Laser Marking of Sintered Compacts for Readable Recess Codes
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Solution Overview
Problem
The existing methods for laser marking on sintered products with metal powder compacts face challenges in minimizing read errors due to voids in the powder compact, which are not adequately addressed by previous techniques, particularly when the average particle size of the raw material powder ranges from 20 μm to 200 μm, leading to issues with code readability post-sintering.
Innovation Solution
A laser marking method involving two steps: a first step with weaker laser power to smooth the surface and a second step with higher power to form recess dots, along with rotary irradiation to create distinguishable patterns, ensuring the dots are readable after sintering. This method includes specific power and speed ranges for each step to prevent blackening or failure in dot formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser marking is applied on the green compact or debinded article, then marking speed is fast and manageability is improved, but read errors occur due to voids in the powder compact structure
Solution Approach 1:
The patent applies preliminary action by performing laser marking on the green compact before sintering, when the powder structure is still intact and can be effectively modified. The laser treatment creates melted regions that fill voids and form readable patterns before the sintering process alters the material structure.
Solution Approach 2:
The patent utilizes parameter changes by controlling laser power, scan speed, and multiple scanning passes to melt and redistribute powder material, creating permanent readable patterns. The laser parameters are optimized to melt the metal powder and form distinguishable regions that remain readable after sintering.
2Measurement precision
If higher laser power is used to form distinct dots, then code readability is improved, but blackening and surface damage occur
Solution Approach 1:
The patent applies segmentation by dividing the laser marking process into multiple scanning passes with different parameters. The first pass uses lower power for preliminary melting, while subsequent passes use higher power for dot formation, allowing control over both readability and surface quality.
Solution Approach 2:
The patent uses periodic action by implementing multiple scanning passes over the same area with varying laser parameters. This periodic treatment allows progressive melting and redistribution of material, forming readable patterns without excessive blackening from continuous high-power exposure.
3Measurement precision
If multiple scanning passes are performed to create readable patterns, then code readability is improved, but processing time increases
Solution Approach 1:
The patent applies dynamics by varying laser parameters (power, scan speed, spot size) between different scanning passes. This dynamic adjustment allows optimization of each pass for its specific purpose, balancing readability achievement with processing time efficiency.
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 method effectively minimizes read errors by creating readable two-dimensional codes on the sintered products, maintaining low oxygen content around the marked areas, and ensuring the dots remain distinguishable post-sintering and thermal treatment processes.
Implementation Method 1
a first step of scanning with laser light of first power which is weaker over a predetermined area in a surface of the powder compact, to melt and smooth inside of the predetermined area
Implementation Method 2
a second step of scanning with laser light of second power which is greater, to form a dot formed of a recess of a predetermined depth at a predetermined location in the predetermined area
Data Source
AI summary
A method according to one aspect of the present disclosure is a laser marking method for a powder compact containing metal powder, which includes: a first step of scanning with laser light of first power which is weaker over a predetermined area in a surface of the powder compact, to melt and smooth inside of the predetermined area; and a second step of scanning with laser light of second power which is greater, to form a dot formed of a recess of a predetermined depth at a predetermined location in the predetermined area.