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Medical device manufacture and distribution requires adherence to the Food and Drug Administration’s (FDA) quality system known as Current Good Manufacturing Practices or CGMP. The FDA exists to ensure that food, drug, biologics, and medical devices distributed in the USA are not only safe, but are also effective. While this quality standard does not specify the details of product manufacture, it does present a quality system (QS) framework which manufacturers must develop and follow when producing medical devices.

Underneath the QS umbrella is the FDA 21 CFR PART 820 – Design Control Guidance for Medical Devices Manufacturers. This regulation governs the facilities, methods, and controls used for the design, manufacture, storage, labeling, installation, and servicing of safe and effective medical devices. FDA-regulated products such as dip-molded medical devices must incorporate a system of checks and balances to prevent deficiencies in design. The design control guidelines ensure that the proposed design specifications transfer adequately to production and likewise, translate into a medical device that is appropriate and safe for its intended use.

The process of dip molding using Plastisol is a sophisticated, highly-controllable method of producing many medical devices that are used every day for medical examinations and procedures. Adherence to FDA quality standards for design control is easily accomplished in the production of dip molded medical devices such as Y-connectors, nasal cannulas, stethoscope sound tubes, medical balloons, dental dams, colostomy bags, and spring-reinforced tubes. Every year, many more manufactured medical devices are turning from injection molding to dip molding due to economy, quality, and efficiency.

What is Dip Molding?

Dip molding is the process where a metal mold (or mandrel) is dipped into a polymer substance, such as Plastisol, latex, silicone, neoprene, urethane, or other plastics, to produce a flexible and durable end product. The exact process varies depending on the material being used. When dip molding Plastisol, the process begins with the submission of a specification drawing that will be used to create the mandrel. The mandrel is turned from an aluminum casting to create the negative, or internal portion of the product needed. After a prototype is made and tested, a production mandrel is created for high or low-volume production runs.

The precision mandrel is then preheated and dipped into the polymer substance. The temperature and the time of the dipping process will determine the thickness of the finished product. Alternatively, multiple dips can be made into the polymer to build up the finished wall thickness. Finally, the material is cured in an oven where the Plastisol fuses into a durable rubber-like material. After cooling, the final product is stripped from the mold manually or with compressed air.

Quality and Economical Benefits of Dip Molding

  • The prototype and production molds are relatively inexpensive to manufacture, meaning even small volume runs are feasible, and delivery time from start to end is short. If you are a manufacturer requiring a flexible medical device, dip molding is an affordable and proven method to meet FDA regulations.
  • Plastisol meets the stringent requirements of Class VI testing by United States Pharmacopeia (USP) and has a long history of success in dip-molded medical devices. Its benefits include a lower cost over other polymers and ease of processing, which ensures the design input parameters result in a closely toleranced end-product.
  • Uniform and repeatable wall thickness is achieved with ovens that maintain a constant temperature and a highly controlled air velocity for each production cycle. Dip molding is preferable for thin-walled products, such as stethoscope sound tubes that must have thin walls to easily pick up the heart and breath sounds from the sensors in the cuff.
  • Drip marks, air pockets, and other blemishes are avoided when you consult with an experienced and reputable dip molding process manufacturer. These manufacturers are also able to provide matte or glossy finishes, a range of colors, and can engineer the polymer substance to accomplish varying hardness, electrical resistance, and material clarity.

Plastisol dip-molded medical devices stand up to the stringent guidelines of the FDA Quality System. These products resist abrasion, corrosion, and deterioration from aging. At Molded Devices, we pride ourselves on a tradition of designing and executing high-quality dip-molded products. Contact us today to discuss how we can help.