MIM Metallic Surface Treatment for Hardness and Machinability
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Solution Overview
Problem
Electronic device enclosures face challenges in achieving a balance of properties such as strength, appearance, abrasion resistance, weight, corrosion resistance, and thermal conductivity, as existing materials often excel in some aspects but not others, leading to suboptimal performance in multi-property applications.
Innovation Solution
A metallic component with a refined microstructure is developed, featuring a first region with a smaller average grain size and higher hardness near the surface, transitioning to a second region with larger grains and lower hardness deeper into the component, achieved through plastic deformation and surface treatment processes that align surfaces and reduce porosity, allowing for optimized material properties like increased durability and reduced interfacial stress with surface layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a single material is used for the metallic body, then manufacturing is simple, but it cannot simultaneously achieve high surface hardness, optimal bulk properties, and good machinability
Solution Approach 1:
The patent applies local quality by creating a surface layer with different properties than the bulk material. The metallic body has a first region near the surface with smaller average grain size and higher hardness, and a second region deeper in the material with larger grains and lower hardness. This gradient structure allows the surface to have high hardness for durability while the bulk maintains good machinability and other desired properties.
Solution Approach 2:
The patent effectively creates a composite structure within a single metallic body by having two distinct regions with different microstructures and properties. The first region has a refined grain structure providing high hardness, while the second region has a coarser grain structure providing ductility and machinability. This composite-like structure resolves the contradiction between surface hardness and overall manufacturability.
2Strength
If thermal processing is used to refine grain structure, then surface hardness is improved, but manufacturing complexity and energy consumption increase
Solution Approach 1:
The patent replaces thermal processing with a mechanical surface treatment process. A tool contacts and plastically deforms the surface of the metallic body, refining the grain structure through mechanical action rather than thermal energy. This substitution eliminates the need for thermal processing equipment and associated energy consumption while achieving the same grain refinement and hardness improvement.
Solution Approach 2:
The mechanical surface treatment is applied as a preliminary or intermediate step during manufacturing, before final assembly. This allows the grain refinement to be accomplished during the manufacturing process itself rather than requiring a separate thermal processing step, reducing overall manufacturing complexity.
3Manufacturing precision
If the tool translates slowly across the surface, then grain refinement is more thorough, but manufacturing productivity decreases
Solution Approach 1:
The metallic body undergoes preliminary cold working or plastic deformation before the surface treatment process. This preliminary action pre-refines the grain structure and reduces the amount of refinement needed during the actual surface treatment, allowing the tool to move faster while still achieving the desired grain size and hardness.
Solution Approach 2:
The patent optimizes the translation speed parameter of the surface treatment tool to achieve the best balance between grain refinement quality and productivity. By carefully selecting and controlling this parameter, along with other process parameters like contact pressure and tool geometry, the process achieves effective grain refinement at practical production speeds.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the electronic device enclosure's surface hardness, durability, and corrosion resistance while maintaining machinability and magnetic permeability, reducing interfacial stress and enabling deeper surface treatment benefits without the need for thermal processing, thus improving overall performance and manufacturing efficiency.
Implementation Method 1
contacting a first metallic surface of the component with a tool to plastically deform the first metallic surface to a first desired depth
Implementation Method 2
The metallic body can have a porosity less than 1% in a first region that extends from the external surface to a depth of at least 100 microns below the external surface
Data Source
AI summary
A component for an electronic device can include a metal injection molded (MIM) metallic body that at least partially defines an exterior surface. The metallic body can have an average porosity less than 1% in a first region that extends from the external surface to a depth of at least 100 microns below the external surface, and an average porosity greater than 1% in a second region adjacent to the first region.