Medical grade polymers are quickly becoming the preferred material for a broad range of surgical devices. In certain applications, the robust mechanical properties of medical polymers allow complete removal of metal from the surgical device design. In other instances, plastic and metal components can combine to create an enhanced product, with attributes that would not be possible in either an all-metal or an all-plastic device.
Incorporating plastic into surgical devices offers a number of benefits including reduced cost, improved ergonomics and increased functionality. Below are some of the main reasons to consider injection molding for surgical devices:
Reduce Device Weight:
New medical polymers, including filled polymers, possess mechanical properties approaching those of conventional metals. In many applications, polymers are a direct substitute for metal: delivering similar device performance while significantly reducing device weight. Reducing the weight of the device can have a significant impact in the operating room, helping to reduce surgeon fatigue during long procedures.
Increase design freedom:
Injection molding processes gives the designer far greater freedom in designing a plastic part than is possible with metal parts. Injection molded parts can incorporate features such as live-hinges or molded handles in a single injection step. Realizing these features requires multiple, costly, assembly steps with metal parts.
Improve Functional Aesthetics:
Since painting of surgical instruments is not practical, metal instruments are constrained to the color of the base metal. Injection molded devices can incorporate pigments into the plastic, creating a wide range of part colors. In some instances, the plastic is naturally transparent. This opens the door to some unique possibilities; instruments can be color-coded for easy identification or, in the case of transparent polymers, the device can allow the surgeon to ‘look-through’ the instrument, providing improved visibility during procedures.
Reduce Sterilization Burden:
Producing instruments with an injection molding process can significantly reduce the part cost. In some instances, the lower part cost eliminates the need to reuse the device and creates the possibility of a disposable surgical instrument. This reduces the risk of infection and eliminates the need for processing and cleaning instruments prior to reusing them.
Improve MRI compatibility:
The magnetic properties of most metals preclude them from use near strong magnetic fields, as found in MRI environments. Plastics are immune to these magnetic fields, meaning devices manufactured from plastics present no safety hazards when used near MRI machines.
The decision to use injection molding is not a metal vs. plastic decision. In some cases, a metal instrument can be made better, or cheaper, by combining metal and plastic. Plastic over-molding is one such example. With over-molding, a polymer coating is molded over a portion of metal to impart specific attributes. A soft over-molded polymer can improve grip and control, while maintaining the strength and impact resistance of the base metal tool. Another example is using plastic to replace a complex portion of a device. Certain geometries and features are expensive to machine on a complex metal part. Injection molding is well suited to producing the complex geometries, while metal may be a better option for handles or portions of the device that need to transmit large forces.
At Kaysun, we have a group of designers and molders with extensive experience designing and manufacturing injection molded surgical devices. Please contact us to learn how we can help with your product improvement or development efforts.