Micro Metal Injection Molding (Micro-MIM)

To create millimeter-sized components with micron-sized features, Micro-MIM overcomes the traditional limitations of machining by converting fine metal powders into near full-density, high-strength metal parts. What sets Micro-MIM apart from standard MIM is scale: parts typically weigh under 1g, features fall below 100 microns, and gate sizes run between 0.1 and 0.5mm, geometries that conventional machining simply cannot reach.

The process begins by mixing fine metal powders with thermoplastic binders, which are then injection molded into precision micro-tooling. Complex internal geometries, threads, and multi-cavity features can all be produced in a single shot, eliminating the need for assembly or secondary operations. The binders are then chemically or thermally removed, and individual metal particles metallurgically bond together during sintering, producing a net-shaped part at approximately 98% theoretical density with a surface finish of Ra less than 1.6 µm.

Our in-house facility is vertically integrated and includes controlled environments, cleanrooms, and rigorous inspection processes. All tooling is built in-house, and automated handling systems ensure these intricate components are manufactured, inspected, and packaged consistently to reduce waste and deliver clean, finished results at the high volumes that Class I, II, and III medical device production demands.

Micro-MIM follows a precise four-stage sequence, each critical to achieving the dimensional accuracy and material density that medical device components demand.

• Feedstock Preparation
  Fine metal powder, with particle sizes below 10 µm, is combined with a thermoplastic binder to form a homogeneous feedstock. The consistency of this mixture directly determines the uniformity of the finished part, making powder quality and blending control a foundational step in the process.
  
  
• Micro Injection Molding
  The feedstock is injected into precision micro-tooling at carefully controlled temperature and pressure. All tooling at DuPont™ Spectrum™ is designed and built in-house, allowing us to maintain tight control over gate sizes, cavity geometry, and shot consistency across high-volume production runs.
  
  
• Debinding
  The binder is removed either chemically through solvent exposure or thermally through controlled heating. This stage produces what is known as a brown part: a porous structure that has shed its binder but retains the injected geometry, ready for final densification.
  
  
• Sintering
  The brown part is heated to near its melting point in a controlled furnace environment. Metal particles fuse together through solid-state diffusion, achieving approximately 97 to 99% of theoretical density. The result is a net-shaped metal component with final dimensional control, high strength, and the surface integrity required for Class I, II, and III medical device applications.

DuPont™ Spectrum™ processes a range of medical-grade alloys through Micro-MIM, selected for their biocompatibility, mechanical performance, and suitability for regulated device applications.

• 316L Stainless Steel is widely used for surgical instruments, catheter components, and general implantables, offering excellent corrosion resistance and proven biocompatibility.
  
  
• 17-4 PH Stainless Steel delivers higher strength and hardness, making it well suited to structural components and orthopaedic tools where mechanical load-bearing is a requirement.
  
  
• MP35N® is a premium cobalt-nickel alloy offering ultra-high strength, excellent fatigue performance, superior corrosion resistance, and biocompatibility, making it ideal for demanding medical implant applications.

Micro-MIM is particularly well suited to medical device manufacturing, where part complexity, material purity, and dimensional consistency are non-negotiable.
At DuPont™ Spectrum™, we produce Micro-MIM components across a broad range of therapeutic areas and device categories.

• Minimally invasive surgical instruments, including jaws, clips, and trocars, require intricate geometries and reliable mechanical performance in extremely small form factors, precisely the conditions where Micro-MIM outperforms conventional machining.
  
  
• Drug delivery device components such as pump parts and valve bodies demand tight tolerances and clean, consistent surface finishes to ensure accurate dosing and long-term device reliability.
  
  
• Cardiovascular components, including stent delivery hardware and catheter components, benefit from Micro-MIM's ability to produce small, complex metal parts at the high volumes that cardiovascular device programmes typically require.
  
  
• Orthopaedic anchors and bone screws are produced in biocompatible alloys with the thread geometry and surface integrity needed for secure fixation and osseointegration.
  
  
• Electrophysiology electrode housings require precise dimensional control and material consistency to support the electrical performance and patient safety standards of cardiac rhythm management devices.
  
  
• Dental implant components are manufactured to the tight tolerances and surface finish specifications that determine long-term implant stability and clinical outcomes.

Micro-MIM offers several major benefits over conventional machine processing:

• Like plastic injection molding, parts can be made with intricate features; and undercuts, threads, and slots can be effectively produced.
  
  
• Two or more components can be molded into one, eliminating the need and cost for assembly.
  
  
• Because parts can be produced in net shape, there is little waste or scrap compared to traditional machining.
  
  
• Plus, no secondary machining operations are needed.
  
  
• Parts can be produced with 98% purity and feature smooth, consistent surface finishes.
  
  
• The process is cost effective, particularly for large runs. Customers can realize substantial savings over other conventional production methods.