SMAW THEORY. Course # WELD1110

Transcription

1 Course # WELD1110 SMAW THEORY OBJECTIVES: At the completion of this course the student will be able to recall from lectures, demonstrations and audio visual aids the theory and applications of the (SMAW) Shielded Metal Arc Welding process. The student will also be required to identify and correctly set- up various power sources with different electrodes. EVALUATION: The evaluation of the student will be made as follows: 25% - Midterm Quiz 50% - Final Written Exam 5% - Class attendance 5% - Home work assignments. 15%- Demonstration by the student of safe and correct set up of SMAW power source. NOTE: Grading aligned with SECC guidelines

2 REQUIRED TEXT: MODERN WELDING Copyright 2004 REQUIRED HOME WORK ASSIGNMENTS: Chapter 5 review questions 1-20 on page 129. Chapter 6 review questions 1-20 on page 162. Chapter 11 review questions 1-10 on page 296. NOTE: Because of the hazards related to Shielded Metal Arc Welding, SAFETY will be emphasized throughout the course!

3 COURSE # WELD1110 SHIELDED METAL ARC WELDING EQUIPMENT I. Introduction A. SMAW Process 1. Definition II. III. IV. History of SMAW Hazards A. Burns 1. Base Metal 2. Slag 3. Molten metal droplets B. Ultraviolet Rays C. Infrared rays D. Visible radiation or light rays E. Fumes 1. Lead, cadmium, chromium 2. Zinc F. Electric shock Safety and Protective Equipment A. Safety Glasses W/side shields (ANSI Z87 approved) B. Welding Helmet or Hood 1. Filter lens 2. Protection from Rays 3. Adjustment of Hood C. Welding Booth 1. Curtains 2. Ventilation 3. Fire Protection D. Protective Clothing V. Safety Rules (Student review from WELD1100 Orientation) VI. Basic Electricity for SMAW Power Sources A. Terms for Electricity 1. Voltage a. open circuit b. closed circuit c. Arc 2. Amperage 3. Resistance B. Magnetism 1. What is Magnetism 2. Magnetic permeability

4 3. Reluctance 4. Lines of flux 5. Flux density C. Generation of Electricity 1. Relative motion of conductor to magnetic field 2. Define Alternating current (AC) 3. Define direct current (DC) VII. Power Sources for Welding A. Primary Power B. Secondary Power 1. Mutual induction a. Primary = amperes b. Secondary = amperes c. Turns in secondary C. Basic Current types produced by: 1. Transformer = Alternating Current only 2. Alternator = Alternating Current 3. DC Generator = Direct Current 4. Transformer/ Rectifier = Alternating or Direct Current a. Selenium Rectifier b. Diodes D. Types of Current Controls 1. Moveable Primary 2. Shunt 3. Tapped Secondary 4. Electrical Resistance 5. Reactor Control E. Direct Current Types (Polarity) 1. Direct Current Electrode Negative (DCEN or Straight) 2. Direct Current Electrode Positive (DCEP or Reverse) F. Polarity Switch 1. AC 2. DCEN 3. DCEP G. Definition of Duty Cycle H. Trouble shooting of Welding Machine VIII. Parts of the Welding Circuit A. Welding Cables 1. Sizes 2. Material a. Copper b. Aluminum B. Connectors C. Electrode Holder

5 1. Rating 2. Possible angels of clamping 3. Slang Term Stinger D. Ground Clamp Rating E. Welding Electrodes 1. Bare 2. Carbon 3. Flux Covered IX. Electrode Applications 1. Carbon a. Applications 2. Bare a. Applications 3. Flux coated a. Applications b. Advantages X. AWS Electrode Classification System A. Meaning of Letters and Digits B. Color Code (No longer used) XI. Variables Affecting Weld Quality A. Current setting B. Arc Length 1. Effect on welding heat (Arc Voltage) 2. Effect on bead width C. Travel Speed 1. Effect on Penetration 2. Effect on Bead Size 3. Metal thickness D. Electrode angle (Bisect Joint) XII. Magnetic Arc Disturbance (Arc Blow) A. Causes B. Corrections 1. Change ground clamp placement 2. Switch to AC if possible 3. Adjust electrode angle 4. Shorten Arc Length 5. Change direction of travel XIII. Type of Joints A. Butt or Groove B. Lap

6 C. Tee D. Corner E. Plug or Slot F. Other XIV. Position and Designation of Weld types A. Fillet welds (Lap & Tee) are designated by the letter F B. Groove Welds are designated by the letter G C. Flat position welds on plate are indicated by the number 1 D. Horizontal position welds by the number 2 E. Vertical position by the number 3 F. Overhead position by the number 4 G. Pipe position 1 indicates that the pipe is rolled during welding H. Pipe position 2 indicates that the pipe is vertical and the weld is horizontal I. Pipe position 5 indicates that the pipe is horizontal and the weld is vertical J. Pipe position 6 indicates that the pipe is fixed at a 45 degree angle K. A designation R indicates that access to the pipe by the welder is restricted XV. XVI. XVII. Types of Deposit or Beads A. Stringers B. Weaves C. Intermittent Welding Design and Bead Profile A. Stress Risers B. Weld bead transitions and tie ins C. Craters, starts and restarts D. Weld termination (Craters and profiles) E. Weld size requirements Workmanship and Weld Quality A. First Line of Inspection B. Defects and Corrections C. Inter- bead Cleaning