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Overview Presented By: Manufacturing Laboratories, Inc. Frequency Response Function (FRF) Stability Map.

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Presentation on theme: "Overview Presented By: Manufacturing Laboratories, Inc. Frequency Response Function (FRF) Stability Map."— Presentation transcript:

1 Overview Presented By: Manufacturing Laboratories, Inc. Frequency Response Function (FRF) Stability Map

2 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-2 Purpose of Software To predict, measure, avoid and control machining Vibrations. Uses common vibration measuring techniques. Applies them specifically to the machining process.

3 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-3 Problems With Todays Machining (Dynamics) All machines and tool stack-ups exhibit dynamic characteristics that will impact the cutting process. Machining by definition is a dynamic process. Dynamic Characteristics Limit Machining Performance (Ti vs AL). These characteristics can vary significantly and can be difficult to predict reliably. Measurement is required. Primary contributor for cutter failure, spindle failure, limits machining capabilities, etc. Theory and understanding well known by many MR&D Depts. and Universities but only recently gaining awareness and acceptance on shop floors.

4 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-4 What Is High-Performance (HP) Machining? There are many definitions: Cutting speed s(m/min)=pd(m/rot)n(rot/min) Spindle speed or DN DN = bearing bore diameter x spindle speed Torque and Power others All of the definitions of high-performance machining are correct in some context. High-Power is a natural artifact of high-speed. Power = Torque x speed

5 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-5 Added considerations for High- Performance (HP) Machining We have the additional influence of machining feed rates. What is the average feed rate. Chip-thinning Surface area

6 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-6 What Limits HP-HS Machining Productivity? Different types of machining operations have different limitations. HP-HS machining may be limited by: The onset of chatter Tool-work piece materials Available power Tool geometry Work piece geometry Controller or servo performance (acc-dec) Inadequate knowledge about machine capabilities

7 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-7 Chatter Limitations Particularly in high speed operations where the objective is to have the metal removal rate as high as possible, the onset of chatter will be a limiting factor. Chatter arises due to insufficient dynamic stiffness Long slender tools Small diameter spindles (DN limitation) Flexible work pieces (although the selection of a tool path can avoid this in most cases)

8 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-8 Tool-Work piece Material Limitations With work piece materials such as aluminum, the availability of a tool material is not a limitation. Tools are available which can tolerate the melting temperature of aluminum. With hard steels, and even more so with titanium, maintaining acceptable tool life is a major problem. There has been some success with light cuts.

9 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-9 Power Limitations In some cases where the machine-tool- work piece combination is dynamically stiff enough, the cutting operation may be limited by the available power. Even for the stiffest machines, there are usually some tools which are not power limited.

10 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-10 Tool Geometry Limitations In cases where the dynamic stiffness and power are sufficient, the cutting operation may be limited by the tool configuration (the length of the cutting edge or tool diameter, for example). Cutting edge geometry may be dictated by material property characteristics, thermal behavior, shearing, etc.

11 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-11 Work piece Geometry In some instances (many die and mold applications), the geometry of the cut is dictated by the desired work piece geometry. For example, the step-over dimension may be limited. In such cases, most of the machining can happen well below the available power.

12 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-12 Controller or Servo Performance Limitations Especially for complex geometries, the block throughput rate of the controller can be a limiting factor. Some easy tests exist As the speed of the axis motions increase, the dynamic performance of the servos become more significant High accelerations/decelerations (acc/dec) Lightweight yet stiff moving elements Look-ahead or feed forward control

13 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-13 Knowledge Limitations A lack of understanding of high speed machine capabilities frequently leads to under-utilization of such machines. A large, traditional experience base does not exist for high speed machine tool use. Many high speed phenomena are counter-intuitive for users accustomed to conventional speed machines. An acceptable part program is usually not the optimal part program. The programmer needs the machine performance information at the time that the program is written.

14 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-14 3 Knowledge Possibilities Exist You understand the performance capabilities of your machine very well and write part programs respecting the limitations. Or You fight chatter problems every day. Or You are under-utilizing your machine.

15 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-15 Which Qualities Of High-Performance High- Speed Machines Are Most Important? Spindle Speed alone is not enough. High power alone is not enough. Fast motions or tool changes alone are not enough. High performance controllers alone are not enough. Advanced tool materials alone are not enough. Certainly, these things are important, but…..

16 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-16 High-speed (HS-HP) machining occurs when the tooth passing frequency approaches the dominant natural frequency of the system. -Scott Smith, UNCC For reasons which will become apparent, the definition we will use is:

17 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-17 What Is Different About HP-HS Machining? HP-HS machining is different from conventional machining, particularly in the strong influence of the dynamic characteristics of the machine-tool-work piece system on cutting performance. In HP-HS machining, the metal removal rate (MRR) is usually limited by the onset of chatter. Success in HP-HS machining depends heavily on the ability to recognize and deal with dynamic problems. Selection of an appropriate spindle speed and depth-of-cut is extremely important and not obvious.

18 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-18 What Kinds of Parts Can Benefit From High Speed Machining? Parts which have a large volume of material to be removed. Aluminum and cast iron parts especially, but also hard materials such as dies and molds. Parts with thin structures. Parts which conventionally spend a long time on the machine either due to large metal removal or large surface areas to be machined. Short runs, or frequently changed designs. Many others.

19 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-19 Pocketed and Thin Section Parts

20 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-20 Monolithic Structures (formerly stack-ups)

21 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-21 Shop Floor Friendly Approach Supply a complete solution to the problems with dynamics and machining. Model and predict dynamic behavior and its affect on the cutting process. Effectively measure and adjust to unexpected changes. Maximize Cutting performance (MMR) Simplify analysis of machine tools and cutters. Distill technology down to its most essential parts (measurement and prediction). Machine a part right the first time!

22 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-22 Exactly what are we talking about? Methods for obtaining information about the cutting process dynamics and quickly utilizing this information to maximize cutting performance. Currently available by various means. Applied in a way for maximum usability. Our goal is to maximize metal removal rate and reduce or eliminate detrimental vibrations. We want to utilize basic frequency analysis at the machine or on the shop floor (machinists, NC programmers, process planners, manufacturing engineers) to improve process setup, correct problems when they occur, and objectively evaluate performance.

23 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-23 What are we evaluating? Design Parameters Frequency (f n ), Stiffness (k) and damping (damping ratio ). They do not change over time or with load. Dynamic stiffness (~2k ) at Frequency (f n ). Sometimes we are concerned with the magnitude response, for cutting performance the negative real part of the FRF Negative Real Peak (chatter) Static Compliance Dynamic flexibility =~1/2k Magnitude Response Real part of FRF Frequency =fn

24 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-24 Why bother? In a dynamic system component behaviors are highly interelated (e.g. everything affects everything). Change one parameter and it is likely that the dynamic response will change, sometimes substantially. Counter-intuitive behavior is inevitable. Dynamic parameters, particularly damping can change. All this will affect how much can be cut and how much the operation will vibrate (normally, resonate or chatter).

25 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-25 Fundamental Tool: Frequency Response Function (FRF) (20 mm 3-fluted Tool in 30 kW 24 krpm Spindle) Flexibility

26 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-26 Basis for Analysis: The Stability Lobe Diagram Process Damping

27 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-27 5 areas of machining Conventional Region B lim1 High-Performance Region PoorMan Region B lim2 – High-Speed Machining

28 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-28 5 Regions of Machining Conventional Typically Slow RPM with high Feed and DOC Blim1 Light DOC where all RPM are chatter-free, but not necessarily most robust Blim2 – High-Speed Region industry accepted low DOC high feed rate finishing All RPM are chatter –free, but not necessarily most robust PoorMan Region Minimal or NO Sweet Spots, almost all RPM chatter High-Performance Region Largest Metal Removal Rates Must select matching RPM and DOC

29 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-29 Desired Benefits Promote Understanding Explain Non-intuitive behavior, e.g. lobing diagram and the dynamics that produce it. Guide user to Optimal Solution Not necessarily looking for precise predictions but good guidance. Fast Improvements 90% results with 10% of the effort. Clearly identify limitations, eliminate……….. finger pointing

30 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-30 Whats Needed? Not as much as you may think. Frequency Analyzer. Widely available Sensors Basic Cutting Theory Commercial applications are becoming widely available that do not require the expertise of a vibration expert. MLIs MetalMAX kit with computer.

31 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-31 PCScopeMilSim TM Packages for Dynamic/Chatter Prediction and Control Harmonizer ® TXF Measurement and AnalysisComputation and Prediction SPA TM Cutting Performance Analyzer for Machine Tools Data Acquisition and Machining Analysis CHiPS TM Milling simulation Finite Element Spindle Analysis and Cutting Performance Analyzer Audio Monitoring of Cutting Process Track Data with particular setup, tool, machine, etc. Page 5 Verification and Tracking

32 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-32 How is it typically applied Front Line Solutions TXF Chatter free speeds and power or depth of cut levels. Harmonizer ® Audio monitoring and chatter detection and correction Existing NC Program correction. PCScope Generic data collection Track balance levels and spindle vibrations, temperatures. Off-Line Solutions MilSim and SPA Off-line in-depth analysis. Good NC-Programmer tool CHiPS Organize and track data.

33 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-33 Two Basic Approaches: Trial and Error and Predictive Trial and Error Similar to how we do it now in that we take test parts or run test work pieces and change things based on experience. Additionally, we can integrate cutting theory and signal analysis to direct the changes more efficiently. Predictive Measure dynamics of tooling before cutting then compute behavior. Simulate cutting and establish maximum parameters. Verify results when implemented and have the ability to correct for subtle changes that may occur.

34 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-34 Predictive Approach. How do we do this? Easiest way is called impact testing or modal analysis. Use a hammer to excite the tool over a wide frequency range and and an accelerometer to measure the response and create an FRF (Frequency Response Function). With proper software and setup measurement takes less than 5-minutes per tool.

35 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-35 Advantages and Disadvantages of Predictive Approach Advantages: Fast with minimal machine down time. No requirement to run machine. Flexibility to determine performance for all operation conditions. Quick check for changes after events. Disadvantages: Limited accuracy depending on inputs. Some technique and equipment needed

36 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-36 What is our concern. Obviously the tool-work piece interface. The flexibility and frequency behavior on the tool and on the part at the location of the cutting interface. The entire machine and all its components contribute to this behavior but we are only concerned with how it is affecting just ONE location: Where cutting occurs (the cut interface). We are only concerned with displacement for a given force, or the flexibility.

37 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-37 FRF Measurement with MetalMAX Equipment Schematic of Measurement Setup for TXF Tap or Ping test. Actual MetalMAX Equipment EXCITATION (HAMMER) RESPONSE (ACCEL) Sensor Interface Module PC Accelerometer STRIKE Hammer Power Cable Sensor Cable

38 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-38 Frequency Response Function to Cutting Performance (Analytical Solution, TXF) Measured Frequency Response Function (FRF) Lobing Diagrams Provide MRR (Depth of Cut) and Spindle Speed values Chatter in red areas MRR Axis Chatter freqs. (in red) and resonant speeds

39 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-39 General FRF Procedure A FRF quantifies a tools flexibility frequency by frequency. Excite system Measure force Measure response Transform into frequency domain (Fourier Transform) divide frequency by frequency See video demonstration. (PLUCKING A TUNING FORK)

40 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-40 Cutting Performance (TXF) Stability LobesPower Lobes Max Torque Max Power

41 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-41 Advantages and Disadvantages of Trial and Error Approach Advantages: Most Accurate Easy Low skill level required Software/hardware aids are commercially available, vibration meters, audio detectors, etc. Disadvantages: Time consuming Consumes work piece material and tools and machine time.

42 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-42 Maximizing MRR with Width of Cut Increases Harmonized 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 > 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!!!

43 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-43 Knowledge of the spindle speed is essential. Spindle speed components generally dominate the audio spectrum unless chatter is very severe. Other audio sources are related to spindle speed, bearing passing frequencies, air-oil hiss, etc. Correct setting of threshold maximizes sensitivity. Unfiltered Filtered

44 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-44 Trial and Error Example 10,000 RPM8393 RPM Corner Cut, 10 mm deep, 12 mm wide

45 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-45 Trial and Error Example 8393 RPM Frequency content no filters. 10,000 RPM Frequency Content with no filters.

46 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-46 Milling Simulation Simulation package needs measured dynamics as input. Rapid more accurate solutions to speeds, depths of cut, feeds, cutting forces, tool deflection and surface error. Include tooth run-out, imbalance, non-uniform pitch. Excellent front-line, solution for process engineers and NC programmers.

47 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-47 Most Important: Cutting Tool Tracking and Control The CHiPS (TM) Database nTo get the maximum payback each cutting tool assembly must be uniquely identified. nMachine, spindle, holder, cutter, manufacturers, stick out lengths, etc. must be tracked by either the customer tool management system or our customized Microsoft Access database for tool setup tracking with dynamics (CHiPS). nRecord optimum speeds, feeds and depths of cut. nBased on measurement and calculation (TXF, MilSim, etc.) and verified by cutting tests (Harmonizer ). nEmphasize slotting information (the least stable case). nData will not change unless a different tool, machine tool, or spindle is used. In fact results for identical model machines and spindles can be used on all machines of that model and spindle type. nControl of tool set up is required to insure database speeds, feeds, and DOCs are valid (Dynamic repeatability and consistency).

48 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-48 CHiPS: Tracking all Tooling information

49 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-49 Is this Technology new? No!, only in the way it is being applied. Vibration measurement is very well developed. Basic machining dynamic theory well-known for decades by academics and large corporate MR&D departments. The process or practice is the focus rather than its affects. Detect what is happening in the cut, not at the bearings, the motor, under the work piece, etc. Modal Analysis or Frequency Analysis has been utilized extensively with the advent of the digital computer and algorithms. Mostly in the design and product test areas. To determine and measure resonance's (aircraft, autos, disk drives, etc.). Even in the design of machine tools and components. Spindle Rotor Analysis Damping of fixtures

50 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-50 Is this all worth it? The Good News: YES! PREDICTABLE and CONSISTENT: Well controlled setups will behave consistently. Identical model machines even of different age will show minimal variation in frequency. Stiffness will not change significantly over time. Damping may change somewhat but its affects can be avoided. PERFORMANCE IMPROVEMENTS: Stable cutting horsepower can generally be increased % or more compared to practically applied techniques. COST AVOIDANCE: Tool life, time between spindle rebuilds, longevity of the machine, rotary table life, any machine component wear can generally see substantial (> 50%) improvements.

51 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-51 Other Benefits of Easy Dynamic Measurement Rapid dynamic measurement can quickly identify many conditions. Non-intuitive behavior. Most flexible mode may not be the most likely to chatter. Quickly identify which component is producing the most flexible mode. Identify when stiffness or damping is loss. Quickly detect changes or compare performance.

52 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-52 Automotive Part Example: Mild Steel Tubing 1. Starting Point: Company, Tooling Company, and Machine Tool company spent 15 months designing process – POOR TOOL LIFE 2 2. Ending Point: DATA driven Stability Diagram provided MAP to change RPM 1

53 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-53 Shop chose: 24,000 rpm 3mm ADOC 10,000 mm/min mm/tooth Tool Life 20 pcs Endmill Cost: $ second cycle time Changed Parameters 15,500rpm 6,000 mm/min mm/tooth Tool Life 80 pcs Endmill Cost: $65 53 second cycle time Not constraint machine Improved Cost: ($10/part – $0.81/part) = $9.19/part Yearly Savings: $9.19/part * 700 parts/day * 250 days/year = $1.6 million Automotive Part Example: Mild Steel Tubing

54 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-54 Story 2: Outsourcing 8000 rpm ADOC Same Tool, Same Toolholder, Same Stickout Different machines have Different Stability Diagram 1

55 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-55 Die Shop Example: Cast Iron 1. Starting Point: Machinist chose DOC based on CAM software and past practice – HEAVY CHATTER 2 2. Ending Point: DATA driven Stability Diagram provided MAP to change RPM 1

56 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-56 Die Shop Example: Cast Iron Die shop chose: 1146 rpm ADOC 23 ipm (0.005 ipt) Chatter Changed Parameters 2120 rpm ADOC 84 ipm (0.010 ipt) No chatter Improved Performance: ( )/4.31 = 17% MRR = 1.5* * 23 = 4.31 in 3 /minMRR = 1.5 * 0.04 * 84 = 5.04 in 3 /min Cost Savings: $175/week ($100 inserts + 1 hour/week time * $75/hour) $8750 savings/year + Reduced spindle wear and tear + improved quality

57 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-57 Cutting Parameter Selection Comparison of how are speeds, feeds and depths of cut chosen? The Conventional Approach nEmpirical/Experimental Guidelines nHighly Experienced Planner. nTechnological database from cutting tool supplier. nOperational limits from machine tool supplier. nTurn Key applications. nNote: The guidelines are subjectively applied depending on the situation. nProgram and Make Parts nDetermine Acceptability nAccept or Modify Program with empirical guidelines Make Part Determine acceptability Modify Yes No nA Process Based Approach (Strategy 2) nMeasure the dynamics. nDefine Dynamic Condition at cutting interface. nCompute optimum cutting parameters and compare to other operational guidelines. nProgram and make part. nMonitor results. Monitor Results Make Part Measure Setups Compute parameters Operational Guidelines

58 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-58 Resource Investment: Conventional vs Process based (MetalMAX ) Resources Expended: Conventional MetalMAX

59 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-59 Implementation Strategy #1: Eliminating Chatter OFF-LINE (new cutter or new program): Use hammer kit and TXF software to develop Stability Charts for problematic cutters. In-Process (current chatter condition with pre-existing NC program). Use microphone and Harmonizer software to monitor chatter signal and suggest new speeds and feeds. Record results in tooling database or CHiPS database program for future reference. Periodically monitor high volume jobs using Harmonizer to insure chatter is not present. Unstable Torque Limit Stable Speeds Chatter TXF Harmonizer

60 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-60 Implementation Strategy 2: Maximizing Machine and Cutter Performance Identify 20% of tooling that performs 80% of metal removal or consumes 80% of machining time. Use MetalMAX hammer kit and TXF program to create stability charts (maps) for each cutter. Perform cutting tests on a few selected cutters using microphone and Harmonizer to validate predictions and to calibrate results on all cutters. Record data in CHIPS database. Make information accessible to NC programmers. Have machinists monitor and provide feedback periodically regarding performance. Use Harmonizer for periodic monitoring, fine tune when necessary, update database and re- measure as needed (generally not required). Highest Power Stable Region with little chance to chatter.

61 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-61 Implementation Strategy 3: Matching tooling to machine (and tool tuning). Identify possibly redundant tooling systems, e.g. multiple length cutter configurations, multiple flute, cutters used across machine platforms, etc. Measure redundant tooling systems across machine tools using TXF. Review stability chart results. Identify those cutters with superior cutting performance in a given machine and machines-cutting tool combinations with superior cutting performance. Will result in dramatic reduction in required setups and provide preferred machine- tooling configurations (e.g. better identify roughers, finishers, face millers, end millers, 2 flute machines, 3 flute machines, etc.) Alternatively, multiple length cutters of a given size can be measured to identify which length provides the optimal cutting performance (e.g. shorter not always better, see right) Shorter Cutter Longer Cutter Larger deeper Stable pocket, (shorter cutter not needed).

62 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-62 Implementation Strategy 4: New Equipment Qualification Similar to matching machine to tooling strategy except current measurements will afford the analyst benchmark results for popular shop setups to be compared against test cutters or alternative OEM designs without having to run cutting tests. These setups can be quickly compared with any new setups considered for the shop through a quick TXF hammer test. Additionally, the shops current stackups may be taken and measured on potential new machines to see what stability performance improvement may be expected on the new machines. Benchmarked cutter Test Cutter Performance at Least 2X

63 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-63 Implementation Strategy 5: Part-Try-Out (PTO) Optimization Tooling should already have been qualified and measured with prior strategies. Work piece and fixturing can now be added at selected machining states with TXF. Milling Simulation MILSIM package can be used concurrently with programming to optimize feed rates based on bending moment limits, cutting force and dynamic cutting accuracy. Harmonizer should be used to provide feed back for next

64 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-64 Implementation Strategy 6: Predictive and Preventive Maintenance. Establish a measurement artifact for each spindle interface in the shop (e.g. HSK, ISO, etc.). Dimensions of artifact should be approximately a 1 L/D with a diameter approximately equal to the gage length. With machine in known good condition make TXF measurement, store, and during routine maintenance checks re-measure artifact and compare (reduction of damping or loss of stiffness will precede typical spindle wear or de-commissioning signals by at least 3 months). After spindle or machine crashes or extraordinary events spindle dynamic condition can be check. Dynamic performance and hence proper refurbishing or replacement of machine components, particularly spindle can be verified. Dynamic consistency of machine can be established. Spindle In Good Condition Spindle In Bad Condition

65 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-65 Summary of Implementation Issues Exploiting Dynamic Consistency By controlling our tool setups and measuring the dynamics the optimal operating conditions can be repeatably targeted with corresponding benefits. High production rates can be reached as well as high machine utilization. Improve control of cutting processes Apparent random vibration behavior can be controlled by implementing a means to define a previously unknown critical characteristic of the machine setup. Better more consistent part quality is achieved. Maintenance improved The control of vibrations dramatically reduces machine and tool wear thereby reducing maintenance and repair costs. Quality control is improved as machines that are near design life of more easily identified.

66 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-66 Summary Dynamic analysis can be applied easily and in a Shop Floor Friendly Fashion. Both for trial and error approaches and predictive analytical approaches. Cost and down time is minimal. It can provide objective and clear understanding as to the dynamic affects driving cutting performance. Benefits include both performance enhancement and cost- avoidance. It is an excellent compliment to other machining systems for tool wear, cutting accuracy (machine metrology), etc.

67 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-67 Downstream Benefits Proper implementation of HP-HS techniques will lead to: Elimination of adverse vibrations Reduction of catastrophic wear on machine and tools thereby lowering maintenance costs and consumables Expanded flexibility in types of parts and manufacturing processes. Improved quality and more predictable processes leading to better cost estimation.

68 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-68 Overall Benefits 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. Eliminate Finger-Pointing Accurately compare machines or tool stack-ups. Select the best machine and/or tool setup for a particular application.

69 MetalMAX TrainingManufacturing Laboratories, Inc.MMOVER-69 Limitations of Approach Critically dependent on cutting stiffness and process damping wavelength. Once established for a particular grind of tool and material then will produce accurate predictability. Will change after tool wears (usually increase stable limits). FRF measurement of 1/4 diameter tool is practical lower limit of effective measurement. Improvements currently being developed In worse case an indirect measurement approach can be applied. Measurement of dynamics performed under static conditions. Measurements can be made at speed with non-contact sensor. A few advance and current spindle designs have poor dyna repeatability and consistency.


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