The quality of a multi-blade razor system is determined by both the design of the technical characteristics
of
the individual blades such as the cutting performance and the edge-holding property as well as the
maintenance
of the geometric tolerance specifications of the entire cartridge. The latter are determined with a visual
inspection along with the contactless measurement of the geometric dimensional accuracy of multi-blade razor
systems. The included characteristics are illustrated in detail below.
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Visual evaluation and contactless measuring
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Using an XYZ measuring instrument we check the main geometric technical data of multi-blade razor
systems.
During
this, random samples of cartridges from the entire volume of the produced, previously final-packaged
product
intended for the trade are removed from the razor blade system.
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Optical measurement and appraisal of multi-blade razor systems
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Measuring instrument for measuring geometric values
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For recording the geometric parameters we use a non-destructive test method during which the cartridge is
illuminated with a confocal point sensor and optically scanned. Software that has been specifically
programmed for these measurements evaluates the signals from the confocal point sensor and supplies the
measurement results in the micrometer range. This enables metrological recording of the geometry of the
cutting side of a multi-blade razor system and characterization of the following product
characteristics:
| Angle of each blade to a reference level |
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| Clearance of each blade to a reference level
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| Span and vertical clearance between the individual
blades and to the Guardbar and the
Lubrication
Strip
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| Curvature, tipping and straightness of each blade
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Furthermore, we also analyze the geometric state of the test sample based on a microscope video and
document
the product characteristics that are visible for the consumer such as the manufacturing quality of the
lubricant strip and the guard bar along with the location and position of the blades in the cartridge.
The
objective tests are performed by our trained laboratory employees, who are able to identify and analyze
all
product characteristics that are relevant for the consumer. Using our optical analyses, on top of the
product characteristics recorded with metrology the following characteristics are also
characterized:
- Functionality of the docking system
- General manufacturing quality of the product
- Feel of the products
The cutting performance and edge-holding property characterizes the main technical characteristics of a
razor blade. The user feels the cutting performance as the sharpness of the razor blade, which he
perceives in particular during the first use of a new set of blades. This perceived sharpness during
shaving is one of the main quality characteristics since it has a lasting effect on the customer’s
satisfaction with the product. Another important criterion is the durability of the blade. This is
consistent with the technical characteristic of the edge-holding property which states the cut travel
and the utilization time that can be achieved with a blade before the user perceives it as worn out,
i.e. as useless for its end-use.
PWFT uses a patented, destructive test method for both these characteristics. With the Razor Sharpness &
Durability Tester developed by PWFT it is possible to automatically make metrological recordings of the
quantified technical data to evaluate the values of cutting performance and the edge-holding
property.
The method for determining the cutting performance and edge-holding property values is included in the
destructive test methods during which the individual blades are checked until they reach a limit value.
The
individual blades are first released from the cartridge and fixed in the test instruments clamping
device.
The basic principle of the patented layout with the corresponding method to determine the cutting
performance and edge-holding property of razor blades is based on recording force displacement curves
during
the repeated severing of a hair substitute. Here, during a relative movement between the razor blade
under
test and the test medium in which the test medium is cut through, a force displacement measurement is
performed. During this both the cutting performance and the edge-holding property of the razor blade is
metrologically and realistically recorded.
The average value of the force required from the first five cuts is drawn-on as the parameter for the
cutting
performance. At the same time, the ascertained value is used as the sharpness parameter and provides
insight
into the quality of the cutting geometry.
The edge-holding property is metrologically determined during the repeated severance of the test medium
until
a limit value is reached. The achieved number of cuts until this limit value is reached is drawn-on as
the
durability parameter and permits conclusions about the quality of the material and the material
microstructure
Sequence of a cut with a record of a force displacement curve
The test to determine the cutting performance and the edge-holding property is used as a supplement to
the
non-destructive methods of most geometrically-based quality controls of the manufacturer on
representative
random samples.
