Certified Robotic Arc Welding (CRAW) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

DCEP polarity

Direct current electrode positive: electrode is positive, workpiece negative. Provides deeper penetration and is standard for GMAW and SMAW.

Contact tip to work distance

Distance from contact tip to workpiece. Affects current and arc stability; typically 1/4 to 1/2 inch for short-circuit GMAW.

Shielding gas flow rate

Typical GMAW flow is 10-20 CFH; GTAW 15-25 CFH. Too high causes turbulence and porosity; too low allows contamination.

Spray transfer

GMAW mode with high current and argon-rich gas; fine droplets transfer axially. Smooth arc, deep penetration, no spatter.

Short-circuit transfer

GMAW mode where wire contacts puddle and pinches off. Low heat input, used for thin sheet and out-of-position welds.

SMAW electrode E7018

Low-hydrogen iron powder electrode; requires dry storage; used for structural steel; 70 ksi tensile strength.

GTAW AC for aluminum

Alternating current alternates cleaning (DCEP) and penetration (DCEN); breaks oxide layer and provides good weld.

Penetrant testing

Surface NDT method: apply penetrant, remove excess, apply developer; reveals surface-breaking defects in nonporous materials.

Magnetic particle testing

NDT method using magnetic fields and iron particles; detects surface and near-surface defects in ferromagnetic materials only.

Ultrasonic testing

NDT using high-frequency sound waves; detects internal defects; requires couplant; good for planar defects.

Radiographic testing

NDT using X-rays or gamma rays; detects internal volumetric defects; produces film or digital image; radiation safety required.

Weld joint types

Five basic joints: butt, lap, T, corner, and edge. Each has specific groove or fillet weld configurations.

Heat input formula

Heat input (J/in) = (voltage × current × 60) / travel speed (in/min). Used to control cooling rate and mechanical properties.

Duty cycle

Percentage of a 10-minute period a welding machine can operate at rated output without overheating. Example: 60% means 6 minutes welding, 4 minutes cooling.

Fillet weld symbol

Right triangle placed on reference line; size on left, length on right; arrow side below line, other side above.

Weld-all-around symbol

Circle at junction of reference line and arrow; indicates weld continues around entire joint perimeter.

Field weld symbol

Flag at junction of reference line and arrow; indicates weld to be made at installation site, not in shop.

Shade lens selection

Arc welding requires shade 10-13 depending on amperage; gas cutting shade 3-6; safety glasses always under helmet.

Hot work clearance

Keep combustibles at least 35 feet away or protected; fire watch required during and 30 minutes after welding.

Confined space oxygen level

Safe oxygen range for entry is 19.5% to 23.5%. Test atmosphere before entry and monitor continuously.

Bend test purpose

Destructive test evaluating ductility and fusion; specimen bent to specified angle; defects appear on convex surface.

Charpy V-notch test

Impact test measuring toughness; pendulum strikes notched specimen; results in energy absorbed (ft-lb or J) at test temperature.

Macro etch examination

Cross-section of weld polished and etched with acid; reveals penetration, fusion, and internal defects at low magnification.

Inch to millimeter conversion

1 inch = 25.4 mm exactly. To convert mm to inches, divide by 25.4. Common: 1/8 in = 3.175 mm.

CFH to L/min conversion

1 cubic foot per hour = 0.472 liters per minute. To convert L/min to CFH, multiply by 2.12.

Deposition rate calculation

Deposition rate (lb/h) = 13.1 × wire feed speed (in/min) × wire cross-sectional area (in²). Efficiency factor applied for process.

Linear motion instruction

Robot moves TCP in straight line at programmed speed; used for welding and cutting paths; requires clear path.

Joint motion instruction

Robot moves each axis to target at maximum speed; path not straight; used for air moves and approach.

Circular motion instruction

Robot moves TCP through circular arc defined by start, via, and end points; used for curved weld seams.

WPS essential variables

Variables that, if changed, require requalification: process, filler classification, polarity, thickness range, preheat, etc.

PQR document

Procedure Qualification Record: records actual welding variables and test results proving a WPS produces sound welds.

Robot singularity

Configuration where robot axes align, causing loss of degree of freedom; can cause unpredictable motion; avoid in programming.