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Using a quality gripper with the right size of drive pins can significantly increase machining speed and accuracy and reduce machining time and cost accordingly. Clamps are a versatile tool with which a wide range of machining operations can be performed.

Complete O.D. Machiningin one Operation

Face drivers locate a shaft type part between centers and hold the part in place by utilizing several knife edge drive pins. Because of the tool clearance a face driver provides, it allows the operator to machine the entire outside diameter of the workpiece in one clamping. This guarantees excellent concentricity and reduces both set-up and run time. Used primarily for turning, face drivers can also be used for hobbing, milling and grinding operations.

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Complete OD Machining in One Clamping Face  Drivers  permit  machining  the  entire  outside  diameter  of  any  workpiece  in  one  clamping,  because  the  gripping  and  turning  power of the driver is exerted only on the face of the workpiece. If driving dogs  or  chucks  are  used,  any  workpiece  requiring  turning  over  its  total length has to be unclamped after initial machining, reversed, and reclamped  for  completion.  This  means  increased  handling,  wasteful  downtime and possible loss in concentricity . The  chisel-edged  drive  pins  bite  into  the  end  face  of  the  part,  and  with  the  increasing  torque  generated  as  the  cutting  tool  makes  its  cut,  the  drive  pins  bite  even  deeper  into  the  face,  thus  providing positive clamping.Greater Accuracy in Machining OperationsThe center point of the face driver establishes the axis of rotation, and the  chisel-edged  drive  pins  clamp  the  piece  part  face.  With  only  one  clamping  required,  and  the  part  rotating  between  centers,  a  single  reference point is established for all operations, assuring high accuracy in concentricity.Accurate End LocationAccuracy  of  end  location  is  assured  with  face  drivers.  The  drive  pins,  which locate the workpiece axially, will indent uniformly within ± .002” from one piece to another under uniform tailstock force.

Faster Loading TimeFace drivers require less load time than driving dogs or chucks because of  their  self-centering  ability  and  simplicity  of  operation.  Parts  can  be  loaded  on  the  machine  and  clamped  in  only  a  few  seconds,  thereby  reducing machine downtime to a minimum and substantially increasing production.Eliminates Preliminary Machining of End FacesExcept  for  center  hole  drilling,  irregular  or  out-of-square  faces  need  not  be  machined  before  clamping  with  face  drivers

How the Face Driver Works

Face Drivers are composed of two main assemblies:

(1) the locating shank,  which  fits  on  the  spindle  nose  having  either  a  taper  shank  or  flange  mount;  and  (2)  the  driving  head.  The  basic  components  in  the  driving  head  are:  the  spring-loaded  center  point,  the  drive  pins,  and  a  compensating  medium  which  permits  each  drive  pin  to adjust to irregular face variations.

Face  clamping  is  a  simple  two-step  operation.  Centering  takes  place when the spring-loaded center point engages the workpiece, establishing the precise axis of rotation. As the tailstock is engaged in the workpiece and axial force is applied, the center point retracts against  its  spring.  The  drive  pins  then  contact  the  face  and  adjust  themselves  to  its  surface.  Increasing  tailstock  force  causes  the  drive  pins  to  penetrate  the  workpiece  face,  thus  completing  the  clamping operation.Irregularities  or  out-of-squareness  of  the  workpiece  face  present  no problem to face drivers, because the drive pins are actuated by an interconnected, self-compensating medium which enables each chisel  point  to  penetrate  with  equal  force,  regardless  of  surface  irregularities.

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TOOL SELECTION DATA

Drive Pin StylesThe  ability  of  each  face  driver  series  to  cover  a  wide  range  of  work . diameters  is  accomplished  through  the  use  of  four  styles  of  interchangeable  drive  pins.  Each  pin  style  adapts  the  basic  tool  to  a  specific gripping diameter range.

The dual range type hydraulic face driver is equipped with two sets of drive pin holes. This built-in flexibility of pin locations, combined with the  variety  of  drive  pin  styles  available,  enables  the  tool  to  cover  a  wide range of gripping diameters.

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Operation and Maintenance Information:

Center Hole Size for Proper Face Driver Function:

While center hole diameter is not critical, it can adversely affect face driver operation if not taken into consideration in the selection of the proper center point for a given application.

In the case of an undersize center hole, the center point cannot retract enough to allow the pins to penetrate to the required depth. (See Fig. 4). In this case, pins cannot engage the workpiece face and cutting cannot take place. Conversely, if the center hole is oversize, the center point cannot locate the part properly before the drive pins contact the face of the workpiece (See Fig. 5). As a result, the workpiece will be machined eccentrically with respect to other center hole. The correct size center hole (Fig. 6) allows centering and proper pin penetration to take place. For proper face driver function, check the center hole diameter of your workpiece to be sure it falls within the required limits for the center point being used.

Lubrication:

To prevent rust and to increase tool life, the center point and drive pins should be periodically removed from the carrier body and coated with lubricant.

 

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Operation and Maintenance Information

Installing Face Driver on Machine

In mounting the face driver, accuracy and rigidity are of prime importance. Whenever possible, it is best to mount the drivers directly in the machine spindle.

To save setup time and to avoid removing the chuck, it is possible to clamp the driver directly in the chuck.

Before using the driver, make sure that the drive pins are oriented with respect to driver rotation.

After the driver has been mounted on the machine, it should be checked for runout. In the case of morse taper style drivers, the maximum radial runout will not exceed .002. Flange-mount drivers have four centering set screws located at 90 ̊ intervals around the periphery of the flange drive shank. These screws permit radial adjustment of this style driver to virtually eliminate runout.

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Care and Maintenance:

face drivers are rugged and trouble-free but, like any precision-made tool, they should not be subjected to undue abuse. Chips, dirt and other foreign matter cannot easily penetrate the face driver because of close manufacturing tolerances maintained in the design; thus, only infrequent disassembly for cleaning is required.

Regrinding Drive Pins and Center PointsDrive pins can be resharpened. After repeated regrinding, check the center point for additional retraction after the work has contacted the driving pins to ensure proper face driver function. This can be done by marking the center point projection at the face driver when work is clamped. Upon removing the work, depress the center point to see whether the mark disappears inside the face driver. If so, the center point has adequate travel.

We offer regrind service for drive pins and center points.

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Machining The Workpiece:

Workpiece Hardness

Generally speaking there will be no problem with drive pin penetration at normal tailstock force if the workpiece hardness does not exceed 36 Rockwell “C”. Above 36 Rockwell “C”, tailstock forces must be increased and the cutting section area reduced because of the increased torque encountered. For most turning operations, the practical upper limit of workpiece hardness for satisfactory use of face drivers is about 40-42 Rockwell “C”.
Since lower torques are involved in operations such as grinding or hobbing, it is often possible to achieve satisfactory pin penetration on workpieces having a hardness greater than 42 Rockwell “C”;

All manufacturers want to improve efficiency while maintaining quality. In today’s competitive and volatile world, efficiency just may be the difference between survival and demise. Efficiency is the ability to produce something with a minimum amount of effort. A Face Driver workholding solution will cut your cycle times in half to provide increased production and better quality.

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