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Chucks 101 Agenda
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Types of Chucks
Grip Force
Maintenance
Jaws
Special applications
WWW.KITAGAWA.COM
Types of Chucks
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Thru hole style
Closed center
Wedge
Lever
Self Contained Air
Pullback
Thru Hole style chuck
Bar Feed
Chucker Work
Accurate
Durable
High Speed
High Grip Force
Wide Range Of
Application
Most Common
Body Is High
Grade Alloy Steal
All Wear Surfaces
Are Hardened And
Ground
Closed Center Style Chuck
Chucker Work
Accurate
Durable
High Speed
High Grip Force
Wide Range Of
Application
Body Is High
Grade Alloy Steal
All Wear Surfaces
Are Hardened
And Ground
Wedge Style Chuck
Master Jaws
Interaction between angle on master jaw to
angle on wedge plunger. 2 “wedge” surfaces
interacting to give motion and mechanical
advantage.
Wedge Plunger
Lever Style Chuck
PW & PWT (BALL LOCK) STYLE PULLBACK CHUCKS
STANDARD
* PW series (3 Jaw)
*PWT series (2 Jaw)
COMPENSATING
*PW-C series (3 Jaw)
*PWT-C series (2 Jaw)
ADVANTAGES
OD OR ID GRIPPING
PULL BACK CHUCK – NO WORKPIECE LIFTING
COMPLETELY SEALED
CHUCK ON UPTO 20 DEGREE DRAFT ANGLE
JAWS EQUALIZE UPTO 5 DEGREES
EXCELLENT FOR 1st OPERATIONS
Special Features Of The PW(T) Chuck
SPECIAL FEATURES OF THE PU SERIES
PULL DOWN FEATURE – IDEAL FOR
2ND OPERATIONS REQUIRING HIGH
PRECISION
HIGH GRIPPING FORCE RETENTION
HIGH ACCURACY (.0004”)
HIGH DURABILITY – ALL SLIDING
SURFACES ARE HARDENED AND
GROUND
COMPLETELY SEALED DESIGN
Inner Workings Of PU Chuck
SPECIAL FEATURES OF THE PUE SERIES
PULL DOWN FEATURE – IDEAL FOR
2ND OPERATIONS REQUIRING HIGH
PRECISION
HIGH GRIPPING FORCE RETENTION
HIGH ACCURACY (.0004”)
HIGH DURABILITY – ALL SLIDING
SURFACES ARE HARDENED AND
GROUND
COMPLETELY SEALED DESIGN
PU200 MAIN PARTS
BODY
MASTER
JAW
PLUNGER
THE PULL-DOWN MECHANISM
PU200 PLUNGER ASSEMBLY
THE MASTER JAW MOVES IN BOTH THE Y & Z AXES BECAUSE OF THE BODY’S
ANGLE, WHILE THE PLUNGER JUST MOVES ALONG THE Z AXIS.
SPECIAL FEATURES OF THE UVE & UB SERIES
SELF CONTAINED AIR CHUCK
EASY INSTALLATION
EXTRA LARGE BORE – NO DRAWTUBE
BUILT IN CHECK VALVE
HIGH SPEED
UVE750
PISTON
HOW THE UVE SERIES WORKS
AIR FLOWS INTO THE CHUCK AND
PUSHES ON THE PISTON.
TOP
JAW
THE PISTON DRAWS THE WEDGE
PLUNGER IN OR OUT DEPENDING ON
WHICH CAVITY THE AIR FILLS.
THE WEDGE PLUNGER MOVES AND
CAUSES THE MASTER JAWS TO SLIDE IN
OR OUT ALONG THE WEDGE.
AS THE MASTER JAWS MOVE ALONG THE
WEDGE IN THE WEDGE PLUNGER THE
TOP JAWS OPEN AND CLOSE.
AIR FLOWS IN
Grip Force Is Affected By:
• Speed (RPM) Of Chuck – As speed increases grip force
decreases.
• Jaw Height – As the gripping center height increases
the grip force decreases.
• Jaw Mass – As the mass of the top jaw increases the
grip force decreases.
• Chuck Condition - If the chuck has damage or
excessive wear grip force can be impacted.
• Lubrication – Proper chuck lubrication can increase grip
force up to 50%.
Grip force and maximum rpm ratings are based on using Kitagawa soft jaws
W
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Chuck Specifications
3
1)
2
1
MECHANICAL ADVANTAGE = MAX GRIP FORCE/MAX DRAWBAR PULL FORCE
5812(Kgf)/2243(Kgf)=2.59(Kgf) MECHANICAL ADVANTAGE
2) CYLINDER STROKE MUST EQUAL OR EXCEED CHUCK PLUNGER STROKE
3) JAW STROKE IS ON DIAMETER. TO GET STROKE PER JAW DIVIDE BY 2
5.5mm/2 = 2.75mm STROKE PER JAW
You can find this information for all our chucks at WWW.KITAGAWA.COM
GRIP FORCE LOSS
WITH INCREASED SPEED
JAW HEIGHT VS. GRIPPING FORCE
WITH INCREASED HEIGHT
Jaw Mass Effect On Grip Force
A=B
A
B
H
37 mm
R
A
B
B-24
H: H * Grip Force = Grip Force * mm
Grip Force / H = New Grip Force
H
*
A=B
Mass (M) = 9.186 Kg
Mass Center Radius (R) = 254 mm
M * R * 3 = 7000
23,861 Kg * 37 mm = 23,861 * 37 = 882,857 Kg/mm
882,857 Kg/mm / 105 mm = 8408.16 Kg New Max Grip Force
Gripping Coefficient Of Friction
TS = HOLDING FORCE (Kgf/mm) = (DYNAMIC GRIP FORCE * u (see table above) * GRIPPING DIAMETER)/2000
EXAMPLE: 200mm grip diameter, 3671 Kgf dynamic grip force, serrated fine axial grip with wedge chuck
TS = (3671 Kgf * .24 * 200mm)/2000 = 88.104 Kgf/mm
TR = CUTTING TORQUE (Kgf/mm) = CUTTING DIAMETER (mm) * FEED RATE (mm/rev) * DEPTH OF CUT (mm) * MATERIAL CUTTING
RESISTANCE (Kg/mm2) /2000
EXAMPLE: 300mm CUTTING DIAMETER, .100mm/rev FEED RATE, 1.5mm DEPTH OF CUT, MATERIAL IS LOW CARBON STEEL (367.2 Kg/mm2)
TR = (300mm * .100mm *1.5 * 367.2) / 2000 = 8.262 Kgf/mm
TS/TR = SAFETY FACTOR
88.104/8.262 = 10.66 SAFETY FACTOR
YOU WANT AT LEAST 2.5
Other Factors That Affect Cutting Torque
Workholding
1) Gripping Diameter
2) Friction Coefficient ( u )
3) Gripping Force
Other Aspects
1) Gripping Accuracy
Cutting Conditions
2) Toppling Moment Of Part
1) Cutting Diameter
3) Part Pushback Force From Cut
2) Depth Of Cut
4) Imbalance Of System (Part & Chuck) - Vibration
3) Feed Rate
5) Rigidity Of System (Chatter)
4) Material Cutting Resistance
5) Speed
Items In Red Can Be Altered To Suite The Application
Chuck Maintenance
Greasing The Chuck Not Only
Lubricates, But Also Helps
Remove Contamination From
The Chuck
Proper Lubrication Can Prevent
The Loss Of Up to 50% Of A
Chucks Grip Force
How CHUCK-EEZ Works
Comparison Of Grip Force With CHUCKEEZ and Lithium Grease
CHUCK-EEZ GREASE VS LITHIUM GREASE
18
GRIP FORCE (KN)
16
15.4
15.1
13.8
14
11.8
12
10
8.7
8
8.1
9.2
7.1
CHUCK EEZ
LITHIUM
5.4
6
4
3.4
2
0
1000
2000
3000
4000
5000
RPM
With CHUCK-EEZ Grease You have More Grip Force At 5000 RPM Than Lithium
Grease Has At 0 RPM
Chuck Maintenance – Periodic Disassembly
Clean
Inspect
BENEFITS
Increase Chuck
Life
Decrease
Unplanned
Downtime
Safety
Maintain chuck
performance and
accuracy
Jaws
• Jaw Lift – Sliding jaw chucks will impart a slight lift when
they clamp.
• Forming Soft Jaws – Form soft jaws under clamp load
• T-Nut Position – There is a maximum front and back
position.
• Potential Problems With Aftermarket Jaws – If the
serrations are not made correctly it can cause wear
issues and grip force problems.
Jaw Lift In Sliding Jaw Chucks
THE SLIDING JAW STYLE POWER CHUCKS OPEN AND CLOSE WHEN THE
MASTER JAWS SLIDES ALONG THE WEDGE PLUNGER’S FITTED SLOTS. THE
FIGURE ABOVE SHOWS A CASE OF OD CLAMPING. THE MASTER JAWS MOVE
UNTIL THE TOP JAWS TOUCH THE WORK PIECE. HOWEVER, THERE IS A GAP
BETWEEN THE MASTER JAW TABS AND THE WEDGE PLUNGER’S SLOTS. SO IN
ORDER FOR THE MASTER JAWS TO MAKE CONTACT WITH THE WEDGE
PLUNGER THE JAWS WILL TILT WHEN THE WORK PIECE IS GRIPPED. THE
INNER TOP AND OUTER BOTTOM OF THE MASTER JAWS TAB WILL CONTACT
THE DOVETAIL GROOVES (SLOT) IN THE WEDGE PLUNGER. .
THE AMOUNT OF LIFT UP IS INCREASED BY THE FOLLOWING CONDITIONS:
HIGH
GRIPPING FORCE
TALLER
SMALL
JAWS (HIGH GRIPPING CENTER HEIGHT)
GRIPPING DIAMETER
Forming Soft Jaws For A Sliding Jaw Chuck
Step 1
Step 4
Step 2
Step 5
Step 3
Why You Need To Reform Soft Jaws After Removal
EVEN IF YOU RE-MOUNT THE TOP JAWS THAT WERE MADE ON THE CHUCK AT THE SAME POSITION,
THE GRIPPING ACCURACY WILL MOST LIKELY BE WORSE THAN BEFORE THE REMOVAL OCCURED.
IF YOU NEED THE ACCURACY TO REMAIN THE SAME AS BEFORE, YOU WILL NEED TO RE-CUT THESE
JAWS ON THE CHUCK.
THE FIGURE SHOWS THE WORST CASE SCENARIO. TOP JAWS WERE FINISHED TOUCHING THE
RIGHT-AND SIDE OF T-NUTS (AS SHOWN ON THE LEFT SIDE OF THE FIGURE). THEN, THEY WERE
DETACHED AND RE-INSTALLED TOUCHING THE LEFT-HAND SIDE OF THE T-NUTS. IN THIS CASE,
SINCE THERE IS A GAP BETWEEN THE T-NUT AND THE TOP JAWS, THE POSITION OF THE TOP JAWS
IS NOT COMPLETELY THE SAME. THIS IS THE CAUSE FOR THE DETERIORATION OF ACCURACY.
T-Nut Positioning
COMMERCIAL SOFT JAW ISSUES
IMPROPER
IMPROPER
CHAMFERING
PITCH
Serrations
Need To
Properly Mate
Up Between
The Master
Jaw And Top
Jaw
COMMERCIAL VS. PRECISION SOFT JAWS
COMMERCIAL
PRECISION
COMMERCIAL VS. PRECISION SOFT JAWS ON
CHUCK SURFACE
Special Applications
Some Parts Will Not Run Productively Or Accurately On Standard
Chucks and Workholding. In These Instances We Would Utilize
PW, PU Or Other Types Of Pullback Chucks. Some Parts May
Also Be More Suited To An Indexing Chuck.
Advantages Of Specialized Workholding
Achieve Higher Output
Improve Accuracy To Meet Statistical Process Controls
Lower Maintenance
Suitable For Automated Loading
Engineered To Meet The Needs Of A Specific Part And Process