Shedding some light on coating problems

July 1, 2003
A NEW COATING SYSTEM LETS manufacturers use ultraviolet (UV) light to detect defects. Developed by NCP Coatings Inc., Niles, Mich., the Optically Active Coating System (OACS) adds an exclusive UV-light-sensitive pigment to paints and coatings.

Mixing the NCP OACS system into a first coat lets users see improperly coated areas, such as the textured areas of this critical part.

With OACS, inspectors can check structural steel on buildings and bridges for corrosion or stress fractures. Exposed or problem areas glow under the UV light.

In two-coat situations where the primer is the same color as second-layer coating, OACS lets quality-control departments check for full coverage while paint is still wet.

Even at its slowest speed, the Agiecut Progress is faster than most other high-speed wire EDMs, says the machine's manufacturer.

With its new IPG generator, the Progress wire EDM cuts a wide range of part thicknesses fast.

Shops can cut machine setups from 30 min to 30 sec with the Quick-Pallets modular workholding system.

Software and control advancements are helping robots tackle the machining of soft materials.

A NEW COATING SYSTEM LETS manufacturers use ultraviolet (UV) light to detect defects. Developed by NCP Coatings Inc., Niles, Mich., the Optically Active Coating System (OACS) adds an exclusive UV-light-sensitive pigment to paints and coatings.

"We infuse an optically active additive to our coating formulations that makes the coating reactive to specialized UV light," explains Randy Terrill, technical director of NCP Coating Laboratories. "You then coat or impregnate this pigment onto whatever you want to monitor — structural-steel beams, storage-tank walls, automotive frames, or the smallest manufactured parts. At inspection time, structural or material changes or imperfections show clearly. Not only can you monitor structure or substrate integrity, but you can also use the UV properties to monitor coating quality for exact coverage," he comments.

The OACS system works in several application areas and industries, including marine, shipbuilding, automotive, building/construction, industrial maintenance, metalworking, foundries, tool-and-die, aerospace, and nuclear-power generation.

Ben Hannewyk, NCP's COO (Admin.), relates a typical application of OACS. "In our marine experience with U.S. Navy vessels and large marine-tankerballast tanks, a common trouble with paint films is that they crack with aging. Adding our OACS materials to an existing paint formulation makes the coating reactive to inspection by specialized UV light. Any paint cracking, crazing, imperfections, or total failures appear as brighter areas. When the cracks expose the substrate, the OACS will form a halo around a black area."

NCP Coatings claims OACS is less time-consuming and labor-intensive versus conventional electronic, spotchecking processes. In addition, the process also helps shops monitor the quality and coverage of a coating as it is applied. "With a simple sweep of a specialized UV light, missed areas or thin-application areas can be quickly identified and remedied during painting," Hannewyk relates. "The time, materials, and efficiency savings are potentially huge."

Coming up fast
IN THE HIGH-SPEED WIRE-EDM RACE, the Agiecut Progress is the machine to beat, says its manufacturer, Agie, Lincolnshire, Ill. Reportedly, it cuts between 350 and 500 mm2/min and does so using standard brass wire.

According to Jon Dobosenski, technical manager at Agie, the Progress' speed spans a wider spectrum of part thicknesses up to 150 mm as compared to most other EDMs. What makes this possible is a new generator called Intelligent Power Generation (IPG) featuring a power module for high-speed cutting.

The IPG monitors 30 million instructions/sec in the work zone to respond quickly to changing gap conditions. A disruption in the optimum current level triggers the generator to automatically adjust itself to prevent wire breakage. The result is a more efficient spark, which allows the Progress to run standard brass wire at high speed.

"The IPG pushes the standard erosion curve forward to higher speeds," says Dobosenski. "Typically, most wire EDMs achieve maximum generator efficiency at a certain speed and part thickness. When parts are thicker or thinner speed drops."

For the Progress, optimum speed is at 500 mm2/min on 70-mm-thick part. But just as significant, says Dobosenski, is that the machine's slowest speeds for thicker and thinner workpieces are faster than the top speeds of most other highspeed wire EDMs.

The new generator includes a feature called eCut, which lets users produce 0.8-Ra part-surface finishes in one pass using 0.006-in.-diameter wire. Without such technology, achieving a 1-Ra surface finish requires a main pass and probably two trim passes.

"eCut produces the same part accuracies of a 0.010-in.-diameter wire but with 0.006-in.-diameter wire and one pass. The result is a 40% reduction in wire and filter consumption and no shadow lines," says Scott Kowalski, a manager at Agie.

Agie believes speed isn't everything when it comes to wire-EDM productivity. Other factors it takes into consideration include setup, programming, and optimization of nonproductive time.

To reduce setup and positioning time, the Progress sports an axis speed of 3 m/min, a feature called Agiesetup to eliminate manually adjusting workpieces, and a 15-sec cut-and-thread time for wire. Agie's special wire-guide-and-threading system accommodates diameters from 0.004 to 0.013 in., so shops don't have to change guides every time they switch wire diameters.

The Progress is also completely automatable and inexpensive to operate. According to Kowalski, it's the highest-performance machine with the lowest operating cost — less than $3.00/hr.

Swap out pallets up to 60X faster than before
A modular-workholding system that uses a vacuum to hold special templated plates or pallets dramatically cuts setup time — from an average of 30 min to 30 sec, reports manufacturer Datron Dynamics Inc., Milford, N.H. Users of the Quick-Pallets system simply place pallets on a machining bed, where they are keyed to a fixed position and secured.

Changeover is simple. Users remove a pallet, sweep the surface, and install another one. No tooling or clamping is necessary, and the whole process takes only about 15 sec. For additional timesavings, users set up parts on Quick-Pallets outside of the machine and switch them out.

To ensure X, Y, Z-location repeatability, Quick-Pallets are registered using a beveled-boss in cavity system. A small vacuum pump holds pallets in place during machining operations.

"Whether you need a workholding vise or a custom tray configuration for rapid pallet changes, this is a versatile solution for speed, convenience, and accuracy in workholding," says Datron President Dr. Walter Schnecker.

Quick-Pallet configurations include: T-nut with pneumatic short-stroke clamps, Vacumate vacuum-table setup for machining flat stock, machine vise module for higher holding force, retrofit kits for existing machinery, and an empty pallet that can be easily machined and adapted.

Quick Pallets are also furnished with Datron Dynamics' high-speed CNC 60,000-rpm Micro machining centers with the vacuum pump pre-installed, such as with the new M35 Aluminator and the M8 Raptor models.

Another STEP ahead
MANUFACTURERS ARE CONTINUING PROGRESS ON AN international standard that is expected to boost productivity, safety, reliability, and CNC machine tool usability and interoperability. This news comes out of a recent meeting where members of the STEP-NC Industrial Review Board and attendees from major U.S. manufacturers, machine tool companies, and software developers viewed a STEP-NC demonstration at the National Institute of Standards and Technology's (NIST) Manufacturing Engineering Laboratory.

STEP Tools Inc., Troy, N.Y., announced the results of its STEP-NC technology meeting cohosted with NIST. The most significant advancement presented at the event was the process of integrating complex surface models into STEP-NC (AP-238) CNC-independent control data. The full fidelity data was successfully used to machine a demonstration part constructed by Boeing Defense on a multi-axis CNC machine tool.

The demonstration showed OEMs that they can send surface-model definitions to their suppliers as a part of the STEP-NC file. In turn, the supplier can evaluate a full-fidelity description of the surface on a CNC machine.

The benefits are twofold. First, users obtain greater production accuracy by eliminating approximations. In addition, a surface's functional STEP-NC definition is quite small as compared to megabytes of outmoded G and M codes, so OEMs work with a vastly reduced data volume.

The demonstration also debuted an ST-Machine plug-in for Mastercam software from CNC Software, Tolland, Conn., which was used for toolpath generation. The STEP-NC team also previewed a probing application with NIST.

Machine soft material with a robot
WHILE SHOPS MOST LIKELY WON'T be abandoning their machining centers just yet, new developments from CAD/CAM developer Delcam plc, Birmingham, UK, and industrial-robot manufacturer Kuka UK, Halesowen, UK, are furthering the idea of machining by robot. The companies believe that robots could provide a low-cost alternative to machine tools for many large-scale manufacturing operations carried out on softer materials.

Until now, machining with a robot has been limited to a small number of special production operations. However, advancements in Delcam's PowerMill machining software and in Kuka's control systems have made it easier to program robots for a wider range of applications.

"The cost of installing a robot is far less than the price of a large machine tool with a similar working envelope," claims Brett Green, general sales manager for Kuka. He says that a robot's flexibility allows complex operations to be done in a single setup, slashing production times and the number of fixtures used. In addition, users can program the robot offline from 3D CAD data.

"We anticipate that the main applications will be in patternmaking and in trimming of composite components," comments Delcam's Public Relations Manager Peter Dickin. "However, the technology can be used in any area where softer materials need to be machined to accuracies of tenths of a millimeter. While this does not match the tolerances possible with a machine tool, it can often be more than adequate for components that might be several meters in length."

Delcam worked with Kuka to develop easy-to-use routines within its PowerMill CAM software. According to Dickin, "These routines can quickly generate programs for its robots that allow smooth machining of large components. Now that this development work has been completed, we will be working together to promote this new approach to large-scale machining operations."

Seeking help to improve manufacturing simulations
DISCRETE-EVENT COMPUTER SIMULATIONS CAN SERVE AS POWERFUL TOOLS TO improve manufacturing processes and reduce product-design time and costs. But holding them back is a lack of standard interfaces that would promote interoperability among different systems. Such a standard is the goal of the new Simulation Standards Consortium, recently launched by the National Institute of Standards and Technology (NIST) Manufacturing Engineering Laboratory.

According to NIST, the group's work could help more manufacturers, particularly smaller and medium-sized companies, use advanced discreteevent simulations. The consortium is now working to share production management, product, process, resource, location, and other information among multiple systems at different locations. Visualization tools may or may not be used.

The consortium currently has 19 organizations as members, including 10 major software vendors and several manufacturers. It is also seeking additional participants. Members will have the opportunity to influence the direction of the standards-setting effort, establish partnerships with other researchers, and get a head start on the application of simulation technology and neutral interfaces.

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