Metal injection molding process is an effective way to produce high strength and tolerance MIM parts with complex geometries, which forms metal powder to parts shape and sinter it into final parts. MIM parts have excellent physical characteristics as high strength, wear and corrosion resistance, all these properties is difficult to achieve by other manufacturing processes.
Die casting process consist same injecting liquid metal into a die or mold, which is similar as MIM. Die casting has several economic advantages, in right circumstance and component volume, will save large cost for components designers.
Major difference between Metal Injection Molding and Die Casting is material selection, metal injection molding uses steel or other MIM alloys, the common alloys including: stainless steels, titanium, nickel, tungsten, copper and various combinations. While die casting often us metal as aluminum alloy, magnesium alloy or zinc alloy.
It is easy to find out the main difference between MIM and Die casting material is metal melting point. MIM can manufacturing metal materials with higher melting point than Die casting.
Die casting is fast and economical way for high volume metal parts with simple shape. The metal material like zinc, aluminum, copper and magnesium will be mixed into ingot. Then, ingot will be melted by die casting machines and central furnace. All molted alloys inject into dies or molds with pressure by pump. Cooling and ejection final molded metal are final steps of die casting. Its cycle time depends on component size range from 1 to 30 seconds.
MIM is a dense and complex process, metal alloys is formed into very fine powder, and then mixed with thermoplastic binder into feedstock. The feedstock will be heated into liquid form and injected into molds, cooled and ejected form mold as green parts. Then de-binding process use catalyst to remove most of binder. Sintering process will sinter fine metal powder to combination together, create strong net-shape metal component.
As MIM and Die casting are both suitable for high-volume metal parts production, MIM still has higher tolerance than die casting, this guarantee that MIM can produce high repeatable metal parts.
MIM is more suitable for small metal parts manufacture with complex geometries. From above graph, we can recognize small features less than 2 mm only can use MIM technology to process, die casting will never satisfy this requirement.
Size & weight
Die casting has wider manufacture size than MIM. For metal parts under 200 grams production, MIM has higher productivity than die casting. It is difficult to create thin section less than 0.5 mm in die casting, but easily to complete in MIM.
As these comparison, we will notice that, MIM is ideal for small lightweight metal parts with complex geometries. The most suitable parts are small than 100 mm and less weight than 100 grams, in addition with production quantity above 1000. MIM is the most cost-effective way for this item production, even comparing to die casting, precision machining.
MIM technology mix metal powder with binder, then remove binder, sinter into MIM parts finally. So its normal density will achieve 95-99%, this is less than 100% of die casting. However, this never affect MIM parts functional properties, on the other hand, reduce MIM parts amount weight.
As MIM and die casting will both produce metal parts with conventional metal properties. In reason of various raw material usage in these two different method, we will find that MIM parts have more excellent chemical and physical properties:
High Strength: MIM parts always apply steel alloys, nickel alloys or titanium alloys, which have high mechanical properties than die casting materials like aluminum alloy, magnesium alloy or zinc alloy. This give rise to MIM parts strength is significant higher than die casting, surface hardness, wear performance,fatigue strength, fracture toughness,corrosion resistance.
Good hardness: As MIM materials are normal metal with excellent surface hardness, it will encourage MIM parts perform better hardness than die casting. In addition, secondary operation as surface carburization will be used widely to increase MIM parts hardness.
Corrosion resistance: MIM parts have higher surface roughness of 1 μm than die casting parts of μm, this means MIM parts will perform better in corrosion resistance. As secondary operation of surface treatment will raise it into a new level.
Creep resistance: raw materials of MIM with excellent creep resistance decide high performance of MIM parts. Die casting materials as aluminum, zinc and magnesium alloys, are lack of this properties in nature, this will also affect performance of Die casting parts.
Quantity & Costing
Although die casting seems more cost-effective than MIM, consider about all aspects of materials, process and properties. MIM has its unique characters to satisfy special metal parts requirement. Its wider range of materials choices and corresponding properties are key factors attract millions of customers in worldwide.
ZCMIM provides best metal injection molding for customer in worldwide, our experienced engineers team and excellent facilities will satisfy your any projects requirement.