Originally Published MPMNJune 2004

PRODUCT UPDATE

Metal Fabricator Die-Casts High-Resolution Ultrasound Housing 

Other providers offer cutting, photolithography, and laser technologies

SusanWallace

More than 10,000 hand-carried all-digital ultrasound systems are in use worldwide, according toChicago White Metal Casting Inc. (CWM; Bensenville, IL). In designing these products, several objectives must be met. Themachines must be lightweight, durable, and offer fail-safe shielding against the ultrahigh EMI noise levelsof hospital environments. Other material and process considerations for such devices include design freedom and the ability to produce intricate features with minimum assembly.

CWM was involved in the development of a next-generation cart-based ultrasound system.The heart of the device was an 11.9 ¥ 10.9 ¥ 3-in. housing with self-contained display and keypad. It had to be instantly removable from its mobile docking system for total flexibility. 

The company first rejected a resin-based design because it would require thicker walls, had lower drop strength, and presented some difficulty in ensuring EMI/RFI shielding. CWM then considered magnesium die-casting and thixotropic metal molding. While metal molding could meet the shielding advantages and ruggedness of die-cast magnesium, it could not meet the minimum wall thicknesses required. The company determined this could only be achieved with advanceddie-casting.

The new housing consists of four hot-chamber die-cast parts produced by CWM in high-purity magnesium alloy. The parts consist of an internal shield and three external panels--the display backing, keypad, and enclosure cover with self-contained handle. The total magnesium part weight is 1.725 lb. 

Special circuit board design, tight-fitting die-cast housing joints and the inherent shielding characteristics of magnesium provide total EMI/RFI isolation without the use of additional plating or EMI gasketing. A total of 155 holes and openings are cast in the four housing parts, 139 are die-cast to size. Postcasting machining by CWM consists of drilling, tapping, and milling to final specifications. A conversion coating is applied and external parts are powder coated in one or two colors, silk-screened, and pad printed. The handle receives a special clear coating. 

Tubular Components Can Be Cut at High-Speeds 

Popper & Sons (New Hyde Park, NY) uses advanced technologies for cutting metal tubular components. Its high-speed precision electrochemical cutters and grinders achieve consistent burr-free results at minimum cutting lengths of 0.100 in. Gauges are as small as 30 g, with 0.31 mm OD. Materials include all varieties of 300-series stainless steel, titanium,Inconel, and other alloys.
 
The company also specializes in metal fabrication of tubular components including swaging, bending, flaring, tip reducing, coiling, EDM, CNC turning, and laser welding. Other services include laser engraving, surface finishes such as electropolishing, micropolishing, grit blasting,wire bending, and forming and general machining. 

Precision Photolithography Services Available for Testing Applications

Core technologies of a company include high-resolution photolithography, microminiature 2-D and 3-Delectro-forming, thin-film vacuum deposition, and ion-beam etching. Dynamics Research Corp.(Wilmington, MA) uses precision electroforming to produce a wide variety of devices for control, test, and measurement applications in medicaland analytical instrumentation on glass, quartz, and other substrates, both coated and uncoated. 

The company offers linear scales in frequencies up to 125 lp/mm and in lengths up to 2 m. Encoder disks are provided in glass with line counts from 20-12,000 cycles. Typical products are slits, grids, targets,reticles, gratings, linear scales, encoder disks, and other optical components.

Metal Fabricator Offers Contract Wire EDM Services

Contract wire EDM services are available in quantities from prototype to production volumes. Test cuts on medical parts and drawings are also offered. Xact Wire EDM Corp. (Waukesha, WI) works with titanium, tungsten, nitinol, and medical-grade stainless steel. Workpieces can measure up to 16.0 in. thick and taper angles to 30°. Small wire diameters, down to 0.004 in. can be accommodated. Closed-loop glass scales on all five axes of the company's machines offer positional accuracy of 0.000020 in.

The company's quality control department is compliant with ISO 9000, and equipped with statistical process control. Advanced CAD/CAM equipment with file transfer and translation capabilities is also provided.

Stents Are Precision Cut with Laser Technologies

A contract manufacturer specializes in high-precision material processing using lasertechnologies. A specialty of the company is the precision cutting of stents.
 
MeKo Laserstrahl-Materialbearbeitung (Sarstedt, Germany) provides laser cutting of steel, aluminum, copper, ceramics, nitinol, magnetic alloys, and others materialswith tolerances of ±0.0001 in. Holes with diameters as small as 0.001 in. can be drilled as well.

Laser welding capabilities include vacuum-tight welding and joining of dissimilar materials. In addition toits laser processing, the company provides postprocessng operations such as electropolishing, annealing, surface finishing, and bending.

Copyright ©2004 Medical Product Manufacturing News