Microelectronics Clean Room Electrical and Computer Engineering Orbital Tube Welder by Clayton Gatewood.

Microelectronics Clean RoomMicroelectronics Clean RoomElectrical and Computer Electrical and Computer EngineeringEngineeringOrbital Tube Welder

by Clayton Gatewood

OverviewOverviewGeneral InformationSafetySet-upTube Preparation: facing,

cleaningOperationWeld SchedulesWeld Evaluation

by Clayton Gatewood

Orbital Tube WeldingOrbital Tube WeldingGas Tungsten Arc

Welding (GTAW) process

Fusion WeldingModel 8 Weld

HeadModel 207A Power

SupplyArgon Gas

CylinderFacing ToolARC Machines, Inc.

by Clayton Gatewood

Gas Tungsten Arc Welding (GTAW) Gas Tungsten Arc Welding (GTAW) ProcessProcess

Used to weld tubing that remains in-place while the tungsten electrode rotates around the target joint.

Material edges are heated by an arc and are fused together without a filler.

by Clayton Gatewood

SafetySafety Electricity Hazard: Shock, RF

Starting, Pacemaker, Electric Storage Devices

Fire Hazard: Clothing, Sealed Containers, Welded Material Hot to Touch

Harmful UV Radiation (eyes and skin)

Toxic Fumes from Welding Stainless Steel, Hexavalent Chromium (lung cancer)

Air Displacement by Argon Gas Factory Training Essential Keep Hands and Fingers Clear Compressed Gas Cylinders Cleaning Chemicals

by Clayton Gatewood

Set-UpSet-UpEnsure Power is

OffConnections:

Weld Head, Argon Gas,main power cord

Apply Argon (¼ turn) @ 20 psi

by Clayton Gatewood

Tube PreparationTube PreparationFacing

by Clayton Gatewood

Welding CleanlinessWelding CleanlinessMaterials to be welded must be

free of grease, oil, rust, dirt, paint and other contaminants.

Dirty materials can result in porosity, discoloration, slag deposits, and generally poor quality welds.

by Clayton Gatewood

OperationOperation Align target joint with

tungsten electrode Connect Argon Purge

Line and set for 5 psi (for ¼” OD tubing)

Select Weld Schedule Ensure Power Supply is

“Ready to Weld” Press “Seq Start” Prepurge, Weld,

Downslope,

Postpurge

by Clayton Gatewood

Weld Schedule Weld Schedule DevelopmentDevelopment

An orbital tube weld may be done in 4 or more levels.

It must include enough time for tie-in before the downslope.

by Clayton Gatewood

Weld SchedulesWeld SchedulesPre / Post Purge

TimeUp / DownslopeRotation DirectionRotation DelayPulse ModeRotation ModeRPM (Rotor Travel

Speed)Level TimesLevel AmpsBackground AmpsPulse Times

by Clayton Gatewood

Power Supply SequencePower Supply Sequence

by Clayton Gatewood

Sample Weld SchedulesSample Weld Schedules

by Clayton Gatewood

Weld EvaluationWeld Evaluation60 to 80% overlap

on outer diameterPoor rotation delayBorescope to

inspect inner diameter

Full penetrationNo cracks,

undercut,crevices, pits, or embedded or protruding material

by Clayton Gatewood

Weld ProfilesWeld Profiles

by Clayton Gatewood

Weld DefectsWeld DefectsWeld Problem Probable cause(s)

Lack ofpenetration to I.D.

1) Insufficient amperage2) Tungsten offset3) Change of heat number4) Sulfur mismatch5) Variable wall thickness

OD Concavity 1) Too much amperage2) Gravity (heavy wall)3) Very low sulfur

ID Concavity 1) Excessive ID purge pressure

Discoloration of ID(oxidation)

1) Excessive oxygen and/or moisture in IDpurge gas2) Moisture and/or oxygen in or on tubing3) Chemical residue from EP4) Leak in purging set up5) Pinched gas hose

Misalignment 1) Dimensional tolerances - out of round2) Wall thickness mismatch3) Worn out TCIs4) Poor workmanship

Porosity 1) Moisture in purge gas2) Moisture or dirt on weld components

Excessive slagging 1) impurities in base material especiallyoxides of aluminum, calcium, silicon

by Clayton Gatewood

Argon Purge and OxygenArgon Purge and Oxygen

Left to Right = effect of increasing levels of oxygen in the argon purge

by Clayton Gatewood

Possibilities …Possibilities …

by Clayton Gatewood

Works CitedWorks Cited"MODEL 207 Operator Training Guidelines."

Arc Machines, Inc.CD-ROM.Pacoima, CA: Arc Machines, Inc., 2007.

Model 207 Microprocessor-Controlled Power Supply.1 Nov. 1996. Arc Machines, Inc.. 16 Oct. 2007.<http://www.arcmachines.com/prodMed/m207ps/m207ps.html>.

by Clayton Gatewood