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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 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 1 st OPERATIONS
Special Features Of The PW(T) Chuck
SPECIAL FEATURES OF THE PU SERIES PULL DOWN FEATURE IDEAL FOR 2 ND 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
HOW THE UVE SERIES WORKS PISTON 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. WEDGE PLUNGER 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
3 Chuck Specifications 2 1 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 DECREASED FORCE 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 H 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
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/mm 2) /2000 EXAMPLE: 300mm CUTTING DIAMETER,.100mm/rev FEED RATE, 1.5mm DEPTH OF CUT, MATERIAL IS LOW CARBON STEEL (367.2 Kg/mm 2 ) 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 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) 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 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 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 JAWS (HIGH GRIPPING CENTER HEIGHT) SMALL 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 CHAMFERING IMPROPER 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