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This paper aims to experimentally determine the influence of the tool shoulder depth value on the structural and strength properties of the single lap joints made of 7075-T6 aluminium alloy made with friction stir welding (FSW) technology. The aim of the preliminary tests is to optimize the parameters of joining process of thin-walled structures such as the skin-stringer joint or skin-frame joint of the aircraft fuselage. The tests were carried out for materials commonly used in such structures, i.e. 1.6 mm thick sheet 7075–T6 aluminium alloy with cladding on both sides (cladding thickness 4% per each side). The layer of clad protects plates from corrosion.

This study shows the results of the investigation for the joining of 7075–T6 ALCLAD aluminium alloy sheets. The welding process was carried out on a computer numerical control milling machine SOLARUCE TA–20A. Linear FSW welding was performed using a commercial tool from RSS SCHILLING with the symbol 10–K–4–Z–M–O, which is fabricated of hot work tool steel. Constant parameters of the technological process were applied. The welding process was executed for different values of the shoulder depth ZS.

This paper investigated the dependence between the thinning of the welded material and the depth value of the tool shoulder during the FSW process. The influence of the depth value of tool shoulder on joint strength in the static tensile/shear test was also performed. With the increase of the depth of the tool, the size of flash and structures of the face of the joint changes as well (its annular surface resulting from the tool’s work and the accompanying process of material flow on the run-off side). Such conditions in the process require a proper tool depression to reduce the occurrence of flash and minimize material thinning to achieve high joint strength and maintain the conditions for plasticizing the material.

Based on the experimental tests carried out, a number of guidelines for the correct conduct of the welding process can be outlined.

Taking into account the various aspects of the process, the optimal range of the tool depth into the material is a value of approximately 0.06 mm. At this value, the face of the weld is not porous; the flash is easily removed; and the strength of the joint and the deformation of contact line are at an acceptable quality level.

In this paper, after an elucidation of several central concepts of the topic, the author focuses on the sales channels in tourism and clarifies the role retailers play in the market. He shows that the existence of institutional travel retailers is generally based on transaction costs, and that thanks to the automation the level of dependence on transaction costs can be reduced. This thesis induces the question to what extent the retailers' performances can be automated. In answer to this question the author creates a list of criteria including the following aspects; the general and occasional suitability of retail products (e g tickets, travel packages), the availability of technical equipment and information necessary for the automation at the points of sale and in the households (buyers), the level of complexity and acceptance regarding the handling of automated travel services. The paper comes to the conclusion that the automation of travel services will probably be used mainly by business travelers, whereas private customers will more likely keep their affinity for conventional retailers.