118 Questions
What is the purpose of a softener in lifting and hoisting procedures using a sling?
To protect the sling from sharp edges of the load
What is the axial distance a nut advances on a screw thread after one complete turn?
1 turn
How much is the strength of a fibre rope reduced when it is hitched?
25%
Which hacksaw pitch blade is used for cutting high carbon steel drill rod?
14
What type of products is the WHMIS system designed to provide safety for?
Dangerous
What is a worker's responsibility when dealing with WHMIS?
To follow safe handling and use procedures
What is the purpose of a sling in lifting and hoisting procedures?
To lift and move heavy loads safely
What is the importance of following safe handling and use procedures when dealing with WHMIS products?
To ensure worker safety and prevent accidents
What is the primary function of the MCU in a CNC machine?
To coordinate all machine operations and act as the nerve centre of the CNC machine.
What is the purpose of a centre drill?
To drill and countersink lathe work.
What is the primary advantage of using an oil mist lubrication system?
It reduces tool wear and tear.
What is the effect of a floating reamer holder on reamer misalignment?
It stabilizes the effect of reamer misalignment.
What does the M code M30 cause to happen in a CNC program?
It stops the machine and resets to the beginning of the program.
What is the primary purpose of a jig?
To hold and guide the drill bit in a specific location.
What is the common rotary resolution for most CNC machines in degrees?
0.1
What is a characteristic of a uni-junction transistor?
It is a highly compact device.
What is the angle θ when β = 630 and α = 400?
14.6 degrees
What percentage of 965 is the value 627?
65%
What is the result of the function (3x + 2)/(x - 2) when x = 4?
10
What is the value of 365.76 cm in feet, given that 1 inch = 25.4 mm?
14.4
What happens to the CNC turret index when it indexes in only one direction?
It is uni-directional.
What is a characteristic of an open loop CNC feedback system?
It monitors servo consistency though the use of ROM.
What is the value of 113.4 kg in pounds, given that 2 pounds = 0.908 kg?
102.97
What is the decimal expression of 12.5%?
0.125
In what year was the first practical digital supercomputer developed?
1969
What is the advantage of using a lathe to cut a thread with a tap versus tapping by hand?
The tailstock will keep the tap aligned with the axis of the workpiece.
What is the perimeter of a rectangle with sides 5.4 ft and 8.2 ft?
27.2 ft
How is an angle denoted with polar coordinates when measured counter-clockwise?
Positive.
If a stack of 35 pieces of steel weighs 1800 pounds, how many pounds will a stack of 43 pieces weigh?
2211 pounds
What is the total infeed per side to finish the thread of a 16-UNC thread when cutting a thread using a lathe and a compound rest set at 29 degrees?
0.0470 of an inch.
Why is the Cincinnati Hydrotel vertical milling machine significant in history?
It could simultaneously control three axis of machine tool movement.
What type of CNC system is one that does not use positional verification?
Open loop system.
What is the term for the average deviation from the centerline measured in microinches or micrometers?
Surface roughness
What is the function of a cutting plane line in machinist blueprints?
It indicates where the sectional view came from
What type of self-threading screw would be used to assemble zinc?
Thread forming screws
What is the term for the unrepeated or random irregularity in the surface finish of a workpiece?
Waviness
What is the difference in area between a circular tolerance zone and a square tolerance zone?
74%
What type of self-threading screw would be used to assemble sheet metal?
Thread cutting screws
What is the term for the widely spaced irregularities caused by vibration or chatter?
Waviness
What type of 'nut' is shown in diagram B?
Hex Flange
What is the primary purpose of the employer providing a material safety data sheet?
To provide a safety data sheet to inspectors.
What type of product does the employer need to provide a material safety data sheet for?
Controlled product
To find the minor diameter of an external thread, you would measure:
Across the roots of the thread
What part of a hand-held tap does most of the cutting?
The flute
When choosing the correct hacksaw blade pitch, which is a true statement?
Use a fine pitch blade for soft material
A long range dial indicator has a pointer movement of how many revolutions?
10 revolutions
What is a worker's responsibility when dealing with WHMIS products?
To follow safe handling and use procedures
What is the purpose of a lathe dog?
To engage a slot in the drive plate
What is the correct location of the feed reverse lever on a lathe?
Near the bed
What is the term for machining curved surfaces?
Profiling
What should the feed rate be for a roughing cut?
As high as the cutting tool and the machine can handle
What is true about single spindle-single turret arrangements in CNC turning centers?
It is the most common arrangement
What is a vise used for?
A very versatile and convenient work holding device
How does the feed rod move the carriage on a lathe?
At a slower rate than the lead screw does for threading
What is a blotter?
A heavy piece of metal attached to each side of a grinding wheel
What is the advantage of using an oil mist lubrication system?
It is not affected by oil viscosity
What is the RPM for drilling a 0.585-inch hole into 3.5 diameter leaded steel using an HSS twist drill?
1305.9
When is tailstock support for a CNC turning machine important?
When it is more than 4 times its diameter
What is the function of the servo drive control in a CNC machine?
Its function is to develop appropriate signals from program data for driving servo motors
What direction does a right-hand offset cut from?
It cuts from left to right
Where does the compound rest on a lathe?
It rests to the right of the cross-slide
What is machine zero when referring to a CNC machine?
The absolute reference point and origin of the machine coordinate system
What is the function of the CPU of a CNC machine?
It is the heart of any computer system
What does the number preceded by T stand for in a CNC program?
The station number for a turret index.
What is the value of 125 lbs in kg, given that 1 pound = 0.454 kg?
56.7
What is the fraction 1/10 expressed as a percentage?
It is 12 percent.
How is the amount of taper expressed in the imperial system?
It is expressed as taper per foot.
What is the value of 589 mm in cm?
58.9
Which of the following best describes a tapered pin?
It has a 3 1/2 inch taper per foot.
What holds the base plate and guide bar in place in a plain taper attachment?
The binding screws.
What is the angle θ if side is the same length as side , and what is the relationship between the sides?
Angle θ is equal to 45 degrees.
What is the program speed when reaming on a CNC turning machine?
25 to 33 % of that used for drilling
What is an advantage of slant CNC turning machines?
The open space in front of the spindle permits easy loading and unloading of workpieces.
What measurement must be used for a CNC lathe when doing a drilling operation?
RPM
What is a transducer?
A device that monitors external variables and converts them into signals for a machine control unit.
What type of CNC turret has the fastest indexing time?
Quick change.
On a CNC turning machine, the purpose of centre drilling is to provide what degree conical surface for a bearing centre?
60 degree.
What is a soft limit switch on a CNC machine?
A software-based limit that prevents the machine from exceeding its physical limits.
What is a softener in lifting and hoisting procedures using a sling?
A device used to protect the sling from sharp edges of the load
What is the axial distance a nut advances on a screw thread?
After 1 complete turn
By what percentage is the strength of a fibre rope reduced when hitched?
25%
What type of products is the WHMIS system designed to provide safety for?
Dangerous products
What is a microset adjustable centre?
It uses an eccentric or dovetail.
What type of hacksaw pitch blade is used for cutting high carbon steel drill rod?
14
What is a worker's responsibility when dealing with WHMIS products?
To handle products safely
What is the primary function of a facing tool?
It is used to cut a flat surface at right angles to the axis of the workpiece.
What was the significance of the first Electrical Numerical Integrator and Calculator?
It inspired the development of automated control.
What is the purpose of a sling in lifting and hoisting procedures?
To lift heavy loads safely
What is a self driving centre?
It is used when the entire length of the workpiece must be machined in one pass.
What is the primary purpose of providing a material safety data sheet?
To provide safety information to workers
What is the recommended cutting speed in SFPM for high speed steel drills when the workpiece material is an Alloy/cast steel?
80
What is program zero when referring to a CNC machine?
The absolute reference point and origin of the machine coordinate system.
What is carbide as a cutting material?
It retains its hardness to a very high temperature and is also known as Stellite.
What is a facing tool used for?
Cutting a flat surface at right angles to the axis of the workpiece.
When choosing the appropriate pitch of a band saw blade for a particular cutting operation, how many teeth should be in contact with the work piece at all times?
Four teeth
What type of CNC turning center is also called the Swiss style turning center?
A sliding headstock turning center
What is the calculated RPM for drilling a 0.585-inch hole into 3.5 diameter brass using an HSS twist drill?
1305.9
How large should the flange be as compared to the wheel of the grinder?
One third the diameter of the wheel
Which type of drill is used for deep holes in softer metals like copper and zinc?
The core drills
On a lathe, what does the term 'backlash' refer to?
The space between meshing gears
Which of the following best describes a sensitive drill press?
The spindle accepts drills with tapered shanks
What is the primary advantage of using an oil mist lubrication system?
It increases tool life
What is the value of β when α = 400 and θ = 26.3 degrees?
630
What is the result of the function (3x + 2)/(x - 2) when x = 5?
19/3
What is the value of 113.4 kg in pounds, given that 2 pounds = 0.908 kg?
249.92
What is the perimeter of a rectangle with sides 8.4 ft and 5.2 ft?
26.8 ft
What is the value of 365.76 cm in feet, given that 1 inch = 25.4 mm?
12.4 ft
What percent of 965 is the value 627?
65%
If a stack of 35 pieces of steel weighs 1800 pounds, how many pounds will a stack of 43 pieces weigh?
2211 pounds
What is the decimal expression of 12.5%?
0.125
What does the term 'parting-off' refer to in CNC turning centres and lathes?
Machining to separate a part from the main bar stock
What determines the size of a lathe?
The type of material being machined
What is a characteristic of a stop shaft?
It is clamped to the ways to stop the movement of the carriage
What is a disadvantage of a drill chuck?
It has poor accuracy
What is true about twin spindle-twin turret arrangements in CNC turning centres?
It is used in high production machining
Where is the headstock always attached to in a lathe?
The right side of the bed
What describes a turret stop?
It is used to support the turret in a specific position
What determines the size of a drill?
The diameter of the drill bit
Study Notes
CNC Machines and Machining
- CNC machines can be reduced by a factor of pi.
- A bi-directional CNC turret index can move in two directions.
- In an open loop CNC feedback system, positional verification is achieved through a linear or rotary encoder.
- The first practical digital supercomputer was developed in 1969.
Lathe and Threading
- When cutting a thread using a lathe and a compound rest set at degrees, the total infeed per side to finish the thread of a 16 UNC thread would be 0.0625 of an inch.
- The advantage of using a lathe to cut a thread with a tap is that the tailstock will keep the tap aligned with the axis of the workpiece.
Coordinate Systems
- In polar coordinates, an angle is denoted as positive when measured counter-clockwise.
History of CNC
- The Cincinnati Hydrotel vertical milling machine has a place in history because it could simultaneously control three axes of machine tool movement.
Safety and Measurement
- When referring to lifting and hoisting procedures using a sling, a softener is a device used to protect the sling from sharp edges of the load.
- The lead of a screw thread is the axial distance a nut advances on a screw thread after one complete turn.
- When a fibre rope is hitched, the strength of the rope is reduced by 25 percent.
- Hacksaw pitch blades are used for cutting materials with small cross-sections, such as high carbon steel drill rod.
- WHMIS (Workplace Hazardous Materials Information System) is designed to provide safety for controlled products.
- A worker's responsibility when dealing with WHMIS is to participate in WHMIS training and follow the instructions on the Safety Data Sheet (SDS) and the label.
Drilling and Reaming
- A centre drill is used for holes from one to six inches in diameter.
- A floating reamer holder decreases the effect of reamer misalignment.
CNC Programming
- The MCU (Machine Control Unit) of a CNC machine coordinates all machine operations.
- In a CNC program, the M code M30 causes the program to stop executing and reset to the beginning of the program.
- A jig is a special work-holding device used to guide the drill.
Rotational Systems
- The common rotary resolution for most CNC machines is 0.01 degrees.
Lubrication Systems
- The advantage of using an oil mist lubrication system is that it reduces the amount of oil needed.
Geometry and Trigonometry
- Angle calculations can be performed using trigonometric functions, such as finding the angle in a right triangle.
Conversions
- 1 inch is equal to 25.4 mm.
- 1 pound is equal to 0.908 kg.
Percentages and Decimals
- 12.5% is equal to 0.125 as a decimal expression.
Perimeter and Area
- The perimeter of a rectangle can be calculated using the formula P = 2(l + w).
- The area of a rectangle can be calculated using the formula A = l x w.
Materials and Manufacturing
- Steel can be machined in various forms, such as stacks of steel plates.
Blueprints and Surface Finishes
- A cutting plane line on a blueprint indicates where the sectional view came from.
- Surface roughness refers to the average deviation from the centerline measured in microinches or micrometers.
- Waviness refers to the widely spaced irregularities caused by vibration or chatter.
Screws and Fasteners
- Thread forming screws are used to assemble zinc.
- Thread cutting screws are used to assemble sheet metal.
Safety and Hazards
- The employer must ensure that appropriate control measures are in place to protect workers.
- A material safety data sheet must be provided for each controlled product used in the shop.
- The employer must ensure that hazardous products are properly classified as per the hazardous products regulations.
Threads and Measurement
- The minor diameter of an external thread is measured across the deepest point of the thread.
- The part of a hand-held tap that does most of the cutting is called the land.
Fire Safety
- A blue color fire class symbol is associated with a specific type of fire.
CNC Machines
- The program speed when reaming with CNC turning machines is generally 25 to 50 % of that used for drilling.
- A transducer is a device that monitors external variables and converts them into signals for a machine control unit.
- A soft limit switch is an advantage on CNC machines that ensures the oil is always clean.
- The servo drive control in a CNC machine coordinates all machine operations and develops appropriate signals from program data for driving servo motors.
CNC Turning Machines
- Centre drilling on a CNC turning machine provides a 60-degree conical surface for a bearing centre.
- Tailstock support is important when the work overhang is more than 4 times its diameter.
- Machine zero on a CNC machine is the absolute reference point and origin of the machine coordinate system.
Lathe Operations
- The compound rest on a lathe rests to the right of the cross-slide.
- The feed rate for a roughing cut should be as high as the cutting tool and the machine can handle.
- The feed reverse lever on a lathe is found on the headstock.
- Machining of curved surfaces is known as profiling.
CNC Programing
- In a CNC program, the number preceded by T stands for the station number for a turret index.
Trade Mathematics
- 1 pound is equal to 0.454 kg.
- The amount of taper in the imperial system is expressed as taper per foot.
- The value of 589 mm is equal to 58.9 cm.
CNC Machining and Turning
- A microset adjustable centre is a type of adjustable centre that uses an eccentric or dovetail.
- A facing tool is used to cut a flat surface at right angles to the axis of the workpiece.
- The first Electrical Numerical Integrator and Calculator (ENIAC) inspired the development of automated control.
- A self driving centre is used when the entire length of the workpiece must be machined in one pass.
CNC Machines and Program Zero
- Program zero is the absolute reference point and origin of the machine coordinate system.
- It is a fixed reference point that is established at shut down.
Cutting Materials and Speed
- Carbide is a cutting material that retains its hardness to a very high temperature and is also known as Stellite.
- The recommended cutting speed in SFPM for high speed steel drills when the workpiece material is an Alloy/cast steel is 150.
CNC Turning Centres and Lathes
- A sliding headstock turning centre is also called the Swiss style turning centre.
- Parting-off refers to machining to separate a part from the main bar stock.
- The size of a lathe is determined by the largest diameter of workpiece that can be supported over the ways and the greatest length of workpiece that can be supported between centers.
Drilling and Machining
- A sensitive drill press is used for drilling larger holes and is usually driven by a V-belt.
- A stop shaft is clamped to the ways to stop the movement of the carriage.
- A turret stop is used to disengage the feed lever.
Safety and Measurement
- A softener is a device used to protect the sling from shape edges of the load during lifting and hoisting procedures.
- The lead of a screw thread is the axial distance a nut advances on a screw thread after one complete turn.
- When a fibre rope is hitched, the strength of the rope is reduced by 25 percent.
- WHMIS is a system designed to provide safety for controlled products.
- A worker's responsibility when dealing with WHMIS is to choose the appropriate pitch of a band saw blade for a particular cutting operation.
Test your knowledge of CNC machine operation, including turret indexing and feedback systems.
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