DIY CNC machine milling polycarbonate

CNC machinery and tools

A CNC machine tool is a powered mechanical device used to fabricate metal components of machines by the selective removal of metal. The term machine tool is usually reserved for tools that used a power source other than human movement, but they can be powered by people if appropriately set up. Many historians of technology consider that the true machine tools were born when direct human involvement was removed from the shaping or stamping process of the different kinds of tools. For instance, they consider that lathe machine tools were invented around 1751 by Jacques de Vaucanson because he was the first to mount the cutting instrument on a mechanically adjustable head, taking it out of the hands of the operator.
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CAM intended for skilled artisans

CAD/CAM provider will demonstrate its artistic software designed for skilled artisans such as jewellery machinists at MACH 2008 and will include 'entry level' products

At the UK's MACH 2008 machine tool exhibition, Delcam will demonstrate its ArtCAM family of artistic CADCAM software alongside its range of more conventional manufacturing systems. The ArtCAM range comprises four key products, as follows. 1 - ArtCAM Express. 2 - ArtCAM Insignia. 3 - ArtCAM Pro.

4 - ArtCAM JewelSmith.

The whole ArtCAM software family is aimed at skilled artisans rather than engineers and requires little knowledge of engineering or computing.

* ArtCAM Express - an entry-level version of ArtCAM is believed to be the easiest to learn and fastest to use engraving and routing software currently available.

It offers basic 2D drawing, and 2D and 3D machining functions, and so provides an ideal introduction to computer-based manufacturing for companies in the signmaking, woodworking and engraving industries.

Designs can be imported in DXF, DWG, AI and EPS 2D formats, while the 3D formats supported include STL files from any CAD system, plus designs from Alias Wavefront, 3D Studio and other members of the ArtCAM family.

The software includes a range of drawing tools for creating both geometric and free-form shapes, and also for editing and repairing imported 2D files.

The options for text creation support a wide range of fonts and also give complete control over spacing, kerning, and line and paragraph formatting.

Once the design has been finalised, the software offers a variety of strategies for CNC machining.

2D strategies supported include area clearance, profiling, engraving, vector-based machining and drilling, plus V-bit carving on a number of fonts.

The software is supplied with a tooling database, which can be edited or added to by the user, plus drivers for many of the leading CNC engraving and routing machines.

* ArtCAM Insignia - while ArtCAM Express is aimed at producing one-off items, ArtCAM Insignia has a much greater emphasis on mass production applications.

It includes vector-based design, extensive 2D machining and basic 3D machining functionality.

It also allows users to import, scale, position and machine 2D and 3D decorations and textures onto their designs, and so to manufacture more distinctive and more attractive products.

All the import formats available with ArtCAM Express are supported with ArtCAM Insignia.

Alongside the increased machining functionality, the main addition to the latest release is a highly-automated method for the manufacture of designs imported as layered DXF or pdf files from other CAD systems.

Machining templates allow any combination of machining strategy, cutting tool and machining parameters to be assigned to each layer within the design.

The toolpaths are calculated for each layer, using the cut depth extracted from the DXF or pdf data.

The calculated toolpaths can be simulated within ArtCAM Insignia, if required, before being output to the machine.

More than 180 machine tool control options are supported, including those featuring multiple drilling heads and automatic tool changing.

* ArtCAM Pro - ArtCAM Pro incorporates a special file type called the 3D Project.

This allows the user to create multiple models within a single project, using the wide range of 3D modelling tools within the software.

The individual models can then be arranged to create larger assemblies.

For example, the sides of a cabinet could be designed as individual components and then assembled into a 3D model of the complete piece.

3D Projects also allow the simultaneous visualisation of objects that will be created from different materials and the subsequent division of the components into separate files for manufacturing in the various materials.

Items can be cut and pasted between different files, so allowing libraries of components to be built up for use in a variety of designs.

The main enhancement in ArtCAM Pro's machining is a new 3D offset strategy that gives a much better surface finish with harder materials.

This will be especially useful when machining production tooling from ArtCAM designs, such as dies for greeting cards, and when engraving decorations created in ArtCAM into moulds for plastics.

* ArtCAM JewelSmith - ArtCAM JewelSmith is the special version of ArtCAM Pro for the jewellery industry, with additional tools for designing rings of all types, and for creating and rendering gems.

Like ArtCAM Pro, ArtCAM JewelSmith has ability to create and edit designs as a series of layers, rather than always having to work with the complete model.

This makes it quicker and easier to create designs made up of different types of relief, for example a combination of a 3D shape, a texture and some lettering.

Recent machining enhancements include two new wizards.

1 - The first covers index machining and allows machining at a series of fixed angles on rotary equipment.

2 - The second can be used to develop mould designs automatically from product designs, generating the parting line and the two mould sections from a user-specified block of material.

* Delcam at MACH 2008, NEC, Birmingham, UK, April 21-25, Hall 4, Stand 4010.
http://www.manufacturingtalk.com/news/dea/dea708.html

SolidWorks donates 3D CAD software

The nearly 400 college students who compete in this year's American Society of Agricultural and Biological Engineers (ASABE) 1/4 Scale Tractor Student Design Competition will have access to free SolidWorks Student Edition software. The 100 recipients of this year's Presidential Awards for Excellence in Mathematics and Science Teaching (PAEMST) will each get a free license of SolidWorks Education Edition. And up to 1,000 teachers from middle school through college will also be given free copies of SolidWorks Student Edition through the SolidWorks - STEM Educators grant.
All of these gifts are part of SolidWorks Corporation's (www.solidworks.com) commitment to support the fusion of science, technology, engineering and math (STEM) in education. "STEM education is absolutely critical for the U.S. to lead the world in high technology innovation," said Dr. Krishna Vedula, executive chairman of the Massachusetts STEM Collaborative and former dean of engineering at the University of Massachusetts - Lowell. "STEM integrates pure math and science with the disciplines to which they are applied, and CAD software can play an integral role in this endeavor."
"Teachers trained on SolidWorks software will be better equipped to teach math and science concepts," said Marie Planchard, SolidWorks Corporation's director of education marketing. "For example, CAD software is adept at conveying 2D and 3D geometry concepts to younger students and illustrating algebra and physics principles in later years. Teachers can apply these topics in engineering projects such as designing a CO2 car and simulating the effects of airflow with respect to changes in geometry."
In the ASABE tractor design competition students have one year to design a tractor about the size of a riding lawn mower that a panel will judge based on written design report, team presentation, individual design judging, maneuverability and a performance competition. "We've seen a dramatic improvement in student creativity in the past couple of years since students began using SolidWorks for the competition," said Matt Darr, professor of food, agriculture, and biological engineering at Ohio State University. SolidWorks lets students make their ideas a 3D reality and enhances their ability to work with suppliers to create a production-grade prototype"
"The number of math and science related degrees, including engineering, has been dropping in the past decade in the United States," said Planchard. "As corporate citizens in this field, it's our duty to support frontline teachers. We are giving the best teachers in the country a powerful tool to demonstrate what students can achieve with a solid math and science education. Hopefully this will encourage more students to pursue STEM careers."

http://www.americanmachinist.com/304/News/Article/False/18168/

CAD/CAM and nesting programs CNC punching

CAD/CAM and nesting software programs all CNC punching and profiling machines and has been optimised to to further improve the cutting path in complex nests

Jetcam International has announced its latest version V16 of its Expert CAD/CAM and nesting software for all CNC punching and profiling machines. Offering twice the power of the earlier V8 system, the latest version V16 includes features aimed at providing enhanced functionality for interactive tasked and further automation for users looking for semi or completely unmanned systems.

Jetcam will also be increasing the number of end user releases in 2008, ensuring that users can immediately take advantage of each new feature as soon as it is available.

JETCAM Expert V16's sequencing routines have been optimised to further improve the cutting path, which can considerably reduce the overall cutting time of complex nests.

A new reporting engine has also been included to provide comprehensive and customisable reports.

A report designer is included, where users can simply 'drag and drop' the required fields or tables of information onto the page.

Single component or complete nest images can also be added.
Reports of any size or format can be generated, including labels for single label printers.

* CNC punching - further development specific to punching machines has also been announced.

Automatic tooling placement logic has been further optimised, providing users of punching machines with the same level of automation as profiling machines.

Tools are automatically placed on the component based on highly configurable parameters.

This information is then carried through to all related nests - if the component is updated then this is automatically reflected on the nest.

'Tool teach mode' further enhances the automatic tooling facilities by allowing JETCAM to 'learn' a user's preferred method of tooling a particular contour.

* Nesting - JETCAM's free form high performance nesting module (FFHPN) for V16 has also undergone further development, with the latest release offering even greater efficiencies.

With metal prices increasing even a 1% material saving can quickly mount up to a considerable amount, said Jetcam to manufacturingtalk.com.

Jetcam is also offering prospective customers a free 'nesting benchmark comparison' whereby they will compare a user's existing nests with one created through FFHPN.

Commented Mike Weber, managing director Jetcam International: 'These features in Release V16, when combined allow a JETCAM Expert system to rapidly become self-sufficient.

It intelligently and accurately applies logic so that the whole CAM process can become truly hands-off, especially when JETCAM's Remote Control Processing (RCP) system is employed' He continued: 'With our knowledge of the complexities of today's powerful CNC machines this frees the operator for other tasks, maximises machine runtime and reduces material waste.

For any size of organisation this level of automation has to be their goal to remain competitive in today's climate of cost reductions.

Companies employing manufacturing efficiency methodologies such as 'Six Sigma' will benefit from a system that provides a data-driven approaches to problem solving with a focus on customer impact.

Any business purchase has to be justified by return on investment, and JETCAM continues to deliver this in three key areas: material utilisation, machine cycle time and programming time'.

V16 will be available for download from the JETCAM.com web site in February 2008.

Existing customers under maintenance will be able to download the software immediately at no cost.

Customers out of maintenance need only to purchase a maintenance contract to gain access to the latest features - there is no additional upgrade price to pay.

http://www.manufacturingtalk.com/news/jea/jea176.html

Breton CNC Machine

CNC lathes designed to provide solutions

The HL 150-E and HL 200-E CNC lathes are designed to provide turning solutions for productivity.

These lathes feature a spindle that can accept a three-jaw chuck or a collet without using a spindle adapter; a turret top plate that directly adapts tooling used on discontinued models such as the Cobra 42 and Cobra 51; and spindle speeds as high as 5,000 rpm. A 12-station turret top plate and 0.48-second bi-directional turret indexing are also standard features.

The company says the machines are suited for a range of machining operations in a single setup.
http://findarticles.com/p/articles/mi_m3101/is_6_77/ai_n6354232

CNC Technology For Mold Applications

CNC technology is changing rapidly, and the changes are helping to improve the productivity of machine tools used in the mold industry. Faster central processing units (CPUs) are at the heart of many CNC changes. However, the improvements go beyond just faster processing, and the speed itself touches on many different CNC advances. With so much that has changed in recent years, it's worthwhile to present a summary of the state of mold-making CNC technology today.

BPT And Beyond

As CPU speeds have increased and CNC manufacturers have incorporated this speed into highly integrated CNC systems, there have been phenomenal changes that increase CNC performance. The faster, more responsive systems do more than just process program blocks faster. In fact, a CNC system that can process part program blocks at a very high rate may perform as well as a system that processes data at a slower rate, because there are other potential bottlenecks downstream that the overall feature content of the CNC system also has to address.

Most mold shops today intuitively understand that high speed machining requires more than just block processing time (BPT). In many ways, the analogy of a race car illustrates why this is so. Should the fastest car win the race? Even a casual observer of racing knows there is more to it than this.

First, the driver's knowledge of the race track is important. He has to know a sharp curve is coming so he can slow down just enough to take the curve safely and efficiently. CNC look-ahead performs a similar role in high-feed-rate mold machining, giving the CNC advanced knowledge of the sharp curves coming up.

Control features making five-axis machining easier to use
Control features making five-axis machining easier to use may encourage many mold shops to make the transition from using five axes for positioning only to using full five-axis machining. Photo courtesy GE Fanuc and Ingersoll Milling Machine.
Similarly, how quickly the driver reacts to what other drivers do, and other unpredictable effects, can be compared to the CNC's servo loop times—including position loop, velocity loop and current loop.

Consider also the smoothness of the driver's execution as he goes around the track. Skillful braking and accelerating have a significant impact on performance. Bell-type acc/dec in the CNC system gives similar smoothness to machine tool acceleration. Look-ahead helps here as well, because it allows many small acc/dec adjustments to replace an abrupt acc/dec change.

The analogy also applies in other ways. The power of the engine can be compared to the drives and motors. The weight of the car can be compared to the mass of the moving elements of the machine tool. The strength and rigidity of the car can be compared to the strength and rigidity of the machine. And the CNC's ability to maintain a specified path error can be related to how well the driver keeps the car on the track.

One other way the analogy relates to the state of CNC today is this: A car that isn't one of the very fastest may not need the most skilled driver. In the past, it was only high-end CNCs that could maintain high accuracy at high speeds. Today, mid-level and low-end CNCs are so powerful that they may also do an acceptable job. The high-end CNC still offers the best available performance, but perhaps for the machine you have, the lower-level CNC will permit the same performance as a CNC at the top of the line. It used to be that the CNC was the limiting factor determining the maximum feed rate in mold machining, but today the limiting factor is the mechanics of the machine. A better CNC won't deliver more performance if the machine itself is already operating at its performance limit.

Features Inherent To The CNC System

Here are some of the CNC features fundamental to many mold machining processes today:

* NURBS Interpolation. This technology for interpolating along curves instead of dividing curves into short, straight line segments is still gaining in popularity. Most of the CAM packages for die/mold applications today now have an option for outputting NURBS-formatted part programs. At the same time, more powerful CNCs have allowed CNC manufacturers to add five-axis NURBS capability, as well as NURBS-related features that deliver improved surface finish, smoother motor performance, faster cutting rates and smaller part program size.

* Finer command unit. Most CNC systems issue motion and positioning
mold-making application
One mold-making application in which linear-motor machine tools are already being used is the machining of very large molds. Technology improvements are making linear motors more powerful, compact and energy efficient.
commands to machine axes using a command unit of 1 micron or coarser. Taking advantage of the increase in processing power, some CNCs today offer a command unit of 1 nanometer (0.000001 mm). This control increment is 1,000 times finer, providing for improved accuracy. It also provides for smoother motor performance, which can allow some machines to accelerate faster without increasing the shock to the machine.
* Bell-shaped acc/dec. Also called "jerk control" or "S-curve acc/dec," bell-shaped acc/dec allows a machine tool to accelerate faster than linear acc/dec. It also provides less position error than various acc/dec types including linear and exponential.
* Look-ahead. This is a widely used term, with many performance differences separating the way the feature works on low-end versus high-end controls. In general, look-ahead lets the CNC pre-process the program to ensure superior acc/dec control. The number of look-ahead blocks can range from two blocks to hundreds of blocks depending on the CNC. The number of blocks required depends on factors such as the minimum part program execution time and the acc/dec time constant, but 15 blocks of look ahead is probably the minimum acceptable value.
* Digital servo control. Digital servo technology has improved significantly, and most CNC manufacturers can now offer a digital servo solution. Advances include faster communications, serial connections between the drive and CNC, and faster and more numerous digital signal processors. These advances have combined to allow CNCs to control the servo loops more tightly and thus control the machine better.

The technology helps in many ways:

1. Increasing the sample speed of the current loop, combined with better current control, results in the motor heating up less. This not only extends motor life, it also means there is less heat transfer to the ballscrew and therefore improved accuracy. Increased sampling speed can also make possible a higher velocity loop gain, helping to increase the overall performance of the machine.

2. Because many newer CNCs offer a high-speed serial connection to the servo system, the CNC can now get a lot more information about motor and drive operation through this communication link. This has resulted in improved maintenance features.

3. Serial position feedback permits higher accuracy at high feed rates. As CNCs got faster, the position feedback rate became a bottleneck in determining how fast a machine could move. Conventional feedback is carried by a signal type that limits speed according to the sample rate of the CNC and the electronics of the external encoder. Serial feedback eliminates this bottleneck, allowing fine position feedback resolution even at high speeds.

* Linear motors. This technology has improved significantly in recent years in both performance and acceptance. Every IMTS sees more machining centers offered with linear motors, and to date, Fanuc has shipped more than 1,000 units. Some of GE Fanuc's advances have resulted in machine tool linear motors with a maximum force of 15,500 newtons and a maximum acceleration of 30 G. Other advances have led to smaller size, lighter weight and more efficient cooling. All of these changes serve to enhance the benefits linear motors offer over rotary motors—benefits that include higher acc/dec rates; superior position control and higher stiffness; improved reliability; and inherent dynamic braking.

Features Added From Outside:

Open-System CNC

Open-system CNC products have changed rapidly. The higher speed communications choices available today have led to many different types of open architecture. Most of these open-system CNCs integrate the "openness" of a standard PC with conventional CNC functions. The key advantage of specifying an open-system CNC is that it can allow the CNC features to remain current with the state of technology and the needs of the process even while the machine hardware ages. Among the capabilities that can be added to an open-system CNC via third-party software, some are more relevant and some are less relevant where mold machining is concerned. But across all shops using open-system CNCs, some of the most common choices include:

* Low-cost network communications

the CNC must continuously update the tool offset
To keep the ball-nose tool's contact point constant during full five-axis machining, the CNC must continuously update the tool offset in X, Y and Z as the rotary axes are in motion.

* Ethernet
* Adaptive control
* Interfaces to bar code readers, tool ID readers and/or pallet ID systems
* Mass part-program storage and editing
* SPC data collection
* Documentation control
* CAD/CAM integration or shopfloor programming
* Common operator interfaces

The last item is particularly significant. A growing requirement in the mold industry is for the CNC to be easy to use. An important component of this ease of use is commonality of operation from CNC to CNC. Typically, operators must be trained separately for separate machines because the CNC interface differs between machine types and between machine tool builders. Open-system CNCs provide new opportunities for working toward a control interface that's common throughout the shop.

Now, machine tool owners can design their own interfaces for CNC operation—and they don't have to be C programmers to do so. In addition, open-system controls can permit individual log-on so personnel performing various functions—operator, programmer, maintenance and so on—see only the screens they need. Eliminating unnecessary screens makes CNC operation even more straightforward.

Five-Axis Machining

Five-axis machining is increasingly being applied to complex mold work. The technology can reduce the number of setups and/or machine tools required to produce a part, thereby minimizing work-in-process inventory and reducing total manufacturing time.

As CNCs have become more powerful, CNC manufacturers have been able to add more five-axis features. Capabilities once found only in high-end controls are now available in mid-range products. Most of these features have to do with making five-axis machining easier to use for shops that have little five-axis experience. Today, accessible CNC technology can deliver all of these benefits to the five-axis machining process:

* Eliminate the need for qualified tooling
* Allow tool offsets to be set after the part program has been posted
* Support "machine anywhere" programming, so that posted programs are interchangeable from machine to machine
* Improve surface finish
* Support various machine configurations, so the program no longer has to account for whether the spindle pivots or the workpiece pivots. This is now accounted for by parameters at the CNC.

One example of a five-axis machining feature specifically suited to mold machining is ball-nose end mill compensation. In order to properly compensate for a ball-nose end mill as the part or the tool pivots, the CNC must be able to dynamically adjust the cutter compensation vector in X, Y and Z. (See illustration above.) Better finish is one benefit of keeping the tool's contact point constant.

Other five-axis CNC functionality can be separated into the features related to pivoting the tool; features related to pivoting the part; and features that allow the operator to manually move the tool to a new vector.

When rotary axes pivot the tool, the tool length offset that normally affects

manual positioning of a five-axis machine
The CNC can also assist with manual positioning of a five-axis machine. Control features can allow the machine to be positioned in XYZ along the tool vector and positioned in the rotary axes without changing the tool tip location.
only the Z axis now has components in X, Y and Z. In addition, tool diameter offsets that normally affect only the X and Y axes also have X, Y and Z components. And because the tool may be feeding in the rotary axes while it's cutting, all of these offsets have to be updated dynamically to account for continuous changes in the tool's orientation.

A CNC feature called "tool center point programming" can take of this. The feature lets the programmer define the path and speed of the center point of the tool, while leaving it to the CNC to take care of the commands in the rotary and linear axes to ensure that the tool follows this programming. This feature makes the tool center point independent of the specific tool loaded into the machine, meaning (A) tool offsets can be input at the machine tool just as in three-axis programming, and (B) programs don't have to be re-posted to account for tool length changes. The feature simplifies programming and posting for machines that achieve rotary-axis motion by pivoting the spindle.

Machines achieving rotary motion by pivoting the workpiece use similar functionality. Newer CNCs can compensate for this movement by dynamically adjusting fixture offsets and rotating coordinate axes to match the part's rotary motion.

The CNC can also have an important role when the operator is jogging the machine manually. Newer CNCs allow the axis to be jogged in the direction of the tool vector . . . and allow the tool vector to be changed without the location of the tool tip changing. (See illustrations above.)

These features make a five-axis machine easier to use for 3+2 programming—the most common use of five-axis machines in mold making today. However, as new five-axis CNC features continue to evolve and gain acceptance, true five-axis mold machining is likely to become more common.http://www.mmsonline.com/articles/070102.html