Red Seal Machinist flashcards

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

WHMIS 2015 SDS

A 16-section Safety Data Sheet aligned with the Globally Harmonized System; it must be available in the work area and includes hazard pictograms, signal words, and first-aid and handling information.

Lockout tagout purpose

A procedure that isolates and locks all energy sources, including electrical, hydraulic, pneumatic, gravity, and stored spring energy, before maintenance so the machine cannot start or release energy unexpectedly.

Compressed air cleaning limit

Cleaning with compressed air must be regulated to 30 psi (207 kPa) or less and use a safety nozzle; air must never be directed at skin or used to clean clothing.

Sine bar formula

The sine of the set angle equals the difference in gauge-block stack height divided by the sine bar centre distance; a 5 in bar with a 1.000 in stack sets 11.537°.

Taper per inch formula

Taper per inch equals the large diameter minus the small diameter, divided by the length of the taper; the included angle is twice the arctangent of the half-difference over length.

Tap drill size rule

For inch threads, tap drill size is approximately the major diameter minus one divided by the threads per inch; for metric threads it is approximately the major diameter minus the pitch.

Hacksaw blade pitch

Use 14–18 teeth per inch for thick sections and soft metals, and 24–32 teeth per inch for thin wall tube, sheet, and hard material; at least three teeth must contact the work.

File cut direction

A file cuts on the forward stroke only; pressure is applied going forward and released on the return so the teeth stay sharp and the surface stays flat.

Micrometer least count

A 0–1 in micrometer with a 0.025 in sleeve and a 25-division thimble reads to 0.001 in; the reading is the sleeve value plus the thimble division times 0.001 in.

Abbe principle

The measurement axis should be in line with the scale axis; this is why a micrometer is more accurate than a caliper for the same nominal size.

Gauge block wringing

Gauge blocks are wrung together to build a stack; select blocks from largest to smallest and use the fewest blocks possible to reduce accumulated error.

Go no-go gauge rule

A go plug gauge must enter the hole and the no-go end must not enter a hole within tolerance; the gauge checks limits, not the actual size.

Hand tapping procedure

Start the tap square with a tap guide, apply cutting fluid, and back the tap off a quarter turn periodically to break chips; use the correct tap drill for the thread.

Reaming direction rule

A hand reamer must turn in the cutting direction only; never reverse it in the hole, because reversing dulls the edges and can score the finished bore.

Scraping contact pattern

Blue the mating surface, scrape the high spots, and repeat until the contact pattern is uniform; scraping is used to correct flatness and fit bearing surfaces.

Standard drill point angle

A standard twist drill has a 118° included point angle; a 135° split point is used for harder materials and reduces walking when starting a hole.

Peck drilling purpose

Retracting the drill periodically clears chips, prevents chip packing, and reduces drill breakage in deep holes; coolant is used for deep holes and tough materials.

Band saw blade pitch

Blade pitch must keep at least three teeth in the cut; use coarse pitch for thick sections and fine pitch for thin wall and hard material.

Turning RPM formula

RPM approximately equals four times the cutting speed in feet per minute divided by the work diameter in inches; use the largest diameter in the cut.

Compound rest threading angle

Set the compound rest at 29–30° for a 60° unified thread and engage the half-nut on the same spindle mark each pass to keep the tool in the thread groove.

Four-jaw chuck centring

Adjust each jaw independently and indicate the work true with a dial test indicator; a four-jaw chuck holds irregular work and is more accurate than a self-centring three-jaw chuck.

Parting off requirements

Use a rigid tool set on centre, slow speed, plenty of coolant, and a feed that keeps the chip flowing; chatter or rubbing indicates the tool is off centre or overhanging.

Climb versus conventional milling

Climb milling rotates the cutter in the feed direction and gives a better finish on machines with backlash compensation; conventional milling is safer on worn machines.

Dividing head crank turns

For simple indexing, the number of crank turns equals 40 divided by the number of divisions; the sector arms set the additional fraction on the index plate.

Milling feed rate formula

Feed rate equals feed per tooth times the number of teeth times RPM; feed per tooth depends on the cutter material and the workpiece material.

Abrasive wheel marking

The marking sequence gives abrasive type, grit size, grade, structure, and bond; a harder grade holds abrasive longer and is used for softer workpiece material.

Wheel ring test

A wheel is ring-tested and visually inspected before mounting, blotters are used under the flanges, and the marked maximum RPM must never be exceeded.

Grinding burn cause

Burning and cracks come from too heavy a cut, the wrong wheel grade, or insufficient coolant; inspect for discolouration and use crack detection on critical parts.

G54 work offset

G54 through G59 are work coordinate offsets that set the part zero; G90 selects absolute positioning and G91 selects incremental positioning.

Cutter radius compensation

G41 offsets the tool path to the left of the programmed path, G42 to the right, and G40 cancels it; the control uses the tool radius stored in the offset register.

Third-angle projection

In third-angle projection the top view is placed above the front view and the right side view to the right; first-angle projection places the top view below the front view.

Feature control frame order

The frame reads left to right as the geometric symbol, the tolerance zone, and the datum references; a diameter symbol before the tolerance means a cylindrical zone.