MSCE Metalwork flashcards

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

Duty of care hierarchy

The order of risk control: eliminate the hazard first, then substitute, then apply engineering controls, then administrative controls, and use personal protective equipment only as the last resort.

Class D fire

A fire involving combustible metals such as magnesium, sodium or titanium. It requires a special dry powder extinguisher; water and CO2 are ineffective and can react violently.

Acetylene pressure limit

Free acetylene becomes unstable above about 1 bar, so working pressure must never exceed 1.5 bar (approximately 15 psi). Cylinders must be stored upright and secured.

Local exhaust ventilation

An extraction system that captures welding fume and grinding dust at the source before it enters the breathing zone. It is an engineering control, not a substitute for assessment.

Mild steel carbon range

Low carbon or mild steel contains up to about 0.3 percent carbon. It is ductile, weldable and machinable, but cannot be hardened by heat treatment alone.

Austenitic stainless steel

A stainless steel with an austenitic structure, typically 18 percent chromium and 8 percent nickel. It is non-magnetic when annealed and resists corrosion through a chromium oxide layer.

Galvanic corrosion

Corrosion caused when two dissimilar metals are in electrical contact in the presence of an electrolyte. The less noble metal becomes anodic and corrodes preferentially.

Tensile strength

The maximum load a material can withstand before necking, divided by its original cross-sectional area. It is expressed in megapascals and differs from yield strength.

Cold chisel angles

The cutting angle is about 60 degrees for mild steel, 70 degrees for cast iron, and 30 to 40 degrees for softer metals such as aluminium and copper.

Hacksaw blade pitch

Use 14 to 18 teeth per inch for thick sections and soft metals, and 24 to 32 teeth per inch for thin tube, sheet and hard metals. At least three teeth should be in contact.

File cut types

Single-cut files have parallel teeth for fine finishing. Double-cut files have crossing teeth that remove material faster. Files cut on the forward stroke only.

Vernier least count

The smallest value a vernier scale can read, calculated as main scale division minus vernier division. A 0.02 mm caliper has 50 vernier divisions spanning 49 mm.

Micrometer zero error

The reading shown when the anvils are closed. A positive error is subtracted from measurements and a negative error is added, so readings are always corrected.

Datum selection

Choosing a machined or reference face from which all dimensions are taken. A single datum avoids tolerance stack-up and keeps the part within specification.

Tap drill size rule

For metric coarse threads, subtract the pitch from the major diameter to estimate the tap drill size. For example, M8 with a 1.25 mm pitch needs about 6.75 mm.

Drilling spindle speed

Spindle speed in rpm equals 1000 times the cutting speed in metres per minute, divided by pi times the drill diameter in millimetres.

Clearance fit

A fit in which the hole is always larger than the shaft, so a gap always exists. H7/h6 is a common location clearance fit for interchangeable parts.

Brazing temperature range

Brazing uses filler metal that melts above 450 degrees Celsius but below the melting point of the parent metals, drawn into a close joint by capillary action.

Rivet hole clearance

The hole is usually about 1.5 to 2 mm larger than the rivet diameter for hot riveting. Cold riveting uses tighter holes to fill the hole properly.

Blind rivet grip range

The range of material thicknesses a pop rivet can clamp. Selecting outside the grip range gives a loose or failed joint, so check the specification before use.

MMA electrode current

As a guide, use 30 to 40 amps per millimetre of electrode diameter. A 3.2 mm electrode therefore runs at roughly 100 to 130 amps.

Oxy-acetylene flame types

A neutral flame has equal oxygen and acetylene and suits steel. An oxidising flame has excess oxygen and suits brass. A carburising flame has excess acetylene and suits high-carbon steel.

Weld undercut

A groove melted into the parent metal at the weld toe that is not filled by filler. It is caused by excessive current or travel speed and acts as a stress raiser.

Bend allowance formula

Bend allowance equals the bend angle in radians multiplied by the sum of the inside radius and the neutral-axis factor times thickness. It gives the developed length of the bend.

Minimum bend radius

The smallest inside radius that can be formed without cracking. It depends on material and temper, typically one thickness for soft aluminium and more for hard tempers.

Corner relief in folding

A notch or radius cut at the corner of a folded box to prevent tearing and overlap. The relief radius should be at least equal to the material thickness.

Annealing purpose

Heat the metal above its critical temperature, hold, then cool very slowly in the furnace. This softens the metal, refines structure and relieves internal stress.

Tempering after hardening

Reheating hardened steel below the critical range, usually 150 to 650 degrees Celsius, then cooling. It reduces brittleness and trades some hardness for toughness.

Forging temperature range

Mild steel is forged at roughly 1100 to 1250 degrees Celsius, appearing bright yellow-white. Forging below about 900 degrees Celsius risks cracking.

Cutting speed formula

Cutting speed in metres per minute equals pi times the workpiece diameter in millimetres times spindle speed in rpm, divided by 1000.

Climb versus conventional milling

Climb milling feeds the cutter in the same direction as the work feed, giving a better finish on rigid machines. Conventional milling opposes the feed and is safer on worn machines.

First-angle projection

A drawing convention in which the view from the front is placed above the plan, and the left view appears on the right. Third-angle projection reverses these positions.