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BOC Smootharc MMA 170 Скачать руководство пользователя страница 16

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Slag inclusions occur when slag particles are
trapped inside the weld metal which produces a
weaker weld. These can be caused by:
• erratic travel speed
• too wide a weaving motion
• slag left on the previous weld pass
• too large an electrode being used
• letting slag run ahead of the arc.
This defect can be prevented by:
• a uniform travel speed
• a tighter weaving motion
• complete slag removal before welding
• using a smaller electrode
• keeping the slag behind the arc which is done

by shortening the arc, increasing the travel speed,
or changing the electrode angle.

Undercutting

UNDERCUTTING

Undercutting is a groove melted in the base
metal next to the toe or root of a weld that
is not filled by the weld metal. Undercutting
causes a weaker joint and it can cause cracking.
This defect is caused by:
• excessive welding current
• too long an arc length
• excessive weaving speed
• excessive travel speed.

On vertical and horizontal welds, it can also
be caused by too large an electrode size and
incorrect electrode angles. This defect can be
prevented by:
• choosing the proper welding current for the

type and size of electrode and the welding
position

• holding the arc as short as possible
• pausing at each side of the weld bead when a

weaving technique is used

• using a travel speed slow enough so that the

weld metal can completely fill all of the melted
out areas of the base metal.

Lack of Fusion

LACK OF FUSION

Lack of fusion is when the weld metal is not
fused to the base metal. This can occur between
the weld metal and the base metal or between
passes in a multiple pass weld. Causes of this
defect can be:
• excessive travel speed
• electrode size too large
• welding current too low
• poor joint preparation
• letting the weld metal get ahead of the arc.

Lack of fusion can usually be prevented by:
• reducing the travel speed
• using a smaller diameter electrode
• increasing the welding current
• better joint preparation
• using a proper electrode angle.

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Содержание Smootharc MMA 170

Страница 1: ...Smootharc MMA 170 O P E R AT I N G M A N U A L...

Страница 2: ...orrecting any error or omission which may become apparent after the document has been issued Neither BOC nor any of its agents has independently verified the accuracy of the information contained in t...

Страница 3: ...TungstenArcWelding GTAW TIG 17 3 1 Introduction 17 3 2 Process 17 3 3 ProcessVariables 18 3 4 Welding Techniques 19 3 5 Shielding Gas Selection 20 3 6 Consumable Selection 21 3 7 Typical Welding Joint...

Страница 4: ...spaces Be alert to this at all times Keep your head out of the fumes rising from the arc Fumes from the welding of some metals could have an adverse effect on your health Don t breathe them in If you...

Страница 5: ...f damaged return cylinders to BOC immediately CylinderValve Safety When working with cylinders or operating cylinder valves ensure that you wear appropriate protective clothing gloves boots and safety...

Страница 6: ...ectrode and holder under your arm 1 4 User Responsibility Read the Operating Manual prior to installation of this machine Unauthorised repairs to this equipment may endanger the technician and operato...

Страница 7: ...ering Arc Weld Pool Workpiece Before arc welding can be carried out a suitable power source is required Two types of power sources may be used for arc welding direct current DC or alternating current...

Страница 8: ...rode Selection As a general rule the selection of an electrode is straight forward in that it is only a matter of selecting an electrode of similar composition to the parent metal It will be found how...

Страница 9: ...ans that if 1 5 mm sheet is being welded 2 0 mm diameter electrode is the recommended size The following table gives the recommended maximum size of electrodes that may be used for various thicknesses...

Страница 10: ...rtant to ensure a smooth even transfer of metal The recommended angles for use in the various welding positions are covered later CorrectTravel Speed The electrode should be moved along in the directi...

Страница 11: ...WELDING Used on plate of 12mm and over in thickness when welding can be applied from both sides It allows faster welding and greater economy of electrodes than a single V preparation on the same thic...

Страница 12: ...which tends to form sharp corners that cannot be penetrated with subsequent runs Electrodes larger than 4 0 mm are not generally used for vertical or overhead butt welds The diagrams following indica...

Страница 13: ...to have a gap or a slight overlap on the corner The use of a 1 0 2 5mm gap has the advantage of assisting penetration at the root although setting up is a problem The provision of an overlap largely...

Страница 14: ...enetration and where larger electrodes and high currents are used undercut is likely to occur Fillet Weld Data Nominal Fillet Size mm Minimum Throat Thickness mm Plate Thickness mm Electrode Size mm 5...

Страница 15: ...uns Correct selection of electrodes is important for vertical welding In overhead fillet welds careful attention to technique is necessary to obtain a sound weld of good profile Medium current is requ...

Страница 16: ...ed excessive travel speed On vertical and horizontal welds it can also be caused by too large an electrode size and incorrect electrode angles This defect can be prevented by choosing the proper weldi...

Страница 17: ...eristics of the power source can have an effect on the quality of the welds produced Shielding gas is directed into the arc area by the welding torch and a gas lens within the torch distributes the sh...

Страница 18: ...diameter of tungsten electrode higher amperage can be used with straight polarity Straight polarity is used mainly for welding Carbon steels Stainless steels Copper alloys The increased amperage provi...

Страница 19: ...ntal position 2G Torch and filler metal manual control guidelines 60 75 15 30 Nozzle Direction of travel Welding Rod Shield gas Vertical Tungsten electrode The suggested electrode and welding rod angl...

Страница 20: ...For manual welding argon is recommended Successful welding depends on the skill of the welder Helium is preferred for high speed automatic welding where deeper penetration than with argon is required...

Страница 21: ...aterial BOC Consumable C Mn and low Carbon steels BOC Mild steel TIG wire Low Alloy steels 1 25Cr 0 5Mo Comweld CrMo1 2 5Cr 1Mo Comweld CrMo2 Stainless Steel 304 304L Profill 308 316 316L Profill 316...

Страница 22: ...in sections Control penetration ACHF Zirconiated EW Zr Only thick sections Increase penetration or travel speed DCSP 2 Ceriated EW Ce2 Mild Steels Carbon Steels Alloy Steels Stainless Steels and Titan...

Страница 23: ...ent arc starts Good stability 75 Argon 25 Helium Best stability at medium currents Good arc starts Medium tendency to spit Medium erosion rate 75 Argon 25 Helium Low erosion rate Wide current range AC...

Страница 24: ...y can have a significant influence not only on the weld bead width depth of penetration and resultant quality but also on the electrical characteristics of the arc Below is a guide for electrode tip p...

Страница 25: ...ece and the flat surface of the second piece flow together Since the edge will melt faster dip the filler rod next to the edge and make sure you are using enough filler metal to complete the joint T j...

Страница 26: ...f the contamination and eliminate it promptly 6 Use appropriate chemical cleaners wire brush or abrasives prior to welding Inclusion of tungsten or oxides in weld 1 Poor lift starting technique 2 Exce...

Страница 27: ...or notches Change the weld joint design 4 Increase bead size Decrease root opening Use preheat Prevent craters 5 Eliminate sources of hydrogen joint restraint and use preheat Inadequate shielding 1 Ga...

Страница 28: ...or 3 Welding current regulator 4 On Off switch 5 Process selector switch MMA Lift TIG 6 Heavy duty 15A input plug 7 Negative 35 dinse connector 8 Positive 35 dinse connector 4 0 Machine Specifications...

Страница 29: ...Manual Metal Arc welding MMA Select the current as per the recommendations of the consumable manufacturer Select the polarity of the electrode cable as per the recommendations Select the process sele...

Страница 30: ...Industrial Heavy duty 15A Rated Current A MMA 27 5 TIG 20 3 No loadVoltage V 65 Output Current Range A 20 170 Rated OutputVoltage V 26 8 16 8 Duty Cycle 35 100 MMA 170A 132A TIG 170A 132A No load Loss...

Страница 31: ...ack of the unit for ventilation 7 2Troubleshooting Main switch signal light is not lit Unit does not get electricity Check mains fuses and replace if necessary Check mains cable and plug replace damag...

Страница 32: ...ed 8 2 Limitations on Warranty The following conditions are not covered Non compliance with operating and maintenance instructions such as connection to incorrect faulty voltage supply including volta...

Страница 33: ...cylinder Never use oxygen for venting containers 9 0 Recommended Safety Guidelines Diagram and safety explanation Electrical safety alert Welding electrode causing electric shock Fumes and gases comin...

Страница 34: ...34...

Страница 35: ...35...

Страница 36: ...correct at the time of printing Whilst proper care has been taken in the preparation no liability for injury or damage resulting from its improper use can be accepted BOC Limited 970 988 Great South R...

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