Our 16th Year of Publication
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Cover Story

Medical Plastics Components Industry

Plastics - A Material of Choice for Medical Innovations

Plastics remain at the forefront of medical innovations. We rely on plastics in every aspect of our lives. The plastics used in healthcare and medicine support us from birth through maturity and eventual old age. The dynamic and relentless pace of medical development has been matched by the development of specialist plastics.

Injection Molding of Medical Components

Injection molding is a manufacturing process for producing parts from both thermoplastic and thermosetting plastic materials. Material is fed into a heated barrel, mixed, and forced into a mold cavity where it cools and hardens to the configuration of the mold cavity. After a product is designed, usually by an industrial designer or an engineer, molds are made by a mold maker from metal, usually either steel or aluminum, and precision-machined to form the features of the desired part. Molders can achieve virtually identical parts by controlling several key variable of the molding process. Although many variables affect the molding process, four variables having the greatest impact on the maintenance of a systematic injection molding process are: injection velocity, plastic temperature, plastic pressure, and cooling temperature and time.

Material Selection for Injection - Molded Devices

Injection molding has been employed widely for manufacturing a great variety of medical device and system components. Functional performance and quality of a medical device stems from the integrity of three fundamental elements: materials, design, and processing. These three elements have to interact with each other in a synergistic manner to generate a unique function for a device to meet the customer's requirements. A typical new product development cycle starts with customer requirement definition. Only when customer requirement are fully understood and clearly and accurately defined from the end user's perspective can the ultimate product succeed in the marketplace. A design engineer takes the customer requirements and translates into product requirement definition in engineering terms. That will then allow the materials requirements to be defined by an experienced materials engineer based on the functional requirements of a device. Materials selection and optimization process begins with the preliminary material requirement definition.

Injection Molding Machine Basics

There are two basic components to an injection molding machine: an injection unit that melts and transfers plastic into a mold, and a clamp unit that opens and closes the mold and ejects the part.

Injection Molds for Molding of Medical Components

The injection mold is a key component in the overall process of making a finished medical product. The process of building injection molds to produce components for these products is best understood if one knows the driving factors of why plastics are the material of choice in the first place. It is through an understanding of what the medical customers are looking for that we can define what steps are important in the design and construction of medical injection molds. The process for constructing injection molds for medical components has become more complex as the medical industry places higher demands on plastic products. Medical companies are expecting molders to provide parts that meet all their requirements of dimensional stability, low cost, fast turnaround and particulate free (clean).

Preventing Failure through the Proper Design of Parts and Molds

MEDICAL PART QUALITY depends on factors that include part design, resin selection, the quality and design of the molding tool, and processing conditions. Design and molding considerations, in turn, depend on the type of resin to be molded. By understanding how part design affects injection molding, tooling, and production costs, part designers and engineers can significantly reduce mold complexity. By understanding how tool design affects the process ability of polyester resins, they can avoid complications during molding.

Designing premature Failure out of Molded Medical Parts

Part failure occurs when a part does not perform its expected function. Premature failure signifies the cessation of function before the end of expected life. The designed life of an improperly or inadequately designed part can be far less than its expected or intended life. Premature failure of medical parts and applications may cause irreparable damage to someone's health. When a part prematurely fails because of lack of proper design, the designer alone does not take the blame. The major portion of the blame unjustly goes to the material of construction. To avoid such failures and the resulting disappointments, it is essential to put major stress on proper part design. Functional design is the focal point of all other aspects of design, which must support it. The function could include aesthetic appearance, which can be addressed by industrial design, if the part function involves load bearing capability, a structural design would be needed. The part must be produced by a commercial process and hence must be designed for manufacturing, in this case, for injection molding.

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