Beyond the Daily Grind

Originally Published MPMN April 2002

EQUIPMENT NEWS: Metal Fabrication Equipment

Beyond the Daily Grind

New machining, drilling, and cutting technologies offer a range of benefits

Katherine Sweeny

By definition, medical device components require high precision and tight tolerances. Metal, a generally difficult material to work with, must be manipulated into forms that suit those standards. In response to increasing demands by manufacturers, metal fabrication technology developers are constantly updating their systems to meet the needs of the medical device industry. A long-life mold and die miller, a laser micromachining system, and an electrofission cutting and forming machine are some of the new products discussed in this article. These and other products with metal fabrication applications are included below.

Mold and die miller offers precision milling without thermal distortion

A vertical mold and die miller is designed to mill steel mold inserts, mold components, and die parts directly from a hardened block. The YBM-950V from Yasda Precision America Corp. provides high stock-removal rates, long cutter life, and excellent surface-finish results. According to the company, its stock-removal rates are as much as five times higher and its surface-finish results are as much as three times better than other machines in its class.

The YBM-950V features a self-adjusting spindle that enables stock removal with fine-finishing machining and is guaranteed to perform for 20,000 hours. Because the spindle system contains the largest exothermic parts, it suffers most from thermal deformation, which can cause inconsistent machine accuracy. The machine prevents deformation by circulating heat-exchange fluid through the spindle assembly and other main components to bring them to room temperature. This causes the machine to be suitable for finishing operations that require long durations with the same cutter. In addition, a direct-drive system includes a diaphragm coupling that enables accurate spindle rotation, isolates vibration and heat from the spindle drive motor, and enhances machining accuracy and surface finish.

A self-adjusting system provides an appropriate preload for a range of spindle speeds, whether for heavy-duty cutting at a low rpm or low heat generation for rotation at high speeds. The spindle and drive motor are connected coaxially by a diaphragm coupling to achieve high-precision rotation throughout the entire speed range. High-precision machining can be achieved even in tough machining conditions such as varied-directional cutting resistance machining, high-helix-angle end milling, and back-face machining.

A window-shaped, bridge-style construction employs an extra rib on the base of the bridge to improve the rigidity of the structure. The YBM-950V has a 40 x 20-in. table with an x-y-z travel of 30 x 20 x 14 in., a 1760-lb load capacity, a 20,000-rpm maximum spindle speed, an 800-items-per-minute maximum rapid feed, and a 500-items-per-minute maximum feed rate.

Portable plasma cutter offers speed and cost improvements

A portable plasma cutting system incorporates input sensing, which allows it to run on 200–600 V in one or three phases, or on 230–400 V in three phases without the need for manual linking. The Powermax 1000 G3 from Hypertherm uses the same power supply and torch technologies as the company's previous model, but offers more speed and efficiency. The 1000 G3 has a power supply that compensates for voltage variation. Its digitally controlled inverter delivers continuously adjustable constant current output from 20 to 60 A and permits high-quality cuts over a range of metal thicknesses. According to the company, the system's torches, T60 and T60M, feature electrodes that extend consumable life by as much as 10 times in tests against previous models. Nozzle wear is reduced by a dual-threshold pilot circuit. A coaxial-assist jet design boosts cutting speed by up to 20% and blow-back technology delivers a pilot arc without high-frequency interference. The system operates under harsh environmental conditions with a variety of options to respond to the specialized needs of different applications.>uses the same power supply and torch technologies as the company’s previous model, but offers more speed and efficiency. The 1000 G3 has a power supply that compensates for voltage variation. Its digitally controlled inverter delivers continuously adjustable constant current output from 20 to 60 A and permits high-quality cuts over a range of metal thicknesses. According to the company, the system’s torches, T60 and T60M, feature electrodes that extend consumable life by as much as 10 times in tests against previous models. Nozzle wear is reduced by a dual-threshold pilot circuit. A coaxial-assist jet design boosts cutting speed by up to 20% and blow-back technology delivers a pilot arc without high-frequency interference. The system operates under harsh environmental conditions with a variety of options to respond to the specialized needs of different applications.

Laser micromachines tiny features in hard materials

A new model in a series of industrial-grade diode-pumped solid-state lasers delivers 10 W on average and ≥100 GW/cm² peak power intensity. Offered by Lambda Physik Inc., the PowerGator 355-10 microfabricates high-aspect-ratio features in hard materials measuring more than 1 mm thick. Short 15-nanosecond pulses and 355-nm wavelengths improve plasma penetration and reduce heat-induced effects, microcracking, and redeposition of material to produce high-quality surfaces. These capabilities make the machine suitable for manufacturing components out of difficult-to-machine materials that require drilling and cutting of micron-size features. High beam quality allows focusability for feature sizes less than 10 µm down to submicron levels. The PowerGator 355-10 can machine most materials including metal alloys, ceramics, silicon, and polymers. It is available in 1064- and 532-nm wavelength versions to enable further process optimization by matching spectral absorption characteristics of the material. Other features include a hermetically sealed laser head, RS-232 function control for hands-free operation, and remote and removable supply units.

Laser system features robust software package

A complete turnkey workstation marks, engraves, and cuts a variety of medical materials using laser technology. The Laser Mate II from Online Inc. can function as a stand-alone unit, or it can be mounted over an existing conveyor line in a cleanroom setting. Devices such as dials, conveyors, and indexers can be attached for high-volume applications via extra inputs and outputs on the system's periphery. A software package operates in a Windows format and enables users to import different types of files without converting them. Both raster and vector graphic images can be marked while controlling speed and power settings. In addition, industry-standard bar codes that can mark more than 150 characters per second with text smaller than 0.015 in. are included for marking and traceability.

Graphite-machining center works with small electrodes and intricate tooling

Equipped with sealed and pressurized linear guideways and ball screws, a high-speed graphite-machining center is suitable for working with small electrodes that requires intricate tooling. The M4 from Datron Dynamics also features intuitive control with look-ahead buffers and a 60,000-rpm liquid-chilled spindle with an automatic tool changer. The machine measures 48 x 50 in. and offers a 15.75 x 15.75 x 11.8-in. working envelope. Its solid one-piece construction provides structural stability and vibration dampening. The high-speed spindle, combined with intricate tools and a stable construction base, produces a high-quality surface finish and the accuracy required for intricate electrodes. The unit comes with a Pentium-based PC operating system that offers canned cycles. An accompanying handheld pendant is designed for easy access and operation. Customized for optimal airflow, its enclosure captures airborne dust and can be retrofitted to work with existing graphite-dust collection systems. A central lubricating system facilitates part replacement. An optional z-height precision sensor enables users to measure the contours of a workpiece in 3-D before running a job. The M4 is compatible with standard carbide tools and can be used with the company's line of microtooling products.

Vibration-free tooling minimizes breakage

Able to handle bore diameters from 0.03 to 0.5 in., two numerically controlled drilling machines have maximum depths of 16–50 in. Available from TBT Automotive Div., the ML200 and ML250 use high-frequency controlled motor spindles with rotary oil couplings integrated into the motors to eliminate external vibration. According to the company, tools as small as 0.0315 in. running at speeds up to 24,000 rpm and oil pressure of 2400 psi can break with even the slightest vibration. Elimination of drive belts helps to make the spindles maintenance free. The feeds and speeds of the drills can be changed depending on the tool position in the workpiece. Process repeatability can be observed with spindle power consumption and coolant pressure indication. The machines are offered in 1-, 2-, 4-, and 6-spindle versions and have counterrotation for the workpiece to reduce bore runout. Field reliability can be as high as ± 96%.

Pressing systems offer precise operator control

A line of pressing systems offer 100% in-process control and monitoring. The ServoPress systems from Schmidt Feintechnik Corp. are compact and precise, providing easy-to-understand and easy-to-use operator interfaces and flexible components. Each lectromechanical ServoPress module has a servomotor-driven press ram and a Windows-based PressControl 4000 system with CNC and PLC controls. The machines continuously perform precise assembly operations without mechanical stops in the components or tooling. This is achieved with the closed-loop control of the numerically given force, stroke, and ram feed-rate parameters. A dual-channel light-curtain control system, with a complete guarding of work area, protects the operator. The systems organize, administer, and graphically present production data. The PressControl 4000 can perform either random or simultaneous operations on up to six ServoPress units or other CNC-operated axes such as positioning devices and robots. Data communication is via the serial field bus CANopen, enabling problem-free integration of frequency convertors and I/O modules that meet the CANopen standard. All four ServoPress models function as modular units, and can be operated as single-station benchtop cell units, or integrated into existing systems.

Fiber-optic laser system suitable for welding applications

A pulsed Nd:YAG fiber-optic beam-delivery laser system covers a working range of up to 200 W. Provided by Lasag Industrial-Lasers, the SLS 200C-16 is an air-cooled system with a compact design that can be integrated into new or existing workstations. A real-time power supply makes the system suitable for peak-power controlled welding applications with high demands on precision, quality, and throughput. The SLS 200C-16 is available with up to six fiber outputs for energy and time-sharing with a pulsed-on-demand operation. Fibers are offered in 100-, 200-, 400-, and 600-µm core diameters. Other features include a completely sealed power supply with active water or air cooling, a PC interface and Windows-based software, and a modem for remote operation and diagnostics. The system is suitable for precision spot and seam welding, hermetic sealing of medical parts, cutting, and micromachining.

Electrofission cutting and forming machines eliminates extra tooling

Using an electrofission process, machines can cut and form wire and tubing without the need for tooling. Working with a range of alloys with diameters to 0.0787 in. for wire and 0.1 in. for tubing, the UDR-series units can cut lengths as small as 0.2 in. The series is supplied by a joint venture between Jouhsen Bündgens and Cold Header Machine Corp. The electrically powered UDR units heat the wire and perform a cutoff through one mobile slide and one stationary slide. With the parting of the heated wire, both ends of the cutoff are identical and slightly rounded. The machines can operate with tight tolerances at speeds of 500 parts per minute. Their electrodes prevent the need for extra tooling, thereby reducing cost. In tubing-cutting applications, the systems reduce the need for honing because there is little diameter reduction in the cutoff process.

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