Originally Published MPMN October 2001

EQUIPMENT NEWS: Rapid Prototyping Equipment

Solid-Imaging System Operates in Standard and High-Resolution Modes

Machine recently made available for commercial use

A new solid-imaging system incorporates the versatility of stereolithography via a dual-mode laser to reduce the design iteration cycle and perform secondary tooling applications. The Viper si2 SLA system allows the user to choose between standard-resolution and high-resolution modes during part preparation to maximize the machine's functionality and effectiveness. The machine can build accurate parts with a smooth surface finish and thin, vertical walls. The system was originally released to users for testing purposes; their comments have led to additional system refinements. Now commercially available, the Viper si2 is intended for use in specialized applications such as medical devices and electronic components.

Since unveiling the Viper si2 SLA in March, 3D Systems Corp. has enlisted customers to participate in a product testing program. Data collected during testing was used to make improvements to the Viper system before it became commercially available in July. "The Viper si2 system has the ease of use of a larger SLA machine on a smaller platform," says Rob Connelly, president of FineLine Prototyping, a test site for the new system. "We are able to use this system to produce a variety of highly detailed medical devices such as syringes, diagnostic kits, and parts with small flow channels," he adds.

The Viper si2 system offers a range of solid-imaging applications. The user can choose between standard-resolution mode for a balance of speed and part resolution, and high-resolution mode for detailed small parts and features. An integrated processor-controlled high-speed scanning system has a solid-state laser that delivers 100 mW of available power at a 354.7-nm wavelength. Standard spot size is 0.01 in. ± 0.001 in.; high-resolution spot size attains 0.003 in. ± 0.0005 in. The system builds parts with a smooth surface finish, good optical clarity, and high accuracy, as well as thin, straight vertical walls. Parts weighing up to 20 lb can be formed at speeds up to 0.2 in./sec.

Optimized for the company's Cibatool SL materials, the high-throughput system comes equipped with upgraded versions of 3D Lightyear part preparation and Buildstation control software. It also features a fast scanning system, interchangeable vat, and a choice of materials. Additional vats, build platforms, and postcuring equipment are available as options. Applications include small to medium-sized models and prototypes, patterns for injection molding and investment casting, precision builds of detailed parts, and detailed part fabrication.

Machine creates testable models from polycarbonate, ABS, and sulfone

A rapid prototyping machine creates models using high-performance engineering materials such as polycarbonate, ABS, and sulfones, which exhibit characteristics for functional testing. Available from Stratasys Inc., the FDM Titan can build models from each of the three materials, minimizing changeover steps. "Many of today's plastic products are composed of polycarbonate, ABS, polysulfones, or blends of these," says president Scott Crump. "The Titan was developed in response to users performing more demanding functional tests on their prototypes." These materials offer impact strength, flame-retardant qualities, strength at high temperatures, sterilization capabilities, and resistance to oils, gasoline, chemicals, and acids.

Models measuring up to 5 in. are accurate to within ± 0.005 in. Accuracy on models larger than 5 in. is ±0.0015 in.

Applications include concept modeling, prototype development, casting, and concurrent engineering. The system's platform permits upgrading to other materials, such as a polycarbonate/ABS blend that will be available in the future.

The FDM Titan does not require special facilities or venting and does not involve the use of hazardous materials or the release of by-products. It operates on the company's Insight software, which uses a Windows NT platform.

Milling machine offers generous work envelope and compact footprint

A milling machine is suitable for small-part manufacturing of medical devices. The M4 system, offered by Datron Dynamics Inc., features a 60,000-rpm spindle, a 16 x 15 x 7-in. work envelope, and a 60 x 38-in. footprint. An automatic tool changer and tool-length offset sensor enable unattended operation and provide quick and easy set-up for the operator. Automatic tool-length measurement operating software is PC-based and allows the system to interface with many CAD/CAM software packages, resulting in quick turnarounds of rapid prototype models or short-run production molds. An easy-to-use control interface requires two to three days of operator training. Capable of milling, drilling, tapping, and engraving, the machine has feed rates up to 475 in./min. An integrated spray mist coolant system minimizes the need to deburr or degrease surfaces. Applications include production of EDM electrodes, hot stamping and embossing dies, 3-D mold making, rapid prototyping, and 3-D precision engraving. Options include a z-height correction sensor, pneumatic and vacuum clamping systems, EDM electrode clamping systems, 9- or 18-tool changers, a microdrop oil coolant system, and programmable RPM control software.

Laser sintering system features increased speed and productivity

A selective laser sintering system allows users to turn CAD solid models into durable and functional plastic, metal, or ceramic parts and tools in a fraction of the time required by traditional machining and tooling processes. The Vanguard SLS system from DTM Corp. was designed to be an improvement over the company's Sinterstation system, which also uses a selective laser sintering process. "Today's manufacturers want the benefits of rapid prototyping such as speed, versatility, and minimized downstream labor and costs, but they also demand accuracy, repeatability, and the ability to move into rapid manufacturing," says vice president Patrick Lordi. "We have made the Vanguard SLS a practical rapid manufacturing system."

Based on benchmark comparison builds, the system offers an improvement of up to 20% in dimensional tolerance over the Sinterstation 2500. In another benchmark test, the Vanguard was able to complete the Sinterstation's 15-hour augur in less than 7 hours. The speed at which the CO₂ laser transforms the powdered material into a solid and builds the part has also been enhanced. The new system is capable of delivering smoother surface finishes due to an improved scanning and beam-delivery system. In addition, parts can be created with 0.02–0.025-in. walls.

Users can nest, stack, and add parts during a build, and most parts require only 1 to 3 hours of attended operation before final finishing begins. "The culmination of these improvements means users will have the ability to produce more parts per hour directly from their CAD data," says vice president of marketing and business development Kevin McAlea. "The parts are created with less labor, and at less cost than ever before."

Milling and engraving machine equipped with functional software

A rapid prototyping and mold-making machine has a high-torque spindle that allows it to mill light metals including aluminum, brass, and copper. When the high-torque spindle is replaced with a high-speed spindle, the MDX-500 is capable of engraving 3-D names, logos, and images on a range of materials. Available from Gold International Machinery Corp., the machine comes standard with 3D Engrave, Modela Player, and Virtual Modela software.

3D Engrave adds thickness to a flat, two-dimensional graphic to create a 3-D form and allows the machine to model or engrave on curved surfaces. The Modela Player can produce 3-D models, relief signage, and prototypes; it accepts DXF or STL files created by commercial CAD/CAM packages, and outputs to the machine for heavy-duty design applications. Virtual Modela simulates the machining process by showing suitable modeling and engraving depth and time parameters before the job is sent to the system.

The MDX-500 supports industry standard NC codes and can link with standard 3-D and CAD/CAM software. The machine is equipped with an emergency stop switch and can be supplied with a safety cover that makes the cutting mechanism inaccessible during operation. The optional cover prevents swarf and dust from entering the surrounding environment, making it suitable for use in an office. Compatible materials include ABS, modeling wax, aluminum, brass, and other nonferrous metals.

Katherine Sweeny

Copyright ©2001 Medical Product Manufacturing News