Miller Millermatic 251 Owner's Manual
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Miller Millermatic 251 Owner's Manual

Arc welding power source and wire feeder
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Millermatic 251
And M-25 Gun
OM-1326
205 654P
January 2004
Processes
MIG (GMAW) Welding
Flux Cored (FCAW) Welding
Description
Arc Welding Power Source
and Wire Feeder
R

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Summary of Contents for Miller Millermatic 251

  • Page 1 OM-1326 205 654P January 2004 Processes MIG (GMAW) Welding Flux Cored (FCAW) Welding Description Arc Welding Power Source and Wire Feeder Millermatic 251 And M-25 Gun Visit our website at www.MillerWelds.com...
  • Page 2 ISO 9001:2000 Quality System Standard. particular model are also provided. Miller Electric manufactures a full line of welders and welding related equipment. For information on other quality Miller products, contact your local Miller distributor to receive the latest full line catalog or individual catalog sheets.

  • Page 3: Table Of Contents

    TABLE OF CONTENTS SECTION 1 − SAFETY PRECAUTIONS - READ BEFORE USING ........1-1.
  • Page 4 TABLE OF CONTENTS SECTION 8 − MIG WELDING (GMAW) GUIDELINES ..........8-1.

  • Page 5: Section 1 − Safety Precautions - Read Before Using

    SECTION 1 − SAFETY PRECAUTIONS - READ BEFORE USING som _8/03 1-1. Symbol Usage Means Warning! Watch Out! There are possible hazards with this procedure! The possible hazards are shown in the adjoining symbols. This group of symbols means Warning! Watch Out! possible Y Marks a special safety message.
  • Page 6 ARC RAYS can burn eyes and skin. BUILDUP OF GAS can injure or kill. D Shut off shielding gas supply when not in use. Arc rays from the welding process produce intense D Always ventilate confined spaces or use visible and invisible (ultraviolet and infrared) rays that can burn eyes and skin.

  • Page 7: Additional Symbols For Installation, Operation, And Maintenance

    1-3. Additional Symbols For Installation, Operation, And Maintenance FIRE OR EXPLOSION hazard. MOVING PARTS can cause injury. D Do not install or place unit on, over, or near D Keep away from moving parts such as fans. combustible surfaces. D Keep all doors, panels, covers, and guards D Do not install unit near flammables.

  • Page 8: Principal Safety Standards

    1-5. Principal Safety Standards Safety in Welding, Cutting, and Allied Processes, ANSI Standard Z49.1, Boulevard, Rexdale, Ontario, Canada (phone: from American Welding Society, 550 N.W. LeJeune Rd, Miami FL 33126 800−463−6727 or in Toronto 416−747−4044, website: www.csa−in- (phone: 305-443-9353, website: www.aws.org). ternational.org).

  • Page 9: Section 2 − Consignes De Sécurité − À Lire Avant Utilisation

    SECTION 2 − CONSIGNES DE SÉCURITÉ − À LIRE AVANT UTILISATION som_fre 8/03 2-1. Signification des symboles Signifie « Mise en garde. Faire preuve de vigilance. » Cette procédure présente des risques identifiés par les symboles adjacents aux directives. Ce groupe de symboles signifie « Mise en garde. Faire preuve de vigi- Y Identifie un message de sécurité...
  • Page 10 LES RAYONS DE L’ARC peuvent cau- LES ACCUMULATIONS DE GAZ peu- ser des brûlures oculaires et cuta- vent causer des blessures ou même nées. la mort. Le rayonnement de l’arc génère des rayons visibles et D Couper l’alimentation en gaz protecteur en cas de invisibles intenses (ultraviolets et infrarouges) suscep- non utilisation.

  • Page 11: Autres Symboles Relatifs À L'installation, Au Fonctionnement Et À L'entretien De L'appareil

    2-3. Autres symboles relatifs à l’installation, au fonctionnement et à l’entretien de l’appareil. Risque D’INCENDIE OU D’EXPLO- LES ORGANES MOBILES peuvent SION causer des blessures. D Ne pas placer l’appareil sur une surface inflam- D Se tenir à l’écart des organes mobiles comme les mable, ni au−dessus ou à...

  • Page 12: Principales Normes De Sécurité

    2-4. Principales normes de sécurité Safety in Welding, Cutting, and Allied Processes, norme ANSI Z49.1, Rexdale, Rexdale (Ontario) Canada M9W 1R3 (téléphone : (800) de l’American Welding Society, 550 N.W. LeJeune Rd, Miami FL 33126 463−6727 ou à Toronto : (416) 747−4044, site Web : www.csa−interna- (téléphone : (305) 443−9353, site Web : www.aws.org).

  • Page 13: Section 3 − Definitions

    SECTION 3 − DEFINITIONS 3-1. Symbols And Definitions Do Not Switch Wire Feed Output Duty Cycle While Welding Volts Increase Gas Metal Arc Wire Feed Spool Welding (GMAW) Gas Input Gas Output Rated No-Load Voltage Input Press To Reset Voltage (Average) SECTION 4 −...

  • Page 14: Welding Power Source Duty Cycle And Overheating

    4-2. Welding Power Source Duty Cycle And Overheating Duty Cycle is percentage of 10 minutes that unit can weld at rated load without overheating. If unit overheats, Thermistor (T) opens, output stops, and cooling fan runs. Wait fifteen minutes for unit to cool.

  • Page 15: Volt-Ampere Curves

    4-4. Volt-Ampere Curves Normal Volt-Ampere Curves The volt-ampere curves show the normal minimum and maximum voltage and amperage output capabilities of the welding power source. Curves of other settings fall between the curves shown. AMPERES ssb1.1 10/91 − 196 844 / S-0700 4-5.

  • Page 16: Connecting A Spoolmatic 15A Or 30A Gun

    4-7. Connecting A Spoolmatic 15A Or 30A Gun The Spoolmatic 15A or 30A welding gun connects directly to the 10-pin receptacle on the front of the welding power source − no adapter required. NOTE: Two welding guns may be connected to the welding power source at the same time, but only one welding gun may be in use at any one time.

  • Page 17: Installing Gas Supply

    4-9. Installing Gas Supply Obtain gas cylinder and chain to running gear, wall, or other stationary support so cylinder cannot fall and break off valve. DO NOT use Argon/Mixed gas regulator/flowmeter with CO shielding gas. See Parts List for optional Cylinder Valve gas regulator/flowmeter.

  • Page 18: Installing Wire Spool And Adjusting Hub Tension

    4-10. Installing Wire Spool And Adjusting Hub Tension Use compression spring When a slight force is needed with 8 in (200 mm) spools. to turn spool, tension is set. To install either a 1 lb or 2 lb wire Installing 1 Or 2 lb Wire Spool spool, follow the procedure as Spindle shown in the illustration.

  • Page 19: Electrical Service Guide

    4-12. Electrical Service Guide Input Voltage Input Amperes At Rated Output Max Recommended Standard Fuse Or Circuit Breaker Rating In Amperes Circuit Breaker , Time-Delay Normal Operating Min Input Conductor Size In AWG Max Recommended Input Conductor Length In Feet (Meters) (29) (39) (47)

  • Page 20: Threading Welding Wire

    4-14. Threading Welding Wire Wire Spool Welding Wire Inlet Wire Guide Pressure Adjustment Knob Drive Roll Outlet Wire Guide Gun Conduit Cable Lay gun cable out straight. Tools Needed: Hold wire tightly to keep it from unraveling. 6 in (150 mm) Open pressure assembly.

  • Page 21: Using Gun/Cable Holder

    4-15. Using Gun/Cable Holder Side Panel Latch Cable Holder Press latch down to release and open door. Holster (2) Wrap cable around cable holder, and place gun nozzle into holster. Ref. 802 726-A OM-1326 Page 17 Return To Table Of Contents...

  • Page 22: Weld Parameters

    4-16. Weld Parameters OM-1326 Page 18 Return To Table Of Contents...
  • Page 23 201 202-A Return To Table Of Contents OM-1326 Page 19...

  • Page 24: Section 5 − Operation

    SECTION 5 − OPERATION 5-1. Controls Voltage Control Turn control clockwise to increase voltage. Wire Speed Control Turn control clockwise to increase wire feed speed. JOG Mode If the trigger on either gun is held for more than 3 seconds without striking an arc, the unit will automatically shut off weld power (and shielding gas output on MIG gun only), but will feed...

  • Page 25: Voltmeter And Wire Feed Speed Meter Operation

    5-2. Voltmeter And Wire Feed Speed Meter Operation Voltmeter If welding resumes before unit displays Wire Feed Speed Display (001) preset voltage, actual welding voltage will Wire Feed Speed Meter HL.P 001 − Communication Lost between appear on the voltmeter. Power Up Status Control Board PC1 and Display Board PC2 The wire feed speed meter always displays...

  • Page 26: Section 6 − Maintenance &Troubleshooting

    SECTION 6 − MAINTENANCE &TROUBLESHOOTING 6-1. Routine Maintenance Maintain more often Y Disconnect power during severe conditions. before maintaining. 3 Months Replace unreadable labels Repair or replace cracked weld cable Clean and tighten weld terminals 6 Months Remove drive roll and Blow out or vacuum inside.

  • Page 27: Changing Drive Roll And Wire Inlet Guide

    6-4. Changing Drive Roll and Wire Inlet Guide Securing Screw Inlet Wire Guide Loosen screw. Slide tip as close to drive rolls as possible without touching. Tighten screw. Anti-Wear Guide Install guide as shown. Drive Roll The drive roll consists of two different sized grooves.

  • Page 28: Cleaning Or Replacing Gun Liner

    6-6. Cleaning Or Replacing Gun Liner Tools Needed: Y Disconnect gun from unit first. 5/16 in, 10 mm Head Tube Remove nozzle, contact tip, and adapter. 5/16 in 10 mm Remove liner. Lay gun cable out straight before installing new liner. Blow out gun casing.

  • Page 29: Replacing Switch And/Or Head Tube

    6-7. Replacing Switch And/Or Head Tube Y Disconnect gun first. Remove handle locking nut. Slide handle. Remove switch housing. Note: If installing new switch, push switch lead connectors onto terminal of new switch (polarity is not important). Install switch back into handle, and secure with handle locking nut. If replacing head tube, continue to end of figure.

  • Page 30: Troubleshooting

    6-8. Troubleshooting Trouble Remedy Be sure line disconnect switch is On (see Section 4-13). No weld output; wire does not feed. Replace building line fuse or reset circuit breaker if open (see Section 4-13). Secure gun trigger connections (see Section 4-6). HL.P 001 appears on meters.
  • Page 31 Trouble Remedy No wire feed. Turn Wire Speed control to higher setting (see Section 5-1). Clear obstruction in gun contact tip or liner (see Sections 6-3, and 6-6). Readjust drive roll pressure (see Section 4-14). Change to correct size drive rolls (see Section 6-4). Rethread welding wire (see Section 4-14).

  • Page 32: Section 7 − Electrical Diagram

    SECTION 7 − ELECTRICAL DIAGRAM Figure 7-1. Circuit Diagram OM-1326 Page 28 Return To Table Of Contents...
  • Page 33 211 406-C Return To Table Of Contents OM-1326 Page 29...

  • Page 34: Section 8 − Mig Welding (Gmaw) Guidelines

    SECTION 8 − MIG WELDING (GMAW) GUIDELINES 8-1. Typical MIG Process Connections Y Weld current can damage electronic parts in vehicles. Disconnect both battery Regulator/ cables before welding on a Flowmeter vehicle. Place work clamp as close to the weld as possible. Shielding Supply Wire Feeder/...

  • Page 35: Typical Mig Process Control Settings

    8-2. Typical MIG Process Control Settings NOTE These settings are guidelines only. Material and wire type, joint design, fitup, position, shielding gas, etc. affect settings. Test welds to be sure they comply to specifications. Material thickness determines weld parameters. 1/8 or 0.125 in Convert Material Thickness to Amperage (A)

  • Page 36: Holding And Positioning Welding Gun

    8-3. Holding And Positioning Welding Gun NOTE Welding wire is energized when gun trigger is pressed. Before lowering helmet and pressing trigger, be sure wire is no more than 1/2 in (13 mm) past end of nozzle, and tip of wire is positioned correctly on seam. Hold Gun and Control Gun Trigger Workpiece...

  • Page 37: Conditions That Affect Weld Bead Shape

    8-4. Conditions That Affect Weld Bead Shape NOTE Weld bead shape depends on gun angle, direction of travel, electrode extension (stickout), travel speed, thickness of base metal, wire feed speed (weld current), and voltage. Push Drag Perpendicular GUN ANGLES AND WELD BEAD PROFILES Short Normal Long...

  • Page 38: Gun Movement During Welding

    8-5. Gun Movement During Welding NOTE Normally, a single stringer bead is satisfactory for most narrow groove weld joints; however, for wide groove weld joints or bridging across gaps, a weave bead or multiple stringer beads works better. Stringer Bead − Steady Movement Along Seam Weave Bead −...

  • Page 39: Troubleshooting − Excessive Spatter

    8-8. Troubleshooting − Excessive Spatter Excessive Spatter − scattering of molten metal particles that cool to solid form near weld bead. S-0636 Possible Causes Corrective Actions Wire feed speed too high. Select lower wire feed speed. Voltage too high. Select lower voltage range. Electrode extension (stickout) too long.

  • Page 40: Troubleshooting − Lack Of Penetration

    8-11. Troubleshooting − Lack Of Penetration Lack Of Penetration − shallow fusion between weld metal and base metal. Lack of Penetration Good Penetration S-0638 Possible Causes Corrective Actions Improper joint preparation. Material too thick. Joint preparation and design must provide access to bottom of groove while maintaining proper welding wire extension and arc characteristics.

  • Page 41: Troubleshooting − Waviness Of Bead

    8-14. Troubleshooting − Waviness Of Bead Waviness Of Bead − weld metal that is not parallel and does not cover joint formed by base metal. S-0641 Possible Causes Corrective Actions Welding wire extends too far out of nozzle. Be sure welding wire extends not more than 1/2 in (13 mm) beyond nozzle. Unsteady hand.

  • Page 42: Common Mig Shielding Gases

    8-16. Common MIG Shielding Gases This is a general chart for common gases and where they are used. Many different combinations (mixtures) of shielding gases have been developed over the years. The most commonly used shielding gases are listed in the following table.
  • Page 43 Problem Probable Cause Remedy Welding arc not stable. Wire slipping in drive rolls. Adjust pressure setting on wire feed rolls. Replace worn drive rolls if necessary. Wrong size gun liner or contact tip. Match liner and contact tip to wire size and type. Incorrect voltage setting for selected wire feed speed on Readjust welding parameters.

  • Page 44: Section 9 − Parts List

    SECTION 9 − PARTS LIST Hardware is common and not available unless listed. 803 008-B Figure 9-1. Main Assembly OM-1326 Page 40 Return To Table Of Contents...
  • Page 45 Item Dia. Part Mkgs. Description Quantity Figure 9-1. Main Assembly ....Fig 9-2 . . . BAFFLE, center w/components ........
  • Page 46 Hardware is common and not available unless listed. 803007-D Figure 9-2. Baffle, Center w/Components OM-1326 Page 42 Return To Table Of Contents...
  • Page 47 Item Dia. Part Mkgs. Description Quantity Figure 9-2. Baffle, Center w/Components (Fig 9-1 Item 1) ....058 427 . . . RING, retaining spool ..........
  • Page 48 Ref. 800 792-C Figure 9-3. M-25 Gun OM-1326 Page 44 Return To Table Of Contents...
  • Page 49 Item Dia. Part Mkgs. Description Quantity Figure 9-3. M-25 Gun (Fig 9-1 Item 18) ..200 258 NOZZLE, slip type .500 orf flush ..........
  • Page 50 Item Dia. Part Mkgs. Description Quantity Figure 9-4. Panel, Front w/Components (Fig 9-1 Item 17) ....208 357 LABEL, nameplate ..........
  • Page 51 Item Dia. Part Mkgs. Description Quantity Figure 9-5. Wire Drive And Gears (Fig 9-2 Item 26) ....602 009 . . . SCREW, .250-20 x 1.25 soc hd gr 8 .
  • Page 52 Item Dia. Part Mkgs. Description Quantity Figure 9-6. Panel, Rear w/Components (Fig 9-1 Item 3) ....148 809 . . . BLADE, fan 9 in 5wg 34deg .309 bore CCW .

  • Page 53: Drive Roll And Wire Guide Kits

    9-7. Drive Roll And Wire Guide Kits Note Base selection of drive rolls upon the following recommended usages: V-Grooved rolls for hard wire. U-Grooved rolls for soft and soft shelled cored wires. U-Cogged rolls for extremely soft shelled wires (usually hard surfacing types). V-Knurled rolls for hard shelled cored wires.
  • Page 54 Notes...
  • Page 55 Call LIMITED WARRANTY − Subject to the terms and conditions Induction Heating Coils and Blankets below, Miller Electric Mfg. Co., Appleton, Wisconsin, warrants 1-800-4-A-MILLER APT & SAF Model Plasma Cutting Torches to its original retail purchaser that new Miller equipment sold...

  • Page 56: Options And Accessories

    FAX: 44 (0) 1204-598066 www.MillerWelds.com Contact the Delivering Carrier to: File a claim for loss or damage during shipment. For assistance in filing or settling claims, contact your distributor and/or equipment manufacturer’s Transportation Department. PRINTED IN USA 2004 Miller Electric Mfg. Co. 1/03...

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