1
Q
How many key concepts are there to be proficient with a cnc machine. And how many for programming and for set up/operation
A
10 key concepts
6 for programming and 4 for set up
2
Q
3 basic items you must understand about the machine
A
-machine components
-motion directions or axes
-programmable features
3
Q
One way to control spindle speed and feed rate on most conventional lathe
A
Rpm for spindle speed
Per revolution for feed
4
Q
Positions through which cutting tools move
A
Coordinates
5
Q
Coordinates which are required to determine an orifin from which you specify coordinates
A
Program zero point
6
Q
Where do you specify all coordinates withing the program
A
Program zero
7
Q
The assigning of program zero is also the set up persons responsibility. T or f
A
True
8
Q
3 basic motion types
A
-rapid motion (G00)
-linear interpolation (G01)
-circular interpolation (G02 CW, G03 CCW)
9
Q
3 types of compensation used on turning centers
A
-wear offsets
-geometry offsets/work shift
-tool nose radius compensation
10
Q
Provides a way to size in workpiece attributes during set up
A
Wear offset
11
Q
Specifies program zero assignment values
A
Geometry offsets/work shift
12
Q
3 reasons cnc programs must be strictly structured
A
-helps familiarize with programming
-provides consistently among programs
-allows cutting tools to be re run on their own
13
Q
3 special features designed to simplify and shorten cnc programs
A
-Canned and multiple rep cycles
-sub programming
-other special programming features
14
Q
Minimizes the commands needed to program machining operations. Shortens time and effort to create cnc programs
A
Canned and multiple repetitive cycles
15
Q
Keeps you from repeating redundant commands in cnc programs. If you need to machine multiple identical workpiece attributes
A
Sub programming
16
Q
4 special programming features
A
-block delete
-automatic corner round and chamber
-programmable offsets entry
-spindle limiter
17
Q
Gives the machine operator a choice between one of two conditions
A
Block delete
18
Q
Simplifies the task of programming corner breaks with chamfers and radius
A
Automatic corner rounding and chamfer
19
Q
Provides a way to program the entry of an offsets when you know its value as you create a program
A
Programmable offset entry
20
Q
Lets you specify a maximum spindle speed in revolutions per minute
A
Spindle limiter
21
Q
3 basic modes of operation
A
-manual mode
-manual data input MDI
-program operation mode
22
Q
3 reasons to structure g code program
A
- familiarize with g code programming
-helps maintain consistency
-ensures that tools can be re run
23
Q
4 types of formats for programming
A
-program start up format
-tool start up
- tool ending
-program ending format
24
Q
All programs begin with a program number specified with which letter
A
O
25
What is g99
Per revolution feed rate mode
26
What is g20
Imperial measurement system mode
27
G23
Cancel stored stroke limit
28
Characters in parenthesis must be upper case and machine ignores messages when executing program. T or f
True
29
What is g50
Spindle limiter
30
T0101 stands for?
Turret (tool) station number and geometry offset number
31
What is m41 and m42
M41 - low spindle range (roughing)
M32 - high spindle range(finishing)
32
What is g96?
Constant Surface speed node
33
What is g97?
Rpm mode
34
What is m03 and m04?
M03 turns spindle to forward direction Common for RH cutting tools
M04 turn spindle in reverse directions
35
Does coolant and spindle stop when you use m01 command? Y or n
Yes
36
Block delete is also sometimes called
Optional Block skip
37
Where do you place Block delete
Before the command you want to block at any part of the line
38
What is m00?
Program stop
39
These g00,g01,g02/3 share 5 things in common
-they are modal
-requires you to program with an end point
-can be done with absolute or incremental positioning
-require you to include only moving axes
-allow you to omit the leading zero
40
This means the cnc machine does its best to provide the intended motion based upon a limited amount of program data
Interpolation
41
The rapid motion distance that keeps the cutting tool for a short distance from the part that is being machined. And what is the rule of thumb distance
Rapid approach distance and .1in
42
The distance that ensures that the cutting tool fully machines the last Surface and above the largest diameter. And rule of thumb distance
Escape distance and .05in
43
Recommend in these modules, you create a ___ before writing a program
Coordinate sheet
44
What is g98 and g99
G98 per minute feed rate. Mainly for mill turn machines, live tooling or bar feeders
G99 ipr mode for almost all turning centers like lathes
45
What is the preffered positioning method between absolute and incremental?
Absolute
46
What are the 2 positioning methods?
Absolute (uses x and z)
incremental (uses u and w)
47
48
49
Provides a way to machine circular surfaces such as fillet, radius and outside radii
Circular interpolation
50
What is g02 and g03?
G02 is CW circular motion
G03 is CCW circular motion
51
2 ways to command arc radius that is being machined when using circular interpolation
R word
Or directional vector
52
Is the R word modal? Y or n
No
53
When using directional vector for machining an arc, what letter addresses X and Z
X = I
Z = k
54
___ automatically compensates for tool nose radius. It allows you to program the work surface path and keeps the cutting tool in contact with the work Surface
Tool nose radius compensation
55
If you dont use TNRC. Outside chamber and outside radius will be smaller while making fillet radius and chamber bigger by half the tool nose size, t or f?
True
56
What are the 4 programming features that are built in to machines?
-one pass facing/turning and boring canned cycles
-multiple repetitive cycle
- sub programming
-hole machining canned cycles
57
A ___ performs a series of predetermined movements based upon one cnc command
Canned cycle
58
What is the return zero command?
G28
59
Every canned cycle doesnt require you to send the cutting tool to a convenient position, t or f?
False. You have to set it
60
All canned cycles can be used for both internal and external machining? T or f
True
61
G00 or G01 cancels canned cycles? T or f
True
62
What is G94
One pass facing cycle
63
When using g94 one pass facing cycle, what letter do you use when adding a taper?
And what is it for G90 one pass turning?
K for g94
I for g90
64
What is G90?
One pass turning/boring cycle
65
66
67
___ makes it easy to program complex machining operations like roughing, finishing, peck drilling,grooving and threading
Multiple repetitive cycle
68
What is G70 to G75?
G70 finishing for g71,72,73
G71 rough turning and boring
G72 rough facing
G73 pattern repeating
G74 peck drilling/ face groove
G75 radial groove
69
3 steps to program g71
-set convenient starting tool position
-specify g71
-specify finish pass
70
What are the g71 command words/letters
P- specifies sequence N# of the command that begins finish pass definition
Q- same as P but the one that ends finish pass definition
U- how much stock left before finishing + for turning, - for boring
W-how much stock left for facing
D- depth of cut. 4numbers for imperial and 3 for metric
F- feed rate
71
An alarm sounds if you leave out the G00,G01 or include a Z word in the command specified by the P word. T or f
True
72
When using G71 for boring. Does U value have to be negative or positive?
Negative
73
2 limitations of G71 command
-machining recesses
-efficiency
74
___ is quite similar to the rough turning/boring cycle. Major difference is that the machining is done in a facing manner
Rough facing multiple repetitive cycle
75
What is rought facing MRC g code
G72
76
Using G73 pattern repeating cycle almost always results in some wasted air cutting time, t or f?
True
77
Commonly called __, this action causes depth of cut to instantly increase to the point that the spindle or cutting tool may be damaged
Burying the cutting tool
78
For g73 pattern cutting, what does the word D, I and K stand for?
D - specifies # of rougjing passes
I- specifies the amount of raw material that is on all dia surfaces
K- specifies amount of raw material that is on all faces
79
G75 radial grooving is also called __?
Necking
80
Limitation of g75 radial grooving is it does not break edges, t or f?
True
81
G75 words I, K and F definitions
I -used to break chips, specifies peck amount
K - specifies move over amount on Z axis when multiple passes must be made
F- specifies plunging feed rate
82
What size is the overlap for grooving g75?
Atleast 0.01in
83
Using g73 pattern repeating cycle almost always results in some water air cutting time, t or f?
True
84
Commonly called __, this action causes DoC to instantly increase to the point that the spindle may still or cutting tool may be damaged
Burying the cutting tool
85
What does D,I and K mean for g73 pattern repeat
D- # of roughing passes
I- amount of raw material that is on all diameter surfaces
K- amount of raw material that is on all faces
86
__ is done by plunging a grooving tool into a face
Face grooving
87
G74 face grooving words K,I and F definition
K- used to help break chips, specifies peck amount
I- specifies the move over amount in the x axis when multiple passes must be made
F- feed rate
88
Peck drilling is done to break chips at manageable lengths, t or f?
True
89
For deeper holes, peck drilling is done to keep chips from packing into the drilling flutes, t or f?
True
90
G74 is used for both face grooving and peck drilling, t or f?
True
91
G74 words for peck drilling. Z,K and F.
Z-specifies bottom position of hole
K- peck amount
F- feed rate
92
3 types of compensation offsets
-Geometry offset/home shift
- wear offsets
-tool nose radius compensation
93
4 nose radius sizes for single point cutting tools (lathe)
-1/64
-1/32
-3/64
-1/16
94
Without TNRC, outside chamfers and radius are smaller while internals are larger, t or f?
True
95
TNRC is only required for single point cutting tools? T or f
True
96
Turning centers made in the last 30yrs have a "look ahead buffer" that eliminates the need for motion vectors, t or f?
True
97
3 steps to program TNRC
-instate tnrc
-program toolpath motion
-cancel tnrc
98
3 g codes for TNRC
G41 - instate tnrc with tool left conditions
G42- instate tnrc with tool right conditions
G40- cancel tnrc
99
You must tell the turning centers 2 things about cutting tools using TNRC. It needs to know the
Tool nose radius size
Type of cutting tool being used
100
Types of cutting tools and there T register values
T1- back boring bar
T2- boring bar
T3- turning tool
T4- back turning tool
T5- button tool 3 oclock
T6- button tool 12 oclock
T7-buttom tool 9oclock
T8- button toom 6 o'clock
T9- centerline
101
2 of the most popular tool T registers
T2- boring bar
T3- turning tool
102
G code used to enter program data entrys
G10
103
What does API stand for?
American petroleum Institute
104
Almost all types of threads share one thing in common. They are __ used to secure one component to another
Fastener
105
The most popular thread form is the __?
V thread
106
Most popular angle size on a v thread
60deg
107
What does API stand for?
American Petroluem Institute
108
Almost all thread types share one thing in common. They are all __, used to secure one component to another
Fastener
109
The __ of a thread determines the direction you use to tighten/loosen mating components
Handedness
110
The distance from one thread to the next determines the threads __?
Coarseness
111
Thread __ is the amount of snugness between mating components
Fit
112
6 classes of fits for threads
For external 1A,2A,3A
For internal 1B,2B,3B
Higher class number= tighter fit
113
The larger of the 2 extreme diameters on a thread
Major diameter
114
The smaller of the 2 extreme diameters on a thread
Minor diameter
115
The diameter at which the thread thickness is equal to the space between threads
Pitch diameter
116
The radial distance between major and minor thread diameter
Thread depth
117
The included angle between the tread sides
Thread angle
118
The distance between adjacent threads
Pitch
119
With a single thread start, the __ is the same as the pitch
Lead
120
The distance across the flat at the major minor diameter
Root
121
The angle of the thread crest
Helix angle
122
With external male threads, each thread crest and root gets progressively larger in diameter
Taper angle
123
For threads, UNC stands for?
Unified Coarse
124
UNF for threads stands for?
Unified Fine
125
The 2 in 2B is specifies class fit. 1-3 looses to tightest. What are there uses
1- rarely used
2- common for commercial use
3- common in aerospace industry
126
__ diameter is needed for programming internal threads
Major diameter
127
__ diameter is needed for programming external threads. Calculate it by subtracting twice the thread depth from the major diameter
Minor diameter
128
It is commong to machine a thread with thread chamfering turned off when there is a groove called the thread relief. And is turned on if there is no thread relief, t or f
True
129
You can produce threads on a cnc turning centers in a least 3 ways, what are they?
- chasing
- tapping
-roll forming
130
The DOC when threading is called?
Infeed amount
131
How the threading tool is positioned for each pass is called?
Infeed method
132
Limitation for standard single point v thread tool is it doesnt cut the major dia on external threads and minor dia in internal, t or f?
True
133
Called a __ or __ tool, this machines the entire thread form on a single point tool
Cresting or topping tool
134
A cresting insert kachijed the diameter of the thread being machined, eliminates the burrs and better finish. T or f?
True
135
Limitation of a cresting threading insert is?
It can only machine 1 pitch. You'll need a different insert for every pitch
136
3 infeed methods for cutting threads
-compound infeed
-radial infeed
-alternating compound infeed (also called incremental infeed)
137
Compound infeed is used usually with threading tools with just 1 cutting edge, t or f?
True
138
__ infeed causes the threading tool to simultaneously machine on both sides of the thread. Provides better finish
Radial infeed
139
All cresting tools have the ability to machine on both sides, t or f?
True
140
The ___ infeed method tends to prolong the cutting tools life while still proving a good surface finish
Alternate compound infeed
141
2 ways to retract the threading tool after each threading pass are
Straight retract
Angular retract
142
Between straight and angular retract, which is the more popular Between the 2 methods
Straight retract
143
The angular retract method machines a nice looking thread and minimizes the possibility of insert chipping should the machine not be precise enough to perform a straight retract, t or f?
True
144
Machine tool builders recommend approach distance for turning centers for threading based upon the motion rate tou need to achieve, t or f?
True
145
For threading, a good rule of thumb is to make the approach distance 4x the thread lead or 0.2in, whichever is smaller, t or f?
True
146
The __ determinesnthe number of threading passes. If no suggestion from manufacturer, good rule of thumb is 20% of pitch
First pass depth
147
A good minimum pass depth is 0.005in. T or f?
True
148
Programmers usually set the last pass depth to 0.0002, to or f?
True
149
Spring passes for threads are NOT always required, t or f?
True
150
Formula for rpm
3.82×sfm÷diameter =rpm
151
F word when cutting threads stands for ?
Lead or pitch. It is always a 4 place number eg 0.0625
Use E for more numbers =better accuracy
152
153
154
3 factors that contribute to whether a threading tool will machine a RH or LH threads are
-handedness of cutting tool
-spindle direction (forward or reverse)
-motion dirextion during each pass
155
M03 and m04 of lathes
M03= forward CCW
M04= reverse CW
156
To determine handedness, place cutting tool upright on a flat surface and view it from the cutting edge. If cutting edge is on the RH side, it is right hands and same with left. T or f
True
157
Another feasible way to machine a left handed thread is to use a __?
Left hand threading tool
158
3 major components on threading tool on a cnc
- shank
- insert
- clamping mechanism
159
A ___ insert is more flexible. it can machine any pitch in the thread form. It's limitation of that it may leave a burr. A cresting insert is more preferable
Non cresting
160
3 G code threading commands from oldest to newest
G32- threading motion command
G92- one pass canned cycle threading
G76- multiple repetitive cycle for threading
161
4 things threading commands have in common
- they synchronize spindle rotation with axis motion
-disable spindle speed override switch
-disable feedrate override switch
-with g92/g76 , the single block switch is disabled during each threading pass
162
Programming thr extreme leading edge of a threading tool is recommended for cylindrical threads, t or f?
True
163
Many programmers do not use G32 for threading. It is however helpful when tapping. Especially if the turning centers does not have a hole machined canned cycle for tapping. T or f?
True
164
G92 is seldom used since the multiple repetitive cycle for threading g76 automatically causes Z axis position for compound and alternating compound infeed, t or f?
True
165
2 types of G76 commands
One line
Two line
166
3 basic letter addresses for G76 command
D- first pass depth
I - taper amount
P- infeed method
K- thread depth
A- tool angle
F- lead angle (same as pitch)
E- same as F for more decimals
167
168
169
Letter P for g76 specifies infeed method. What are the 4 P codes
P1- compound infeed, reduced DOC per pass
P2- alternating compound infeed, reduced DOC
P3- compound infeed, constant DOC
P4- alternating compound infeed, constant DOC
170
2 line G76 allows you to program ALL threading variables ? T or f?
True
171
P in two line G76. They have 6 digits.
1st 2- number of spring passes
2nd 2- thread chamfer amount
3rd 2- tool angle
172
If you leave P word oit of the first line of G76, the machine uses the parameter settings for number of spring passes and chamfer amount, and uses radial infeed, t or f?
True
173
Where can you find the taper angle for the thread form to machine?
Machinerys handbook
174
Taper angle for NPT threads in decimal form
1.783
175
What does NPT stand for?
National pipe thread
176
Since so many safety related functions are disabled during threading motions, it is recommended that you exaggerate the normal method of trial machining, t or f?
True
177
Multiple start threads provide more distance per rotation than can be achieved with a coarse single start thread while providing the fit and smoothness of a fine thread, t or f?
True
178
What g code to use when tapping on a lathe for feed rate
G99 feed per revolution feed rate modr
179
Most machine tool builders recommend using a __ tap holder, which allows the tap to adjust to the hole while it is tapping. Also called tension/compression tap holders
Floating tap holder
180
G code for tapping on a lathe without live tooling
G32
181
G32 is better than g01 for tapping as it disables feed hold, feedrate override and spindle speed override, t or f?
True
182
Single block must be turned OFF when tapping using g32, t or f?
True
183
How do you get the feed rate when tapping on a lathe?
Feed = thread pitch
184
5 types of thread gauges
-go/no go plug gauges
-go/no go ring gauges
-thread pitch mic
-lead pitch mic
-pitch and form gauge
185
All turning centers have a limit as to how fast they can cause each axis to move in a machining command like g01,g32,g92 and g76. It is called __
Maximum feed rate
186
Sometimes the machines maximum feed rate cant keep up with the sfm given by the tool manufacturer which leads to the lead of a thread coming out less than it should. What should you do to fix this?
Adjust rpm so that the feed rate can keep up. More time but better thread
NEW Machinist 3
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