decide what type of work you want to do. If you have two or more users using the same computer, you just call up your version."
Automating processes that are easily used by shop-floor personnel is a key trend for customers, notes Steve Hobbs, development director, Delcam plc (Birmingham, England), developer of PowerMILL CAM software. "Automating basic functions of applications is driven by the desire to ensure that CAM applications that are producing high-speed, high-efficiency, and five-axis toolpaths can be operated by shop-floor users and occasional users.
With its upcoming PowerMILL 6, Delcam adds new tools for automatic tool-axis tilting, improved global thickness control, integration of flat machining with area clearance, and better handling of arcs in raceline roughing. "The biggest area of development activity at Delcam on CAM has been associated with five-axis machining and enabling users to produce gouge-free five-axis toolpaths quickly and easily with confidence--in short, five-axis machining with the ease of use of three-axis machining," Hobbs notes. "This has involved not only significant work associated with toolpath calculation, but also in the areas of machine tool dynamic simulation and cutting-condition simulation."
With its latest SurfCAM release, Surfware Inc. (Westlake Village, CA) aims to reduce cycle time for CAM users with dramatic reductions in machining time. Surfware's patent-pending controlled-engagement technology is said to increase the productivity of NC machine tools with a new toolpath engine that manages the tool's engagement with the material, resulting in toolpaths that never overload the cutting tool. Since the toolpaths are free from spikes or sudden changes in tool load, machining parameters such as spindle speeds, feed-rates, depths-of-cut and step-overs are used in combinations that are said to significantly cut cycle time. Surfware says that the technology is completely independent of the machining hardware, including cutting tools, toolholders, the controller, and the machine tool.
NC toolpath simulation also can help manufacturers make their operations more efficient by capturing data from the manufacturing process. "There is a huge need to capture existing manufacturing process information and provide that information throughout the organization, to suppliers and to customers," notes Bill Hasenjaeger, product manager, CGTech Corp. (Irvine, CA). "Simulation software, such as CGTech's Vericut, contains comprehensive process information which exists no where else in electronic form. Presenting this information to the various manufacturing participants helps them see the entire process and documents the processes for future reference and improvement."
The next release of Vericut version 6.0, contains more features to make setup and simulation easier for complex multi-stage setups, operations, and machines such rotary transfer cells, and multi-slide, multi-spindle, mill-turn machines, Hasenjaeger says. "It will also be possible to model and simulate using the complex tooling used on these machines, accurately representing material removal and cutting conditions.
"We also continue with ongoing enhancement of Vericut's control emulation, including embedding actual CNC control logic in Vericut's off-line simulation," he adds. "The enhanced control emulation and embedding of actual CNC logic is part of our constant improvement to more accurately simulate the CNC control's logic and the machine tool's motion directed by that logic."
New solutions from Delmia Corp. (Auburn Hills, MI) will permit attacking manufacturing industry challenges with an end-to-end machining solution that will enable process planning, NC set-up, validation, NC programming, part verification, machine tool building/simulation, and inspection in a common digital machining environment.
Among Delmia's machining solutions, machine toolpath simulation enables organizations to optimize machining operation definition. Through integrated product environment, users have a seamless solution to address all their manufacturing environment needs, and NC programmers can easily validate the machining setup for machine tools and toolpaths upfront during machining-operation definition.
This article was first published in the April 2005 edition of Manufacturing Engineering magazine.