Tutorial: Engineering technology Topic: Metal welding – stainless steel, aluminium, zinc coated materials Prepared by: Ing. Josef Martinák st. Projekt Anglicky v odborných předmětech, CZ.1.07/1.3.09/ je spolufinancován Evropským sociálním fondem a státním rozpočtem České republiky.

 Weld is protected against air by inert gas  By argon or helium  We weld – stainless steel, zinc coated materials, aluminium alloys and high- alloyed alloys MIG method weldment Weld bead Welding torch Gas jet Wire line and arc contact Safety gas Weld bathElectric arc weldment Welding wire Ground terminal Current and wire travel switching Input bundle Voltage setting Control line Safety gas Cooling water line Current and welding wire line Bottle with safety gas Wire travel speed Reduction valve Coil with wire Network input Wire travel drive

Chart: Welding types in protective atmosphere Metal electrode welding in protective atmosphere (melt electrode) Wolfram electrode welding in protective atmosphere (non-melt electrode) Metal electrode(M), active gas (AG), MAG Metal electrode, inert gas, MIG Wolfram electrode, inert gas, WIG Wolfram electrode, plasma, WP Chart: Safety gases and their usage SignGas group Chemical composition Usage Reduction gas mixture Inert gases, inert mixtures Slightly oxidant gas mixtures Heavily oxidant gas mixtures

 Solid non-melting wolfram electrode is used  Safety gas is argon or helium  Inert mixtures argon and helium Gas jet Wolfram electrode Welding wire Arc (2 to 3 mm long) Ground terminal weldment Safety gas control Safety gas and welding current switches Welding torch Input bundle Cooling water line Control line Welding current Safety gas

 By negative pole wolfram electrode  Usage – to weld alloyed steels and non ferrous metals ( stainless steel and copper)  Electrode has pointed tip, it enables regular arc, accurate line  Penetration with welding bath is thin and deep Direct welding Wolfram electrode Safety gas arc Electrone flow Usage for Cr-Ni steel and coppet

 Light metal welding – mainly aluminium  Electrons travel from weldment to electrode at positive half-wavelength, they pull out surface oxide particles. It has higher melting point (2500°C) than aluminium (660°C) Changable welding Wolfram electrode Safety gases arc Electrone flow Usage for aluminium alloys

 At manual torch moving, we move it by right hand which is inclined of 15° right to weld  We move additional material wire by left hand  Arc keeps 2-3mm lenght  We reduce current after welding (danger of hole burning)  We should hold a bracket with flowing air over weld end until getting cold  Electrode is titanium

 New cold welding process MIG/MAG uses technology of steel and aluminium joining  This joining process is enabled by cold material transition  Additional aluminium material melts with basic aluminium material – liquid alloy wets zinc coated steel basic material

 Alloyed elements Cr-Ni steel  Chromium - Cr increases oxidation and corrosive resistance, chromium makes thin chromium oxide coating on steel surface  Nickel - Ni increases strength at higher temperatures  Titanium - Ti decreases IK (intercrystalic corrosion)  Welded metal and basic material should have the same mechanical, chemical and thermic qualities Quality colour Thermal conductivity Way of magnetization hardenability Corrosive resistance Electric conductivity Common constructional steels Greyish black yes no steel silvery no yes

 Where is the difference between MIG/MAG welding method?  When is direct current used at WIG welding ?  When is changeable current used at WIG welding?

 DILLINGER. KOLEKTIV. Moderní strojírenství pro školu i praxi. ISBN pro konkurenceschopnost, ESF 2007 –  Metodika svařování – odborný výcvik ve 3. tisíciletí Translation:    JANATA, Petr. Handy slovník technický anglicko-český a česko-anglický. Plzeň: Nakladatelství Fraus, ISBN  Lingea LEXIKON 5, Technický slovník anglicko-český a česko-anglický