Shafts and Attachments Flashcards
These transmit motion and power from one machine to another
Shafts
These are used to locate parts precisely
Keys and keyseats
Axial grooves manufactured into attachments and shafts are known as
Splines
Key stock is manufactured to this tolerance
A plus tolerance (oversize)
Key-stock material
low to medium carbon steel (AISI 1020 cold drawn)
Bar stock is made to this tolerance
A minus tolerance
Sizes up to 0.75” -0.002
Sizes 0.75 to 1.5” -0.003
Rectangular keys are also known as
Flat keys
Square keys are recommended for shaft sizes up to
165mm (6.5”)
Rectangular is recommended for larger sizes
This key is used when the shaft keyseat is a different size than the hub keyseat, and also align machine parts
Offset key (stepped key)
This key does not require a keyseat in the shaft, uses friction from the set screws upon it
Saddle key
This key is equal length to the keyseat, and less than the width of the hub
Boxed (blind) keys ex. Buried, Pratt and Whitney
Similar to boxed keys, but are 2/3 in the shaft, 1/3 in the hub (also sizes they come in)
Sunk keys (sizes from No 1. 1/2” long by 1/16” wide to No 34. 3” long by 5/8” wide
This key has a tight fit in the keyseat, sometimes secured by screws and allows some axial movement of the hub
Fixed feather
This key slides in a keyseat with the part along the shaft, prevents the rotation of one part on the other
Sliding feather
This key secures the component firmly to the shaft with no set screw
Tapered key
The standard taper for tapered keys
1 in 96 or 1/8” in 12”
Metric ratio is 1 in 100
Woodruff keys with a diameter larger than ___ may have their ends flattened
1.5”
The last two digits in a woodruff key give this
Nominal diameter in eighths of an inch
ex. #406 = 06x1/8 = 3/4
The digit(s) before the last two digits in a woodruff key give this
Width of key in thirty-secondths of an inch
ex. #406 = 4x1/32 = 1/8
The width of the key is ___ ______ the nominal diameter of the shaft
one quarter
How do you find the key length
Same as the shaft diameter
End mills produce this keyseat
Profile
Horizontal milling cutters produce this kind of keyseat
Sled runner or runout
Keyseat alignment has these maximum tolerances
- 25mm (0.010”) for offset alignment.
0. 10mm (0.002”) in a distance of 100mm (4”) for angular misalignment
How is the depth of a keyseat measured
Diametrically from the bottom of the keyseat to the opposite side of the shaft
How are parallel keyseats cut in bores
Enough to accommodate half the height of the key plus clearance
End mills used to cut keys are called this
Slot cutters
What tolerance do end mills have on the diameter
+0.0000 to -0.0015
What is the method for cutting key seats in attachments
Hand-broaching
How much does each tooth protrude on a broach
0.003” (0.07mm) further than the preceding tooth (last 3 are the same)
Each pass cuts to a depth of 1/16”
Keyway broaches are furnished with this amount of rake
8 to 10 degrees
What are the classes of fit for keys
Class 1 is a clearance fit
Class 2 is a relatively tight fit
Class 3 is an interference fit
What are the clearances for the key in a keyseat
0.005” above, 0.002” on the sides
When should adhesives not be used for keys
Temperatures above 93 C
How are set screws categorized
By the style of their heads (forms) and their points
Set screw head styles
Hex socket, slotted socket, flat socket, square head (protrude from component)
The most common set screw head used
Flush hex head
Set screw used to lock pulleys, sheaves, gears, collars directly onto soft shafts
Cup point
Knurled cup for vibration and permanent position
Set screw used to secure stops, screws, gears to hardened shafts
Flat point
Set screw used where it is spot drilled first
Cone point
Set screw used to lock parts that are adjusted frequently relative to each other
Oval point
Set screw used to engage directly into slots milled longitudinally in shafts, also acts as stop to limit travel
Half-dog
Are set screws compression or tension
Compression
When more than one set screw is required where are they placed?
90 degrees to each other
What is the size of socket locking screws
Length is one half their diameter
What do you use to remove gib-headed keys
Fox wedge between gib and face of hub (may need more than one)
What is one way to remove a parallel key if theres room in the keyseat
a dutchman
What is the process of removing scale off the hot-rolled shafting
pickling and bright dipping
This is known is precision shafting
C1045/C1050 (high speed applications)
What weight and strength loss in a hollow shaft
Lose 25% of it’s weight but only 6.25% of it’s strength
This is defined at the internal resistance offered by a unit area of a material to an externally applied load
Stress
Normal stresses are either these two things
Tensile or compressive
A combination of tensile and compressive stresses
Bending stress
Occurs when the applied force tends to cut through the shaft
Shear stress
Which keyseat has less stress concentrations, profile or runout
Runout because of it’s smooth longitudinal radius at the ends
The reduction in diameter on a shaft for a shoulder should be no more than this
1.5:1
Fillet radius large as possible
Machines are usually not set within __% of their critical speed
20%
This runout occurs when the shaft and the attachments are not concentric in their rotation
Radial
This runout occurs because of imperfections in the corss section of the part
Circular
This runout occurs because attachments do not rotate perpendicularly to the shaft axis
Axial
Styles of hubs (bosses)
A - No shoulders
B - Shoulder on one side
C - Both sides
D - Split sprocket
The two types of couplings
Rigid and flexible
For a manual puller the diameter of the adjusting screw should be at least this large
At least half as large as the shaft
Two helical gears in mesh and rotating under toque produce this
Thrust
Tapered bushing recognized by an axial split through the barrel and flange
Quick detachable bushings
Tapered bushing that has an axial split through the barrel and is internally and externally keyed
Split taper bushing
The taper on a dowel pin
1/4” per foot
This shafting is not good for shock load applications
Hollow
The maximum distance between bearings on a standard line shaft
8 feet
Define RC, LC, LT, LN, and FN fits
RC - Running and sliding fit LC - Clearance LT - Same size LN - Press fit FN - Shrink fit
On end mills a split collar is required to accept shanks with a diameter smaller than
1/4”
This process is the technique of spraying a metal coating onto a metal object
Metalizing
This refers to the minimum clearance between mating parts
Positive allowance
This refers to the maximum interference
Negative allowance
This clearance provides clearance between mating parts for lubrication
Running and sliding
A machine screw fit into a bolting hole is an example of this fit
Locational clearance
A dowel pin in a mating hole is an example of this type of fit
Transition fit
An anti-friction bearing being pressed into a housing is an example of this fit
Locational interference
The range in size of hydraulic presses
10 tons to 150 tons
A puller needs to withstand this force in tons
7 to 10 times the shaft diameter in inches
How far should the gib head be from the front of the hub
6mm (1/4”)
Precision shafting over this size is supplied in fibre tubes
1-1/4”
Most anti-friction bearings require a shaft surface finish up to
0.30 um
Babbitt and bronze sleeve bearings require a surface finish of up to
0.81 um
This is used to adjust the clearance between mating parts
A gib
Type of key used for reverse torque
Kennedy
