As an independent service provider, PWFT GmbH carries out quality tests on random samples of multi-blade
shaving systems.
Using engineering methods, patented testing procedures and high-resolution measuring instruments, we
regularly test quality-determining product features which are relevant for customers.
The test results are based on the quality perception of the product user. We guarantee the dependable and
repeatable calculation of quantitative values, and thus provide statistical values for comparison. By
providing test results to manufacturers, we strive for sustainability and live the process of continuous
improvement.
We have in-depth knowledge and extensive experience in the field of cutting tool performance evaluation. As a
team of scientists and engineers, we have acquired our expertise in research and industrial projects. We
have developed the methods for the visual assessment and cutting performance evaluation in cooperation with
universities, technical colleges and industrial companies.
During visual inspections, the products are examined from a consumer perspective by an experienced
inspector.
- Testing process - Step 1: analysis of the packaging quality
- Testing process - Step 2: analysis of the firm fit of the test piece in the dispenser
- Testing process - Step 3: removal of the test piece from the dispenser to test the functionality of the interface between the handle and the cartridg
- Testing process - Step 4: analysis of the product condition by visual inspections
- Testing process - Step 5: microscopic analyses
During microscopic analyses, the samples are examined using a high-resolution digital microscope with a 10x to 200x magnification. This way, previously documented abnormalities and defects can be analysed and measured more precisely. Based on the measurement, these areas are quantified and documented in videos and images.
During the contact-free measurement, the samples are linearly scanned with a confocal point sensor in the
shaving area (front side) and geometrically measured.
- Testing process - step 1: sample measurement
To obtain the most precise information about the sample’s geometry, a previously defined number of measuring lines is moved along the shaving area. The measurement data is provided as raw data and converted into interpretable key values according to a calculation algorithm.
- Testing process - step 2: analysis of measurement data and documentation
The previously specified limits are checked based on the key values determined by measurement technology. Measurement of the samples is carried out as a downstream process of the visual inspections. During the visual analyses, abnormalities and defects are detected and quantified by the geometry (surface area). By measuring the samples, characteristic key values (e.g. blade angle, blade spacing) are determined by means of measurement data in the micrometre range and conclusions are drawn on the manufacturing quality with reference to the dimensional accuracy and compliance with manufacturing tolerances. The characteristic key values of a multi-blade shaving system are the blade angle, the direct blade spacing and blade height position in relation to the reference level of the cartridge, which regulates contact to the skin in the shaver. These main key values and other secondary key values are stored on the basis of measurement data.
PWFT uses a patented testing procedure to determine both characteristics. Using the testing instrument
developed by PWFT, quantified key values for assessing the cutting performance and durability are recorded
automatically. This involves a destructive testing procedure, in which the individual blades are extracted
from the cartridge and tested until a limit is reached. The basic principle of the patented arrangement is
based on the inclusion of force-path sequences during the repeated severing of a hair substitute material
(testing medium). Forces and path of travel are recorded during the relative movement between the razor
blade to be tested and the testing medium. The result is the progression of force on the razor blade, i.e.
during the cutting process, as the testing medium is cut. As a result, key values, such as the maximum force
in the cutting process, can be determined. These are used to assess the use-related product characteristics:
cutting performance and durability.
- Testing process - step 1: mounting individual blades into the testing instrument
- Testing process - step 2: cutting force measurements
The initial cutting performance of a blade is represented by the arithmetic mean of the maximum forces of the first five cuts. This sharpness value correlates to the “perceived sharpness” and is an indicator of the quality of a blade (in line with DIN EN ISO 8442-5: ICP value). The durability of the razor blade is expressed by the maximum number of cuts until reaching a force limit. The force limit corresponds to an approximate value, which would already be reached by used razor blades in the cutting performance test. The cutting force measurements are carried out using previously defined process parameters.
- Testing process - step 3: documentation of measured values
Documenting measured values on the basis of force-path sequences for each cut as well as the maximum forces per cut.
The test results, image and video materials and the measurement data are documented in a monthly test report
and provided to the customer. However, critical variations in inspection characteristics are forwarded
immediately. The product manufacturer reviews the results and incorporates them into their quality
improvement process.
