Characterizing the Surface Texture of AM Parts Upon Surface Finishing: Alternative Methods of Evaluating the Surface Quality of AM Parts

Transcription

1 Characterizing the Surface Texture of AM Parts Upon Surface Finishing: Alternative Methods of Evaluating the Surface Quality of AM Parts Agustin Diaz, Ph. D. Senior Research Chemist Website: REM Chemicals, Inc. All rights reserved REM, ISF and REM Surface Engineering are registered trademarks of REM Chemicals, Inc. This presentation contains proprietary information of REM Chemicals, Inc., and may not be reproduced or redistributed without the express written consent of REM Chemicals, Inc.

2 Facilities Worldwide Southington, CT Brenham, TX Cambridgeshire, UK Market Aerospace Automotive Decorative Medical Military Motorsport Off Highway Power Generation AS9100:2009 Rev. C & ISO9001: REM Chemicals, Inc. 1

3 Surface Roughness Factors and Considerations in AM Parts

4 Powder grain size Pyka, G., et al. Adv. Eng. Mater., 2012, 14, 363. Mahamood, R.M., et al. J. Manuf. Sci. E-T ASME, 2014, 135, Tumor, I. Y., et al. J. Manuf. Syst., 1998, 17, REM Chemicals, Inc. 3

5 Powder grain size Beam size and power Pyka, G., et al. Adv. Eng. Mater., 2012, 14, 363. Mahamood, R.M., et al. J. Manuf. Sci. E-T ASME, 2014, 135, Tumor, I. Y., et al. J. Manuf. Syst., 1998, 17, REM Chemicals, Inc. 4

6 5 Powder grain size Beam size and energy 0.20 mm 8.0 mils Eric Wycisk et al., Physics Procedia, 2014, 56, 371

7 Powder grain size Beam size and energy Layer thickness Shape and orientation Process speed Pyka, G., et al. Adv. Eng. Mater., 2012, 14, 363. Mahamood, R.M., et al. J. Manuf. Sci. E-T ASME, 2014, 135, Tumor, I. Y., et al. J. Manuf. Syst., 1998, 17, REM Chemicals, Inc. 6

8 REM Surface Finishing Process and Capabilities

9 Some Challenges: Surface Roughness/Waviness Internal Support Removal Loose Particles Partially Sintered Particles Partially Melted Particles Surface and Near Surface Defects REM Chemicals, Inc.

10 9 ISF Process & Extreme ISF Process Chemical mechanical finishing process Generates an isotropic surface Improves external and internal surfaces Eliminates loose particles Improves mechanical performance Ti 6-4 Eliminates Al rich surface layer and surface impurities Accommodates very complex geometries

11 100x 150x 200x

12 100x 150x 200x

13 12 SEM Original Extreme ISF

14 13 Optical (2D) Original Extreme ISF

15 14 Optical (3D) Original Extreme ISF

16 15 SEM Original Extreme ISF

17 16 Optical (3D) Original Extreme ISF

18 Extreme ISF Original 2016 REM Chemicals, Inc. 17 Optical (3D) Optical (2D)

19 Extreme ISF Original 2016 REM Chemicals, Inc. 18 Optical (3D) Optical (2D)

20 Surface Texture: Introduction

21 20 Roughness and Waviness: the constituents of Surface Texture Exploring Surface Texture: A Fundamental Guide to the Measurement of Surface Finish, 7 th Ed., Taylor Hobson, 2014

22 21 Exploring Surface Texture: A Fundamental Guide to the Measurement of Surface Finish, 7 th Ed., Taylor Hobson, 2014

23 Roughness Average (Ra), Mean Roughness Height (Rz) and Total Roughness (Rt) Rt Rz Ra λc λr = Evaluation Length = 5 x λc λc = Sample length => Cut-off Exploring Surface Texture: A Fundamental Guide to the Measurement of Surface Finish, 7 th Ed., Taylor Hobson, REM Chemicals, Inc. 22

24 23 Recommended Cut-off (ISO ) Periodic Profiles Non-Periodic Profiles Spacing Distance RSm (mm) Cut-off (Filter) Roughness Sampling Length Roughness Evaluation Length Rz (µm) Ra(µm) λc (mm) λr (mm) λn (mm) To 0.1 To Exploring Surface Texture: A Fundamental Guide to the Measurement of Surface Finish, 7 th Ed., Taylor Hobson, 2014

25 24 EBM Surface Granular Surfaces A common group of surfaces encountered are granular in make up and can be difficult to measure meaningfully. It is obvious that a parameter such as Ra would be very misleading on this type of surface. they will probably be impossible to trace correctly with a stylus Exploring Surface Texture: A Fundamental Guide to the Measurement of Surface Finish, 7 th Ed., Taylor Hobson, 2014

26 Surface Texture: Anatomy of an AM Part Surface

27 26 XZ planes XY plane Layer growth Waviness: Beam path

28 27 XZ plane XY plane

29 28 λc = 0.08 mm -> Ra = 2.2 µm, Wa = 24 µm λc = 0.25 mm -> Ra = 6.5 µm, Wa = 22 µm λc = 0.8 mm -> Ra = 14 µm, Wa = 15 µm λc = 2.5 mm -> Ra = 21 µm, Wa = 12 µm Ra values are meaningless unless the cut-off length is known. Exploring Surface Texture: A Fundamental Guide to the Measurement of Surface Finish, 7 th Ed., Taylor Hobson, 2014

30 Surface Texture Analysis

31 30 Waviness matching:

32 31 Waviness matching:

33 32 Waviness matching:

34 33 λc = 0.08 mm -> Ra = 2.2 µm, Wa = 24 µm λc = 0.25 mm -> Ra = 6.5 µm, Wa = 22 µm λc = 0.8 mm -> Ra = 14 µm, Wa = 15 µm λc = 2.5 mm -> Ra = 21 µm, Wa = 12 µm The Ra value is meaningless unless the cut-off length is known.

35 Surface Texture Analysis: 3D Optical (Non-Contact) Profilometer

36 35 Initial Extreme ISF ISO Initial Final Ra 28 μm 15 μm 45% Sa 30 μm 19 μm 59% Sdq 57 deg 22 deg 60% Sdr 94% 8% 91% *Bruker-NPFLEX-LA instrument performed by Michigan Metrology, LLC.

37 36 Initial Extreme ISF ISO Initial Final Ra 28 μm 15 μm 45% Sa 30 μm 19 μm 59% Sdq 57 deg 22 deg 60% Sdr 94% 8% 91% Sdq is a general measurement of the slopes which comprise the surface. *Bruker-NPFLEX-LA instrument performed by Michigan Metrology, LLC.

38 37 Initial Extreme ISF ISO Initial Final Ra 28 μm 15 μm 46% Sa 30 μm 19 μm 37% Sdq 57 deg 22 deg 61% Sdr 94% 8% 91% Sdr is the ratio of the increment of the interfacial area of a surface over the sampling area. SSSSSS = *Bruker-NPFLEX-LA instrument performed by Michigan Metrology, LLC. TTTTTTTTTTTTTT SSSSSSSSSSSSSS AAAAAAAA (CCCCCCCCCC SSSSSSSSSSSSSSSSSS AAAAAAAA) (CCCCCCCCCC SSSSSSSSSSSSSSSSSS AAAAAAAA)

39 REM Surface Finishing Process: Mechanical Performance Implications

40 39 Notches and surface imperfections removal Extreme ISF Surface As-build Surface

41 40 Total removal of notches and surface imperfections. Extreme ISF Surface As-build Surface

42 41 Horizontal As-built Machined Extreme ISF Ra (μm) Sa (μm) Sdr (%) Sdq (deg) UTS (MPa) YS (MPa) Vertical As-built Machined Extreme ISF Ra (μin) Sa (μm) Sdr (%) Sdq (deg) UTS (MPa) YS (MPa) Special thanks to Cesar Terrazas, Rich Merlino and David Hill.

43 Conclusions and Remarks

44 43 Surface Quality Evaluation Stylus profilometry (Ra) does not suit AM surface characterization AM surface quality is driven by multiple build parameters AM surface quality is a mixture of roughness and waviness AM surface roughness is highly influenced by waviness AM surface evaluation, if using stylus profilometry, must consider measurement filters (outside of standard ISO guidelines) AM surface quality is more suitable to optical profilometry (Sdr)

45 44 Surface Quality Challenges Surface Roughness & Waviness Loosely attached particles Surface stress risers Complex geometries Solutions: Surface Finishing ISF & Extreme ISF Processes Significant roughness & waviness reduction Removal of loose particles (FOD) Accommodates complex geometries (channels, lattice, etc.) Increases resistance to bending fatigue Increases tensile strength

46 REM Chemicals, Inc. All rights reserved REM, ISF and REM Surface Engineering are registered trademarks of REM Chemicals, Inc. This presentation contains proprietary information of REM Chemicals, Inc., and may not be reproduced or redistributed without the express written consent of REM Chemicals, Inc..