Associate professor N.P. Gerasimov
Kazan National Research Technical University named after A.N. Tupolev (KNRTU-KAI), Naberezhnye Chelny affiliate

Keywords: ski sliding surface, sliding qualities, teflon, paraffin, gliding wax, topography.

Background. Skis were invented in times of the first primitive cultures to help ancient hunters move across snow-covered terrains and find food in winter time for their tribes. Sliding properties of skis have always been appreciated and a variety of slide improvement methods have been always applied. One of the most popular methods in the primitive times was to nail fell to the ski sliding surface. Alternatively or in addition to fell, our primitive ancestors used to rub the surface with different fats or wax. To protect skis from moister, they impregnated them with tars. Attempts to improve the quality of skis on the whole and their sliding qualities in particular are still taken nowadays.

The ski sliding quality improvement methods may be classified into the following key ones [4]:

- Physical-and-chemical treatment of the ski sliding surface by waxes;

- Сhoosing special ski sliding surface material;

- Structural (topographical) modification of the ski sliding surface.

Choosing the ski sliding surface material

Modern skis are manufactured using a wide variety of plastic, wood, composite materials and allows. Presently it is the ultra-high molecular weight polyethylene (UHMW-PE) that is commonly used to cover the ski sliding surface (SSS) [4, 7]. However, projects to improve the sliding surface of race skis have never been stopped. One of such projects was implemented in the Fractal Structures Synthesizing Technologies Laboratory under Kazan National Research Technical University named after A.N. Tupolev (KNRTU-KAI). The project resulted in a new technology to cover the ski base with a solid teflon tape firmly jointed to the surface being invented and the teflon-covered skis were produced [1, 5]. The new skis with the teflon-covered sliding surface were tested to rate their sliding properties; and the following conclusion was made: “The teflon-covered SSS was tested efficient in a wide range of weather conditions without special paraffin, accelerators or fluoric additives” [1],[3],[5].

Physical and chemical treatment of the sliding surface with gliding waxes

Modern slide-improvement waxes include a variety of paraffin types, fluorocarbon lubes and powders, and fluorocarbon emulsions. Modern physical and chemical SSS treatment technologies include multiple successive agent application stages [2]. This is the reason for the SSS waxing method being very labour-intensive and subject to many serious restrictions including the following:

‑ The method cannot guarantee the required ski sliding quality in the whole range of weather conditions that may be faced in actual competitions as the slide may vary with the air/ snow temperature and humidity and type and structure of snow;

‑ The method cannot guarantee the required ski sliding quality on difficult ski tracks under variable snow and weather conditions, including snow humidity, structure etc. during competitions; and

‑ The method requires the adequate wax being found and applied prior to every training or competitive race [1],[3],[5].

Structural (topographical) modification of the ski sliding surface

Historically, wooden skis were impregnated with special tars prior to the sliding waxes being applied over the tar. The tarry wooden skis are well protected from swelling/ soaking and snow sticking in warm weather, and the additional benefit is that imperfections of the sliding surface are levelled with tar.

When the plastic coverage on the ski sliding surface was invented, it was a real revolution in the sliding quality improvement and since then the method dominated in the sliding efficiency improvement technologies. In addition to many benefits of plastic, they are waterproof by definition that means that different surface structures and variably smooth patterns may be designed to ensure the skis sliding as required in different weather conditions [4], [6].

Objective of the study was to identify the most promising method of the race ski surface sliding quality improvement based on a comparative analysis.

Methods and structure of the study. For the purposes of the comparative analysis of different methods to improve the race ski surface sliding quality we selected and applied the following key criteria for the comparisons:

 - Effective temperature range of the surface cover;

 - Surface treatment periodicity;

- Surface cover service stability within a wide range of race conditions on the whole race distance;

- Cover efficiency in momentary accelerations of the ski stride and prior to a descent; and

- Sliding stride length.

We assumed the structure/ topography of the ski sliding surface being adequate and the same in every of the sliding surface improvement methods subject to the comparative analysis.

Study results and discussion. Given in Table 1 hereunder are the results of the comparative analysis of the surface waxing (physical-and-chemical treatment of the sliding surface with gliding waxes) and teflon cover (cover material selection) methods.

Table 1. Results of the comparative analysis of the surface waxing and teflon-covering methods

The teflon-covering (cover material selection) method to improve the ski sliding quality, conditional on the surface structure/ topography being effectively selected, was found to have big advantages over the traditional ski waxing technologies since the sliding quality improvement is achieved without additional paraffin/ lube/ fluorocarbon additive being applied to the surface, the teflon cover being highly efficient in a wide variety of weather conditions during the competitions.

Conclusion. Teflon covering on the race ski surface was found the most promising method to improve the ski sliding surface quality.

References

1. Bogoslov E.A., Gerasimov N.P., Danilaev M.P., Mikhaylov S.A., Polskiy Y.E. Eksperimental'nye issledovaniya effektivnosti skolzyashchey poverkhnosti lyzh iz ftoroplasta (Experimental studies of efficiency of teflon ski sliding surface) // Ekstremal'naya deyatel'nost' cheloveka. Scientific-methodical journal. #2(35) 2015, - P. 70-75
2. Gerasimov N.P., Zolotov Y.F. Lyzhnaya podgotovka na zanyatiyakh po fizicheskoy kul'ture v vuze (Ski training at university Physical Education lessons): teaching aid. Kazan: KSTU pub. h-se, 2011. 44 p.
3. Gerasimov N.P. Povyshenie effektivnosti skol'zheniya begovykh lyzh posredstvom ispol'zovaniya ftoroplastovoy skolzyashchey poverkhnosti (Cross-country skis sliding efficiency improvement using teflon sliding surface) / Fizicheskaya kultura: vospitanie, obrazovanie, trenirovka. # 6 2014. – P. 5.
4. Kuz'min L.N. Poverkhnostnoe trenie skol'zheniya lyzh: priroda, puti i metody ikh uluchsheniya. (Surface sliding friction of skis: nature, improvement solutions) // «Sovremennaya sistema sportivnoy podgotovki v biatlone» (Modern sport training system in biathlon): All-Russian res.-practical conference, 24-25 April 2012, Omsk.
5. Bogoslov E., Gerasimov N., Danilaev M., Mikhailov S., Polsky Y., Bogomolova O. Efficiency of Teflon Sliding Surface, International Journal of Science 2013, 3(6): 224-228.
6. Mathia T.G., H. Zahouani, and A. Midol, Topography, wear and sliding functions of skis. Int. J. Machine Tools Manufact, 1992. 32: p. 263–266.
7. Kurtz S.M. The UHMWPE handbook: ultra-high molecular weight polyethylene in total joint replacement2004, Boston: Academic Press INC.

Corresponding author: gernikos@mail.ru

Abstract

The study was designed to find the most efficient method of the ski sliding quality improvement based on a comparative analysis. For the purposes of the comparative analysis of the race ski sliding quality improvement methods, the authors selected and applied the following key performance criteria:

 - Temperature range of the cover;

 - Surface treatment periodicity;

- Surface cover service stability within a variety of race conditions on the whole race distance;

- Momentary accelerations in the start up of the ski race and prior to a descent; and

- Sliding stride length.

The study found that a fluoroplastic (teflon) coating on the sliding surface of a ski offers the highest promises for the ski sliding quality improvements.