Laser Toolpath Shifting to Minimize Thermal Effects
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Solution Overview
Problem
Laser-based machining of materials, particularly thick sheets with brittle coatings, faces challenges such as thermal effects like dull edges, bulging, and discoloration due to plasma and particle interaction, leading to reduced process quality and efficiency.
Innovation Solution
Implementing a two-step laser routing process with a first toolpath followed by a second toolpath that includes a transverse and/or z-axis shift to minimize plasma interference, using high absorption wavelength lasers with short pulses to enhance material coupling and reduce thermal effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a laser is used for machining thick materials with brittle coatings, then material removal capability and ability to avoid cracks in brittle layer are improved, but thermal effects such as dull edges, bulging, and discoloration occur due to plasma and particle interaction
Solution Approach 1:
The laser machining process is divided into multiple passes or segments, where each pass removes material in controlled increments. This segmentation allows the thermal energy to dissipate between passes, preventing excessive heat accumulation that causes dull edges, bulging, and discoloration, while still achieving deep material removal through cumulative effect
Solution Approach 2:
The laser operates in periodic pulsed mode rather than continuous operation. By applying laser energy in periodic pulses with appropriate duty cycles, the process allows thermal diffusion between pulses, reducing peak temperatures and thermal effects while maintaining effective material removal rate through repeated cyclic heating and cooling
2Shape
If mechanical systems with small diameter drill bits are used to achieve sharp corners, then sharp corner capability is improved, but process speed must be slowed down to avoid damage to drill bits
Solution Approach 1:
The patent replaces the mechanical drilling system with a laser-based machining system. The laser beam, being a non-contact tool, can easily navigate sharp corners and complex geometries without the physical constraints of drill bit diameter, eliminating the need to slow down process speed to protect mechanical tools while maintaining sharp corner capability
3Reliability
If mechanical systems are used on materials with brittle coatings, then coating integrity is improved by slowing down process speed, but overall productivity decreases
Solution Approach 1:
The patent changes the fundamental processing parameters by using laser parameters (wavelength, pulse duration, power density, scan speed) that are optimized for the specific material and coating properties. This allows high-speed processing while maintaining coating integrity through precise control of thermal input, eliminating the need to slow down to protect brittle coatings
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
This approach optimizes material removal by minimizing thermal effects, achieving a cleaner edge and deeper cuts with reduced plasma-induced damage, thereby improving the quality and efficiency of the laser machining process.
Implementation Method 1
When a portion of a thick material, such as a plastic, polymer or metal sheet is cut out by a laser
Implementation Method 2
thermal effect appears as a dull edge... The consequential melting along the kerf and the carbonization degrade process quality
Data Source
AI summary
A process to cut sheet material using a laser is improved by performing a first plurality of routings using a first toolpath for the laser and performing at least a second routing using a second toolpath for the laser after performing the first plurality of routings using the first toolpath, the second toolpath traverse from a kerf formed by the laser as a result of performing the first plurality of routings. A z-height shift can be simultaneously implemented with the transverse shift. By shifting the toolpath, interference of plasma generated during laser processing is minimized by maximizing the coupling of the laser and the material, resulting in less discoloration and/or burning of the material.