Miller STi 270 Owner's Manual
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Miller STi 270 Owner's Manual

Miller STi 270 Owner's Manual

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STi 270 And STi 270C
OM-263 706A
Processes
TIG (GTAW) Welding
Stick (SMAW) Welding
Description
Arc Welding Power Source
CE
2013−11

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Summary of Contents for Miller STi 270

  • Page 1 OM-263 706A 2013−11 Processes TIG (GTAW) Welding Stick (SMAW) Welding Description Arc Welding Power Source STi 270 And STi 270C...
  • Page 2 From Miller to You Thank you and congratulations on choosing Miller. Now you can get the job done and get it done right. We know you don’t have time to do it any other way. That’s why when Niels Miller first started building arc welders in 1929, he made sure his products offered long-lasting value and superior quality.

  • Page 3: Table Of Contents

    ............5-2. Preparing Unit For Stick (SMAW) Welding (STi 270 Model Shown) .

  • Page 4: Declaration Of Conformity

    ITW Welding Italy S.r.l Via Privata Iseo 6/E, 20098 San Giuliano M.se, (MI) Italy declares that the prod­ uct(s) identified in this declaration conform to the essential requirements and provisions of the stat­ ed Council Directive(s) and Standard(s). Product/Apparatus Identification: Product Stock Number STi 270 059016022 STi 270C 059016023 Council Directives: •...

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

    SECTION 1 − SAFETY PRECAUTIONS - READ BEFORE USING som 2013−09 Protect yourself and others from injury — read, follow, and save these important safety precautions and operating instructions. 1-1. Symbol Usage DANGER! − Indicates a hazardous situation which, if Indicates special instructions.
  • Page 6 D Remove stick electrode from holder or cut off welding wire at FUMES AND GASES can be hazardous. contact tip when not in use. D Wear body protection made from durable, flame−resistant material Welding produces fumes and gases. Breathing (leather, heavy cotton, wool). Body protection includes oil-free these fumes and gases can be hazardous to your clothing such as leather gloves, heavy shirt, cuffless trousers, high health.

  • 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 injure. 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: California Proposition 65 Warnings

    1-4. California Proposition 65 Warnings Welding or cutting equipment produces fumes or gases This product contains chemicals, including lead, known to which contain chemicals known to the State of California to the state of California to cause cancer, birth defects, or other cause birth defects and, in some cases, cancer.

  • Page 9: Section 2 − Definitions

    SECTION 2 − DEFINITIONS 2-1. Additional Safety Symbols And Definitions Some symbols are found only on CE products. Warning! Watch Out! There are possible hazards as shown by the symbols. Safe1 2012−05 Do not discard product (where applicable) with general waste. Reuse or recycle Waste Electrical and Electronic Equipment (WEEE) by disposing at a designated collection facility.

  • Page 10: Miscellaneous Symbols And Definitions

    Do not weld on drums or any closed containers. Safe16 2012−05 Do not remove or paint over (cover) the label. Safe20 2012−05 Wear hat and safety glasses. Use ear protection and button shirt collar. Use welding helmet with correct shade of filter. Wear complete body protection.

  • Page 11: Section 3 − Specifications

    20 − 30.8 V 7.9 KVA / 7.06 KW (22.4 in.) Net: 23.2 100% Duty Cycle (51.1) Width: 219 mm STi 270 50 VDC (8.6 in.) Ship: 25.2 7.7 KVA / 6.7 KW (55.6) Height: 347 mm 40% Duty Cycle...

  • Page 12: Volt-Ampere Curves

    3-4. Volt-Ampere Curves Volt-ampere curves show minimum and maximum voltage and amperage output capabilities of welding power source. All Models Curves of other settings fall between curves shown. 10 20 30 40 50 60 70 80 90 100 120 130140150 160170180 190200 210 220230240250 260270280 DC Amperage (A) 3-5.

  • Page 13: Section 4 − Installation

    SECTION 4 − INSTALLATION 4-1. Serial Number And Rating Label Location The serial number and rating information for the power source is located on the bottom of the machine. Use the rating labels to determine input power requirements and/or rated output. For future reference, write serial number in space provided on back cover of this manual. 4-2.

  • Page 14: Weld Output Terminals And Selecting Cable Sizes

    4-3. Weld Output Terminals And Selecting Cable Sizes* NOTICE − The Total Cable Length in Weld Circuit (see table below) is the combined length of both weld cables. For example, if the power source is 30 m (100 ft) from the workpiece, the total cable length in the weld circuit is 60 m (2 cables x 30 m). Use the 60 m (200 ft) column to determine cable size.

  • Page 15: Stick Dcep (Direct Current Electrode Positive) Connections

    4-5. Stick DCEP (Direct Current Electrode Positive) Connections Turn off power before mak- ing connections. Negative (−) Weld Output Terminal Connect work lead to negative weld output terminal. Positive (+) Weld Output Terminal Connect electrode holder to posi- tive weld output terminal. 4-6.

  • Page 16: Connecting 3-Phase Input Power

    4-7. Connecting 3-Phase Input Power = GND/PE Earth Ground Tools Needed: input2 2012−05 − 956172127_1-A OM-263 706 Page 12...

  • Page 17: Connecting To 3-Phase Engine Generator W/400 Volt Output

    4-7. Connecting 3-Phase Input Power (Continued) See rating label on unit and check input volt- Connect green or green/yellow grounding Installation must meet all National and age available at site. conductor to disconnect device grounding ter- Local Codes − have only qualified per- minal first.

  • Page 18: Section 5 − Operation

    SECTION 5 − OPERATION 5-1. Controls (STi 270 Model Shown) 956172127_2-A Voltage/Amperage Selector Switch Input Line Voltage Error Indicator Light Parameter Selector Switch When lit and emitting a continuous beep sig- Press and release switch to scroll through Use switch to display welding voltage or sequencer parameters.

  • Page 19: Preparing Unit For Stick (Smaw) Welding (Sti 270 Model Shown)

    5-2. Preparing Unit For Stick (SMAW) Welding (STi 270 Model Shown) Positive Weld Output Receptacle Voltage Reduction Setting (VRD) (STi Arc Force 270 Model) Negative Weld Output Receptacle Use Arc Force to increase short-circuit am- To change voltage reduction setting (VRD), perage at low arc voltage.

  • Page 20: Preparing Unit For Tig (Gtaw) Welding (Sti 270 Model Shown)

    5-3. Preparing Unit For TIG (GTAW) Welding (STi 270 Model Shown) Current (A) Remote 2T Trigger Operation (All Models) Main Amps Time Positive Weld Output Terminal Process Selector Switch time for unit to complete its start-up cycle. Negative Weld Output Terminal...

  • Page 21: Process Control

    5-4. Process Control Process Control Use control to select Stick, or the TIG Lift Arc process. Stick (SMAW) - This is a DCEP (di- rect current electrode positive) process (see Section 5-6). Make connections according to Section 4-5. TIG Lift-Arct - This is a DCEN (di- rect current electrode negative) process in which the electrode must come in contact with the work...

  • Page 22: Stick Start Procedure − Scratch Start Technique

    5-6. Stick Start Procedure − Scratch Start Technique With Stick selected, start arc as follows: Electrode Workpiece Drag electrode across workpiece like strik- ing a match; lift electrode slightly after touch- ing work. If arc goes out electrode was lifted to high.

  • Page 23: Section 6 − Maintenance And Troubleshooting

    SECTION 6 − MAINTENANCE AND TROUBLESHOOTING 6-1. Routine Maintenance Disconnect power before maintaining. Maintain more often during severe conditions. A. Welding Power Source Δ = Repair n = Check Z = Change ~ = Clean l = Replace * To be done by Factory Authorized Service Agent Every Months nl Labels...

  • Page 24: Troubleshooting

    6-3. Troubleshooting Trouble Remedy No weld output; unit completely Place line disconnect switch in On position (see Section 4-7). inoperative. Check and replace line fuse(s), if necessary, or reset circuit breaker (see Section 4-7). Check for proper input power connections (see Section 4-7). No weld output.

  • Page 25: Section 7 − Electrical Diagrams

    SECTION 7 − ELECTRICAL DIAGRAMS 956172128_A Figure 7-1. Circuit Diagram For STi 270 OM-263 706 Page 21...
  • Page 26 956172129_A Figure 7-2. Circuit Diagram For STi 270C OM-263 706 Page 22...

  • Page 27: Section 8 − Selecting/Preparing A Tungsten

    SECTION 8 − SELECTING AND PREPARING A TUNGSTEN FOR DC OR AC WELDING WITH INVERTER MACHINES gtaw_Inverter_2011-06 Whenever possible and practical, use DC weld output instead of AC weld output. 8-1. Selecting Tungsten Electrode ( Wear Clean Gloves To Prevent Contamination Of Tungsten Not all tungsten electrode manufacturers use the same colors to identify tungsten type.

  • Page 28: Section 9 − Guidelines For Tig Welding (Gtaw)

    SECTION 9 − GUIDELINES FOR TIG WELDING (GTAW) 9-1. Positioning The Torch Grinding the tungsten electrode produces dust and flying sparks which can cause injury and start fires. Use local exhaust (forced ventilation) at the grinder or wear an approved respirator. Read MSDS for safety information.

  • Page 29: Torch Movement During Welding

    9-2. Torch Movement During Welding Tungsten Without Filler Rod ° Welding direction Form pool Tilt torch Move torch to front of pool. Repeat process. Tungsten With Filler Rod ° ° Welding direction Form pool Tilt torch Add filler metal Remove rod Move torch to front of pool.

  • Page 30: Section 10 − Stick Welding (Smaw) Guidelines

    SECTION 10 − STICK WELDING (SMAW) GUIDELINES 10-1. Stick Welding Procedure Weld current starts when electrode touches work- piece. Weld current can damage electronic parts in vehicles. Disconnect both battery Equipment Needed: Tools Needed: cables before welding on a vehicle. Place work clamp as close to the weld as possible.

  • Page 31: Electrode And Amperage Selection Chart

    10-2. Electrode and Amperage Selection Chart 6010 DEEP 3/32 MIN. PREP, ROUGH HIGH SPATTER 6011 DEEP 6010 5/32 & 6013 EP,EN GENERAL 3/16 6011 7/32 SMOOTH, EASY, 7014 EP,EN FAST 1/16 LOW HYDROGEN, 7018 5/64 STRONG 3/32 FLAT SMOOTH, EASY, 7024 EP,EN HORIZ...

  • Page 32: Positioning Electrode Holder

    10-4. Positioning Electrode Holder End View Of Work Angle Side View Of Electrode Angle After learning to start and hold an arc, practice running beads of weld metal on flat plates using a full electrode. ° ° Hold the electrode nearly per- pendicular to the work, although °...

  • Page 33: Conditions That Affect Weld Bead Shape

    10-7. Conditions That Affect Weld Bead Shape Weld bead shape is affected electrode angle, length, travel speed, and thick- ness of base metal. Correct Angle ° - ° Angle Too Large Angle Too Small Electrode Angle Drag Spatter Arc Length Normal Too Long Too Short...
  • Page 34 10-10. Welding Groove (Butt) Joints Tack Welds Prevent butt joint distortion by tack welding the materials in position before final weld. Workpiece distortion occurs when heat is applied locally to a joint. One side of a metal plate will “curl” up toward the weld.

  • Page 35: Weld Test

    10-12. Weld Test Vise Weld Joint Hammer Strike the weld joint in the direction shown. A good weld bends over but does not break. If the weld breaks, examine it to determine the cause. If the weld is porous (many holes), the arc length was probably too long.
  • Page 36 Lack Of Penetration − shallow fusion between weld metal and base metal. Lack of Penetration Good Penetration Possible Causes Corrective Actions Improper joint preparation. Material too thick. Joint preparation and design must provide access to bottom of groove. Improper weld technique. Keep arc on leading edge of weld puddle.

  • Page 37: Section 11 − Parts List

    SECTION 11 − PARTS LIST Hardware is common and not available unless listed. 956172127_7-A Figure 11-1. Main Assembly For STi 270 Dia. Item Part Description Quantity Mkgs. Figure 11-1. Main Assembly For STi 270 057116003 Strap, Shoulder Assy . . .
  • Page 38 Dia. Item Part Mkgs. Description Quantity Figure 11-1. Main Assembly For STi 270 (continued) 156005193 Bracket, Door ..............
  • Page 39 ....... . . 956172113 Label, Side STi 270 . . .
  • Page 40 . . . 356029264 . . . Nameplate, Rear, STi 270−270C ........
  • Page 43 Effective January 1, 2013 (Equipment with a serial number preface of MD or newer) This limited warranty supersedes all previous Miller warranties and is exclusive with no other guarantees or warranties expressed or implied. LIMITED WARRANTY − Subject to the terms and conditions 90 Days —...
  • Page 44 File a claim for loss or damage during Phone: 39 (0) 2982901 Fax: 39 (0) 298290-203 shipment. email: miller@itw−welding.it For assistance in filing or settling claims, contact your distributor and/or equipment manufacturer’s Transportation Department. © ORIGINAL INSTRUCTIONS − PRINTED IN USA 2013 Miller Electric Mfg. Co. 2013−01...

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