TechFront: Subtractive Rapid Prototyping Advances
Tech Front is edited by Senior Editor Jim Lorincz.
While the market share for additive manufacturing (AM) technologies for rapid prototyping complex parts, tooling, and fixturing from materials ranging from engineered plastics to metals has grown recently, traditional Subtractive Rapid Prototyping (SRP) technology and manufacturing processes are focusing on their strengths to enable manufacturers to shorten time to market for product design, development, and even production.
According to Roland DGA Corp. (Irvine, CA) in a white paper from which this article is excerpted, subtractive manufacturing systems can provide a complementary solution to additive systems in several key areas, providing superior ease of use, greater material flexibility, higher dimensional accuracy, smoother surface finishes, and more accurate simulation of actual manufacturing processes.
AM processes, often referred to as desktop printing, build up parts by fusing, binding, or solidifying materials, such as liquid resin, powders, or metals, usually layer upon layer, using an energy source to produce an object from 3-D model data. Subtractive manufacturing processes, including benchtop milling machines and engravers, remove layers of material from a block of material to produce an object from 3-D model data, 2-D CAD data, or G-Code.
SRP machines have evolved from large stand-alone machines into smaller, office-friendly, automated machines, making the technology available to everyone from the designer to the marketer, the engineer, and the production team. The SRP machines have pushed the boundaries of what engineers design and manufacturers produce to reduce the time-to-market cycle enabling quick iterations and proof of concepts. As a result, companies today can deliver products focused on "right cost and right features" faster and more profitably than ever before, Roland points out.
Roland’s MDX series of benchtop milling machine line enables designers and engineers to build repeatable, high-precision prototypes and parts right from their desktops, enabling them to optimize workflow processes, improve operation efficiencies, and expand customized applications. By bringing the process in-house, designers and engineers can quickly create prototypes, produce limited production runs, and test new materials for production in a matter of hours vs. days or weeks. The MDX can be combined with a 3-D printer, or used as a stand-alone system for the production of one-off, customized parts, product-concept models, functional prototypes, master patterns, and expendable patterns for the production of end-use parts. The MDX enables designers and engineers to generate functional prototypes before committing to injection-molding tools or high-volume machining. The MDX mills aren’t limited in the materials that can be machined, which include engineered plastics, clear plastics, resin, wood, ferrous, and nonferrous metals.
Programming of the MDX is simplified and doesn’t require knowledge of G-Code. Programming is accomplished by designing a 3-D model, exporting it in .STL, .DXF, .3DM, or .IGS/IGES file format. The 3-D CAD file is opened in Roland’s SRP Player CAM software, and following the five-step wizard process, software determines the feeds and speeds, cut depth, surface selection, and generates a machine-ready program. The SRP Player software can orient and scale the part, generate toolpaths, and provide a finished preview before the tool path is sent to the machine. Work envelope of the MDX-40A is 12 × 12 × 4.1" (305 × 305 × 104 mm); an optional rotary axis is available that can handle a part 10.6" long x 4.7" diam (269 x 119 mm). The MDX-540 line includes a larger work area, optional rotry fourth axis and an ATC.
For dental applications, Roland’s DWX-50 dental milling machine features five-axis simultaneous machining capability and a five-station ATC with tool length sensor for production of prosthetics. The milling machine is equipped with a diagnostic notification system that alerts the operator of system errors and upon job completion, enabling dental laboratories and technicians to carry out the milling process with minimal operator intervention.
The DWX-50 supports a wide range of software and tools and is built on open technology, allowing for integration with any commercially available dental prosthetic production solution. The DWX-50 offers multicast capability, making it possible to connect up to four machines to one computer.
Other key features include an integrated air blower system that aids with difficult-to-machine materials, such as PMMA or zirconia, along with a built-in dust collection tray that can be easily connected to any lab vacuum system, keeping the cutting area clean and free of debris.
Also available from Roland are its JWX jewelry milling machines, rotary engravers, and ink jet printers.
For more information on Roland DGA Corp., go to www.rolanddga.com, or telephone 949-727-2100. ME
New VMCs for the Shop Floor
It seems to make a lot of sense that MC Machinery Systems Inc. (Wood Dale, IL) is introducing a line of vertical machining centers (VMC), a first for the company. The Diamond Cut VMCs are aimed squarely at the shops that, in many cases, are the users of its Mitsubishi EDM, laser, and waterjet machine technology. Given the entrée that these advanced machining systems offer, MC Machinery has introduced its MC Milling brand Diamond Cut VMCs to cover the wide range of likely applications performed in these shops ranging from general purpose and mold and die to drilling and tapping. Standard features of the Diamond Cut series of VMCs include Mitsubishi M70 CNCs (on four of the five models) and M720 CNC controls on the other one, 70-gal (265-L) coolant tank, chips auger, auto oil lube, disk oil/coolant separator, spindle oil cooling systems, and hand-scraped ways.
The MCV Series is a general-purpose machining center with an 8000-rpm belt-driven spindle, CAT 40 tooling, preparation for 1000 psi (70 bar) coolant-thru spindle, and Mitsubishi’s M70 CNC. The MCV is aimed at applications including, but not limited to, fixtures, mold bases, and secondary operations. The DV Series features a 15,000-rpm direct-drive spindle and shares similar features as the MCV Series.
For mold and die applications and tight tolerance work, the DM Series features a 20,000-rpm integral motor spindle, HSK-63 tooling, and linear glass scales, especially designed for mold and die applications. For large-parts machining using larger tools, the SV Series is built with heavy-duty box way construction and Meehanite cast-iron ribbed structure with hand-scraped Tercite B way guides. The SV has a 10,000-rpm belt-driven spindle and CAT 50 tooling. It can handle tools up to 12" (305-mm) long and has longer Y-axis travel of 28" (711 mm).
The TV Series is a high-speed drilling and tapping machine with a 24,000-rpm high-speed spindle driven by a 4.6-kW motor. BBT30 dual-contact tooling delivers rigidity and effective Z depth control during operation. The ATC is a bi-directional tool magazine, which is driven through advanced PLC software and the Mitsubishi M70 control. Optional features available for the Diamond Cut Series include mist collector, oil cooling, and on-machine metrology from Blum LMT (Erlanger, KY), including parts probe, touch pad tool length measurement, and noncontact tool length measurement.
For more information on MC Machinery Systems Inc., go to www.mitsubishi-world.com, or telephone 630-616-5920. ME
PKM Machining Center
PKM (parallel kinematics machine) technology is at the heart of a new modular six-axis machining center series called the ICON Tripod Powerflex from the ICON Division of Hydromat Inc. (St. Louis, MO). PKM technology continues to evolve from its earlier appearances in the Hexapod (1985) and Tricept (1990s). PKM derives machine flexibility, high-dynamic stiffness, and accuracy from its parallel actuator (strut) configuration. Targeted applications for the Tripod Powerflex are found in the aerospace, automotive, and energy industries, as well as where the advantages of high-speed six-axis machining come into play. The Powerflex can also be installed in cellular or transfer-line machine applications.
The Tripod Powerflex is scalable. Different sizes are determined by the length of the actuators, which can range from 300 to 800-mm long and size of the spindle. Machine bases are made of polymer concrete for stiffness to dampen vibration. The machine doesn’t have ball joints and features stiff bearing points. The machine, which is 14' (4.27-m) high, weighs 35 t. A machine with 800 × 800 × 400-mm actuators was exhibited at EMO with an 18,000-rpm, 23-kW Weiss spindle and an 800-mm B-axis pallet with zero-point clamping. A 40 or 80-tool ATC with HSK A63 toolholder can accommodate tools 250-mm long, weighing 10 kg. CNC control is the Siemens Sinumerik 840D sl.
For more information on ICON Technologies, Div. Hydromat Inc., go to icon.hydromat.com, or phone 314-462-4644. ME
Cold Process Takes Welding Heat
Submerged arc welding may already be the most productive welding process, but productivity during submerged arc welding can be inhibited by the need to limit heat input. ESAB Welding and Cutting Products (Florence, SC) has introduced its ICE (Integrated Cold Electrode) technology, which is designed to yield higher deposition rates without increasing heat input. Instead of adding more energy, ICE utilizes the excess heat already available to melt an additional nonpowered welding electrode.
According to ESAB, this results in up to 50% higher deposition rates depending on the application and up to 100% increase in productivity working with a tandem welding application in root passes. A 50% higher deposition rate can reduce flux consumption by as much as 20%, and the increased deposition rate can also be used to increase welding speed. This increase in speed is said to significantly improve productivity in applications where welding speed is the key to maximizing productivity.
Because, welding is energy-intensive, any reduction in energy consumption offers significant environmental and financial benefits. The ability to achieve a dramatic increase in deposition rate with no additional energy input will substantially reduce energy consumption. The multiple gains offered by ICE technology stretch across a broad range of applications in many industries. These include major sectors such as the fabrication of on-and-offshore wind towers and other offshore components, pipe welding, general heavy fabrication, and shipbuilding.
ICE reduces energy requirements, leading to a smaller carbon footprint and resulting in more environmentally-friendly and lower-cost production. ICE technology enables the use of tandem welding in root passes, which results in improved penetration and higher productivity. The need for back gauging is eliminated. Other savings include productivity improved with the Flat Cap Control feature. Fine adjustment to the ratio of "cold wire" used for cap runs makes it possible to produce a flatter cap to the weld. The result: improved fatigue resistance and a reduction in the amount of post-weld treatment required. Also, many applications can be completed with fewer runs. Finally, ICE technology is said to boost output without investment in new welding systems, extra capacity, or additional skilled welders.
For more information from ESAB Welding & Cutting Products, go to www.esabna.com, or telephone 800-372-2123. ME
This article was first published in the January 2012 edition of Manufacturing Engineering magazine. Click here for PDF.