The goal of metal injection molding (MIM) and metal additive manufacturing (metal AM) is the same--to make durable, high-quality metal components, implants, instruments, and other devices. Both methods offer medical device manufacturers (MDMs) and their contract manufacturers (CMs) an alternative to traditional machining.
MIM is well-suited for small, complex geometries and intricately shaped components. It is also a good option for manufacturing medium- to high-volume parts for medical devices for laparoscopic surgeries and other high-volume applications, such as surgical instruments.
"We have used MIM successfully for over 20 years to manufacture millions of parts yearly for single-use surgical instruments, including powered device drive chains, end effectors, connectors, and other applications," said Steve Santoro, executive vice president for MICRO, a Somerset, N.J.-based full-service contract manufacturer of precision medical devices and provider of injection/insert/metal injection molding services. "MIM is versatile and low-risk from a manufacturing standpoint and used broadly across a range of industries."
MIM is also a highly scalable and cost-effective metal manufacturing technique, which is one reason the global market for MIM "is growing at a rate of 7.5 percent annually, as more industries adopt the process for an expanding range of applications," added Nick Eidem, director of business development for Advanced Powder Products, a Philipsburg, Pa.-based provider of metal injection molding and 3D metal printing (3MP).
For metal AM, medical device applications continue to expand as the process becomes more widely accepted as a viable alternative to traditional machining. AM is especially popular in orthopedics because of its ability to create monolithic, porous structures that can promote bony in-growth. "In addition, metal AM eliminates the need for tooling, which helps to reduce costs," said Jeph Ruppert, director of the application innovation group for 3D Systems, a Rock Hill, S.C.-based provider of additive manufacturing solutions. "Metal AM also is a great solution for the production of personalized implants and instruments because of the design freedom it can provide."
The most utilized metal AM processes for medical device production are powder bed fusion (PBF) technologies, which weld layers of metal powder together utilizing a high energy source, typically a laser or electron beam. Titanium is the metal of choice for most AM applications.
"Metal AM is used mostly for manufacturing titanium alloy implantable devices with integrated lattice or porous structures that encourage osteointegration," said Ryan Kircher, senior additive manufacturing engineer for rms Company, a Coon Rapids, Minn.-based contract manufacturer for medical devices. "Companies are manufacturing these types of devices for a variety of applications throughout the body, including spine, knee, hip, and extremities."
There is also a market for AM stainless steel plates and instruments, but is limited to mostly small-run and special projects due to higher costs. Other materials include cobalt-chrome (CoCr) for implants.
Titanium MIM is becoming the preferred manufacturing method for products with long lifecycles in the market and large annual production volumes. Also, because of COVID-19, more MDMs are moving toward single-use devices, which are a good match for MIM.
Injection molding is advantageous because...