Part 1

CNC Machining and Turning

• To support the workpiece, a compound rest can be used.
• CNC lathes require a specific measurement during tapping operations, which is Frequency (D).

Cutting and Drilling

• Drilling provides a quick way of making an accurate hole with a good surface finish.
• The recommended cutting speed (SFPM) for high-speed steel drills when the workpiece material is Aluminium is 150 (B).
• Boring, threading, and reaming are other machining processes.

Stopping the Carriage and Fasteners

• A stop shaft has six adjustable screws in an indexable head (A).
• Applying too much pressure to fasteners can cause the component to become deformed (B).

CNC Programming

• In a CNC program, G code G20 specifies that all information must be in the imperial measurement system (A).
• The letter "T" in CNC programming stands for tool selection (C).

Cutting Fluids and Grinders

• A good quality cutting fluid should resist corrosion, becoming rancid, and be non-toxic (D).
• A side wheel grinder has an advantage over a bench grinder in supporting larger workpieces (A).

Lathe Operations

• A taper attachment has an advantage over a compound rest for cutting tapers in ease of transformation from taper turning to parallel turning (A).
• The compound rest is located on top of the cross-slide (C).
• A parting and grooving tool is used to cut a flat surface at right angles to the axis of the workpiece (D).

NC Machines and CNC

• NC machines were soft-wired (A).
• CNC refers to Computer Numeric Control (B).
• The term "grit" in grinding wheels refers to the abrasiveness (D).

Mathematics and Geometry

• A triangle with an angle greater than 90° is called an oblique triangle (D).
• The circumference of a circular hole with a diameter of 35.6 mm is approximately 111.8 mm (B).

Tapers and Fits

• A taper with D=14, d=2, TL=10 has a taper per foot of approximately 14.4 (A).
• The large diameter of a taper with d=2, TL=10, TPF=10.08 is approximately 11.14 (A).
• A fit referred to as RC4 is an accurate location of parts where parts move and turn freely but are not intended to run freely (C).

Print Reading and Orthographic Drawings

• Material section lines on a blueprint for plastic are represented by #4 (D).
• The angle most often used to draw isometric drawings is 30° (A).
• A circle drawn in an isometric projection would form an ellipse (A).
• The three common views of an orthographic drawing are top, front, and right side (D).

Machining Operations

• A servo motor controller develops appropriate signals from program data to drive servo motors.

Lubrication Systems

• The advantage of an oil mist lubrication system is that it ensures the oil is always clean.

Cutting Speed

• The cutting speed for a 4-inch diameter workpiece when the RPM is 900 is 945.71 RPM.
• The cutting speed for a 3-inch diameter workpiece when the RPM is 550 is 425.21 RPM.

Viscosity

• A liquid that pours slowly has high viscosity.

American Standards for Coded Information Interchange

• American Standards for Coded Information Interchange uses an odd parity format.

Lathe Components

• A spider is used when long, tubular work pieces require a centre.
• The headstock is always attached to the left side of the bed.

Machining Techniques

• Machining of curved surfaces is known as profiling.
• Undercutting is not a machining technique for curved surfaces.

Band Saw Blades

• The set of the blade provides the clearance for the back of the blade.

Cutting Fluids

• A sulphur-based cutting oil is suitable for drilling into Brass.

Shoulders

• A filleted shoulder is a type of shoulder that is strong and does not weaken the shaft.

Lubrication Systems

• A flow-through system allows lubricant to escape into the environment after it has been applied to the machine.

Chattering

• Chattering can be reduced when cutting a groove into a workpiece by moving the carriage back and forth slightly, mounting the grooving tool with as little overhang as possible, and supporting the workpiece with the tailstock center.

CNC Turning Centres and Lathes

• "Parting-off" refers to machining that separates a part from the main bar stock.

Drill Point Angle

• The recommended drill point angle for hard materials is 118.

Drill Machines

• A radial drill machine is suitable for drilling in very large work pieces that are difficult to position.

CNC Programming

• The letter "T" in CNC programming stands for tool selection.

Taper Attachments

• The advantage of using a taper attachment over a compound rest for cutting tapers is that mating tapers are easily produced with only two taper set-ups.

Lathe Components

• The compound rest rests on top of the cross-slide.

Part and Grooving Tools

• A part and grooving tool is used to cut a flat surface at right angles to the axis of the workpiece.

NC Machines

• NC machines were not soft wired, easy to program, or had no memory.

Chisel Edge

• The chisel edge of a drill bit is provided by grinding the heel lower than the cutting edge.

CNC Term

• CNC stands for Computer Numeric Control.

Surface Speed Formula

• The number 12 in the surface speed formula represents a conversion factor to metric.

Lubrication Systems

• A ring oiler lubrication system is an enclosed circulating lubrication system.

Grinding Wheels

• The "grit" of a grinding wheel refers to its abrasiveness.

Angle Denotation

• An angle denoted with polar coordinates measured counter-clockwise is positive.

CNC Terminology

• Odd parity in CNC terminology means each program character is represented in rows containing an odd number of holes.

Coordinate Systems

• In CNC machines, the direction toward the spindle centerline is denoted by -Z.

Triangles

• A triangle with an angle greater than 90° is called an oblique triangle.

Tapers

• A taper with D=14, d=2, TL=10 has a taper per foot of 7.5.
• The large diameter of a taper with d=2, TL=10, TPF=10.08 is 11.14.

Circumference

• The circumference of a circular hole with a diameter of 35.6 mm is 111.8 mm.

Drills

• A self-holding taper with an approximate taper of 5/8 inch per taper foot is known as type D-1 and type L.

Unit Conversion

• 125 cm is equal to 49.21 inches.

Trigonometry

• In a right-angled triangle, if one angle is 62 units and the other is 45 units, the value of the third angle is 58°.

Print Reading

• In material section lines on a blueprint, the ANSI standard material section for plastic is represented by #4.

Isometric Drawings

• A circle drawn in an isometric projection forms an ellipse.
• The angle most often used to draw isometric drawings is 30 degrees.

Blueprints

• Arrows on the ends of section lines on a blueprint indicate the direction to view the section.

Machine Tools and CNC Programming

• A tap's flute provides a passage for cutting fluid and a spot for chips to accumulate.
• Parallax error is a visual error.
• The tap drill size for a M10 1.25 thread is 8.75 mm.
• When cutting cast iron with a hacksaw, the best blade to use is a raker blade.
• A hacksaw's kerf is the width of cut in the work material.
• A 6 inch caliper can measure up to 6 inches.

CNC Programming and Machine Tools

• A wire wheel is used on a grinder when cleaning a workpiece of scale and dirt but not removing metal.
• In the surface speed formula, as the rpm increases, the CS (surface speed) increases.
• Chattering can be reduced when parting off a workpiece by moving the carriage forward slightly.
• In a CNC program, the M code M05 stops the spindle's rotation.
• In a CNC program, the M code M00 causes the machine to stop executing a program.
• Jacob's impact keyless chucks use steel collets to align and secure the straight shank.
• When doing spindle calculations for threading operations with a CNC machine, the major diameter of the thread being cut is used.
• The X axis is the length controlling motion direction on a CNC machine.
• The spindle speed control of a CNC machine is a type of transitional spindle control.

Cutting Tools and Materials

• A flap wheel is used on a grinder when doing light finishing and chamfering.
• When drilling into Brass, a soluble oil is the best cutting fluid to use.
• A square shoulder is a simple cut but can weaken the shaft by creating a stress.
• A flow-through system is a type of lubrication system that allows lubricant to escape into the environment.
• Chattering can be reduced when cutting a groove into a workpiece by mounting the grooving tool with as little overhang as possible.
• Parting-off refers to machining to separate a part from the main bar stock.
• A recommended drill point angle for hard materials is 118.
• A radial drill machine is best suited for drilling in very large workpieces that are difficult to position.

CNC Machines and Operations

• A drill chuck has poor accuracy as a disadvantage.
• A revolving centre is used when the entire length of the workpiece must be machined in one pass.
• In a CNC program, the G code G04 causes the machine to pause for a specified period.
• When using the front face as program zero, all X coordinate values are positive.
• In Quadrant 3 of an X and Z axis, all X coordinate values are negative and all Z coordinate values are negative.
• The letter "S" in CNC programming stands for spindle speed.
• A pump is used in a pressure lubrication system to force oil into a bearing.

Tolerances and Fits

• A 12 inch taper key has a 1/16 inch taper.
• The difference in area between a circular tolerance zone and a square tolerance zone is 57%.
• The term "nominal surface" refers to the intended surface of the workpiece as specified in the drawing.
• A sliding fit is an accurate location of parts where parts move and turn freely but are not intended to run freely.
• A FN2 fit is used for ordinary steel parts or light shrink fits on thin sections.