Glossary

Operation which finishes the surface of a cylindrical hole using a multi-edge tool.

Non-ferrous metal rarely used pure, generally used in alloys with copper and zinc, for example, to improve its mechanical strength.

Aluminium surface treatment which forms a layer of oxide that develops on the surface as an integral part of the metal itself, to improve its resistance and provide added protection against corrosion.

Material removal process which increases a diameter with precision finishing in terms of both roughness and tolerance.

Creation of grooves and teeth inside holes in metal parts for machining (internal broaching) or shaping of the external profile (external broaching). This process is able to produce square, elliptical and hexagonal holes, splines and even very complex contours.

A copper alloy: it may be "common", containing just copper and tin, or "special", containing other elements as well as copper and tin to improve its mechanical and technological characteristics.

A surface treatment also known as black oxidation in which a metal is coloured black in order to improve its appearance and protect it from corrosion.

Machining process which reduces mainly cylindrical or spherical objects to the same diameter.

Surface treatment which coats the metal with a thin layer of chromium to improve its resistance and provide added protection against corrosion.

Material removal machining process which uses a tool with cutting edge in line with that of the cavities to cut the teeth of a gear.

Surface material removal machining process used to create a helical ridge on the metal piece (external threading) or a helical groove (internal threading).

Axial thread-cutting using a multi-edge tool.

Surface material removal machining processes that creates a threading using a multi-edge tool.

Process which creates threads by deforming the material.

Surface material removal machining process carried out to create a hole, which may include the following phases: - centring (alignment with the axis of the hole); - drilling; - widening (increasing the diameter of the hole); - reaming (finishing of the hole).

Drilling operation to create a hole with depth 10 times the diameter of the hole.

Drilling operation perpendicular to the axis of rotation.

Material removal process capable of producing a vast range of surfaces, including planes, grooves and shoulders, using a multi-edge tool of a specific shape.

Material removal process using a disc-shaped tool to produce parallel planes or slots in the heads of screws.

Milling operation perpendicular to the axis of rotation.

A procedure that uses pressure to create grooves and ridges in a chequered or diamond pattern on surfaces. It is used on coins or mechanical pieces such as regulator knobs, crank handles, etc. to give them a rough surface that offers a firmer grip.

A process that super-finishes the surface of a piece to reduce its roughness to a minimum.

A process which uses pressure to mark the metal piece.

Internal thread-cutting using a multi-edge tool.

Metals which contain iron and carbon.

Metals which do not contain carbon: copper and its alloys (bronze and brass), aluminium and its alloys.

Surface treatment which coats the metal with a thin layer of phosphonickel alloy to improve its resistance to wear and provide added protection against corrosion.

An alloy of copper and zinc, it may contain other metals such as lead.

Material removal machining process which produces square or hexagonal parallel planes on the outside of light alloy pieces.

Non ferrous metal unsuitable for material removal machining process.

The combination of surface irregularities, relatively small distances apart, caused by the machining process, the shape of the tool, non-uniform materials and any vibration during the process.

A pressure rolling procedure carried out to improve the surface finish or to create a tougher thread than could be obtained by turning, since this method induces more hardening in the material.

Matt or semi-gloss finishing process for stainless steel, used for reasons of appearance.

Finishing process which removes the residues from the upstream machining operation.

Material removal machining process which uses a tool to create circular grooves.

Material removal machining process which uses a tool to remove sharp edges.

Material removal machining process which shapes the insides of through and blind holes.

Material removal surface machining process. Turning takes place with rotation of the workpiece and generally rectilinear travel of the tool (in contrast with milling and drilling, when the tool is rotated). The edge of the tool penetrates into the workpiece material and removes the surplus (machining allowance), creating a shaving.

ISO System, Set of standardised tolerances and deviations for shaft-hole fits, adopted by the UNI (Italian technical and industrial standards authority).

A machine tool very widely used in industry for material removal machining processes (turning) for the creation of external and internal turning surfaces of different shapes, including threaded surfaces.

Lathes on which the operator only has to make the initial feed and operating control settings. In lathes of this kind, workpiece clamping, tool approach and feed, working stroke start and stop, and bar feed to start machining a new workpiece, all take place automatically.

Automatic lathes with drive centres, normally with horizontal axis, which house more than one piece-holder spindle (from 2 to 12) which may also rotate at different speeds, allowing simultaneous machining of several pieces.

Lathes capable of performing complex machining instructions in response to computerised instructions. On CNC lathes, all phases of the operating sequence are completely automatic, both during actual production and during auxiliary procedures (positioning, tool change and adjustment, feeding of the blank and removal of the finished workpiece); this means that during operation the operate has only to check and supervise the machine. The use of CNC lathes saves money above for the machining of small lots of complex pieces which are repeated frequently.

Material removal machining operation carried out with tools, using a lathe: external cylindrical, tapered, flat or faceted turning. Turning may also consist of a drilling, reaming, threading or contouring process; sometimes it may be milling or grinding.

Operations carried out on metals to modify their characteristics, such as corrosion resistance, appearance, colour and resistance to wear.

Operations carried out on alloys, below the melting point, involving heating and cooling to modify their characteristics such as hardness, strength, malleability, etc.

Operation which removes the dirt which accumulated during the previous machining steps from the materials, preparing it for the processes which follow. The results of this procedure depends not only on the type of solutions used but also the washing methods.

Machining procedure which uses a tool to separate the machined workpiece from the bar-stock.

A procedure that uses pressure to create grooves and ridges in a chequered or diamond pattern on surfaces. It is used on coins or mechanical pieces such as regulator knobs, crank handles, etc. to give them a rough surface that offers a firmer grip.

Surface treatment which coats steel with a thin layer of zinc to provide added protection against corrosion.