PRESENTATION ON INDUCTION HEATING

GROUP

TWO

Induction heatingwhat is induction heating?

• It is a process used to bond , harden or soften metals or other conductive materials

• It heats metal parts without any physical contact ,open flame and loud noise

• it offers an attractive combination of speed , consistency and control

Background of induction heating

• its basic principles have been understood and applied to manufacturing since 1920

• during world war 2,the technology developed rapidly to meet urgent war time requirements for a fast and reliable process to harden metal engine parts

What makes induction heating unique?

• No torch or open flame is directly applied to the metal part

• Heat is actually “induced” with in the part (metal) itself by circulating electrical current

• heat is transferred to the metal through electromagnetic waves (RF)

• It is repeatable and controllable process

How induction heating works?• Set up

• Inductor with metal

How induction heating works?

• It works on basic principles of electricity• a solid state RF power supply sends an ac

current through an inductor • the part (metal) to be heated is placed inside

the inductor• the inductor serves as transformer primary

and the metal as secondary

How…

• as the metal part enters the magnetic field circulating eddy currents are induced within the metal

• these eddy currents flow against the electrical resistivity of the metal

• this generates precise and localized heat with out any direct contact between the metal and inductor

How…?

• this heating occurs with both magnetic and non magnetic parts (joule effect)

• additional heat is produced within magnetic parts through hysteresis

• hysteresis is an electrical resistance to the rapidly changing magnetic fields

• this produces internal friction which in turn produces heat

Important factors to consider

1. The characteristics of the part (metal) metal or plastic - plastics and other non conductive

materials can often be heated indirectly by first heating the conductive metal

magnetic or non magnetic - it is easier to heat magnetic materials

because they produce additional heat through hysteresis effect

Important…

thick or thin

- small or thin parts generally heat more quickly than large thick parts, especially if the larger parts need to be heated all the way through

this is because

-heating effect occurs on the surface or skin of of the part (85%)

Important…

resistivity

- Metals with strong resistance to the current flow, builds up heat quickly

- Low resistivity metals such as copper,

aluminum take longer to heat ,so

- a very hot piece of steel will be morereceptive to induction heating than a cold piece

Important…

2.Inductor design - A well-designed inductor provides the

proper heating pattern for your part and - maximizes the efficiency of the induction

heating power supply3.Power supply capacity -The size of the induction power supply

required for heating a particular part can be calculated

Important…

-First, determine how much energy needs to be transferred to the work-piece

-This depends on mass of the material to be heated specific heat of the material rise in temperature required heat losses should be considered 4. Degree of temperature change required

Important…

-more induction heating power is generally utilized to increase the degree of temprature change

Advantage of induction heating

optimized consistency

-once the system is properly set up, the heating pattern is repeatable and consistent

maximize productivity

this is due to

-it works so fast then heat is developed directly and instantly

Advantage…

-start up is instantaneous

-no warm up or cool cycle is required

improved product quality

-it decreases distortion , reject rates of the product because

-no contact between the part to be heated and inductor

increases fixture life

Advantage… -it only delivers site-specific heat to small area

of the part with out heating any surrounding parts

environmentally sound -it is clean and non polluting process -no smoke, no waste heat ,no loud noise -non conductive materials are not affected reduce energy consumption -it needs no warm up and cool down then heat loss is decreased

Disadvantage it is expensive

WHY RIGRT DESIGN OF THE INDUCTOR?

with the right design

-it is possible to heat conductive materials at any size and form

-it is possible to heat only the required portion of the material

- temperature uniformity can be achieved

Basic construction of inductor

-they are often made up of copper (very good conductor of heat and electricity)

-they can have single or multiple turns

-they are most often custom made to fit the shape and size of the part to be heated

-they are cooled by circulating water

-placing the part (metal) close to the inductor increases the flow of current and the

BASIC …amount of heat induced in the part ~ this

relationship of the part and the inductor is called Coupling efficiency of the inductor

THE – END

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