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One of the problems in machining Al alloys represents machinability of these materials. Machinability is a characterised by several characteristics. One of these characteristics is a cutting temperature. This paper is focused on the effect of selected modifiers in AlSi7Mg0.3 alloy on this temperature. Several variants of this material modified by strontium, calcium and antimony are used. All these materials are compared with non-modified alloy. Moulded castings of non-modified alloy and for each modified variant were made. Gravity-die castings into a metal mould with a thermal insulation were used.

Precision machining and especially hard machining is a topic of high interest at present. Surface integrity requirements increase. Hard precision machining may substitute some abrasive operations. There are some advantages of hard cutting over the abrasive machining. Abrasive machining has traditionally performed the finishing process of hardened steel. But, the availability of hard and super hard cutting tools enable the machine tools to reach surface quality of hard machining like to those obtained in grinding processes. A surface is not only a geometric entity but also a layer with its own structure and properties. These properties are affected by many factors, e. g. by cutting temperatures, friction, deformations in the primary deformation zone and the surface layer of the transient (machined) surface, by cutting tool geometry, work hardening, cutting environment, etc.

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