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Metal Injection Molding (MIM)
Metal Injection Molding (MIM) excels at applications that require shape complexity and high final properties such as high strength, excellent magnetic permeability, high temperature strength, corrosion resistance and thermal conductivity - which cannot be fulfilled by plastic and light metal alloys.
AMT pioneers the development and application of Metal Injection Molding, using materials such as magnetic alloys, stainless steel and low thermal expansion alloys to manucfacture intricate precision metal parts.
MIM Hinges
Metal injection molding (MIM) is increasingly adopted to fill the niche where other metalworking processes are not viable. MIM allows designers to create tiny custom hinges for handheld electronics such as cell phones.
MIM hinges are mostly found in cell phones with flipping or folding "clamshell" designs where the hinges connect the base to a folder unit. Unlike hinges of doors, cell-phone hinges must be able to control the angle of opening. Popular angles include 30, 60, 90, 120, and 150. But free-stop designs, where the folding stops at any angle, are gaining in popularity.
The flipping motion of the clamshell hinges on the cam. The cam is a multiple curved wheel mounted on a rotating shaft that produces variable or reciprocating motion in another mating part. Torque values are primarily derived from the shaft, cam, and spring. Secondary factors that affect torque are friction of the cam curve, tolerance between the base unit and the folder unit, the weight centre location of the folder unit, and the distance between the axis of the hinge and weight centre.
Part shown in figure A is made from MIM stainless steel. The complex geometry of the parts would be cost prohibitive to machine from metal bar stock. The other cost-saving advantage of MIM includes molded-in internal threads.
But consumer demand for more features is driving hinges towards two degree-of-freedom movement. Flip-and-twist hinges combine two rotary hinges with axes that are perpendicular to each other. This lets the clamshell flip open then twist 180°. Refer to Fig B.
In brief, the design freedoms afforded by MIM together with the miniaturization of cellular phone components creates greater flexibility in design and protection. |
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