SHOPFLOOR OPTIMIZATION FOR PERFORMANCE MACHINING

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SHOP-FLOOR OPTIMIZATION FOR PERFORMANCE MACHINING

• Dr. Thomas S. Delio (Tom Delio)
• E-Mail delio_at_mfg-labs.com
• IRL www.mfg-labs.com

MLI
Manufacturing Laboratories, Inc.
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What is Performance Machining?
There are many Definitions, but our best
definition is

• High-Performance machining occurs when the tooth
  passing frequency approaches the dominant natural
  frequency of the system.
• -Scott Smith, UNCC

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Dynamics is Todays Main Machining Issue for
Productivity Improvement

• Dynamics define the frequency (harmonic) behavior
  of the machine/spindle/tool stack-up.
• It is of particular importance in performance
  machining.
• All machines and tool stack-ups exhibit dynamic
  characteristics that impact the cutting process.
• These characteristics vary significantly
• and are difficult to accurately predict
• by conventional means.

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How Is the Dynamic Behavior Efficiently Handled?

• Solutions include trial and error, test cuts
  (detection and correction), and prediction and
  avoidance (scientific solution).
• The ability to predict and then avoid chatter is
  by far the most efficient and beneficial
  approach. Until MetalMAX it has been
  impractical to apply on the shop floor.
• MetalMAX now provides the scientific solution in
  a package that is quickly and easily implemented
  on the shop floor.
• MetalMAX provides DOC, speed and feed
  predictions that maximize productivity (MRR,
  metal removal rate) and quality (improvements on
  part finish).

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Cutting Parameter Selection How are speeds, feeds
and depths of cut chosen?

• The Conventional Approach
• Highly Experienced Planner.
• Technological database from cutting tool
  supplier.
• Operational Guidelines from machine tool
  supplier.
• Turn Key applications.
• Note None of the above is based on a sound
  scientific or objective approach.

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Consequences of the Conventional Approach

• Poor material removal rates (speed, feed, DOC
• Scrapped Parts
• Excessive benching
• Power tool life and tool failures
• Accelerated spindle wear
• Poor process reliability
• Unpredictability
• Inferior quality
• All of this results in wasted time and money

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Trends That Exacerbate These Problems

• Move to monolithic structures
• Massive material removal.
• Bigger,deeper parts with high L/D ratios.
• Expensive, less margin for error.
• Greater opportunity to shine
• Move to Flimsier, lightweight parts
• Move to more exotic materials

Common factor in the above trends is the
increased importance of dynamic influences.
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How Are Cutting Parameters Scientifically
Selected to Optimize Machining Processes?

• MetalMAXs approach is to
• Quickly obtain required dynamic information
  (scientific values).
• Use this information to obtain optimum cut
  parameters (speeds, feeds, DOCs).
• Rapidly verify cutting performance.
• Record data in a database (CHiPS).

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MetalMAX Uses
Process Planning
Compare tool performance Determine optimum Stackup
NC Programming
ToolCrib
Program optimal cutting parameters.
Optimize and reduce setups
Part First Article (Try-Out)
Maintenance
Easily monitor results and quickly adapt to
unknown affects.
Quick checks of dynamic condition.
Production
Monitor output and maintain stable
processes. Realize productivity increases from
cut optimization.
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What MetalMAX Does

• EMPOWERS the shop floor.
• Very FAST determination of the effects (to
  stability and accuracy) from machine tool
  dynamics.
• Provides NC programmers, Machine Tool Operators,
  Process Engineers, and others with optimized
  stable DOCs, speeds and feeds.
• Maximizes the utilization of the machine tool.
• Reduce, spindle, machine and tool failures.
• Produce the most with your tool setups and
  stack-ups.
• MACHINE THE PART RIGHT THE FIRST TIME

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Production Optimization Process(maximize
material removal rate w/stable process)
1. MetalMAX(TXF, Harmonizer, Milsim)
Data Collection
Process into DOCs, Speeds and Feeds
Record DOCs, Speeds and Feeds
THEN
2. MetalMAX(CHiPS)
Provide info to Shop Floor for immediate use.
Provide info to NC Prog. for future use.
RESULTS IN
3. Benefits For Your Company
Highest Quality
Fastest Production
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Whos Using the Approach

• Boeing (St. Louis)
• Sikorsky (United Technologies), Bell (Textron)
• Vought Aircraft Corporation
• Aerostructures (Carlyle Group)
• TRW
• Rolls Royce
• Cosworth (Ford) and Ilmor
• many more both aerospace and non-aerospace with
  over 10 YEARS of proven success.

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Whats Needed?

• Not as much as you may think.
• User Friendly Software.
• Frequency Analyzer.
• Sensors.
• Basic Cutting Theory.
• Setup man or engineer with progressive attitude.
  (does not require a vibration expert).
• Less than 35k.

MLIs MetalMAX kit with computer.
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Packages for Dynamic/Chatter Prediction and
Control
Current Packages
Measurement and Analysis
Computation and Prediction
Cutting Performance Analyzer for Machine Tools
Finite Element Spindle Analysis and Cutting
Performance Analyzer
SPATM
TXF
Data Acquisition and Machining Analysis
PCScope
MilSimTM
Milling simulation
Verification and Tracking
Provides NC Dept. and Tool Crib with accurate
cutting parameters.
Audio Monitoring of Cutting Process
Harmonizer
CHiPSTM
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A Typical FRF Measurement Setup
Machine tool and Spindle
Schematic of Measurement Setup for Bump, Ping
or Modal test.
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Example Frequency Response Function (FRF) (20 mm
3-fluted Tool in 30 kW 24 krpm Spindle)
Flexibility
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INFORMATION NEEDED TO GENERATE LOBING DIAGRAMS
FROM FRFS
Edit Material Parameters specific to
material and tool.
Material/ Tool Spec Orthogonal Meas.
File Cutting Limitations
Tool geometry and Cutting Parameters
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Stability Lobe Plot 20 mm 3-fluted Tool in 30 kW
24 krpm Spindle
Process Damping Region
Torque Limit
Unstable
Chatter Frequencies
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Power Lobe Plot 20 mm 3-fluted Tool in 30 kW 24
krpm Spindle
Full Power
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An Example of One Benefit Obtained (Savings 35
per load)

• Spar Mill Cutting with 1.25 Diameter indexable
  mill with 2 inserts.
• Initial Conditions (5 mm depth, max. full dia.)
• 21,500 rpm, 0.11 mm chip load, 118 mins. per load
  machining time.
• Getting chatter when cutter becomes fully
  immersed, lowered chip load to attenuate damage
  to part.
• New Conditions
• 24,000 rpm, .2 mm chip load, 62 mins. per load
  machining time.
• Benefits
• Savings 35 per load.
• Approximate 50 increase in machine capacity
  (near 50 reduction in machining time per load).

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Milling Simulation (MilSim)
Stability Lobe Diagram
Y-Displacement at 12,000 rpm, 2 mm DOC
Chatter Frequency
Power Lobe Diagram
Y-Displacement at 11500 rpm, 2 mm DOC
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PTP Diagrams(MilSim)

• Shows resonant and chatter problems (at cutting
  point).

Force Plot
Displacement Plot
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• Must know
• Spindle Speed
• Max. Allowable speed
• Number of teeth
• Nothing else
• Basic Procedure
• Set speeds and cutter teeth.
• Record cutting.
• Select new spindle speed.
• Package applies fundamental rule

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Maximizing MRR with Width of Cut Increases
Harmonized
gt 475 increase in Power and MRR
Spindle Speed 16,580 RPM Axial Depth of Cut 25
mm Radial width of cut 1.8 mm Cut Power 1.75
kW GREAT SURFACE!!!
Spindle Speed 20,000 RPM Axial Depth of Cut 25
mm Radial width of cut 0.25 mm Cut Power 0.3
kW BAD SURFACE
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The CHiPS(TM) Database

• Records 0ptimized speeds, feeds and depths of
  cut.
• Based on measurement and calculation (TXF,
  MilSim) and verified by cutting tests.
• Emphasizes slotting information (the least stable
  case).
• Data will not change unless a different tool,
  machine tool, or spindle is used.
• Control of tool set up is required to insure
  database speeds, feeds, and DOCs are correct.

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Track and Store ALL (including dynamic) Tooling
information (CHiPS) for Programming and Tooling
Departments.
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Repeatable Dynamics are Required for Repeatable
Performance

• Same kind of tool holder
• Same tool material
• Same overhang
• Same diameter
• Same number of teeth
• Same tightening torque on collets and retention
  knobs
• Same drawbar force

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CHiPS(TM) Database Benefits NC Programmers

• Common communication on tooling setup between
  shop floor and programming department.
• Can be accessed using companys intranet site.
• NC Programmer no longer has to guess at cutting
  parameters.
• As long as the database is followed, then the
  parts come out chatter-free the first time, and
  even better, the machine and tool setup is fully
  utilized.
• NC Programmers modifications to NC program are
  eliminated and program does not need to be
  modified until part is moved to a different
  machine or a different tool setup is used.

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MetalMAX(TM) Overall Benefits

• Maximize MRR with the best quality.
• Deal with chatter problems effectively and
  quickly.
• Minimal or elimination of down time due to
  chatter problems.
• Minimize part damage and scrap/rework.
• Extend machine and tooling capabilities.
• Fewer tools needed to machine same features.
• Reduce tool fatigue failures and extend tool
  life.
• Add flexibility to part programming strategies.
• Objectively deal with the natural limitations
  imposed due to machine and tool dynamics.
• Accurately compare machines or tool stack-ups.
• Select the best machine and/or tool setup for a
  particular application.

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Machine the Part Right the First Time

• Air frame tray, approx 2 high by 0.060 thick.