5-Axis Machining Some Best Practices

Transcription

1 5-Axis Machining Some Best Practices Longxiang Yang FANUC America IMTS 2018 Conference September 11, 2018

2 Full Utilization of 5-axis Machines 5-axis machines were developed and used in production more than 50 years Because of limitation of computing hardware, the compensation functions were not available in early use. FANUC developed tool length compensation for Ingersoll 5-axis machines in late 80s. Many advanced 5-axis functions have been developed in the last 20 years. These functions greatly enhanced the application of 5-axis machines.

3 Full Utilization of 5-axis Machines However, in many machine shops, these functions are not used due to unawareness or lack of understanding. A story about a job shop in Seattle area 5-axis machines with table-table configuration from OKK, Matsuura and GROB Customer used some 5-axis functions like TCP and WSEC but has stopped using them since the NC programmer left

4 5-axis Machining Process Positional (3+2) 5-axis Machining Applications Rotary axes do not move in a cutting block. Only X, Y and Z-axis are commanded in a cutting block. 1. Cutting multi-sided parts Rotate tool/table to be perpendicular to part surface Establish new program coordinate using Tilted Working Plane Command Machining is done in 2.5D or 3D milling 2. Roughing 3D surface parts Mainly used in 3D surface roughing Rotate tool to a vector position that provides optimum cutting results

5 5-axis Machining Process Simultaneous 5-axis Machining Applications Rotary axes move in a cutting block. All five axes X, Y, Z, A and C are commanded in a cutting block 1. Part Cutting Thin wall structure, such as turbine blades, rib and spar of airplanes Both tool side and tool tip are used in cutting 2. Mold Cutting 3-D sculptured surface, such as die and mold Only tool tip is used in cutting Use of 3+2 Machining vs Simultaneous Machining A small sampling of machine shops in Seattle area shows that about 40%-50% of 5-axis machines are used in 3+2 machining Mainly on table-table machines for smaller parts

6 Advantages of 5-axis Machining Easy Setup for Machining Reduce setup time and setup error Reduce fixture cost Reduce machining time by about 20-30% 3-axis machine 5-axis machine Use of Short Tool Increase machining speed Better surface Increase tool life 3-axis machine 5-axis machine

7 Advantages of 5-axis Machining Machining Cavity Increase part surface accuracy 3-axis machine 5-axis machine Optimization of Tool Cutting Point Increase surface accuracy Increase tool life 3-axis machine 5-axis machine

8 Advantages of 5-axis Machining Efficient Machining with Tool Side Increase surface accuracy Reduce machining time significantly Factors that Limited Application of 5- axis Machines in the Past Higher cost of machines More complex operations Difficult to program Lack of good CNC 5-axis functions Not easy to understand and use 5-axis functions 3-axis machine 5-axis machine

9 CAD/CAM Simulation CNC/Servo Setup Actual Cutting Part Inspection Z Y X Good CNC Functions for 5-axis machining Compensation for tool length and radius Choice of programming coordinate for simultaneous 5-axis machining Compensation for workpiece Easy and flexible programming for 3+2 machining Servo Guide 3D Viewer Fine surface finish Easy setup and calibration Real time interference check Volumetric machine error compensation for linear and rotary axes Optimization of post processor

10 Tool Center Point Control (TCP) Tool Length Compensation Features need to be considered: Control tool center point (TCP): control point is tool center point not pivot point Control tool vector: tool posture control Use of different types of tool: cutting point command Choice for programming: physical rotary angles such as B/C or A/B and tool vector in I/J/K TCP with physical rotary axes G43.4 H1 Xx Yy Zz Aa Bb Control point is pivot point Control point is TCP TCP with tool vector I/J/K G43.5 H1 Xx Yy Zz Ii Jj Kk TCP generates more accurate surface

11 Tool Center Point Control (TCP) Tool Length Compensation Without Tool posture control: Two rotation axes are linearly interpolated and tool posture may not be on a plane With Tool posture control: Two rotation axes are controlled so that tool posture is on a plane Posture Control OFF Posture Control ON

12 Tool Center Point Control (TCP) Tool Length Compensation Cutting point command Same program can be used with different types of tools Cutting point command G43.8 H1 Xx Yy Zz Aa Bb L2 Ii Jj Kk

13 3D Cutter Compensation (3DCC) Tool Cutter Compensation Features need to be considered: Tool side offset G41.2 (G42.2) D1 ; Leading edge offset G41.3 D1 ; Tool axis Offset plane Tool axis Offset plane Offset vector Offset path Tool side offset Programmed path Programmed path Offset path Offset vector Leading edge offset TCP and 3DCC are the most important compensation functions for 5-axis machines

14 Choice of Programming Coordinate Two program coordinate systems: Workpiece-based coordinate (WBC) fixed on machine coordinate, not rotate Table-based coordinate (TBC) fixed on table, rotate with table rotary axes Background Part is designed in modal space in CAD/CAM without machine type information Postprocessor outputs programs for tool type, or table type, or mixed type, and program coordinate needs to be selected Without TCP, program is always posted in workpiece coordinate (rotation centerline) for table type Advantages of Table Coordinate Easier to understand program Both physical angles and tool vector in TCP can be applied Recommendation: Use table-based coordinate for table and mixed type

15 Choice of Programming Coordinate How does it work Program X, Y and C so tool moves along the edges of rectangle X/Y/Z workpiece coordinate X /Y /Z - table coordinate G54 = (10, 50, 0) Move to Point 1: In table coordinate: X0 Y0 C0 ABS X=0, Y=0, MACH X=10, Y=50 In workpiece coordinate: X0 Y0 C0 ABS X=0, Y=0, MACH X=10, Y=50 Move to Point 2: In table coordinate: X10 Y0 C90 ABS X=10, Y=0, MACH X=0, Y=30 In workpiece coordinate: X-10 Y-20 C90 ABS X=-10, Y=-20, MACH X=0, Y=30

16 Workpiece Setting Error Compensation Dynamic Compensation for Workpiece Apply on top of conventional workpiece coordinate such as G54-G59 and dynamically compensate any misalignment in TCP and 3DCC Significantly reduce setup time for 5-axis machining Workpiece setting errors: translational Δx, Δy, Δz and rotational (in R-P-Y) Δa, Δb, Δc G code format G54; G54.4 P1; G43.4 H1;

17 Workpiece Setting Error Compensation Dynamic Compensation for Workpiece How does it work C Z G54 at table rotation center Y X Z Y X G54.4 P1 C=0 C=90 C=90 Y Y 4 3 X G54 10 X Y X G table coordinate Y G54.4 P1 2 3 X Table coordinate Work coordinate G54.4 P1 Y G54 1 X Y 4 X 2 3 Workpiece coordinate

18 Tilted Working Plane Command Flexible and Easy Programming for 3+2 Machining A method to establish new program coordinate system so that 2.5D or 3D milling can be done in a slanted surface Canned cycles or custom cycles can be used Same feature on different planes can be machined using the same program Similar to 3D Coordinate Conversion, but more comprehensive. In the past, it was limited to 3-axis compensation, i.e., only G43 and G41/G42 can be used. Now, it allows 5-axis compensation, such as TCP and 3DCC with Workpiece Setting Error Compensation

19 Tilted Working Plane Command Flexible and Easy Programming for 3+2 Machining Flexible Command Formats Euler s Angle Roll-Pitch-Yaw Angles Three Points Two Vectors Projection Angles Tool Axis Direction Program Format (Euler s angle) G68.2 Xx Yy Zz Ii Jj Kk G53.1 (automatically position rotary axes to make tool perpendicular to the slanted plane) Easy Programming on CNC Euler s Angle Transformation Zc z x β z α z γ Yc x y β γ x y Xc y X y y

20 Fine Surface Finish High Speed Smooth TCP: Smoothing rotary axes Smoothing tool center point Great for cutting with both tool side and tip such as airplane parts Smooth Tolerance + Control: Smoothing tool center point (different algorithm) Great for cutting 3D free surface

21 Fine Surface Finish High Speed Smooth TCP cutting example: Facets with High Speed Smooth TCP is OFF Facets is gone with High Speed Smooth TCP is ON Many customers like Boeing Portland and PMW in Seattle are using this functions HS Smooth TCP OFF HS Smooth TCP ON Faceted surface Smooth surface

22 5-axis Probing Easy Setup and Calibration Measurement of features on a slanted surface: inspection Rotary axis calibration: check offset of rotation centerlines Measurement of Workpiece Setting Error By three spheres By a feature in TWP Spindle Probe Tooling ball

23 5-axis Probing Easy Setup and Calibration Easy input screens are developed Programming Screen: measurement Programming Screen: WSEC calculation and setting

24 Built-in 3D Interference Check Real time interference check during program execution and manual operation Before collision occurs, CNC generates interference alarm and movement is stopped Interference objects: tables, jigs, tool holders, tools and workpiece This is particularly useful in 5-axis manual setup User can add multiple interference objects to a machine for more accurate checking

25 3D Linear and Rotary Volumetric Error Compensation ISO 230-1: 21 errors for 3-axis mill and 6 errors for each rotary These errors are measured by laser tracker or interferometer The measured data is converted to FANUC data: δx, δy, δz, δa, δb and δc for 3D grid for linear axes and 2D grid for rotary axes 3D linear and rotary volumetric compensation greatly improves the machining accuracy

26 Servo Guide 3D Viewer 3D display of TCP path error and tool posture by SERVO GUIDE Position data displayed Part program command CNC command Feedback Surface finish defects can be analyzed in 3D viewer and minimized by servo tuning Part program error can be easily found in 3D view X SERVO GUIDE Z Y 3D tool path C B Impeller

27 Servo Guide 3D Viewer Surface defect can be visually inspected and eliminated using Servo Guide Magnified display of 3D error between command and feedback Before tuning Feedback path After tuning Color-coded display of 3D path error color scale Command path Before tuning After tuning Large deviation Small deviation

28 Servo Guide 3D Viewer (All in one screen: 2D/3D position and waveform in time domain)

29 Servo Guide 3D Viewer (Display of NC program position, CNC command and feedback position)

30 CAM Development PC software that will extract CNC configuration, option contents and parameter setup Assist CAM/Post software to generate proper G code programs and fully utilize 5-axis machining functions Parameters Configuration Proper G code CNC PC software

31 Some Best Practices 1. TCP and 3DCC Tool compensation G code: TCP: G43.4 H1 3DCC: G41.2 D1 Obviously, these two functions are the most important for 5-axis machining Most other 5-axis functions are working together with TCP and 3DCC Without TCP and 3DCC, either qualified tooling has to be used for certified programs, or programs have to be generated for different tools Lower tooling cost Save programming time Widely applied on 5-axis machines 2. HSTCP/ST + C Surface finish G code: HSTCP: G43.4 H1 P3 ST + C: G5.1 Q3 Combination with AICC (high speed machining) provides better results These two functions are enabled by G codes, but a lot of customers are not aware of this. Many customers have used these two functions and got very good results (Boeing, PWM etc.)

32 Some Best Practices 3. WSEC Dynamic workpiece offset G code: G54.4 P1 Dynamically compensate workpiece offset setting error in translations and rotations Work for both table-based program coordinate and machine-based program coordinate Reduce setup time Reduce fixture cost Many customers have used this function (Flow, Boeing, PWM, GKN/Six Digma, Line etc.) 4. TWP 3+2 machining G code: G formats of command to establish feature coordinate, very flexible A lot of 5-axis machines are mainly used for 3+2 machining in industry Reduce programming time All 5-axis compensation functions such as TCP can be used in TWP Many customers have used this function (Boeing, Exotic Metal, Primus etc.)

33 Some Best Practices 5. 5-axis test part NAS 979 Uniform Cutting Tests in The cone is used for testing 5-axis machining. However, the uniform shape does not reflect the complexity of in production parts. Some customers like Boeing Portland developed their own acceptance test parts. These parts are designed to reveal more defects on a machine setup issues for servo and CNC For large users, custom part can used for acceptance test for all machines. Boeing RR part NAS 979 part

34 Some Best Practices 6. 5-axis probing part Check probing cycle setup on CNC as part of machine acceptance test Used for measuring WSEC offset Good training tool for TWP 7. Program verification in NCG NCGuide is CNC simulator on PC Configure same as CNC on a machine More realistic program verification, such as cutter comp interference check etc. More realistic estimate for cycle time Boeing R2D2 part

35 Summary 5-axis machining has been widely used in manufacture because it provides many advantages Many advanced CNC functions have been developed to support better utilization of 5-axis machines A lot of end users are either unaware of the latest development or afraid of taking advantage of the development due to lack of understanding The past development was mainly focused on tool/work compensation and high speed machining The future development need to be focused on fine surface technology Easy of use/application AI application (machine/tool/machining condition/programming/cnc/servo) As a leading CNC manufacturer FANUC, we will closely work with OEM, CAM companies, NC programming community and end users to promote 5-axis machining technology

36 Global Machine Tool Consumption Machine Tool Global: $80 Billion (2015) US: $8 Billion (2015) Gardner 2016World Machine Tool Survey CNC Machine Global: about $50 Billion (2015) US: about $7.25 Billion (2015) Global growth to $55 Billion by 2021 (Technavio)

37 Global 5-axis Machine Consumption Wise Guy Reports In , 5-Axis CNC machining centers market size to maintain the average annual growth rate of 6.22% $1.26 billion in 2014 $1.51 billion in 2017 $2.13 billion by 2022 Technavio Forecast