What are the Possible Defects of MIM? How about the Measures?

Flash

Excessive molding pressure causing mold deformation/gaps

• Use higher-tonnage injection machines
• Optimize mold design/manufacturing
• Reduce injection speed & pressure

Ejection Cracking

High molding pressure, premature demolding, poor mold design

• Lower injection speed/pressure, hold pressure, mold temperature
• Increase hold time
• Eliminate undercuts & increase draft angles
• Optimize ejector placement
• Modify binder formulation

Sink Marks

Thermal shrinkage, low density

• Increase molding/hold pressure & injection speed
• Reduce mold temperature
• Enlarge gates
• Add venting channels
• Slow feedstock flow in thick sections

Voids

Trapped gas, moisture absorption

• Increase hold pressure
• Reduce injection speed
• Raise mold temperature
• Enlarge gates
• Position gates near thick sections

Burn Marks

Binder overheating

• Reduce injection speed & temperature
• Enlarge gates
• Relocate gate position

Weld Lines/Flow Marks

Low feed/mold/barrel temperature

• Increase barrel, nozzle, and mold temperatures
• Raise injection speed
• Add vents/overflow wells near weld lines
• Redesign mold to avoid flow separation
• Adjust gate location

Cracking

Binder swelling, poor powder-binder bonding, low binder strength, high molding pressure, large wall-thickness variations

• Adjust solvent/binder formulation
• Reduce injection speed/pressure
• Minimize wall-thickness differences
• Lower debinding temperature

Warpage/Deformation

Residual stress, unsupported structures (e.g., cantilevers), trapped air

• Control debind temp (50–90°C)
• Use support fixtures
• Optimize molding parameters

Corrosion/Staining

High solvent acidity, humid environment

• Refresh/replace solvent
• Store parts in dry conditions

Cracking/Blistering

Low powder content, uneven binder distribution, feedstock inhomogeneity, rapid heating, moisture absorption, insufficient solvent debinding

• Slow heating rate
• Extend solvent debinding time & shear rate
• Increase mixing/pelletizing time
• Modify binder formula
• Keep materials dry
• Enhance gas purge rate
• Shorten gas flow paths

Warpage/Deformation

Rapid heating, inadequate solvent debinding, unsupported geometries, excessive binder

• Use slower heating
• Extend solvent debinding
• Apply fixtures/sand support
• Increase gas purge rate
• Raise metal powder ratio

Delamination

Excessive heating rate

• Extend solvent debinding
• Reduce heating speed
• Bake below 100°C