INTRODUCTION TO PROJECTION WELDING

LEARNING OBJECTIVES

To provide trainees with a foundational understanding of the principles,  operation, quality control, and maintenance of SA and ST type projection welding machines  as detailed in the “Practical Manual of Welding Work: Projection Manual Edition”. 

COURSE CONTENT

MODULE 1: FUNDAMENTALS OF PROJECTION WELDING 

• Topic 1.1: Introduction to Projection Welding 
  • Definition: A specialized resistance welding method using pressure and  current. 
  • Core Principle: Concentrating current and pressure at specific projections to  generate heat and form a weld, known as the “press connection method”.
  • How it Works: Converting high primary voltage (e.g., 440V) to low voltage  
  • (10-30V) and high current (approx. 20,000A) to melt and fuse workpieces.
• Topic 1.2: The Four Pillars of Weld Quality 
  • A discussion of the four critical factors for a good weld:  

1. 1. 1. Current Flow Area: How smaller areas increase current density for  effective melting. 
      2. Welding Current (KA): The volume of current needed to melt the  connection area. 
      3. Current-Carrying Time (Cycle): The heating time required to reach  the melting point. 
      4. Welding Pressure: The force applied to suppress the molten pool and  prevent material from flying apart. 

• • Nugget Formation: Understanding the fused area and what constitutes a poor  weld. 

MODULE 2: MACHINE COMPONENTS AND SYSTEMS 

• Topic 2.1: Overview of Machine Types 
  • Introduction to the SA Piston Rod, SA Lower, and ST Hose Bracket welding  machines. 
  • Highlighting structural similarities and differences between the models.

• Topic 2.2: Key Components and Their Functions 
  • Electrical System: Timers, contactors, CT (Toroidal) Coils for current  detection, and transformers. 
  • Pressure System: Booster, pressure accumulator, press head, and pressure  cylinder. 
  • Current Path: Secondary conductor, OWNS Copper Plate, upper and lower  electrodes (middle/split). 
  • Cooling System: The importance of water cooling cables and flow meters to  manage heat in conductors and electrodes.

MODULE 3: MACHINE OPERATION AND QUALITY CONTROL 

• Topic 3.1: SA Machine Operation 
  • Step-by-step operational flow from parts conveyance to welding and part  ejection. 
  • Understanding the welding cycle: early applying pressure, welding current,  and retain applying pressure. 

• Topic 3.2: ST Machine Operation 
  • Unique operational steps: setting the bracket positioner, using magnets for part  retention, and the function of the Reject Device. 
  • Role of the “KOBAM” air intake sensor in detecting improper part  positioning. 

• Topic 3.3: Quality Control & S Process Management 
  • Defining “S Process”: Understanding security processes for critically  important parts (S classification). 
  • Worker Requirements: Education and identification for staff working on S  processes. 
  • Initial Quality Checks: Performing visual, hammering, and dimension  checks. 
  • Projection Fit Check: The critical process of using carbon paper to confirm  the contact area balance is >80% for ensuring weld strength. 

MODULE 4: MAINTENANCE AND TROUBLESHOOTING 

• Topic 4.1: Routine Maintenance Procedures 
  • Importance of daily and periodic checks. 
  • Cleanliness: Removing spatter and dirt from electrodes and machine  attachments during implement changes to prevent sparks and abnormal heat.

Component Inspection: 

• OWNS Copper Plate: Inspecting for wear and tear, with a mandatory  replacement when the tear limit reaches 25%. 
• Pipes and Hoses: Checking for abrasion, holes, or tears from spatter  and heat. 
• Cooling System: Visually checking the flow meter to ensure proper  cooling water volume. 
• Topic 4.2: Electrode Care 
  • Split Electrodes: Cleaning spatter, checking for abrasion, and correcting  oxide skin with a brass brush or sandpaper. 
  • Usage Limits: Emphasizing that electrodes should not be used beyond their  defined usage limit line. 

• Topic 4.3: Common Failures and Countermeasures 
  • SA Machines: Troubleshooting issues like Burrs, Burn Marks, Deformation,  and Insufficient Strength by verifying current, pressure, time, and electrode  condition. 
  • ST Machines: Addressing failures such as Lean, Dislocation, and Float by  checking electrode abrasion, guide plates, and welding pressure. 
  • Failure Protocol: The rule for stopping the line after 3 consecutive or 5  intermittent failures and contacting a Group Leader.