Automated Machining

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AutomatedMachining

• Manufacturing Processes

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Outline

• Machining Centers
• Equipment
• Tool Changers
• Centering and Clamping
• Selection of Equipment
• Selection of Tooling
• Machine Performance Monitoring
• Manufacturing Cells
• Manufacturing Economics

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Machining Centers

• Machining Center
• A computer-controlled machine tool capable of
  many types of cutting operations on multiple
  surfaces and directions on a workpiece

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Manufacturing Centers
Z
Y
X
3-Axis Operation
f
4-Axis Operation
f
?
5-Axis Operation
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Components of aMachining Center
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Example of aMachining Center
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Example of aMachining Center
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Example of a Machining Center
Example of a 5-axis CNC machine (the tool pivots
instead of the workpiece)
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Example of a Vertical Machining Center
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Example of a Horizontal Machining Center
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Examples ofManufactured Parts
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Automated Robotic Loading
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Automated Robotic Loading
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Equipment

• Pallets
• The workpiece is placed on a pallet (module)
  which can be oriented in different directions by
  the machine
• Automatic Pallet Changers
• When the workpiece is finished, automatic pallet
  changers remove it and replace it with another
  workpiece

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Pallets
Example of a part mounted on a pallet Courtesy
Toth Industries
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Pallet Changers
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Equipment

• Automatic Tool Changer
• Can switch between up to 200 tools stored in a
  magazine, drum, or chain
• Tool Exchange Arm
• Picks up particular tools with attached
  toolholders

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Tool ChangerTypes

• Automatic (Sequential) Spindle
• Turns one increment in one direction for each
  tool change tools must be placed in the spindle
  in the order they are used
• Indexable (Random Access) Spindle
• Turns either direction to make a specific tool
  accessible tools can be placed in any order as
  long as the computer knows their positions

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Tool ChangerTypes
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1
3
4
6
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Sequential Spindle
1
4
8
2
6
3
5
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Random Access Spindle
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Tool Changer Spindle
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Tool Changer Spindle
Tool changer spindle capable of holding 60
tools Courtesy of Toth Industries
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Tool Changer Arm
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Tool Changer Arm
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Tool Changer Arm
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Tool Changer Live Spindle
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Types ofManufacturing

• Cutting From Bulk Material
• Starting with a readily available shape (rods,
  ingots etc.) and machining the part from this
• Cutting From Near Net Shape
• Starting with a pre-formed (often cast) piece
  with the general shape of the part and removing
  little material

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Centering andClamping

• Pre-cast designs should be made so that the
  machines can clamp and orient them quickly and
  accurately
• Parts to be lathed should have radially
  symmetrical outer surfaces and pre-cast holes to
  mark the center they should also have a center
  of mass on the center line to prevent vibration

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Orienting andClamping
notches
holes

• Pre-cast parts should have at least three
  distinct features that the computer can recognize
  and use to orient the part

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Centering andClamping

• Pre-cast parts should have flat parallel surfaces
  for clamping or cylindrical surfaces for chucking
• Areas to be clamped or chucked can be ground flat
  after casting to improve grip

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Selection ofEquipment

• Various types of parts may require various
  machining centers
• Parts with numerous cylindrical surfaces (or
  other radially symmetrical surfaces) should be
  mounted on a machine center capable of turning
• Specialized machine centers are available for
  high-speed machining and for ultraprecision
  cutting

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Selection ofEquipment

• Example Pump Cover
• Starting with the rough casting, drill and ream
  the center hole, then cut the internal notch with
  a milling cutter. Mount the piece on a mandrel
  and use turning operations to cut the faces and
  outer edge. Mill the external notch and drill and
  ream the smaller holes in the plate.

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Selectionof Tooling

• The proper selection of tools depends on the
  workpiece material, size and shape of holes,
  radii of the corners of milling pockets, and
  various other parameters
• The selection of tools affects the cost and time
  of the operation

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Machine PerformanceMonitoring
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Machine PerformanceMonitoring
Y
Y
Part Orientation
X
X
Cutting Performance
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Machine PerformanceMonitoring

• Tool/Part-Checking Station
• Measures workpieces and tools so that the
  computer can compensate for variations and tool
  wear
• Touch Probes
• Pressed against a workpiece or tool to measure
  its exact size and position

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Touch Probes
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Measurement andAdjustment
critical distances
Holes to be drilled (initial)
Holes to be drilled (adjusted)

• Advanced machining software can use data from
  probes to adjust its coordinate system, ensuring
  that critical distances remain within tolerances
  even in deformed workpieces

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Touch Probes
tool holder
probe
part
Using a touch probe to measure a part Courtesy
Toth Industries
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Touch Probes
A machining center, being used to measure and
determine the orientation of a part Courtesy of
Toth Industries
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Touch Probes
tool changer arm
probe
part
A machining center, being used to measure and
determine the orientation of a part Courtesy of
Toth Industries
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Touch Probes
To determine the orientation of the part, the
machine measures the two large holes and
calculates their centers. A line constructed
between the centers serves as a base for the
computers coordinate system. Courtesy of Toth
Industries
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Machine PerformanceMonitoring

• Tool Failure Detection
• Time
• When the total cutting time of the tool exceeds
  the pre-programmed tool life, the tool is
  replaced
• Horsepower
• Dull tools draw more power if the power exceeds
  pre-programmed limits, the tool is replaced

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Machine PerformanceMonitoring

• Tool Failure Detection
• Acoustic Emissions
• Cutting tools produce ultrasonic vibrations and
  weakened ones produce up to five times the normal
  amplitude when it rapidly increases, the tool is
  immediately replaced

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Machine PerformanceMonitoring

• Tool Failure Detection
• Feed Force
• Records the feed force of sharp tools if the
  force increase exceeds a predetermined
  percentage, the tool is replaced if the force
  suddenly rises, the tool has broken and is
  replaced immediately

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ManufacturingCells
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ManufacturingCells
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ManufacturingCells
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Manufacturing Cells Examples
Courtesy of Toth Industries
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ManufacturingEconomics

• Cost
• If the cutting speed is too low, the cost of
  cutting increases because of increased power
  consumption
• If the cutting speed is too high, the cost of
  tool replacement increases because tools wear out
  faster

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ManufacturingEconomics

• Time
• If the cutting speed is too low, the cutting
  time increases
• If the cutting speed is too high, the tool
  replacement time increases

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Manufacturing Economics
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Summary

• Machining Centers allow increased automation and
  efficiency, especially in large-scale production
• Monitoring, by an operator or the machine itself,
  is necessary to prevent damage to the parts
  produced
• Cutting speed can be varied to minimize the total
  cost or time of the operation

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The End