Material Selection

Leverage Our Material Selection Expertise

There are thousands different materials used in injection molding, making selection of the right material for your device a potentially daunting task. Our medical device specialization combined with our injection molding expertise streamlines the process of finding the right combination of materials for your product.

We maintain a stock of over 200 injection molding materials. Combined with our onsite injection molding capabilities, this stock enables our engineers to quickly sample and test multiple material candidates for your application. For products with more unique requirements, we research and source specialized materials, material additives and surface treatments to suit your product’s requirements.

Matching requirements with ideal material candidates involves careful evaluation of criteria that includes:

We assess the mechanical forces acting upon the part and whether those forces are within the performance limits of the selected material. Tools that we use include finite element analysis and design analysis and testing. See also our Mechanical Design and Engineering Services.

These factors must be considered for materials that will be used in contact with the human body. The USP classifies materials by biocompatibility testing that has been performed on the material to confirm that it meet requirements for biological reactivity. For example, the highest level, USP Class VI, indicates that the material has demonstrated very low levels of biological toxicity and is therefore a good candidate for use in medical products.

Single use disposables and sterilized reusables require use of specific materials and grades. The method of sterilization such as gamma, electron beam, ethylene oxide and steam also affects material choice because these processes alter the material’s properties.

We consider product storage requirements, operation temperature, humidity and any temperature cycling exposure. The materials must also be compatible with any solutions or chemicals in the product or present in the use environment.

Devices that separate or store gases or liquids such buffers, reagents, or biological samples require consideration of the material’s MVTR.

The cost of compatible material candidates can vary widely. We typically recommend the lowest cost material that satisfies all product requirements.

It is surprisingly common for materials to be discontinued or encounter other supply challenges. Therefore, we prefer materials that are available from multiple manufacturers, mitigating the potential for supply interruption during manufacturing.

Assembly methods such as ultrasonic welding, laser welding, press fits, snap fit and interlocks each have a variety of material compatibility issues to consider.

The tolerance requirements of the device directly affects material selection. Tight tolerance parts require selection of materials which are dimensionally stable and isotropic (have uniform shrinkage in all directions).

Heat and flame resistance must also be considered for plastics used in electrical applications. Some applications require plastics to function as conductors or insulators.

Certain medical applications have a high degree of sensitivity to leachable contaminants from certain materials. Our knowledge of plastics with low leachable content is important in such applications. Other solutions include secondary processes such as surface treatments, which can solve leaching challenges.

Products with optical requirements such as lenses and light pipes can use transparent materials that offer a lower cost alternative to glass. Since transparent materials vary in function and performance, we offer our expertise and capabilities to assist you in selecting and testing the right materials for your device.

There may be other unique functions or requirements to consider such as stiffness, color, surface properties, lubrication, radiopacity, conductivity, fragrance, wear resistance, and heat resistance, among others. We can meet special requirements such as these with certain stock materials or through custom compounding the base resin with appropriate additives.