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Agie Charmilles has launched a range of high-speed three- and five-axis Mikron machining centres equipped with linear motors.
The machines are aimed at precision-component manufacturers looking for increased productivity, improved part accuracy and repeatability, consistently high surface finishes and better control and reliability over the milling process.
They have been designed for the high-speed machining of materials including steel, aluminium, titanium, hardened alloys and exotics.
The three-axis machines - HSM 400 LP and XSM 400 LP - and the five-axis models - HSM 400U LP and XSM 400U LP - were launched at EMO 09.
The 400 LP/400U LP machines feature a range of technologies and design features that aid the performance benefits of linear-motor integration, while negating heat buildup.
They have a rigid and ultra-stable bridge structure, and polymer concrete construction that minimises vibration and reduces thermal drift.
Independent (water) cooling systems on all LP machines’ axes also help to reduce thermal displacement and distortion.
Other features include: direct-drive technology on all axes, providing extra rigidity and reliability, and negating potential pitch or reverse errors.
The simpler and more direct drive chain means less moving parts and less cogging, increasing accuracy and reducing wear and repair costs.
The Steptec Opticool spindle system controls the temperature of the machine’s spindle and spindle bearings, which improves part accuracy and surface finish.
This spindle system, working in conjunction with the LP machines’ Smart Technology software helps reduce spindle warm-up cycle times and ensures high accuracy and reliable machining.
The intelligent tool measurement (ITM) system uses a camera that can measure tools down to 0.002mm and which, by digital recalibration, avoids measurement issues caused by swarf sticking to a tool’s tip/cutting edge.
The ITM system, in conjunction with integrated touch probes, ensures improved accuracy and surface finish, and increased reliability.
Integrated automation on the LP machines increases their flexibility and productivity.
Different size tool changers are available - 20 or 40 position ATCs can be specified with HSK E32 tools and 18/36/68 position ATCs can be specified with HSK E40 tools.
A similar choice exists with LP machines’ workpiece pallet changers (APCs) and means that LP machines can become mini-manufacturing cells in their own right.
The machines also have different swarf/chip management systems, depending on the nature of machining.
The three-axis HSM/XSM 400 LP machines provide users with X, Y and Z travels of 500, 450 and 360mm.
The HSM/XSM 400U LP five-axis machines have 500 x 235 x 360mm X, Y and Z-axis travels, with the machines’ five-axis capability being delivered through a B and C axis.
This enables users to machine multiple surfaces of a component, by virtue of its +110/-110deg of movement in B axis and continuous 360deg of movement in the C axis, in 0.0001 increments.
Rapid rates for HSM LP machines are 60m/min in X, Y and Z axis, and rates in B and C axis are 165 and 250rev/min respectively.
XSM LP machines have feed rates of 100m/min in X, Y and Z axis, with 165 and 250rev/min rates in B and C axis.
HSM and XSM three- and five-axis machines are equipped with a choice of spindles to suit every high-speed machining application.
All LP machines have the Heidenhain iTNC 530 control and feature Agie Charmilles’ Smart Technology software - ITC; ITC 5X and the operator-support system.

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Breton has launched the Ultrix high-speed multipurpose vertical machining centre.
The centre has four or five continuous axes for milling, horizontal/vertical turning and grinding of medium-size parts made of superalloys, steel, aluminium and composite.
The Ultrix is capable of performing complex milling operations with three, four and five interpolated axes, together with vertical and horizontal turning and grinding, on the same piece.
With just one positioning of the piece, work can be performed on superalloys, steel, aluminium and composites.
The direct-drive technology and gantry drive ensure high dynamics and system rigidity, as well as machining quality.
Due to automated systems for pallet change and piece automatic loading/unloading, productivity is increased.

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Ultimate sporting achievements are rewarded with the accolade “world-class
athlete”. For machining centers, too, it is only the outstanding results which count: they are required to produce even faster, more powerfully, more exactly and with greater cost-efficiency. The latest generation of large-scale machining centers - HEC 1000 Athletic, HEC 1250 Athletic and HEC 1600 Athletic - addresses precisely these demands.

The manufacturing of large and heavy workpieces with edge lengths of up to 3,000 mm and weights of up to 13,000 kg is now even more economical and flexible. Features of the new HEC Athletic Series are:

o Increased interference ranges (to 3,000 mm)

o Optimum work space conditions with improved traverse end positions of the workspindle (225 mm before pallet center)

o Rapid traverse rates up to 40 m/min

o Higher spindle power (up to 53 kW) and speed (up to 7,500 rpm)

o Suitable for tools up to 800 mm in length

o Optimum coolant preprocessing and swarf disposal

Flexibility and modular construction are characteristics of tool and workpiece handling, as well as the main spindle design. It is possible, for example, to choose between a horizontal main spindle with AC motor or motor spindle, an extendable NC quill and a swivelling horizontal / vertical head for 5-sided machining. This enables the machining center to be matched ideally to customer requirements.

Whether as a stand-alone machine, as a production cell with additional pallet storage, or integrated into flexible manufacturing systems, the HEC machining centers of the Athletic Series guarantee cost-efficient and highly accurate production.

The HEC 1600P is especially versatile, starting with its compact footprint (14,500 x 9,800 x 5450 mm) with optimized subassemblies in crossbed design for tailor-made solutions. X-axis travel is 2,800 mm, Y-axis is 2,000 mm and Z-axis, 2,100 mm. The interference range is up to 3,000 mm, and the extendable NC quill stroke is 500 mm. High dynamic response in the displacement axes at rapid traverse rates up to 40 m/min in the linear axes is through digital servodrives

The work spindle is powered by a 50 kW AC motor with a stepless speed range of 20..4,000 rpm. The toolholder taper is HSK-A 100 (SK 50, CAT 50). Outstanding machine accuracy of linear axes - positional deviation of <0.007 mm, repeatability of <0.004 mm and max. backlash of <0.004 mm - translates to greater precision of complex parts.

Adding to the flexibility and versatility of the HEC 1600 is an NC quill, which provides a quantum leap in machining large gearbox housings, torque support and planetary gear carriers (think aerospace and power generation: very large components.) The NC quill has the following productivity parameters: Torque, 2,150 Nm; drive output, 56 kW; speed, 4,000 rpm, with a 5 sec warm-up time; NC quill travel, 750 mm and rapid traverse, 1,000 mm/min.

The NC quill’s accuracy is largely the result of automatic temperature compensation for thermal influences and thermal stability of the quill by cooling the quill and the quill bearing with a separate cooling unit.

The HEC 1600’s NC rotary table has a clamping area of 1250 x 1600 mm, a backlash on reversal of 3°, a resolution of 0.001° and an interference range to 3,000 mm. Maximum table load is 13,000 kg and maximum workpiece height is 2,200 mm.

The HEC Athletic Series of precision machining centers offers different variants of automatic pallet changers - either a double pallet changer (standard on the HEC 1600) or triple/quadruple changers as an option. This kind of flexibility is critically important as business demands grow and parts proliferate.

The automatic tool changer (ATC) handles tools to 325 mm in diameter (340 mm with tower) and 800 mm in length. Maximum tool weight is 35 kg (50 kg with tower). Tool handling with chain magazine has 60 or 80 magazine locations for tools up to 325 mm in diameter (T-type tools up to 500 mm in diameter). Tool change: 12 sec. with a tool weighing 15 kg. An optional tower magazine has up to 240 tool locations.

The HEC 1600 offers optimum conditions for dry and wet machining. Contributing factors include extraordinarily fast swarf disposal thanks to two swarf conveyors, minimal quantity lubrication for dry machining, external coolant supply via nozzles at 120 l/min and internal supply through the spindle center at a pressure up to 60 bars. The coolant reservoir is 2,500 l. Flexible coolant preprocessing at the cutting material either with a reversible flow filter, turbo filter or fleece gravity filter. Low maintenance through grease lubrication for workspindle, ballscrew and sectional rail roller guides.

State-of-the-art process control and monitoring with Sinumerik CNC 840 D (Fanuc 31i optional) and integrated PLC. Tool life monitoring, 3D sensing probe and direct tool breakage monitoring through laser light-barrier. Tool gauging is via laser, in addition to tool speed monitoring, power and the torque monitoring and tool coding and remote diagnosis.

The HEC 1600 provides a high degree of user-friendliness through a swing-type operator panel, good accessibility at the load-unload station, a completely closed work space paneling, wave shower in the work space for workpiece cleaning and work space emissions extraction.

This new HEC Athletic Series machine also provides the potential for expansion of your fields of application through a mold kit for the tool and die industry, as well as through the existing control options, such as shaping, milling of cylinder paths and spline interpolation. Further, a highly increased degree of automation is possible through the attachment of semicircular magazines with five or six locations for workpiece pallets and linear magazines in one or several planes which facilitates the seamless expansion into flexible manufacturing systems.

For more information, contact StarragHeckert Inc., Skyport Business Park, 2379 Progress Drive, Hebron, KY 41048 USA. (859)534-5201 (v), (859) 534-5212 (f), ussales@starragheckert.com

An even faster, stronger Athletic HEC, the 1600 offers greater flexibility and optimum precision while tackling the really tough, large jobs.

StarragHeckert GmbH

StarragHeckert is a leading company in the field of production technology. We offer our customers a broad range of highly sophisticated precision milling machines, comprehensive engineering and software solutions for process optimization and a perfectly adapted range of special tools and services.

Our demanding customers come from different high-tech industries such as aviation, power generation, vehicle industry and mechanical engineering. Using state-of-the-art technology and all our expertise we will support you to produce in a more productive and efficient, a more precise and innovative manner today and in the future.

StarragHeckert includes production plants in Rorschacherberg, Switzerland (Starrag); Chemnitz, Germany (Heckert); Geneva, Switzerland (SIP) and Haddenham, UK (TTL), as well as sales and service companies in China (Beijing and Shanghai); USA (Hebron, KY, Dallas TX and Laguna Hills, CA); France, the UK and Russia.

Contacts:

General Information:
Greg Dunkley
USA
Phone: 859-534-5201
Company Information:
Name: StarragHeckert Inc.,
Address: Skyport Business Park
City: Hebron
State: KY
ZIP: 41048
Country: USA
Phone: 859-534-5201
FAX: 859-534-5212

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What can a high speed control do for you? In simple terms, it gives you the ability to finish one task faster and move along to the next sooner. In drilling and tapping, this can result in faster hole-to-hole times, quicker spindle reversals for tapping, and substantial cycle-time reductions. The most dramatic benefits, though, come in 3D contouring. Few, if any, drilling and tapping jobs require a million lines of machine codes. In molds, dies, patterns, and prototypes, complex surfaces comprising a million or more line segments are not at all uncommon. Saving just a fraction of a second per move can result in substantial cycle-time improvements.

As an example, the part that formerly took 3 hours and 43 minutes to mill accurately on a machining center. The part is being cut in wax, but is actually commonly milled in carbon as an electrode to burn cashew-shaped gates for plastic injection molds. A control retrofit enabled that same machine to mill a more accurate part in just 17 minutes. The user enjoys greater productivity from his people and machinery. He also enjoys a distinct competitive advantage when selling his work, because he can deliver an equally good or better job for less money, in less time.

In a broader sense, high speed creates many other benefits. Improved accuracy, fit, finish and cutter life are the most commonly reported peripheral benefits. Customers share the benefits of high speed through the entire manufacturing process, not just to produce more work in less time, but also improving the accuracy and finish and reducing polishing and fitting time. They do this by using the high speed to reduce the stepovers and the tolerances. Tools simply last longer because their chip load is much more consistent.
Relativity

“High speed machining” lured us with a promise of going faster. But faster than what? Each of us has a different perspective on what truly constitutes high speed machining, depending on our experience, applications and our needs.

The relative connotation of high speed is evidenced by talking with different people who utilize high speed milling on a daily basis. Going from 10 ipm roughing pre-hardened tool steel to 30 ipm, or from 30 ipm to 180 ipm, can be high speed in the mold business. Still, if your application is the milling of foam patterns for automotive stamping dies, 800 ipm may not be fast enough.

There is no clear threshold where plain old milling becomes high speed milling. High speed is relative, based on your perspective, your materials and your needs.
Surfaces To Points To Surfaces

The evolution of CAD/CAM into a powerful tool for 3D surface creation is the main reason we talk about high speed milling for molds and dies. CAD works with entities and surfaces. Points, lines, arcs, cylinders, spheres, planes, and so on, all join in CAD to create surfaces. CAM then translates those surfaces into point meshes of data for machines. Once that data is passed to the CNC, it executes one point at a time to reconstruct the surface. In order to do this efficiently, points are not milled at random, but rather organized into a data flow along slices or flow lines. These may be along any axis or across a combination of axes, or even along a constantly changing detail on a surface. In any case, the flow of data is from one point to another along the flow line or slice, then typically to step over and repeat that slice either in a single direction box-type cycle or in a zigzag of back and forth movements along the flow.

Point-to-point then is the process of creating surfaces by milling from one point to another in succession. As we apply point-to-point to high speed milling, that succession from one point to another should ideally be quite fast.
Chordal Deviation

CAM typically creates points with various distances between them. Why? If we step back a moment and just consider milling an arc by single point moves, we see that the arc really becomes a series of line segments. Those line segments deviate from the arc by a value commonly called chordal deviation. This value is set in your CAM system to define what the acceptable deviation from the surface will be, based on the accuracy required for the application. The natural desire is to be as accurate as possible, but stating a deviation value that is too tight can result in enormous file sizes and high data density that can be difficult to handle. Chordal deviation must be properly set to lend balance to productivity and required job accuracy.

The result of chordal deviation from CAM is a series of chord segments that are now becoming commonly referred to as “point departures.” This term simply means the distances between successive point-to-point moves.
Look-Ahead

In 3D contouring the cutter must flow through the points without dwelling, but also must not inadvertently overshoot its intended path and consequently gouge the workpiece. Most numerically controlled milling machines take from 0.100 to 0.200 inch to stop from a move at 100 ipm. If a CNC and machine are instructed to flow through data at high feed rates, yet point departures are short, gouges can result at points of abrupt changes in the contour. Look again at the shape shown earlier. There are several close data segments at the bottom of the contour. This is an area of great danger for gouging. The longer line segments going from left to right might easily permit high feed rates. Without look-ahead, the CNC might be surprised by the abrupt change in direction over a short move of only 0.010 inch. If the feed rate is too high to stop in that distance, the result will be an overshoot.

Look-ahead must evaluate data many blocks ahead to prevent such gouges. In most applications one or two, or even ten or 20-block look-ahead is not enough. The amount of look-ahead needed varies based on contours, feed rates and machine performance. In general, look-ahead cannot be limited to any arbitrary value, because conditions are constantly changing. Ideally, look-ahead should be dynamic, varying the distance and number of program blocks based on the part profile and the desired milling feed rate.

Look-ahead is now offered by some companies either as a preprocessing step or as a part of a DNC system. To achieve the effect of look-ahead, the system must add data segments at varying slower feed rates. In this way, gouging and overshoots can be prevented. The drawback is that by adding program lines, the data throughput problem is exacerbated, greatly reducing productivity.
High Feed Rates

How accurate can a CNC really be at high feed rates? We can answer this by analyzing the entire machine system, starting at the CAD/CAM system and ending with the machine iron. Because we are talking specifically about the controls here, let’s assume that everything else is in order, and that the control is the only issue.

Servo cycle time is the amount of time a CNC takes for each measuring and command cycle. In other words, if the control’s servo cycle time is 20 ms (milliseconds, or thousandths of a second), then the axis positions are measured and a new direction commanded by the control 50 times a second. Though 20-ms servo cycles were thought to be good just 10 years ago, servo cycle times over 4 ms are now considered inadequate. At a fairly common 3-ms servo cycle time, positions are being measured and corrected 333 times per second. A machine moving at 100 ipm is moving 1.66 inches per second, so each time the axes are measured, the machine should be moving 0.005 inch.

This might be alarming to you if you are trying to hold tolerances to 0.0001 inch or so, because your machine is basically out of control for 0.005-inch increments at a time. The accuracy problem gets worse when attempting to mill at 400 ipm, where a 3-ms servo cycle results in 0.020-inch moves between measurement and correction commands from the control.

Chart 1 shows a few sample servo cycle times, measuring speeds and distances at feed rates. This chart demonstrates that to mill as accurately at 1200 ipm as at 100 ipm, the control must indeed be very fast.

Feed rates will continue to increase, and the need for faster servo cycle speeds will continue to grow. Cutter technologies are proving capable of supporting amazing speeds and feeds. The other supporting technologies like high speed spindles, end mill holders, and so on are all enabling amazing speeds and feeds. Machines with linear motors are now available with traverse rates to 3,000 ipm and more. They can accelerate to 3,000 ipm faster than most machines today can get to 300.

Block transfer timethat is, the number of blocks-per-second the control executesshould not be confused with the servo cycle time. Ideally, the servo cycle time should be faster than the block transfer time. Still, it is possible for controls that execute a high number of blocks-per-second to execute at slower servo cycle times. In these cases, the number of blocks-per-second is misleading, indicating a higher speed than can really be achieved if each block is an actual discrete motion block. The combination of fast block transfer time with a still faster servo cycle time ensures high data throughput, with optimal accuracy.
The DNC Bottleneck

Now that we’ve looked at the control’s ability to mill accurately at high speeds, we have a new dilemma: how to get the program information to the CNC fast enough to avoid data starvation. Anyone who has milled 3D contours has watched as the CNC has stopped and waited to fill the buffers again to continue program execution. Loading the program into the control helps it run faster, yet that can often be impractical with the small CNC memories or slow communications speeds.

First, let’s consider DNC, the most common communications in use for CNCs today. DNC stands for distributed numerical control, the distribution of numeric cutter path data to CNC machinery, or direct numerical control, the “drip feeding” or dynamic downloading of numeric cutter path data “on-the-fly” as the CNC executes it.

DNC is typically performed through a serial communications link at data rates of 110 to 38,400 baud or bits per second. Most common is 9600 baud, resulting in potential throughput of up to 960 characters per second.

Program information for the CNC usually is in blocks or lines of program data averaging approximately 20 characters per line. For example:

G1 X123.456 Z234.567

Even spaces and invisible “control” characters like the carriage return and the linefeed take time for transmission. The addition of 3-, 4- or 5-axis definitions, line numbers and feed rates simply add to the overhead in data transmission. Given a communications rate of just 960 characters per second, the CNC is then limited by DNC to just 48 blocks per second. In reality, DNC overhead commonly results in still lower performance, generally about half the theoretical potential. At this rate of 24 blocks per second with 0.010-inch point departures, the resulting DNC speed limit is just 14.4 ipm. That is too slow for high speed milling no matter where the observer’s relativity is based.

There are several techniques used to speed DNC performance:

* Use incremental data where points are measured from the last location, rather than absolute where all points are measured from one fixed location.
* Use integer data, where a dimension like 0.012 is instead shown as 120, eliminating the decimal point, but adding trailing zeros.
* Data compression, using mathematical algorithms to make data, takes less space.
* Preprocessing, to reduce data tolerances and eliminate unneeded data.
* Don’t use cutter compensation or fixture offsets, mirror imaging or scale factors.

These techniques increase the operator workload, increase the opportunities for errors, and reduce the operator’s flexibility with the machine. Networking your DNC computer may help work flow, but does not solve the data flow problem. Many DNC computers are networked to get the data from the CAD/CAM to the DNC system fast, but the data flow is still restricted between the DNC PC and the CNC control by the limited bandwidth of RS-232 communications.
Direct CNC Networking

Direct CNC networking, or DCN, offers a better solution to the data flow problems in high speed milling. DCN uses existing networking architectures to provide a direct network link from the CAD/CAM to the CNC, eliminating the DNC system entirely. DCN is normally 1,000 times faster than DNC. This can be illustrated by the fact that a 10-MB file, which takes 3 hours to transfer by DNC at 9600 baud, takes less than a minute by DCN.

While Ethernet is the most common network architecture in use today, Arcnet, Token Ring and Fast Ethernet are examples of other common networks in use. Software protocols used include Novell’s IPX/SPX specification, TCP/IP and NFS as found in most UNIX systems, Netbeui as used by Microsoft’s LAN Manager, and more.

Networking architectures are already commonly available with data rates of 100 megabits per second or more, even ten times faster than standard Ethernet. Direct CNC networking eliminates any data bottlenecks.

DCN also provides infrastructure for growth, a foundation for expansion into the future. On PC-based (personal computer) controls, interesting possibilities include running CAD/CAM, job control and quality control software right in the controller.
Digital Signal Processing

The technology that allows “plain old PCs” to act as high performance CNC controls is known as digital signal processing, or DSP. Digital signal processing uses special dedicated processors to convert and interpret digital signals at very high speeds. Using DSP, a single board can control up to eight axes at the fastest servo cycles discussed earlier. Not so long ago, a much larger board would have been required for a single axis, operating at speeds 200 times slower.

The incredible power of DSP for specific tasks is illustrated by the fact that a DSP chip can execute a multiply-accumulate (MAC) instruction, a fundamental operation, in a single clock cycle. This same operation on a current Pentium processor chip takes 11 clock cycles. Obviously a 120-MHz Pentium will still take nearly four times as long as a 40-MHz DSP processor.

Earlier, we saw how dramatically the control’s servo cycle time can impact the accuracy of the control. DSP is the key to fast servo cycles. DSP also influences the acceleration and deceleration “ramps” of the CNC control. Traditional CNCs simply set up a ramp rate for accelerations. Because of machine dynamics and drive systems, the machine suffered “following error”. With so much power, DSP systems allow tuning the acceleration for real conditions and specific machine characteristics. Acceleration is no longer simply a straight-line ramp, but rather is tuned as a sort of “bell” shape. This optimization minimizes following error, reduces strains on the machine, yet provides greater acceleration overall. DSP’s speed allows better accuracy and speed, yet is gentler on the machines it controls.

There are many varieties of DSPs, and those choices give control builders choices in their priorities for control functions. The variety of DSPs available means that you as a user can obtain different control performance, functions and capabilities to meet your specific needs.

DSP also has the ability to handle a variety of servo amplifier and measuring scenarios. While most traditional CNCs are limited to interfacing with one specific drive type, many DSP boards allow the integrator the flexibility to work with several, or most available interfaces. Given the concept that technology will change over the life of a machine, this flexibility is reassuring.

One of the other great benefits of DSP is that the main CPU (central processing unit) in the PC is still free to perform other tasks. In reality, a PC equipped with a DSP for machine control is using multiple processors, gaining a tremendous performance advantage. The DSP can be measuring and commanding axis positions while the main CPU is handling the receipt of network data and preprocessing that data for look-ahead to optimize milling speeds and part accuracies at the same time.
Open Systems Architectures

The use of an Intel x86 series processor in itself does not mean that a control is open architecture. Even using a PC-based design does not always mean that the architecture is really open. Open architecture can have many interpretations, none necessarily more right or wrong than another.

To me, open architecture implies two key components: an ability to be serviced and an ability to be changed without proprietary parts and/or knowledge. This means that open architecture should empower the owner to have choices in service and in expansion and updates.

There is a general convergence in the industry toward PC-based controls. This gives everyone the widest possible choice of design options and expansion flexibility. Personal computers, serviced by virtually anyone, in a variety of environments, have arguably proven to be as reliable or more reliable than the best of “hardened” CNC controls. The amazing development of PC features and performance has left the industrial CNC control market reeling to stay remotely in step with developments.

For use as a CNC, the PC may be used in a “shop hardened” configuration, available from a limited number of specialty PC suppliers. Alternately, virtually any common PC may be implemented within a variety of shop enclosures, providing protection from the contaminants in the shop atmosphere. If the air we breathe in a shop is worthy of our health risks, though, perhaps a PC need not even be protected from the shop atmosphere to be reliable. Many users of PCs for DNC would argue that plain old office-type PCs are perfectly fine for shop use.

One advantage which some industrial PCs offer is a “watchdog timer.” This is an output that may be incorporated in the Emergency Stop circuit for a machine to add to the CNC’s safety. A dedicated circuit in the computer constantly checks the integrity of the computer processes at very high speeds to ensure that the system is operating normally. If the system does not check out, the output can disable the machine motion by shutting off the drives as an Emergency Stop. This PC watchdog timer does not replace the DSP’s watchdog timer, but rather complements it with additional security.
Multiprocessor Strategies

Earlier we talked about the fact that a PC teamed with DSP is actually a multiprocessing computer. This concept can be carried further in several ways.

Multiprocessors can give the CNC operator the ability to multitask. He may simply edit programs that are about to be run, or carry that further with graphical verification of programs submitted by the CAD/CAM department for operation. The operator may even use shopfloor programming to prepare cutter paths from IGES surface data right in the CNC control.

Within the PC marketplace, there now exists a number of computers that are equipped with or can be updated with multiple processors. For controls operating under Windows NT or UNIX, the multiple processors may offer performance benefits and the opportunity to use other programs effectively within the control while cutting.

An alternative is the use of entirely separate computers, controlled by the same keyboard and monitor. There are several CNCs in the marketplace today using this concept to maintain a high level of CNC control integrity and security while still performing other tasks. Multiple computers may be implemented in a number of different ways. Several companies have long offered dual-processor options, using a physical switch to select the “MS-DOS” mode or the CNC. Others use keyboard commands to select between the computers. Still others obscure the second computer, using one computer with multitasking as the user interface, and having it pass commands to the machine control computer.

The multiple computer strategy can be very simple to implement, gives the operator multitasking capabilities, and offers security for the CNC process. Moreover, multiprocessors offer another level of performance for high speed milling, allowing the operators to perform multiple tasks quickly and efficiently at their machine control station.
A Look At The Future

As we consider the future, the certainty is that CNC will continue to change. CNC will have to be able to accommodate the evolutionary changes in the industry without requiring the complete replacement of those controls as has been the norm with traditional CNC designs.

The example that I like to use to illustrate this is the word processor. When first introduced, it was an impressive contraption, consisting of a large workcenter with a green display screen, keyboard, printer, and built-in logic, the firmware. When new features were introduced, the entire word processor required replacement at a cost of tens of thousands of dollars, and the old system was traded in for pennies on the dollar. Through evolution, today’s word processor is now a shrink-wrapped piece of software that may be used on virtually any personal computer. Costs run in the tens or hundreds of dollars, and updates for new features are less than that. Installation of the update is performed by the user, generally in just minutes. Again, the evolution of the word processor parallels developments in many other computer industries, and is a good example of where CNC is likely to go.

Shrink-wrapped CNC? Is it possible? Imagine buying a fancy new CNC machine, and selecting your CNC as a software package for it, not an entire custom interface.

Think about new features evolving. They have historically made your CNC machine obsolete. Now imagine again getting updates at low cost, as with the word processor, or with your CAD/CAM system. We call these incremental advances in the technology. Simple, low cost changes will keep your present equipment and entire company competitive.

All this is not just a pipe dream, but the developments are taking place right now to make it a reality. Change is the one thing we can count on in the future. CNC must be able to accommodate that change.

Chart 1–Distances Moved At Given Feed Rates And Servo Cycles
Time
ms Cycles/
Second Distance Traveled
100 ipm 400 ipm 1200 ipm
20 50 0.0333″ 0.1333″ 0.4000″
10 100 0.0166″ 0.0667″ 0.2000″
3 333 0.0050″ 0.0200″ 0.0601″
1 1,000 0.0016″ 0.0066″ 0.0200″
0.4 2500 0.0007″ 0.0026″ 0.0080″
0.1 10,000 0.0002″ 0.0007″ 0.0020″
http://www.mmsonline.com/articles/advanced-controls-for-high-speed-milling.aspx

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About 25 years ago, the concept of data collection for process control took a major leap forward. This was about the time that a combination of electronic technology and economics allowed gaging to became digital. With a digital signal available, transferring information via cable directly from a gage or digital indicator to the data collector became possible. This made it much more practical to make process control decisions based on statistical analysis.

Electronic data collection also occasioned a major improvement in data quality. Prior to this leap, data was either handwritten on a sheet of paper and then logged into a computer, or it was logged into the computer directly at the point of gaging. One can easily understand how an operator, sitting at a bench measuring hundreds of parts, could transpose numbers, skip digits or enter wrong numbers. These problems were virtually eliminated by having data go directly to the data analysis software. When electronic data collection strategies were first implemented, it was not unusual to see collection efficiencies and error reduction increase tenfold over manual collection methods.

These days, checking parts at a gaging station with a hand tool or a dedicated fixture gage connected to a computer via a cable is the norm. Today’s hand tools and digital indicators have data output built in, and collecting data is easy and very cost effective. It is also fast, reliable and provides a solution for many process or quality control applications.

But what happens when the part can’t be brought to the bench? Maybe it’s still in the machine, or it is too large to bring to the gaging station. Running a long cable from the gage to the computer can be a hazard, and if multiple dimensions need to be checked with different gaging, a collection of long cables can quickly become a snarled mess.

Technology is ready to take another leap. Just as cell phones and wireless computer peripherals have become common, wireless technology is moving out onto the shop floor. Small transmitters are now available that allow most hand tools, digital indicators and gages to transmit data hundreds of feet to the gaging computer. Each transmitter uses slightly different signal coding that allows many gaging stations to communicate to a single computer simultaneously. Of course, these transmitters are more expensive than data cable—typically five to ten times as much—but the cost is more than justifiable when cabling won’t get the job done.

With these transmitters, very large parts can be measured where they sit, or parts can be measured in the machine tool without cables becoming caught in the tooling. In addition, many transmitters provide feedback by generating a signal to the operator that the transmission was received and acknowledged by the computer. This signal is virtually instantaneous so as not to slow the operator down, and most transmitters can be configured to provide a go or no-go signal to the user depending on whether the part is within tolerance.

Eliminating cables is great, but probably the best application for this technology is right at the machine tool. By transmitting wirelessly into the machine tool’s controller, the data can be put to use as part of the calculation for offsetting. Thus, as the operator measures the parts, the data is used to assign the proper offsets, greatly improving the quality and throughput of the machine tool. Out-of-spec parts are virtually eliminated, and the ability of the machine to make parts to the desired dimension is greatly improved.

At the same time, the data can be stored for long-term archiving, recording when the part was measured and by whom. It can also be used for tracking and improving operator throughput.

Today the triangle is becoming complete, with a combination of digital gaging for accurate shopfloor measurement, unrestricted wireless transmission of reliable data and statistics for process control. These three tools allow for truly effective use of measurement data.
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Multitasking machines offer a number of advantages, including reducing multiple setups that require manual material handling and refixturing. However, many fabricators still use multiple operations on separate machines to process tube and pipe components. Secondary operations such as tapping are especially problematic for large workpieces that are difficult to move and refixture. Thus, adding tapping capability to Mazak Optonics’ Fabrigear series of laser cutters is “the next logical step” for a machine that can already perform many large tube and pipe operations common in a single setup, says Bob St. Aubin, vice president of sales and marketing.

Tapping can be performed on virtually any type of tube or pipe that the Fabrigear can handle. These include not only square, round and rectangular components, but also a range of structurals, including I-beam, U-channel, C-channel and L-channel shapes. The tapping unit can hold six different taps ranging in size from No. 5 to ½ inch and metric sizes ranging from M3 to M12. The drive system uses a servo motor for tap rotation and Z-axis travel to provide “rigid” tapping characteristics, the company says. Other standard features contribute to unattended operation, including automatic tap breakage detection, an automatic tap-paste applicator and air-blast removal of dust and chips that accumulate on the tap.

Designed for large-part applications, the Fabrigear is available in two models. The FG-150 can accomomodate workpieces as long as 26 feet that weigh as much as 727 pounds, while the FG-300 can accommodate 40-foot-long materials as heavy as 1,058 pounds. To process complex 3D shapes such as I-beams, C-channels and others, the machine’s 64-bit CNC controls six axes of motion and four programmable rotary chucks. The multiple axes allow the cutting head to tilt and rotate around spinning workpieces, while the chucks are designed to grip and center tube and pipe of virtually any shape.

The chucks are part of an automatic loading/unloading system designed to limit operator involvement and simplify setup. The four chucks are divided into two sets, one on the infeed side of the machine and one on the outfeed side. Feeding arms move the workpieces from a five-position, V-support conveyor to the first set. The rear chuck grasps the tube or pipe, while the front chuck uses roller bearings to center it. The workpiece can then be handed off to the other set of chucks, either for back-end operations or for unloading via another set of V-conveyors.
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Producing parts with complex, intricate geometries can be a challenge for any shop, but in the medical field, this is routine. With little room for error, medical manufacturers machining high-precision components that require tight tolerances need reliable quality control systems to ensure their products meet specification. However, without an efficient means of collecting and storing measurement data, quality control can become a vexing bottleneck that adversely affects the entire operation.

Quality control inspectors at surgical tool manufacturer T&L Sharpening can attest to that fact. The company’s manual, paper-and-pencil data entry process had slowed data collection to a painstaking crawl and left ample room for human error. In addition, the use of hardwired measurement devices at the shop’s single inspection station limited inspectors’ mobility and created unnecessary clutter. To address these issues, the shop invested in L.S. Starrett’s DataSure Wireless Data Collection System. The new system not only eliminated a troublesome safety hazard caused by tangled wires, but also increased the flexibility, productivity and accuracy of the measurement process.

Located outside of Warsaw, Indiana, T&L was founded 30 years ago and made a name for itself as a manufacturer of hand-ground bone rasps. Today, the company provides manufacturing, sharpening, reconditioning and modification services primarily to the orthopedic industry. On the 7,000-square-foot shop floor, operators run surgical tools such as rasps, twist drills, reamers, end mills, taps and more in batch sizes ranging from one piece to thousands. More than 90 percent of the work is done in stainless steel via CNC machining, Swiss turning and grinding and quality checked with calipers, micrometers and scopes.

T&L’s products are not implants that remain in the body after surgery, so the company does not need to conform to the myriad FDA requirements that typically affect OEMs. Thus, many of the shop’s customers don’t demand full statistical process control (SPC) for the surgical cutting tools. Nonetheless, the shop still strives to provide SPC, according to company president Thomas All.

“Although the industry is not currently requesting full SPC from surgical tool manufacturers, it may move that way. Regardless, our goal is to attain this anyway because SPC inevitably promotes better quality and productivity and fewer errors,” Mr. All says.

With this goal in mind, the company implemented a stringent quality-control program involving an inspection station where multiple operators measured parts with hardwired measurement devices. However, the wires of the measurement devices would constantly become tangled, hampering productivity and creating a safety hazard. Moreover, the manual data-recording process often relied on an inspector’s memory or handwritten notes. Especially for larger jobs, this made quality control a daunting task, whether it involved providing low and high readings or 100-percent inspection of a lot. Entering data in Excel spreadsheets to compile Cpk range, X-bar and R data provided a partial solution to this issue. However, using a wired system meant workers still had to bring parts to the measurement area for inspection.

To remove the wires and increase mobility for quality control inspectors, the company began to investigate available data collection options. When Starrett presented its DataSure Wireless Collection System, T&L was sold on the concept from the start, says Tom Herr, quality manager.

“It wasn’t a matter of if we were going to go with the system; instead, it was a question of how quickly we could get it up and running,” Mr. Herr says.

In fact, the radio-based system proved to be relatively easy to set up. First, six miniature radios (called end nodes) were connected to the data output ports of the shop’s electronic tools. Although T&L’s calipers and micrometers are not Starrett tools, they are fully compatible with the DataSure system, as are most other major brands of electronic tools. The next step was the installation of a wireless signal router, which extended the system’s range by 100 feet. Finally, the company set up a gateway that connects to a PC and acts as the central point for data collection and tool management.

“Once we had things set up and ready to go, there was very little time spent adjusting to the new system,” Mr. Herr says. “We were up to speed in an hour or two with very little training.”

Now, T&L inspectors can move about freely with their measuring devices, allowing several people to work in the same area simultaneously. Additionally, workers can conduct inspections from different points in the shop rather than bringing all parts back to a common area. According to Mr. Herr, the result is a 25-percent reduction in average inspection, collection and documentation time, considerably improving throughput and reliability. Also, the elimination of wires has increased safety by reducing accidents and injuries. Perhaps most importantly, data collection is not only accurate, but in real time.

“DataSure has proven to be a very handy and convenient system for us,” Mr. All says. “When the industry comes knocking, demanding full SPC for surgical instruments, we’ll be ready.”

The R.O.I. on implementing the DataSure system was fast. T&L Sharpening estimates their annual savings at $50,000—and that’s without utilizing the system to its fullest. The company still does some hand documentation because they’ve been too busy to fully implement SPC. But because some customers will not require 100-percent inspection if a shop can provide SPC documentation, T&L is quickly heading that way.
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Shops consider a number of factors when justifying automated parts storage systems, including cost, required floor space and machining application. A clever use of configurable storage racks in place of rotating magazines keeps the design of Erowa’s Robot Compact handling facility simple and affordable for shops of all sizes. The racks are internal to the robot, so the system occupies little space on the shop floor and can get very close to the machine tools it serves. The robot is designed especially for manufacturers of small parts such as medical components and EDM electrodes.

The robot is most useful for shops that need immediate productivity improvements but can’t afford to spend time and money implementing larger, more complicated solutions, says Bob Byers, vice president of sales and marketing at Erowa. Increased customer demand, more exacting tolerances, new jobs involving geometrically complex parts—all these factors can drive shops to seek technological solutions for improving productivity. Often, however, purchasing the latest machine tools and other equipment isn’t always possible or even necessary, Mr. Byers explains. A more economical solution is to find a way to increase the productivity of existing equipment.

“In the era of ‘bigger, faster, stronger,’ we’re going back to a very simplistic approach with the Robot Compact,” Mr. Byers says. “Most people think they need a wholesale change in their shop, but sometimes tweaking one little area can increase profits. Starting out small with something very simple that can increase the productivity of the machine tool is huge.”

With that in mind, the robot is designed to be easy to install and operate. The racks used to store workpiece pallets are easier to change out than a rotary magazine system, Mr. Byers says. This allows shops to easily reconfigure the system for different applications. Moreover, with the racks mounted inside the system to the left and right of a small gripping arm, all movement is internal to the robot. This configuration keeps the robot’s footprint to 2 square meters and allows installation right next to machines with virtually no gap. Despite its small size, the Robot Compact features 160 pallet positions. It can supply one or two machines with pallets weighing 30 kilograms or less.

“This is something a shop can implement, make money from and see immediate benefits without a lot of investment in time and money,” Mr. Byers concludes.
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Since 1995, Pointe Precision, a one-stop machine shop in Plover, Wisconsin, has specialized in producing critical-tolerance parts for the medical and aerospace industries—parts that could endanger lives if they fail. “Our components are what we call ‘life-critical,’” observes company President Joe Kinsella. “Consequently, we take inspection very seriously.” For this reason, Mr. Kinsella likes to point out that “quality” is not a department, but an integral part of the shop’s overall process. In fact, shopfloor inspection is an essential part of its strategy.

Thus, every workcenter is equipped with surface plates and the inspection equipment necessary to allow operators to perform consistent and reliable in-process inspection. One of the busiest pieces of inspection equipment is a Starrett HD400 horizontal benchtop, dual-lens measuring projector, also referred to as an optical comparator. Since purchasing the device, the shop has gained an edge by trimming time from the production cycle without compromising quality.

ISO-certified since 2000, Pointe Precision employs 110 people, 70 of whom are engineers and technicians pursuing a Six Sigma methodology aimed at zero-defects quality output in less time and at a lower cost than the competition. The company operates on a 5-day, two- and three-shift schedule with some lights-out production. The 60,000-square-foot production facility turns out 3,500 different types of products per year. It’s a mid- to low-volume contract manufacturing operation focused on parts with a high degree of precision and variation.

“Our customers’ tolerancing is becoming very stringent,” Mr. Kinsella says. “Right out of the chute, you have to deliver perfect parts.”

With such strict tolerances, the shop needed an inspection system that could repeatedly ensure that critical dimensions and features on machined parts were within customers’ specifications. The Starrett HD-400 not only met the shop’s expectations in terms of accuracy, but also reduced both in-process inspection times and change-over time between work orders.

The horizontal measuring projector provides a 16-inch by 6-inch measuring range using an indexing dual-lens slide and triple-bundle, fiber-optic surface illumination with dual-intensity tungsten halogen profile illumination. The device profiles parts on a 16-inch-diameter screen with 10 to 100 times magnification. Generally, the horizontal-type optical comparator works best with parts that need to be fixtured, held in a vise or held on centers, according to manufacturer L.S. Starrett.

In addition, the comparator is equipped with a Metronics QC200 digital readout device for geometric dimensioning and tolerancing (GD&T) calculations. “The Starrett HD400 allows us to verify a wide variety of product characteristics very quickly,” explains Chris Spranger, quality assurance manager. “We measure many features, including angles, outside diameters, runout, hole sizes, corner breaks, threads, radii and shaft lengths on parts measuring 2 inches or less.”

According to Mr. Spranger, minimizing setup time is a critical factor in keeping the company competitive. Some runs involve as few as 50 pieces. Others may involve a thousand. As any manager knows, setup time does not pay the bills. While the plant depends on a state-of-the-art, climate-controlled metrology lab for some measurements, placing the Starrett comparator in the turning area for visual verification has eliminated many time-consuming trips to the inspection room.

This is possible because the device can be used for some measurements that previously required a CMM, says Randy Grezenski, Pointe Precision manufacturing engineer. “We can take three hits of an arc, for example, on a half-spherical radius measuring 1/2 inch in diameter and take three points, make a circle and establish a centerline on the part,” he says.

Now, Mr. Spranger says, most inspection is done at the machine. He points out that in addition to the optical comparator, the turning department has installed Starrett surface plates and other gages for use with each lathe. Each of the shop’s 12 turning centers is set up for new jobs anywhere between two and seven times in a 24-hour period, with each setup taking between 30 minutes and 3 hours. Mr. Spranger says 10 to 25 percent of setup time is absorbed by the first-article verification process—a procedure now performed on the shop floor rather than the CMM/inspection room.

Additionally, if operators had to inspect precise parts using only micrometers, indicators and other conventional gages, inspections would take much longer than they do with the optical system. That’s because the non-contact technique can graphically display and measure parts with dimensions and shapes that would be hard to measure with regular gages. In fact, using conventional gages rather than the optical comparator would make inspection times two to four times longer, depending on the product, Mr. Spranger notes.

“You can easily see the impact of an inspection process that could take three or four times longer to complete,” Mr. Spranger says. “The Starrett HD400 helps us minimize setup time and get into production mode quickly.”

Unlike the shop’s previous system, the Starrett device enables operators to check distances and concentricity. Additionally, it has sharper, clearer optics that detect edges better, says operator Marty Cattanach. “Before the HD400, features were very fuzzy and shadowed,” he explains. “The Starrett comparator allows you to see much greater detail. It’s just more accurate and much faster.” Mr. Cattanach adds that the device’s quick-release fixture saves time compared with a manual crank handle, and the screen rotates easily for checking different angles.

Mr. Spranger estimates that the Starrett optical measuring system has reduced overall inspection time by as much as 75 percent, depending on the complexity of the part. “We have found optical, non-contact measurement to be an integral part of our turning work,” he concludes. “The Starrett HD400 provides a more reliable, repeatable and far faster method for inspecting parts, including setup and the all-important first-article inspections.”
http://www.mmsonline.com/articles/optical-measurement-keeps-pointe-precision-sharp.aspx

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PROBLEM: Segmented tire molds required complex, time-consuming programming

SOLUTION: HyperMill CAD software from Open Mind

RESULTS: Improved delivery time, part quality

Chris Sipe, owner of Northeast Tire Molds in Akron, Ohio, likens machining tire molds to evolutionary theory—while some firms go out on a branch and never go any higher, others can look a little further down the road and adapt to changing conditions. Mr. Sipe says his company is one of the latter. Having machined tire molds for more than 30 years, Northeast has moved from the traditional model of machining two-piece tire shell molds from castings to machining segmented molds directly from aluminum stock. Business has doubled during the past 2 years as a result.
A key component of this transition was hyperMill, a CAM package developed by Open Mind Technologies. Tire molds are extremely complex, with numerous 3D contours and cavities, and this creates a significant programming challenge. In his evaluation of the software, Mr. Sipe found that one programmer using hyperMill required only 3 months to accomplish the same amount of work that took a year with the company’s previous system. Along with an investment in the simultaneous five-axis machine tools and associated tooling needed for such work, the software has enabled Northeast to provide higher-quality products and faster delivery.

For many years, the standard in tire manufacturing has been two-piece shell molds. Uncured (or “green”) tires consist of layers of inner liners, tire cord fabrics, steel, Kevlar and extruded rubber. The green tires are placed into a press where the upper and lower mold sections meet. Heat energy creates chemical reactions to cure and bind the rubber, steel and fabric layers. Meanwhile, pneumatic bladders inflate to expand the tire against the mold and impart the tread design and required sidewall engraving. Post-press requirements can include dimension checks, X-ray inspections and other section analysis.

However, deforming and shaping a green tire within the contour of a two-piece mold can cause the rubber to move, affecting thickness conformity throughout the tread. On the other hand, segmented molds consisting of 7 to 10 sections with separate sidewall plates can decrease this movement and improve overall tire performance. The downside is that segmented molds take longer to cast, machine and finish, significantly increasing costs.

Although direct-machining techniques debuted in the 1960s, the process was complex, time-consuming and expensive. The advent of five-axis machine tools and 3D CAD models excited many mold builders, but significantly attacking lead time remained a struggle. “Tire molds require a very high standard of five-axis simultaneous methods,” says Mike Christie, Northeast Tire Molds vice president and a 15-year veteran of the company. “We believed in the idea of eliminating castings and direct-machining tire molds from stock, but unfortunately, the programming efforts were immense. And with segmented molds, the same problems repeated themselves in many locations.”

To eliminate castings, Northeast needed simultaneous five-axis machine tools, tooling and programming capabilities that would allow it to machine the molds directly from stock. Procuring such a package, however, took years of education and experience. “We wanted to be self-sufficient,” Mr. Sipe says. “We didn’t have a foundry, and we couldn’t control our costs with outside vendors, so we sought capital equipment where the model didn’t matter.”

Mr. Sipe found one piece of the package at the 2001 EMO show in Hannover, Germany: a five-axis Alzmetall milling machine. “You could purchase three other five-axis machines for the price of one Alzmetall, but you’re not getting three times more capacity,” he says. By 2005, he was ready to take delivery, but not without the programming wherewithal.
One advantage of segmented molds often touted by tire makers is that if a particular tread problem exists, they can correct one segment without recasting the entire mold. However, Northeast found itself writing its own lengthy routines to repeat programs in various mold locations. The company tried to use the same five-axis CAM software used by one of its major customers, but the results were a “nightmare,” Mr. Christie says. All data, including intermediate results, went into one big file, which frequently became too large to handle correctly. Programmers often found themselves waiting a half-hour or longer just to open files.

Believing it had a state-of-the-art system, Northeast gave itself 9 months to learn the programming before taking delivery on the new five-axis machine. Still, the company made little progress. “We were told by experienced people what we could and couldn’t do,” Mr. Christie says. “The amount of time invested to get the end result was astronomical.”

Faced with these difficulties, Mr. Sipe recalled talking to Open Mind Technologies at EMO 2005 about tire mold programming. When he decided to evaluate hyperMill, Open Mind’s CAM system, he found it had a number of advantages over the company’s current system and decided to implement the software in the shop. “We had automatic indexing and collision checking, which we didn’t have before,” Mr. Christie says. “We were able to model the entire machine in hyperMill, and everything is interrelated. Our old package wouldn’t let us check back.”
The software also can quickly handle the large amount of data, and it enables parametric modeling through CAD interfaces. Other features include global swarf machining; stock trimming and stop surfaces in five-axis strategies; associative programming; automation through macros from 2D to five-axis in the same package; and 2D through five-axis program generation via the same postprocessor.

In addition, the software offers a tire-specific package in which all 2D, 3D and five-axis strategies are expanded by a parameter that allows the user to assign a pitch to each machining strategy. This makes segments composed of a specified pattern of pitches easier to produce. Automated segment generation not only assigns NC tool paths to the corresponding mold segments, but also adjusts tool paths that go beyond segment boundaries.

With the right machine tools, tooling and programming support, Northeast Tire Molds is now reaping the rewards of multitasking. The shop has moved from performing as many as eight operations on various machines to loading raw material and proceeding to the finished part on a single machine with no subsequent benchwork. For an average tread, the company can deliver a mold in the time it used to take to get the casting. Mold quality has also proved. “Customers find their molds are lasting longer, and the quicker delivery time means we have more time for testing new things,” Mr. Sipe says. “Business has doubled in the last 2 years, and the amount we’ve advanced in the last 6 months makes it very exciting to envision next year.”
http://www.mmsonline.com/articles/cam-system-simplifies-tire-mold-programming.aspx

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