Razor Blade Coating Hardness and Thickness Profile
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Solution Overview
Problem
Razor blades face a challenge in achieving an optimal trade-off between cutting forces, shaving comfort, and service life due to the difficulty in depositing coatings on their unique geometry, which affects the strength and durability of the blade edge, and measuring improvements is subjective.
Innovation Solution
A razor blade with a substrate coated using a physical vapor deposition process, featuring a strengthening coating layer made of titanium and boron with a featureless structure and nanocrystalline arrangement, applied via a pulsed DC bias voltage, enhancing hardness and durability while maintaining a specific thickness profile.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the blade tip is made robust to enable less wear and longer service life, then the service life is improved, but the cutting forces increase which adversely affect shaving comfort
Solution Approach 1:
The patent applies a strengthening coating layer specifically to the blade edge substrate portion (the critical cutting region) while leaving the rest of the blade substrate unchanged. This localized treatment allows the blade tip to maintain its necessary robustness for durability while ensuring that only the cutting edge has enhanced hardness, thereby minimizing the increase in cutting forces and preserving shaving comfort.
2Duration of action of stationary object
If a coating is deposited on the razor blade edge to enhance strength, then the service life is improved, but the difficulty of depositing coating due to peculiar geometry increases
Solution Approach 1:
The patent employs physical vapor deposition (PVD) process parameters specifically optimized for the blade edge geometry, including controlling deposition rate, substrate temperature, and vacuum conditions. These parameter adjustments enable uniform coating deposition on the challenging tapered blade edge surface, overcoming the geometric difficulties while achieving the desired strengthening effect.
3Force
If the blade substrate thickness is decreased to reduce cutting forces, then the shaving comfort is improved, but the risk of breakage or damage increases
Solution Approach 1:
The patent creates a composite structure by depositing a strengthening coating layer (containing hard phases such as chromium carbide or titanium diboride) onto the blade edge substrate portion. This composite construction allows the blade substrate to be made thinner for reduced cutting forces while the hard coating layer provides the necessary strength and resistance to breakage, effectively combining the benefits of both thin and thick designs.
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 increases the hardness of the blade edge, allowing for a thinner substrate with improved strength and durability, reducing cutting forces and increasing shaving comfort and service life, while providing a measurable improvement in shaving performance.
Implementation Method 1
At least the blade edge substrate portion is covered by a coating including a strengthening coating layer deposited on the blade edge substrate portion via a physical vapor deposition process
Implementation Method 2
The deposition process causes a hardness value of the strengthening coating layer to be increased by altering a configuration of the strengthening coating layer
Data Source
AI summary
A razor blade comprising a blade substrate with a blade edge substrate portion ending in blade tip. The razor blade is covered by a strengthening coating deposited on the blade edge substrate portion via a deposition process. The deposition process causes a hardness value of the strengthening coating layer to be increased, which, among other factors, allows for a decreased thickness of the blade substrate with coating. The blade substrate with coating has (i) a thickness of between about 1.57 and 2.37 micrometers measured at a distance of about five micrometers from the coating tip, (ii) a thickness of between about 4.62 and 6.74 micrometers measured at a distance of about twenty micrometers from the coating tip, and (iii) a thickness of between about 19.82 and 27.52 micrometers measured at a distance of about one hundred micrometers from the coating tip.