What are the Secondary Operations of MIM?

Date：2025-07-24   Views：1004

In many cases MIM serves as a near net-shape technology, with final details achieved via secondary operations. It is also a more economical way than tight control during the MIM process.

Secondary operations are usually required for the improvement of hardness, strength and precision, the removal of blemishes and pores, polishing and so on.

Our Equipments and Quantity

Here shows the equipments and quantity of secondary operations in our self-built mold work shop in Shenzhen. 

After that the various types of secondary operations and their functions are introduced.

Different Types of Secondary Operation

Deformation Steps

• Cold Deformation:

  Flattens or straightens the slightly distorted parts in metallic components after sintering.

• Hot Deformation: 

  Boosts the final density and properties of metallic components to give full density.

Machining

Removes mass from the sintered part.

Commonly employed to add threads, undercuts, grooves and special features that can hardly be achieved with the original MIM tooling.

Heat Treatment

Tailors the phases, microstructure, properties, and distribution of alloying elements after sintering.

• For ferrous alloys: Heat treatments can be used to control hardness.

Joining

• Sinter Bonding: 

  Mates components in the green state and achieves bonding during sintering.

  Stair-step shaped lap joints or gentle taper joints are generally the most successful.

Surface Treatments

Improves function or aesthetics of MIM components. 

All common treatments are able to be used, including coating, spraying, painting, polishing, cleaning, anodizing, plating, sealing, and laser glazing. Among the various coating techniques, plating is used the most commonly.

• Electroplating:

  Improves aesthetics or corrosion resistance.

• Passivation: 

  Protects metal parts against corrosion and contaminants by forming a protective oxide layer.

• Anodization: 

  Enhances durability, corrosion/wear resistance, and aesthetics of non-ferrous metals (typically aluminum alloys).

• Sandblasting: 

  Cleans surfaces, improves adhesion, and modifies surface finish.

• Bead Blasting: 

  Achieves matte finishing, removes scale, enhances mechanical strength, and relieves residual stress.

• Media Blasting: 

  Removes surface stains and loosens paint films.

• Polishing: 

  Reduces surface roughness.

• Coating:

   Provides corrosion/wear resistance and aesthetic enhancement.

  Certain coatings offer specialized functions (e.g., electrical insulation/conductivity).

• Laser Engraving: 

  Creates permanent markings without surface grooves. Maintains smoothness and wear resistance.

• Laser Etching: 

  Laser-based etching, scribing, and cleaning (eco-friendly process).

• Pad Printing: 

  Prints text/graphics on irregular or complex-shaped objects.

Cleaning Process

• Ultrasonic clean:

  Removes surface contaminants using cavitation effects generated by ultrasonic waves in liquid.