The scope of the proposal for a new Technical Information Paper is shown below, as well as the assigned Subject Category, the date when the Work Item was opened, the title of the new proposal and the name of the Working Group Chair (WGC).

0808 - Physical Properties
7/26/18 TIP 0808-XX Measurement of haptic properties of tissue by an objective measuring device

WGC: Giselher Grüner

This is to request development of a TAPPI TIP that would provide a method to characterize the haptic properties of tissue by simulating the human hand by an objective measuring device.
Fundamentals: The haptic feeling of the human hand based on different tactile cells/sensors in our finger tips, what detect vibrations respectively forces, which will be created by moving the fingers over the sample surface as well as by crumpling the sample.
The different cells are sensitive for different frequencies respectively load, what will be generated from the different structure dimensions and specific texture as well as the resistance against deformation (stiffness).
The haptic impression can be split into three basic parameters: micro-surface variations(what can be described as "surface softness"), macro-surface variations (what correlates to "felt roughness/smoothness"), and in-plane stiffness (what correlates to tensile test results).
Because of the nature of our hands and finger tips with the sensor cells, the individual signals will be conducted via nerves to the brain and combined there to an overall impression of the haptic quality of the sample.
Disadvantages of the hand tests are the subjectivity of the results, as well as the fact, that the hand can only feel a combination of the basic parameters. Because of that specific for samples with small differences it is impossible to distinguish by hand, if the difference is felt because of differences in surface softness, or smoothness, or stiffness.
Method and device: The instrument provide parameters, what correlate very good with the three basically parameters of the haptic: micro-surface variations, macro-surface variations as well as in-plane stiffness.
With the software of the instrument it is possible to calculate "HF" hand feel numbers as combination numbers of the three basic parameters (combined with grammage, thickness and number of plies), based on mathematical models of human panels. However, by using the three single parameters separate, information about the relationship of the different components of processes can be obtained.
The provided basically parameters of the device can be used to optimize the tissue production process, because it can help to identify the reasons for changes in overall quality. Because of that it can be used to perform adjustments on the machine, on chemicals or on the pulp. Furthermore it can be used for R&D, benchmarking tests, incoming control in converting.


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