When small is not enough

A medical-device company required a component with a tight tolerance; it turned to Phillips Plastics Corp.

The component was a fastener engineered for a surgical anchor used to attach a mesh patch to internal tissue for repair, says Phillips' Micromolding Manager Dave Munkwitz. Because the component was so tiny, it required a tolerance of ±0.0005 in. “Component stack-up heights do not allow for large tolerances on smaller parts. A large tolerance can produce a big variation on product performance,” says Munkwitz.

Phillips used its micromolding technology to achieve the required tolerance because with conventional molding and multiple tooling, cavity-to-cavity and process variability would not meet the part tolerance required.

“In this case, we reviewed the required tolerance with the customer before tool construction,” says Munkwitz. “The tool-maker was made to realize the importance of meeting the specification. The same topic was then discussed with molding and metrology.” Munkwitz also says the part geometry was extremely challenging because finding a location to gate and eject the part was limited. Further, fixtures had to be manufactured for validation and in-process measurements.

The surgical anchor is made of a proprietary high-strength resin developed by the customer, and it incorporates a suture loop attached to the fastener.

Munkwitz says despite the high cost of materials, the micromolding process provided the customer with a low-cost solution. “With our process, we don't have to worry about part-to-part repeatability. We were able to achieve high shot-to-shot repeatability and high material usage.”

Phillips Plastic Corp, 1165th St, Prescott, WI 54021, (715) 262-8000, www.phillipsplastics.com

Process control for precision

To address the need for reduced medical component size, this company offers micromolding expertise and process control for ultra-high precision micro parts. The system helps to significantly reduce costs when dealing with exotic materials. Production process can be carried out under Class 100 cleanroom conditions, if required. Parts can be automatically monitored with integrated vision systems that guarantee 100% compliance for finished product. Automated parts handling systems ensure parts are manufactured, inspected, and packaged with no human intervention.

Donatelle, 501 County Road E-2 Ext., New Brighton, MN 55112,(651) 633-4200, www.info.hotims.com/24236-501

Precision micro molding

Full-service micro manufacturer custom designs components and subassemblies for medical devices used in minimally invasive surgery. Micro molding is done on an all-electric Battenfeld Microsystem 50 molding machine, which accurately molds components weighing less than 1.0 g, achieves dimensional tolerances of ±0.005 mm, maintains wall thicknesses as low as 0.08 mm, and sustains a shot-to-shot volume consistency of .001 cm³ while enclosed in a class 8 clean room.

Mikrotech, 5811-99th Ave., Kenosha, WI 53144, (262) 857-5128, www.info.hotims.com/24236-502

Silicone mold making

Medical device molding with design and mold-making support are provided by this contract manufacturer, specializing in Lean silicone molding and silicone extruding. The company provides CAD product development and application assistance, mold design and build, and class 10,000 clean room molding. Adjacent post curing, microscopic trim-inspect, wash and package operations, and completed molding and handling are all completed within one cell. Services include liquid silicone molding, gum stock molding, and bonding silicone parts to plastics, metal and other silicone parts using medical grade adhesives. Eighteen liquid injection molding cells incorporate post curing, microscopic trim-inspect, 14 transfer presses, and wash and package operations.

Sil-Pro LLC, 704 Seventh St. South, Delano, MN 55328, (763) 972-9206, www.info.hotims.com/24236-503

Implantable micro molding

This company's expanded manufacturing capacity includes implantable micro molding. Its manufacturing process of high yields in virgin resins results in cost-effective solutions for implantable applications while ensuring non-degradation of material. The process delivers yields of 10,000 parts or 10,000 shots per pound minimum (including runner). Micro molding part sizes start at 0.003 in.³ and smaller, or 0.045 grams or less. Working with a variety of materials such as: PEEK, Ultem, Bioresorbable, and other engineered resins, complex part geometries with fast lead times and high repeatability can be attained.

SMC Ltd, 330 SMC Dr., Somerset, WI 54025, (715) 247-3500, www.info.hotims.com/24236-504

Tight tolerances

Micromolding is about more than just the production of small parts, according to this company. While the company has produced billions of precision plastic parts as small as 0.05434 mm³, with the largest feature being 800 µm, other parts produced are larger than 7-cm in diameter, with micro features having very tight tolerances. The company often develops additional processes to create quality parts, including two-shot micro-molding, automation and packaging, lead frame, insert molding, and over-molding.

Accumold, 1711 SE Oralabor Rd., Ankeny, IA 50021, (515) 965-5741, www.info.hotims.com/24236-505

For more on micromolding, see“Ensuring proper material properties,” page 18.