Spark Plug Ground Electrode Plating Process Inversion
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Solution Overview
Problem
Existing spark plugs with plated ground electrodes face issues of misfire due to peeling of the plated layer during deformation, leading to increased complexity and decreased productivity in production.
Innovation Solution
A spark plug design with a plated layer thickness of 2 μm to 18 μm on both the metal shell and ground electrode, made from a nickel alloy with additives like Si and Ti, minimizes peeling during deformation and eliminates the need for masking, simplifying the production process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ground electrode is plated and then plastically deformed to form the protrusion, then the corrosion resistance is improved, but the plated layer may peel off during deformation
Solution Approach 1:
The protrusion is formed on the ground electrode before the plating process. By pre-forming the protrusion shape, the subsequent plating process deposits material uniformly on the existing surface geometry without requiring deformation of the plated layer, thereby preventing peeling while maintaining corrosion resistance.
Solution Approach 2:
Instead of the conventional sequence of plating then deforming, the invention inverts the process sequence by deforming (forming protrusion) then plating. This reversal eliminates the peeling problem caused by deforming a already-plated surface.
2Reliability
If the ground electrode is masked before plating to avoid peeling, then the plated layer adhesion is improved, but the production process complexity increases
Solution Approach 1:
The protrusion is formed in advance before plating, so that the plating process can be applied uniformly to the entire ground electrode surface including the protrusion area without requiring masking. This eliminates the masking step and simplifies the production process while ensuring good adhesion.
Solution Approach 2:
The masking step, which is an unnecessary and complex process step, is completely removed from the production sequence. The invention achieves the desired adhesion result through process reordering rather than through masking.
3Reliability
If the plated layer is made thicker to prevent peeling, then the adhesion is improved, but the material cost and processing time increase
Solution Approach 1:
By forming the protrusion before plating, the invention allows for the use of a thinner plated layer that still provides adequate corrosion protection without risking peeling during deformation, since no deformation of the plated layer occurs.
Solution Approach 2:
The invention changes the process parameter sequence (deformation timing) rather than increasing the plated layer thickness parameter, achieving reliable adhesion with minimal material consumption.
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 effectively reduces the likelihood of misfires by maintaining the plated layer's adhesion and corrosion resistance, enhancing productivity and simplifying the production process while maintaining ignitability and durability.
Implementation Method 1
a plated layer formed over surfaces of the metal shell and the ground electrode
Implementation Method 2
a protrusion formed plastically on the top end of the ground electrode
Data Source
AI summary
A spark plug for use in an internal combustion engine. The spark plug is equipped with a metal shell, a ground electrode joined to the metal shell, and a center electrode disposed in the metal shell. The ground electrode has a protrusion formed on a top end thereof. The metal shell and the ground electrode are covered with a plated layer which has a thickness of 2 μm to 18 μm, which minimizes the possibility of peeling of the plated layer from the ground electrode while keeping the plated layer as thin as possible without sacrificing the resistance to corrosion on the ground electrode.