The delivery of consistently high-quality products is essential in today’s competitive market, where manufacturers must build trust and loyalty among consumers.
The shaving industry, in particular, has grown considerably over the past hundred years, driven by increasing demand for convenient, effective, and aesthetically focused hair removal solutions.
Shaving continues to be the most accessible and cost-effective hair removal method, with consumers expecting precise, comfortable, and reliable razor blades.
Manufacturers must ensure that razor blades are consistently sharp, appropriately angled in their curvature, and designed with an optimal number of facets - angles as the blade nears its edge - for their intended use.
Not only do high-performance blades enhance the shaving experience, these blades are also key to improving and maintaining a brand's reputation.
Adopting cutting-edge production techniques and quality control measures is key to manufacturers remaining at the forefront of the shaving market and delivering reliable shaving products that meet contemporary consumers’ ever-evolving expectations.
Challenges to Razor Blade Quality
A key challenge in using razor blades for shaving is that there is no one-size-fits-all standard size suitable for use by everyone.
For example, different blades may be more effective depending on factors such as skin sensitivity, the fineness of the cut required, and the type of hair being shaved. Key differences may include the material the razor blade is made from, the type of razor used, and the coating applied to the blade.
The blade’s sharpness (edge thickness) and its number of facets also help determine the closeness of the shave. To properly assess coatings and blade edge thicknesses, it is necessary to characterize a size scale ranging from micrometers to hundreds of nanometers.
Blade curvature can affect blades’ rigidity and chatter (blade's vibration towards and away from the skin), requiring observations in the order of 10 nm. In these instances, a blade featuring 10 nm curvature is considered ‘razor sharp.’
Current Characterization Solutions
Sputter Depth Profiling (SDP) is widely used to determine razor blades’ relative coating thickness due to its capacity to record chemical information as a function of depth, and its high-resolution nature, able to measure less than 1 nm resolution.
SDP is also used with techniques such as Scanning Electron Microscopy (SEM) to acquire roughness information.
Most razor blades are manufactured from stainless steel, but some are made of carbon steel, which is susceptible to rust.
SEM can be used to observe rusting and other surface impacts and blemishes, allowing coating integrity to be monitored and the uniformity and quality of blade sharpness to be evaluated. It can also image defects or damage on the blade surface and edge.
Atomic Force Microscopy (AFM) can be used alongside SEM to provide comprehensive quantitative information on blade coating uniformity and curvature by gathering topographic information on the blade edge.
The FusionScope® Approach
The innovative FusionScope instrument from Quantum Design can simultaneously acquire SEM and AFM information from the razor blade within the same environment.
This approach reduces both sample preparation and overall measurement time. Users can leverage a powerful SEM to determine a location of interest more accurately and precisely than the optical microscopy technology typically found in traditional AFMs.
The FusionScope’s Profile View can accurately position the AFM tip on the measurement position of interest, limiting the risk of tip-sample interaction, tip-sample collision, and potential blade coating or tip damage.
This feature also allows users to precisely position the AFM tip on the razor blade edge more rapidly than can be achieved using conventional AFMs.
Data Analysis
The example presented here features a commercially available razor blade, with the goal of the study to image the blade’s surface with the AFM and, most notably, determine the blade edge’s radius.
First, the unmodified blade was installed in the sample holder before being grounded to avoid electrical charging by the electron beam.
The measurement process involved several steps, including coarse positioning, fine positioning, tip approach, and measurement of the topography.
The coarse positioning step is completed using an optical camera. The cantilever tip is initially moved to the FusionScope’s eucentric point - a simple, rapid process since this point is already known. Next, the razor blade is moved to within approximately one millimeter of the cantilever tip (Figure 1, top). Fine positioning is achieved using the SEM.
It is possible to observe the movement of the tip and the top of the razor blade live, meaning that this can be positioned with an accuracy of much less than 1 µm. Next, the cantilever tip is moved to approach before the 3D topography is executed (Figure 1, bottom).
Rectangular sections of the topography can be created, and the measurement parameters can be adjusted while the measurement is ongoing. The SEM can be used to follow the movement of the cantilever tip over the sample. In the example presented here, a sample section of 5 µm x 24 µm across the blade edge is recorded with nanometer accuracy.
Figure 1. (Top) FusionScope scanner and razor blade sample inside a vacuum chamber. (Bottom) SEM image of the cantilever tip a few micrometers above the razor blade. The tip geometry as well as the topography of the razor blade can be seen. Image Credit: Quantum Design, Inc.
Thanks to SEM's ability to enable fine positioning, different areas on the razor blade can be quickly selected and measured. This allows variations at different points of the same sample to be examined simply and different material properties, such as coatings applied to the razor blade, to be compared with ease.
This is especially important when measuring razor blade radius and surface roughness.
Representative Data
Measuring 3D surface topography enables identifying unusual features on the blade surface, such as the ‘double groove’ shown in Figure 5. Individual line scans of the blade edge can also be extracted, enabling precise calculation of the blade radius (Figure 4).
Figure 2 shows how the blade’s end radius is determined at each section, averaging a value between 60-80 nm in the sample’s sections.
Figure 2. 3D representation of the topography of the surface of a razor blade. The measurement has a lateral size of 5 µm x 24 µm with nanometer resolution. Image Credit: Quantum Design, Inc.
Figure 3. AFM topography image of another spot on the razor blade. A “double-groove” feature can be seen in the 3D representation (Figure 5). Image Credit: Quantum Design, Inc.
Summary
The FusionScope instrument allows users to easily and accurately measure complex samples, even those historically difficult to access using a conventional AFM.
The powerful combination and complementary strengths of AFM and SEM are key to the instrument’s straightforward workflow, with users able to position the cantilever on the blade edge and analyze 3D topography and blade radius with ease.
Figure 4. Line scans at two different positions on the razor blade that enable to analyze the blade radius with nanometer resolution. Image Credit: Quantum Design, Inc.
Figure 5. Three-dimensional representation of the topography from Figure 3. The double groove can be observed very well in this figure. Image Credit: Quantum Design, Inc.
Acknowledgments
Produced from materials originally authored by Quantum Design.
This information has been sourced, reviewed and adapted from materials provided by Quantum Design.
For more information on this source, please visit Quantum Design.