. Chucks 101 Agenda Types of Chucks Grip Force Maintenance Jaws Special applications .

WWW.KITAGAWA.COM

Chucks 101 Agenda

• Types of Chucks

• Grip Force

• Maintenance

• Jaws

• Special applications

WWW.KITAGAWA.COM

Types of Chucks

• 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 ChuckChucker 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

Interaction between angle on master jaw to angle on wedge plunger. 2 “wedge” surfaces

interacting to give motion and mechanical advantage.

Master Jaws

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

UVE750

SELF CONTAINED AIR CHUCK

EASY INSTALLATION

EXTRA LARGE BORE – NO DRAWTUBE

BUILT IN CHECK VALVE

HIGH SPEED

HOW THE UVE SERIES WORKS

AIR FLOWS INTO THE CHUCK AND PUSHES ON THE PISTON.

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.

PIS

TO

N

WED

GE

PLU

NG

ER

TOP JAW

MA

STER

JA

W

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%.

WITH INCREASED HEIGHT

Grip force and maximum rpm ratings are based on using Kitagawa soft jaws

Chuck Specifications

You can find this information for all our chucks at WWW.KITAGAWA.COM

1

1) MECHANICAL ADVANTAGE = MAX GRIP FORCE/MAX DRAWBAR PULL FORCE

5812(Kgf)/2243(Kgf)=2.59(Kgf) MECHANICAL ADVANTAGE

2

2) CYLINDER STROKE MUST EQUAL OR EXCEED CHUCK PLUNGER STROKE

3

3) JAW STROKE IS ON DIAMETER. TO GET STROKE PER JAW DIVIDE BY 2

5.5mm/2 = 2.75mm STROKE PER JAW

GRIP FORCE LOSS

WITH INCREASED SPEED

DECREASED FORCE

JAW HEIGHT VS. GRIPPING FORCE

WITH INCREASED HEIGHT

DECREASED

FORCE

Jaw Mass Effect On Grip Force

A B

H

H

A B

A = B

A = B

Mass (M) = 9.186 Kg

Mass Center Radius (R) = 254 mm

M * R * 3 = 7000

B-24

H: H * Grip Force = Grip Force * mm

Grip Force / H = New Grip Force

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*

R

37 mm

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

Cutting Conditions

1) Cutting Diameter

2) Depth Of Cut

3) Feed Rate

4) Material Cutting Resistance

5) Speed

Items In Red Can Be Altered To Suite The Application

Other Aspects

1) Gripping Accuracy

2) Toppling Moment Of Part

3) Part Pushback Force From Cut

4) Imbalance Of System (Part & Chuck) - Vibration

5) Rigidity Of System (Chatter)

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 CHUCK-EEZ and Lithium Grease

With CHUCK-EEZ Grease You have More Grip Force At 5000 RPM Than Lithium Grease Has At 0 RPM

CHUCK-EEZ GREASE VS LITHIUM GREASE

9.2

3.4

15.4 15.1

13.8

11.8

8.7 8.1 7.1

5.4

0

2

4

6

8

10

12

14

16

18

1000 2000 3000 4000 5000

RPM

GR

IP F

OR

CE

(K

N)

CHUCK EEZ

LITHIUM

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.

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 JAWS (HIGH GRIPPING CENTER HEIGHT)

SMALL GRIPPING DIAMETER

Jaw Lift In Sliding Jaw Chucks

Step 1

Step 2

Step 3

Step 4

Step 5

Forming Soft Jaws For A Sliding Jaw Chuck

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.

Why You Need To Reform Soft Jaws After Removal

T-Nut Positioning

IMPROPER CHAMFERING

IMPROPER PITCH

COMMERCIAL SOFT JAW ISSUES

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