HEAT BALANCE

HEAT BALANCE

Heat Balance

Lesson ObjectivesWhen you finish this lesson you will understand:• Factors Effecting Heat Balance• Solve Heat Balance Problems

Learning Activities1. View Slides; 2. Read Notes, 3. Listen to lecture4. Do on-line

workbook

Keywords: Heat Generation, Heat Conductions, Electrode Geometry, Resistivity, Thermal Conductivity

Factors Affecting Heat Balance• Relative electrical and thermal conductivities of the

metals to be jointed

• Relative geometry of the parts at the joint

• Thermal and electrical conductivities of the electrodes

• Geometry of the electrodes

Factors affecting uniform distribution of heat are :

• Projection design and location.• Thickness of the section.• Thermal and electrical conductivities.• Heating rate.• Electrode alloy.

Heat Balance in Projection Welds

After 20%welding time

At the end ofwelding time

Temperature

Elec

trode

Elec

t rode

Wor

kpie

ce

Temperaturedistribution atvarious locationduring projectionwelding.

Temperature Distribution

Heat Dissipation

Weld Nugget

Water-Cooled Copper Alloy Electrode

Water-Cooled Copper Alloy Electrode

Base Metal

Base Metal

Improving Heat Balance Methods for Spot Welding

(a) (b)

Improving Heat Balance Methods for Spot WeldingHigh ConductivityAlloy High Resistance

Electrode

High ConductivityAlloy

Low ConductivityAlloy

Low ConductivityAlloy

(a) (b) (c) (d)