In nature, scientists are sometimes able to distinguish one species from another only by examining DNA, the unique genetic code in every living cell. In these cases, external appearances do not offer reliable clues. This is much the case with a new breed of vertical machining centers designed for submicron accuracy. These machines do not look strikingly different from other precision machine tools. Yet the submicron model has hidden features and subtle attributes that prove it to be a very different creature, one that has evolved to function in an environment where microns and nanometers (millionths and billionths of a meter) are critical.
Some of the ways in which these machines are likely to deviate from normal expectations for a VMC can be observed in the Hyper2J from Makino (U.S. headquarters in Mason, Ohio). Comparable models from other builders may represent further radical departures from the norm, but looking at this machine helps us understand the design factors that tend to define the "nature of the beast." The chief factors are vibration, heat, rigidity and control unit capability.
* The four-point leveling mounts underneath the Hyper2J rest on a base made of metrology-grade granite that is 250 mm (almost 10 inches) thick. This granite "foundation" isolates the machine structure from vibration in the floor. Granite has 1/10 to 1/20 the thermal conductivity of cast iron, so it resists the effects of ambient temperature changes.
* The spindle is designed to reduce vibration and counter thermal growth. It has a direct tool clamping system that does not require a toolholder or collet. A mechanism inside the spindle uses hydraulic pressure to collapse around the tool shank, much the way the individual hydraulic toolholder would. According to the designers, this feature minimizes rotational vibration inevitably introduced by imperfections in a separate toolholder. Minimizing vibration is a priority because super small cutting tools (end mills with a diameter of 0.03 mm are typical) are susceptible to breakage when subjected to minute vibrations.
* The internal temperature of the spindle is maintained by automatically cooling the lubricant that circulates through it. The work light inside the machine uses LEDs because they are much cooler than other types of lights.
Spindle speeds range from 3,000 to 40,000 rpm (a 170,000-rpm spindle is available.)
* There are no linear motors. Makino has opted for ballscrews and slideways for axis drives, citing the company's ability to achieve the necessary straightness and smoothness in its production techniques. Maximum feed rates and rapid traverse rates are 12 m/min. (472 ipm).
* The machine has provisions for measuring the position of the tool tip to less than 1 micron. An "ultra-low pressure" contact-type measuring device determines tool length. A proximity-style non-contact spindle positioning device allows the position of the tool tip to be corrected in all three (X, Y and Z) axes. After a tool change, the level of machining surfaces will be higher or lower by less than 1 micron. To detect broken tool tips, an electrical current is transmitted through the cutting tool. If the tool breaks, the disrupted circuit triggers an alarm.
Interestingly, Makino says it has the most experience determining appropriate speeds and feeds for a 0.03-mm diameter carbide end mill. Machine settings for other tools are established on an application-by-application basis.
* The axis position feedback system uses a 0.5-nanometer scale to reliably track axis motion commands programmable in steps as small as 10 nanometers. Makino's stated positioning accuracy for this machine is [+ or -]0.3 micron, with a repeatability accuracy of [+ or -]0.2 micron.
* The control unit, which combines Fanuc hardware for CNC processing with a Windows CE graphical user interface, supports nanometer interpolation and millisecond block processing time. A proprietary "Super Geometry Intelligence" servo control system provides smooth machined surfaces. This kind of smoothing feature grows in importance as cutting tools and programmed steps become so small that workpiece features and tool marks approach the same size range.
Makinng Submicron Machining Practical Makino stresses that the Hyper2J is an attempt to make submicron machining in three axes practical for shops intent on moving to this level of accuracy. The company says that the machine is intended for the real world, not the laboratory. The Hyper2J does require a temperature-controlled room. Another version, the Hyper2, incorporates a thermal chamber for controlling its own temperature in ordinary shop environments to achieve submicron accuracy.
Friday, September 01, 2006
Enhancing machine tool productivity
In addition to quickly responding to customer demands, job shops can also reduce programming, tooling and production times with ShopMill version 6.4, says manufacturer Siemens.
Featuring step-by-step, onscreen programming, the software includes 3D views with simulation, including real-time simulation: an engraving cycle; an enhanced tooling list with angle head cutter definition, tap definition and Pace mill geometry; and enhanced workpiece measurements in manual mode.
Users are provided with a 3D view of the part to be cut while in simulation or real-time mode. As a result, possible machining errors can be detected relatively early, says the company.
The new engraving cycle offers the capability of engraving complex text on a radius. This single-button feature can be useful when engraving serial numbers, company names, and dates and times on cut parts.
Additionally, the software can be used in conjunction with the Sinumerik 810D or 840D while running Windows XP.
Featuring step-by-step, onscreen programming, the software includes 3D views with simulation, including real-time simulation: an engraving cycle; an enhanced tooling list with angle head cutter definition, tap definition and Pace mill geometry; and enhanced workpiece measurements in manual mode.
Users are provided with a 3D view of the part to be cut while in simulation or real-time mode. As a result, possible machining errors can be detected relatively early, says the company.
The new engraving cycle offers the capability of engraving complex text on a radius. This single-button feature can be useful when engraving serial numbers, company names, and dates and times on cut parts.
Additionally, the software can be used in conjunction with the Sinumerik 810D or 840D while running Windows XP.
Fast and flexible - EMO, machine tool show
This year's EMO - he premier European machine tool show - saw that continent's builders once again focused on innovative, but practical, product development.
When EMO was last held in Hannover, Germany, four years ago, the show was in a word, depressing. The mighty German machine tool industry, as well as the rest of Europe, was mired in the worst slump in a generation. And the news from this normally technologically elite exhibition had more to do with corporate realignments and cost reduction than with anything else, as so many European companies were moving into a survival mode reminiscent of the American machine tool industry of the mid 1980s.
This time around, however, the story was very different. While the general European economy is still in recession, conditions are far better for the machine tool builders. For one thing, the builders as a group are on stronger financial footing, having cut much of the fat out of their organizations and having established more viable business alignments - we'd call them mergers and acquisitions - where individual companies were in serious trouble going it alone. And equally important, European manufacturing in general is stepping up its investment again, cognizant of the need to cut costs through the development of more efficient production processes.
This situation, thankfully, has many European machine tool builders returning to more aggressive product development strategies of their own. While, like usual, many builders are pursuing a range of approaches to solving the manufacturing puzzle, there were some strong themes that played consistently throughout the halls of EMO. Most apparent were the notions of achieving greater speed and flexibility. By speed, we mean machines that move faster both in and out of the cut. And by flexibility, we mean machines that set up faster or otherwise move more deftly from one workpiece to the next. Here are some of the ways those ideas were on display at EMO.
Simply Fast
Perhaps the most striking presence at EMO is how commonplace high speed machining has become. Most of the leading European machining center builders had high speed models on display, and not just machines with fast spindles, but with significant other machine features that support accurate contouring at high feed rates as well.
High speed spindle makers are looking both to push the speed-and-power combination higher and to make their designs more dependable. Urged on largely by the aerospace industry, some builders are actively pursuing the technological goal of building a 100/100 (100,000 rpm/100 kW) spindle. But more are focused on addressing some lingering practical concerns in the 20,000 to 40,000 rpm range, which is growing common. Once such concern is service life. Currently a good life for a high speed spindle is 3,000 to 6,000 hours. That translates to just about two years.
High speed spindle failure is generally not catastrophic, says Siegfried Weiss, president of the German high speed spindle builder Weiss GmbH (Dyna Drive, Inc., Mentor, Ohio). "We've found that spindles are subjected to numerous little wrecks that over time that add up to a failure." According to Bill Popoli, president of the U.S. arm of Swiss spindle maker Ibag (Milford, Connecticut), there is a need for shops to understand that high speed spindles are not as "tough" as spindles found on standard machine tools. Still, it is a goal for Ibag and other spindle builders to get average service life up to five years.
As for control capabilities, it seems like the whole industry has upgraded to high speed CNCs capable of executing extraordinarily accurate cutter paths at very high feed rates - an enabling technology that has machining centers cutting everything from hardened tool steels (as hard as 62 Rc) to cast iron and aluminum auto and aerospace parts. For die/ mold machining, the newest capability now in the spotlight is curve interpolation, which a number of machine tool builders were touting - mainly those with Siemens and GE Fanuc controls. This feature allows complex curves such as non-uniform rational B-splines (NURBS) to be imported directly into the CNC rather than having to approximate those curves with point-to-point moves as is done in conventional contouring. The CNC interpolator then references the true curve math to contour more accurately, smoothly and, by most accounts, much faster too.
However, not everyone believes that curve interpolation is yet the total answer for high performance contouring. German control builder Heidenhain, Schaumburg, Illinois, for instance, thinks that curve interpolation makes sense only where data points in a conventional part program are clustered too close together to maintain a desirable feed rate. The far larger issue, they contend, is to apply look-ahead capabilities for the sake of real time "jerk control" - that is, to soften abrupt moments of axis acceleration and deceleration in order to create a smoother execution of conventional point-to-point contouring cuts. And that is a feature the builder was emphasizing, though they have introduced a curve interpolator as well.
When EMO was last held in Hannover, Germany, four years ago, the show was in a word, depressing. The mighty German machine tool industry, as well as the rest of Europe, was mired in the worst slump in a generation. And the news from this normally technologically elite exhibition had more to do with corporate realignments and cost reduction than with anything else, as so many European companies were moving into a survival mode reminiscent of the American machine tool industry of the mid 1980s.
This time around, however, the story was very different. While the general European economy is still in recession, conditions are far better for the machine tool builders. For one thing, the builders as a group are on stronger financial footing, having cut much of the fat out of their organizations and having established more viable business alignments - we'd call them mergers and acquisitions - where individual companies were in serious trouble going it alone. And equally important, European manufacturing in general is stepping up its investment again, cognizant of the need to cut costs through the development of more efficient production processes.
This situation, thankfully, has many European machine tool builders returning to more aggressive product development strategies of their own. While, like usual, many builders are pursuing a range of approaches to solving the manufacturing puzzle, there were some strong themes that played consistently throughout the halls of EMO. Most apparent were the notions of achieving greater speed and flexibility. By speed, we mean machines that move faster both in and out of the cut. And by flexibility, we mean machines that set up faster or otherwise move more deftly from one workpiece to the next. Here are some of the ways those ideas were on display at EMO.
Simply Fast
Perhaps the most striking presence at EMO is how commonplace high speed machining has become. Most of the leading European machining center builders had high speed models on display, and not just machines with fast spindles, but with significant other machine features that support accurate contouring at high feed rates as well.
High speed spindle makers are looking both to push the speed-and-power combination higher and to make their designs more dependable. Urged on largely by the aerospace industry, some builders are actively pursuing the technological goal of building a 100/100 (100,000 rpm/100 kW) spindle. But more are focused on addressing some lingering practical concerns in the 20,000 to 40,000 rpm range, which is growing common. Once such concern is service life. Currently a good life for a high speed spindle is 3,000 to 6,000 hours. That translates to just about two years.
High speed spindle failure is generally not catastrophic, says Siegfried Weiss, president of the German high speed spindle builder Weiss GmbH (Dyna Drive, Inc., Mentor, Ohio). "We've found that spindles are subjected to numerous little wrecks that over time that add up to a failure." According to Bill Popoli, president of the U.S. arm of Swiss spindle maker Ibag (Milford, Connecticut), there is a need for shops to understand that high speed spindles are not as "tough" as spindles found on standard machine tools. Still, it is a goal for Ibag and other spindle builders to get average service life up to five years.
As for control capabilities, it seems like the whole industry has upgraded to high speed CNCs capable of executing extraordinarily accurate cutter paths at very high feed rates - an enabling technology that has machining centers cutting everything from hardened tool steels (as hard as 62 Rc) to cast iron and aluminum auto and aerospace parts. For die/ mold machining, the newest capability now in the spotlight is curve interpolation, which a number of machine tool builders were touting - mainly those with Siemens and GE Fanuc controls. This feature allows complex curves such as non-uniform rational B-splines (NURBS) to be imported directly into the CNC rather than having to approximate those curves with point-to-point moves as is done in conventional contouring. The CNC interpolator then references the true curve math to contour more accurately, smoothly and, by most accounts, much faster too.
However, not everyone believes that curve interpolation is yet the total answer for high performance contouring. German control builder Heidenhain, Schaumburg, Illinois, for instance, thinks that curve interpolation makes sense only where data points in a conventional part program are clustered too close together to maintain a desirable feed rate. The far larger issue, they contend, is to apply look-ahead capabilities for the sake of real time "jerk control" - that is, to soften abrupt moments of axis acceleration and deceleration in order to create a smoother execution of conventional point-to-point contouring cuts. And that is a feature the builder was emphasizing, though they have introduced a curve interpolator as well.
KMG Tool & Machine Co. adds more CNC equipment
KMG Tool & Machine Co., Wichita, Kansas, has recently added more CNC equipment.
The 22-year-old firm, which specializes in tooling, precision machining, welding and fabrication, is adding the equipment to handle larger-sized jobs.
Two pieces of equipment were recently installed. The first is a Mazak AN 60/120 3-axis vertical machining center with a 124"X, 58"Y and 23"Z.
The other piece is a Mazak SV-25 4-axis vertical machining center, which features an 80-tool changer.
"This equipment was needed to handle the larger parts and will also help us expand our customer base," stated KMG Tool & Machine's Mike Coffey.
Other equipment in the company's 24,000-sq.-ft. facility includes: a Flow waterjet (6.5' x 24'); a Mazak CNC lathe, four CNC mills; numerous vertical and horizontal mills; grinding equipment; and an 8,000-sq.-ft welding shop (AWS certified) with aluminum-Heli-Arc, steel-MIG, Tig and Arc welding.
KMG works with CATIA version 4 and 5 CAD software and SMARTCAM software with full 3D surfacing, 411 axis and 5th axis indexing.The company also has a QC lab with a CMM (48" x 78") and meets the requirements for DI-9000A, MIL-I-45208A and is a delegated source inspector.
"Our employees have an average of 25 years experience building quality tooling and production parts," stated KMG's Ken Coffey.
He noted that KMG has built long-term relationships with several suppliers and can provide such services as: heat treating; plating; broaching; precision grinding; sandblasting and painting.
The 22-year-old firm, which specializes in tooling, precision machining, welding and fabrication, is adding the equipment to handle larger-sized jobs.
Two pieces of equipment were recently installed. The first is a Mazak AN 60/120 3-axis vertical machining center with a 124"X, 58"Y and 23"Z.
The other piece is a Mazak SV-25 4-axis vertical machining center, which features an 80-tool changer.
"This equipment was needed to handle the larger parts and will also help us expand our customer base," stated KMG Tool & Machine's Mike Coffey.
Other equipment in the company's 24,000-sq.-ft. facility includes: a Flow waterjet (6.5' x 24'); a Mazak CNC lathe, four CNC mills; numerous vertical and horizontal mills; grinding equipment; and an 8,000-sq.-ft welding shop (AWS certified) with aluminum-Heli-Arc, steel-MIG, Tig and Arc welding.
KMG works with CATIA version 4 and 5 CAD software and SMARTCAM software with full 3D surfacing, 411 axis and 5th axis indexing.The company also has a QC lab with a CMM (48" x 78") and meets the requirements for DI-9000A, MIL-I-45208A and is a delegated source inspector.
"Our employees have an average of 25 years experience building quality tooling and production parts," stated KMG's Ken Coffey.
He noted that KMG has built long-term relationships with several suppliers and can provide such services as: heat treating; plating; broaching; precision grinding; sandblasting and painting.
Wednesday, August 30, 2006
Millions of components machined to millionths - Street Smarts - machine tool tolerances
"Inch worm, inch worm. Measuring the marigolds. Seems to me you'd stop and see how beautiful they are."
Let me tell you something about inch worms. We couldn't live without them.
In 1958 a U.S. Air Force contract was let to MIT and Giddings & Lewis Machine Tool to retrofit a standard boring mill for completely automatic operation. The result was the first numerically controlled machine tool, at least in North America. Kearney & Trecker came up with the automatic tool changer and it was off to the races. The advent of PLCs and microprocessors accelerated the manufacturing revolution.
I used to argue with my father that this was clearly the greatest advance in manufacturing in the second half of the 1900s. As he was chief of metrology for the U.S. Army Signal Corps in the early 1970s, his perspective was a little different. He insisted the coordinate measuring machine (CMM) and laser alignment were more important because they provided the foundation for accuracy and interchangeability on a repeatable basis. It really made plants interchangeable as well as parts.
A story told to me many years ago said that it was Henry Ford who brought back the first set of Johansson gauge blocks from Europe to the U.S. to put a sound metrology backbone into his flourishing enterprise. Jo blocks became standard throughout industry but they had limitations. They were ground to an accuracy of 1/100,000th of an inch. The accuracy of anything aligned with Jo blocks would thus be somewhat less than that. And the farther away you got from the master blocks, the looser the assured accuracy would be.
All this came to mind recently as I was visiting the Indianapolis diesel engine plant of International Truck and Engine and later the Sharonville transmission plant of Ford Motor Co. These are the respective homes of the new 6.0 L Power Stroke Diesel and the new R5 TorqShift automatic transmission. The Sharonville plant has recently received the highest score for quality among all Ford powertrain plants.
It is remarkable that both the engines and the transmissions have parts that are machined to the micron level, one millionth of an inch. That means that such parts are actually 10 times more accurate than yesterday's Jo blocks. Just think about that.
The superior shifting characteristics and durability of the new R5 are grounded in the ability to machine to the micron level. The new Siemens G-2 fuel injectors could not approach the level of performance required without micron level accuracy.
It's one thing to achieve micron level accuracy with a couple of parts, but now we're doing it with millions of parts and while it isn't exactly SOP at this point, it is not unusual either. When necessary, it is an advanced weapon available in today's arsenal of mass production manufacturing technology.
Not so long ago, injector parts were often sorted into undersize and oversize classes after machining was complete and then selectively assembled with other components that were broken down the same way Well, that just doesn't cut it anymore. And tell me that isn't an extremely expensive proposition.
Imagine producing over 8000 injectors per day in Carolina and getting them to Indianapolis JIT for tomorrow's 6.0 L production. You sure want to keep selective assembly to a minimum. High precision machining does have an economic payoff. Can you image the havoc that could be wrought by a bad batch of injectors?
There is an extreme need for consistency in order to meet performance and emission standards now and even more so in the future. When we are getting into pilot injection and rate shaping, playing with post injection, when we are peeling a second like an onion, when we need a very precise amount of fuel delivered with an exact atomization pattern, our dependence on micron level accuracy in parts production will only become greater.
It is only with the more accurate metrology base that we have been able to field the new generation of powertrain components and systems. And this is the base on which future progress depends. In short, only the inch worms can help us build a better marigold.
A great new tool for all machine shops
Subtitled The Basic Information You Need to Know in Order to Design and Form Good Parts, no other book about press brakes comes close to equaling the wide breath of information contained in this comprehensive text. Ben Rapien uses his 45 years of experience with press brake tooling applications to provide a thorough understanding of the variables that must be considered in selecting proper tooling, determining minimum machine requirements, using blank size calculations, and arriving at an acceptable bend sequence. Although the information presented is based on a solid engineering background, the technical descriptions have been simplified to allow press brake users to fully comprehend the many complex concepts and techniques used in forming operations. All of the principles and applications provided in the text are derived from "real world" experiences based on the actual parameters that have to be considered in order to produce quality parts. In addition, hundreds of well chosen illustrations, charts, and tables allow the reader to thoroughly comprehend how to get the most out of their press brake.
Contents: Review of the Press Brake. Press Brake Tooling (Normally Called Dies). The Basic 90[degrees] Bend. Air Bend Tonnage. Fundamental Information. Forming Other Types of Material. Gaging. Bend Allowance (What Size Should I Cut My Blank?). Safe Use of a Press Brake. Minimizing Die Marks on the Material. Offsets, Joggles, and "Z" Bends. Simple Channels. Hems and Seams. Radius Dies. Rib shapes. Corrugations. Box Forming. Beads or Curls. Wiping Dies. Plate Forming. European-Style Press Brake Tooling. Punching. Multiple Dies in the Press Brake. Other Important Information Needed for Making Good Tooling Decisions. Determining How to Make a Good Part. Understanding Words Used in the Context of Press Brake Tooling. Index.
Taiwan aspires to a leadership role: finding itself in the forefront of machine tool production, the island gets ready to step forward with its innova
Taiwan has clearly moved into the top ranks of machine tool building countries. It ranks fifth in the world in the dollar value of machine tools produced and fourth in the world in the dollar value of machine tools it exports.
Collectively and individually, Taipei builders are preparing for a leadership role in metalworking technology. This expectation was quite apparent at the most recent Taiwan International Machine Tool Show (TIMTOS) in Taipei. TIMTOS is Taiwan's premier biennial machine tool exhibition (see the box on the next page). The machines on display there would be hard to distinguish in performance or appearance from the best models coming from anywhere in the world.
The only thing lagging a bit is innovative homegrown technology. That is likely to change, however. In a few more years, TIMTOS may well be the show where the world gets its first glimpses of technology developed in Taiwan that is not available anywhere else. The country's current effort to coordinate and enhance R&D initiatives is definitely moving in that direction.
In the meantime, Taiwan builders are working together to change their image. For years, Taiwan presented itself as the source of low-cost machine tools. Today, the country wants the world to see it as the prime source of quality machines at a reasonable price.
Taiwan is especially eager to establish a firm foothold in emerging industrial countries such as Turkey, Russia, Brazil, India and mainland China. These markets are expected to grow rapidly in the short term. Moreover, these markets are not yet dominated by long-entrenched machine tool builders from Japan, Europe or the United States.
A number of Taiwan builders have a strong presence in the U.S. market, but it has taken these companies many years and a relatively large investment to get established. These companies remain deeply committed to the United States, but other builders are showing less patience and resolve in following this path. Their machines are more likely to reach the United States as privately labeled models marketed by U.S.-based importers who understand the U.S. buyer.
Machine tool builders in Taiwan tend to be relatively small, family-owned enterprises. However, all of the builders are well-supported by the national government in the sense that machine tool building is recognized as a key industry essential to the growth and development of high-tech Taiwanese industries. Thus, it is not surprising that the president of Taiwan, Chen Shui-bian, paid a personal visit to TIMTOS, speaking at a press conference and touring the exhibit areas. In his remarks, Mr. Chen characterized machine tools as "the mother of all industries," and reiterated his administration's support for building up central Taiwan as the hub of R&D facilities to promote machine tool building and related activities.
The results of this ongoing national support were evident at the show, especially in two area--the adoption of linear motors and the development of reliable, low-vibration high speed spindles. Compared to leading builders around the world, many Taiwan builders were not able to keep pace with implementing these technologies. With national sponsorship, builders were invited to work together to facilitate the transition to linear motors and advanced spindles. These initiatives made it possible for builders who otherwise lacked the engineering resources to make the transition on their own to do so in a timely and cost-effective manner.
Builders in Taiwan are remarkably realistic and candid about their strengths and about the challenges they face. They see strength in the relatively low wages that prevail on the island. Taiwan is located close to mainland China and India, two of the markets that Taiwan builders have targeted. Finally, Taiwan enjoys a well-developed social infrastructure and strong skills base, making "people power" a key asset.
Challenges are imposing, too. For labor-intensive activities, there is a shortage of job seekers. Companies are restricted from hiring quest workers from overseas above a certain percentage of their workforce. Land for industrial development is limited and facing growing demand. Proponents are seeking a government-backed "machinery industrial park" to be constructed in the central region of the country to solve this problem.
As effective as government funding for shared R&D efforts has been recently, this funding is threatened by spending cutbacks. The cost of steel and iron, the basic raw" materials for building machines, has risen markedly in the last 2 years and is expected to keep rising. On the mainland, the central government has enacted policies to protect and favor state-owned machinery builders, making it more difficult for Taiwan to achieve its goals there. Finally, fluctuations in currency exchange rates are not trending favorably for machine builders.
Machine tool buyers in the United States will do well to keep an eye on machine tool technology from Taiwan. U.S. plants have many options for filling their needs for low- and high-end machine tools. But between these extremes, Taiwan machines will be very well represented and are likely to offer reliable and capable machines at attractive prices.
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