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THE METAL INJECTION MOLDING PROCESS

Feedstock Formulation

Metal powders are mixed with thermoplastic polymers and waxes (binder) using heat to form a mixture in which every metal particle is uniformly coated. Once the mixture cools, it’s granulated to form the feedstock for the injection molding machines.

Molding

The feedstock is fed into the injection molding machines where heaters melt the binder to a toothpaste-like consistency and push it into the mold. The resulting part, once cooled, is ejected from the mold. Runners and gates are removed at this time so that that material can be recycled.

Debind

The “green part” still contains both the original metal and binder material that made up the feedstock. It is approximately 20% larger than the finished part will be. Now a specific portion of the binder must be removed. This is usually accomplished either thermally or chemically, depending on the material being process. FloMet employs both technologies and each use is dependent of the product being produced. The resulting debound part is referred to as a “brown part.”

Sinter

The brown part is placed in a furnace and heated to within 85% of the metal’s melting temperature. The remaining binder is removed and the metal particles fuse together, shrinking to form a solid metal part that is nearly full dense (as compared to wrought density) and meets the desired design specifications. The sintered metal component can then be further processed through machining, plating, heat treating, polishing, etc., if necessary, similar to that of a machined part.



METAL INJECTION MOLDING MATERIALS

Which Material is Right for You?

The Metal Injection Molding process starts with the selection or creation of a feedstock. FloMet possesses an in depth knowledge of metallurgy and can guide you in making the best choice for your application.

FloMet excels at producing custom mixed feedstocks of stainless-steel, cobalt and nickel-based alloys (among others) to produce metal parts with maximum strength and versatility. Our batch atmosphere furnaces deliver the most consistent stainless steel and low-carbon ferrous alloys in the industry.

Below is a small sampling of the broad spectrum of alloys we use at FloMet. If you don’t see the alloy you want or you’d like to discuss a specialty alloy for your individual application.

CHEMICAL TABLE

Type Alloy Chemical Composition (%)
  C Ni Cr Mo Mn Si Co Fe Sn Other
Stainless Austenitic 304 0.03 12-13 17-18 - 0.3 1.0 - Balance -  
  316L (MIM 316L) 0.03 10-14 16-18 2-3 2.0 1.0 - Balance -  
Ferritic 430 0.05 - 16-17 - 1.0 1.0 - Balance -  
Martensitic 420 0.15-0.4 - 12-14 - 1.0 1.0 - Balance -  
  440C 0.95-1.20 - 16-18 0.75 1.0 1.0 - Balance -  
Precipitation Hardened 17-4PH (MIM 17-4) 0.07 3-5 15.5-17.5 - 1.0 1.0 - Balance - 3-5
Duplex 316L Duplex 0.03 8 20 2 - - - Balance -  
Soft Magnetic ASTM A801 Type 1 49FeCo2V 0.025 0.25 0.15 - 0.15 0.15 47.5-49.5 Balance - V 1.5-2.1
ASTM A801 Type 2 Fe27Co 0.025 0.25 0.75 - 0.35 0.35 26.5-28.5 Balance - V 0.35
ASTM A753 Type 2 49NiFe 0.05 47-49 0.30 0.30 0.80 0.50 0.50 Balance - Cu 0.30
ASTM A753 Type 4 80NiFeMo 0.05 79-82 0.30 3.5-6.0 0.80 0.50 0.50 Balance - Cu 0.30
MIM 430L 430L 0.05 - 16-18 - 1.0 1.0 - Balance -  
Controlled Thermal Expansion (CTE) ASTM F15 (Kovar) FeNiCo 0.04 29.0 0.20 0.20 0.50 0.20 - Balance - Cu 0.20
ASTM F1684 (Invar) Alloy 36 (36NiFe) 0.05 36.0 0.25 - 0.60 0.40 0.50 Balance -  
ASTM F30 Alloy 42 (42NiFe) 0.005 42.0 0.250 - 0.80 0.030 1.0 Balance    
Low Alloy Steel MIM 2200 2% NiFe 0.1 1.5-2.5 - 0.5 - 1.0 - Balance -  
MIM 2700 7% NiFe 0.1 6.5-8.5 - 0.5 - 1.0 - Balance -  
MIM 4605 2% Ni 0.35Mo .5C 0.4-0.6 1.5-2.5 - 0.2-0.5 - 1.0 - Balance -  
Carbon Steel 4140 .041 - 1.01 0.23 0.67 - - Balance    
Implantable Alloys ASTM F75 CoCr - - 27.0 5.0 - - Balance - -  
Non Ferrous Copper Cu - - - - - - - - - Cu 100
Bronze CuSn - - - - - - - - 9-10 Cu 90



MECHANICAL TABLE

Type Alloy Mechanical Properties
                   Tensile Properties Hardness
Density (g/cm³) Ultimate Strength Yield Strength (0.2%) Elongation (in 1 inch) Macro (apparent)
  10³ psi 10³ psi % Rockwell
Stainless Austenitic 304 7.58 74 29 40.0 92 HRB
  316L (MIM 316L) 7.60 75 25 50.0 67 HRB
Ferritic 430 7.75 60 35 25.0 65 HRB
Martensitic 420 7.40 200 174 <1.0 44 HRC
  440C 7.65 286 276 14.0 97 HRB
Precipitation Hardened 17-4PH (MIM 17-4) 7.50 130 106 6.0 27 HRC
Duplex 316L Duplex 7.60 84 38 40.0 77 HRB
Soft Magnetic ASTM A801 Type 1 49FeCo2V 7.71 195 185 1.0 36 HRC
ASTM A801 Type 2 Fe27Co 7.55 80 41 12.0 80 HR 15T
ASTM A753 Type 2 49NiFe 7.83 73 12 38.0 80 HR 15T
ASTM A753 Type 4 80NiFeMo 8.39 84 32 40.0 81 HR 15T
MIM 430L 430L 7.55 60 35 25.0 65 HRB
Controlled Thermal Expansion (CTE) ASTM F15 (Kovar) FeNiCo 7.80 75 51 42.0 60 HRB
ASTM F1684 (Invar) Alloy 36 (36NiFe) 8.00 62 35 40.0 65 HRB
ASTM F30 Alloy 42 (42NiFe) 7.79 71 36 42.0 70 HRB
Low Alloy Steel MIM 2200 2% NiFe 7.65 42 18 40.0 45 HRB
MIM 2700 7% NiFe 7.60 60 37 26.0 69 HRB
MIM 4605 2% Ni 0.35Mo .5C 7.50 64 30 15.0 62 HRB
Carbon Steel 4140 7.85 84 57 15.0 18 HRC
Implantable Alloys ASTM F75 CoCr 8.09 95 65 8.0 35 HRC
Non Ferrous Copper Cu 8.66 - - - -
Bronze Cu Sn 8.18 - - - -


FloMet, Your MIM Design Partner

FloMet is much more than a parts manufacturer. Consider us your partner from the start of the process. You can rely on our knowledge of MIM technology to assist you in designing the optimum part.

We’ll Tackle Your Toughest Challenge

You’ll achieve the greatest benefit from metal injection molding when you factor the breadth of its capabilities into your design. That’s where FloMet can help.

We start by making recommendations on material or alloy selection, taking into account strength, corrosion resistance, thermal conductivity, density, hardness and other properties as each relates to your application. We can even create custom alloys when needed.

Next we look at part size, unit volume, component geometry and tolerance restrictions to assist you in developing the most functional and economical design.

The Metal Injection Molding process is highly customizable to meet your requirements, from formulation of the feedstock to the final product, we will work with you to refine the design and develop specialized processes to achieve the best possible solution.

Metal Injection Molding for Diverse Applications

The Metal Injection Molding industry is rapidly changing. Advances in recent years have expanded the limits of MIM technology. Parts can be molded with more intricate shapes, wider range of sizes, with tighter tolerances, and diverse alloy selections.

With these enhanced capabilities, MIM is now a viable manufacturing option for more industries and applications.

MIM Parts in Healthcare:

  • Medical Devices & Surgical Instruments - endoscopic instruments, electrodes, end-effectors, grips
  • Orthopedics - Implantable, brackets, braces, instruments
  • Health & Hearing - Hearing aids
  • Dental/Orthodontic - brackets, buccal tubes

MIM Parts in Various Industries:

  • Electrical - connectors, switches
  • Fiber Optics - connectors
  • Industrial - air knives, brackets
  • Aerospace - aircraft parts, components
  • Locks - lock cylinders, bolts, sidebars
  • Telecommunications - fiber optic switch boxes, hermetically sealed boxes
  • Automotive - steering columns, seating mechanisms, solenoids, fuel injectors
  • Hardware & Appliance - driver tips
  • Marine - fasteners, brackets, latches
  • Firearms - triggers, sights, safety catches, seer blocks
  • Hand Tools - guards, fasteners


Metal Injection Molding Services

Metal Injection Molding (MIM) allows for secondary operations to be performed on metal parts when features cannot be made net shape.

Even with post-manufacturing work, MIM is usually quicker and more cost effective than machining or casting processes. FloMet offers the following additional services:

Machining

FloMet has a full complement of machining capabilities for refining components that require extremely tight tolerances. Our state-of-the-art equipment includes fully-automated CNC machining centers and CNC electrical discharge machining (EDM).

Ultrasonic Cleaning

FloMet offers ultrasonic cleaning to thoroughly remove particulate from solid surfaces.

Surface Finishing

FloMet’s turnkey solutions include many types of surface finishing services such as electro-polishing to improve a part’s appearance or performance.

Heat Treatment

If your parts have a specific hardness requirement, FloMet’s heat treatment services can get the job done.

Passivation

FloMet’s passivation services are used to ensure a part’s metallurgical stability by making its surface more passive and corrosion resistant.