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Projection Welding: An Overview. Chonghua (Cindy) Jiang AET Integration, Inc. 50388 Dennis Ct. Wixom, MI 48393 Cindy.jiang@aet-int.com. Definition.

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projection welding an overview

Projection Welding: An Overview

Chonghua (Cindy) Jiang

AET Integration, Inc.

50388 Dennis Ct.

Wixom, MI 48393

Cindy.jiang@aet-int.com

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

definition
Definition

“Projection welding is an electric resistance welding process that produces welds by the heat obtained from the resistance to the flow of the welding current. The resulting welds are localized at predetermined points by projections, embossments, or intersections”

(Welding Handbook, Vol. 3, Part 2, p50)

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

typical projection designs
Typical Projection Designs

a. Embossed

b. Stud-to-Plate

c. Annular

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide4

Examples of Projection Design

Examples of Various Projection Designs Before and After Welding

(Welding Handbook, Vol. 3, Part 2, p56)

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide5

Examples of Annular Projections

(Welding Handbook, Vol. 3, Part 2, p58)

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide6

Typical Commercially Available Fasteners Used in Projection Welding

(Welding Handbook, Vol. 3, Part 2, p59)

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide7

Projection Welding Equipment

  • Medium Frequency (MFDC) Machine
  • AC Machine
  • Capacitor Discharge (CD) Machine

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide8

Projection Welding Equipment (Cont’d)

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide9

Factors Affecting Heat Balance

  • Design and location of the projection
  • Thickness of the sections
  • Thermal and electrical conductivity of the materials
  • Heating rate
  • Electrode geometry and alloy
  • Tooling alignment
  • Weld force

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide10

Key Process Variables

  • Welding Current
    • Welding current must be at least high enough to create fusion before the projection has completely collapsed
  • Weld Time
    • Weld time is dependent on the welding current and projection rigidity
    • Depending on the type of base metal and its surface conditions, multiple pulses can be applied to yield the desired weld performance
  • Electrode/Dies
    • Proper electrode design and alloy is a major factor in making projection welds
  • Electrode Force
    • Electrode force is critical for proper projection collapse without expulsion and formation of a sound weld

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

formation of projection welds
Formation of Projection Welds

Embossed Projection Weld

(fused nugget forms)

Annular Projection Weld

(solid state bonding develops)

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

materials suitable for projection welding
Materials Suitable for Projection Welding
  • Low carbon steel
  • Hardenable steels
  • Stainless steels-ferritic, martensitic, and austenitic types
  • Nickel-base alloys
  • Copper alloys
  • Aluminum and magnesium alloys
  • Titanium alloys
  • Coated and plated steels

(Welding Handbook, Vol. 3, Part 2, p63)

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide13

Materials Suitable for Projection Welding-Example

Welding Trials on 1.6 mm Magnesium AZ31, AET

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

example of project weld property microhardness
Example of Project Weld Property-Microhardness

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

weld quality
Weld Quality
  • Parts preparation
    • Weld area clean of grease, rust, scale, dirt or shearing burrs
    • Less variance in part tolerance before welding
  • Projection size and shape
  • Materials
  • Welding technique
  • Heat balance

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide16

Fracture surface

No Bonding

Projection Weld Performance Improvement: Example 1

  • Issue: Weld did not pass dye penetrant test and pull test
  • Root Causes:
    • Tooling misalignment
    • Insufficient forging force at the faying surface
  • Actions Taken:
    • Check tooling misalignment by using carbon imprints between faying surfaces
    • Increase applied forging force
    • Adjust welding parameters to get sufficient weld bonding area

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide17

Projection Weld Performance Improvement: Example 2

Intergranular Fracture Mode of a Projection Weld Failed during Service

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide18

Projection Weld Performance Improvement: Example 2 (Cont’d)

Base Metal

Base Metal

HAZ

HAZ

Non-broken Part

Broken part with Intergranular Fracture

  • The broken part with IG fracture shows primary ferrite along grain boundary. This generally results in
  • low ductility and fracture toughness.
  • The base metal microstructure of the broken part with IG fracture is a result of improper heat treatment
  • of the base metal before it was welded.

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide19

Process Advantages and Limitations

  • Advantages
    • Versatility
    • Speed
    • Ease of automation
    • Ability to make multiple welds simultaneously
    • Longer electrode/tooling life
  • Limitations
    • The forming of projection may require an additional step of operation
    • Limitations on materials projection weldability

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

projection welding applications
Projection Welding Applications
  • Tubular connections

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

projection welding applications cont d
Projection Welding Applications (Cont’d)

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

projection welding applications cont d1
Projection Welding Applications (Cont’d)
  • Attaching nuts and stud
  • Sheet metal assemblies
  • Tank fittings and ferrules
  • Fusites

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington

slide23

Potential Projection Welding Applicationsfor Shipbuilding

  • Fabricate the metal sandwich plate of large area
    • Projection welding
    • Adhesive assisted projection welding

(STS Shipbuilding, South Korea)

(Welding in the World, v 53, n 7-8, p 5-11, 2009)

  • Attach nuts and stud

Welding in Shipbuilding

May 10-11, 2011

Seattle, Washington