A NEW APPROACH IN MEASURING OF THE ROUGHNESS FOR SURFACE CONSTITUTED WITH MACHINING PROCESS BY MATERIAL REMOVAL

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1 International Journal of Mechanical and Production Engineering Reearch and Development (IJMPERD) ISSN Vol. 3, Iue, Mar 3, 4-5 TJPRC Pvt. Ltd. A NEW APPROACH IN MEASURING OF THE ROUGHNESS FOR SURFACE CONSTITUTED WITH MACHINING PROCESS BY MATERIAL REMOVAL MITE TOMOV, MIOLAJ UZINOVSI & PAVEL OVAC S. Cyril and Methodiu Univerity in Skopje, Faculty of Mechanical Engineering, Skopje, arpo II. BB., Macedonia Univerity of Novi Sad, Faculty of Technical Science, Serbia ABSTRACT Thi paper ugget a new approach to meauring urface roughne facilitated by the introduction of a new parameter, called parameter of tatitic equality of ampling length. The procedure for obtaining the primary profile, the roughne profile and the wavine profile i preented a a et of recoendation of everal ISO tandard. In addition, the paper ugget the expanion of the preented meauring procedure by direct incluion of the new parameter. Another novelty i that the propoed algorithm now allow the incluion of feedback which thu far ha not been the cae in roughne meauring. The newly propoed parameter wa been verified uing etalon and real urface, repreenting everal machining proce by material removal. EYWORDS: Parameter of Statitical Equality of Sampling Length, Surface Roughne, Roughne Profile, Wavine Profile, Primary Profile INTRODUCTION (THE NEED FOR INTRODUCING A NEW APPROACH) The modern production procee and technologie a well a the nanotechnology development contributed toward urface roughne becoming a dominant factor for the ucceful functioning of the product. The genei of the urface metrology dicipline, a well a the expected direction for future development are preented ytematically and in detail in (Jiang et al, 7а; Jiang et al, 7b), where one of the concluion regarding the future development of urface metrology conider the hift from profile to aerial characterization, from tochatic to tructural urface and from imple hape to complex freeform geometrie. However, the core objective of urface metrology i to enable full control over urface contitution and provide an undertanding of the functionally ignificant urface characteritic. Today achievement regarding the product urface roughne prediction model, at leat for conventional machining, are baed on a planar projection of the geometry of the tool (regardle whether it i with defined geometry or not) onto the urface of the workpiece (Staniław et al, 9; Edward & Łukaz, ). Hence the concluion that invetigation regarding the roughne profile and the roughne parameter will continue to remain current, but the emphai will hift toward way to determine them more accurately. Thi paper look at providing the condition for more accurate determination of the roughne profile and the roughne parameter. In order to enure comparability and replicability of the reult (the parameter value), the procedure for meauring and obtaining the primary profile, the roughne profile and the wavine profile are implemented in accordance with the recoendation contained in everal international (ISO) tandard, where the baic and neceary tandard include: ISO 487:997; ISO 488:996; ISO 374:996; ISO 56:996 and ISO 66 tandard erie. Baed on thee

2 4 Mite Tomov, Mikolaj uzinovki &Pavel ovac tandard and the recoendation contained therein, one can etablih a meauring procedure for obtaining the primary profile, the roughne profile and the wavine profile, by uing contact kidle intrument, hown of Figure. Real urface ISO 487:997 z y x Surface profile ISO 488:996 ISO 374:996 and other. Meaurement proce 3 4 Traced profile ISO 374:996 ISO 374: Total profile Nominal form (removed) ISO 374:996 ISO 487: ISO 374:996 µ m - - ISO 487:997; ISO 374:996; ISO 56:996; ISO 66 erie. ISO 487:997 Mean line for the primary profile m m Application of the profil filter λc Roughne profile Mean line for the roughne profile Application of the profil filter λ Noie Application of the profil filter λf Wavine profile ISO 487:997; ISO 374:996; ISO 56:996; ISO 66 erie. ISO 487:997; ISO 374:996; ISO 56:996; ISO 66 erie Roughne paremeter Ra, Rq, Rt, Rp, Rv.. Figure : Procedure for Obtaining the Primary Profile, the Roughne Profile and the Wavine Profile The focal point of the preented procedure are the referent mean line, which are a bai for obtaining the primary profile (tep 6 and 7), the roughne profile (tep 9 and ) and the wavine profile (tep ), a well a for calculating the

3 A New Approach in Meauring of the Roughne for Surface 43 Contituted with Machining Proce by Material Removal correponding parameter (P, R and W). The preented procedure employ multiple method to determine the referent mean line, uch a the leat quare method, λc profile filter and λf profile filter. Today there are everal type of λc profile filter; however the tandard Gauian filter i motly ued. (Raja et al, ) analyze everal profile filter (RC, Gauian, Rk, Spline, Robut pline, Gauian regreion, Zero-order Gauian regreion, Second-order Gauian regreion, Robut Gauian regreion, Morphological and Wavelet-baed filter) ued to meaure urface roughne, pointing out it metrological characteritic, advantage and diadvantage. New filter introduced by the ISO/TS 66 tandard erie include: Gauian filter (ISO 66-:), Gauian regreion filter (ISO/TS 66-3:), Spline filter (ISO/TS 66-3:9; ISO/TS 66-:6), Spline wavelet (ISO/TS 66-9:6), Dik and horizontal line-egment filter (ISO/TS 66-4:6), Scale pace technique (ISO/TS 66-49:6) and Motif filter (under preparation). In order to remove the diadvantage (ditortion at the end of the filter mean line obtained uing the tandard Gauian filter) ISO/TS 66-8: recoend everal way to increae the length of the primary profile length. Alo ISO 3565-:996 recoend a pecial method of filtering of profile with deep valley. In order to obtain the roughne profile (eparate it from the primary profile) the metrologit hould chooe one of the above mentioned profile filter in tep 9 of the procedure preented in Figure. A logical quetion at thi point would be: Which profile filter to elect? The primary objective that the profile filter need to fulfill i to have the determined mean line pa through the center of the irregularitie compriing the profile through which the mean line pae. (Raja et al,,) in their reearch how that the diadvantage of the mean line determined with ome profile filter are accentuated in pecific cae and directly depend to the hape of the total profile, i.e. the primary profile. Тoday, the operator aee the tate (hape and character) of the primary profile qualitatively (high level of wavine, low level of wavine, ignificant or inignificant end ditortion etc.). Thi qualitative aement of the primary profile i baed on the experience and the conviction of the operator that can lead to an inappropriate election of a profile filter type. But alo, it i impoible to decribe the tate (hape and character) of the primary profile if ued meauring device which doe not allow the graphical diplay of the primary profile (uch a mot of portabilnite device). Hence, the author of thi paper conclude that the qualitative aement of the total or the primary profile hould be replaced with a parameter that will provide information about the irregularitie on the total or the primary profile around the mean line. To corroborate thi way of thinking we note the a-priori accepted practice whereby the profile obtained from the urface are conidered a tationary and ergodic random function. According (John & Irwin, 965), a tationary function i any function that ha the ame tatitical characteritic along it length, and a function i ergodic if the temporal and tatitical mean value between the tationary tatitical enemble (part) are equal. Therefore, the introduction of the new parameter will help link the tate of the profile obtained from topography with the methodology for obtaining the parameter value, Figure, irrepective of whether they are parameter of the primary profile, the wavine or the roughne profile, with an ultimate view to determining thee parameter a accurately a poible. A NEW PARAMETER FOR THE STATISTICAL EQUALITY OF SAMPLING LENGTHS To determine, whether a function i tationary and ergodic, or not, need i the comparing the mean value (tatitical and temporal) for a certain part of the function (with exactly known ize), with other part of the ame ize. From here, in further reearch will be ued only methodology for determination, without to accept the condition of the

4 44 Mite Tomov, Mikolaj uzinovki &Pavel ovac analyzed profile i tationary and ergodic function. If mentioned methodology i applied to the profile obtained by meauring the urface topography and repreented with dicrete value in a reference ytem of coordinate, then the mean value of a egment of the profile need to have an approximately equal value to the value of other egment along the profile. The egment (part) whoe baic tatitical characteritic will be compared to each other, are conidered to equal the ampling length l r, an already tandardized value in ISO 487:997, with the ue of the baic ditribution meaure, i.e. mean arithmetic value, variation (diperion) and the tandard deviation. For the purpoe of deriving the mathematical formulation of the new parameter we will conider two theoretic cae of cattering the irregularitie around the mean line. Firt cae: The point ued to repreent the primary profile within the ampling length have different mean value and approximately equal tandard deviation, Figure. Second cae: The point ued to repreent the primary profile within the ampling length have approximately equal mean value, and different tandard deviation, Figure 3. z Mean value of primary profile Approximately equal tandard deviation Standard deviation of primary profile x Sampling length Different mean value Evaluation length = 5 x Sampling length Figure : Firt Cae: Different Mean Value and Approximately Equal Standard Deviation In practice, the real profile obtained by meauring the real topography of urface uually exhibit irregularity deviation which are a combination of the profile from the firt and the econd cae. The primary profile on Figure and Figure 3 are preented on a Carteian right oriented reference ytem where the horizontal longitudinal axi i marked with x, while the vertical axi i the z-axi. The point ued to repreent the primary profile with it evaluation length and the ampling length, a part of the primary profile, hall be conidered a a ample, ince they are a part (ample) of the point that can be ued to repreent the entire urface topography. The point ued to repreent the entire urface topography hall be conidered to be the population. Hence, the tandard deviation for n data point hall be marked with, while the mean value for n data point hall be marked with z. For graphical preentation of the tandard deviation ize of Figure and 3 adopted i normal (Gauian) ditribution, although there i a poibility where the ditribution of irregularitie, within the ampling length, i not normal (be have another form). In the firt cae the tandard deviation determined for the primary profile hall be greater than the tandard deviation of the individual ampling length a a reult of the cattering of the mean value of the ampling length around the mean line (mean value) of the primary profile. The lower the catter of the mean value of the ampling length, the

5 A New Approach in Meauring of the Roughne for Surface 45 Contituted with Machining Proce by Material Removal lower the tandard deviation for the primary profile will be, and it will converge to the tandard deviation value of the ampling length. z Different tandard deviation x Sampling length Approximately equal mean value Mean value of primary profile Evaluation length = 5 x Sampling length Figure 3: Second Cae: Approximately Equal Mean Value, and Different Standard Deviation In order to decribe thi interdependence mathematically, we introduce the coefficient calculate a follow: p, which we propoe to = () where i the tandard deviation calculated a the mean value of the individual tandard deviation within the ampling length, while p i the tandard deviation calculated for the primary profile, i.e.: = () 5,... are tandard deviation calculated within the ampling length. Equation applie when the total profile contain five ampling length, while if there are n ampling length will be calculated a follow: n = (3) n The tandard deviation,... and Taylor & Cihon 4): ( ) z i z n p, for n data point will be calculated a (ISO 3565-:996; arl 999; = n (4) i= where z i the mean value of the point zi ued to repreent the profile, and if there are n point, it i calculated a follow: n z = n i= z i (5)

6 46 Mite Tomov, Mikolaj uzinovki &Pavel ovac Alo, a can be een from Equation 4, for determining the tandard deviation adopted i to ue a mathematical formulation that i adequate for normal (Gauian) ditribution. Thi prerequiite i neceary, becaue, if adopted to check the hape of the ditribution of irregularitie and the ue appropriate mathematical formulation with accordance to the determined form (type) of the ditribution, the inevitable ituation where will to compare the mean value obtained from different mathematical formulation, which abolutely i not jutified. The value of the coefficient will converge to one if the mean value of the ampling length data point are equal or approximately equal with the mean value of the primary profile, provided that the ampling length data point have equal or approximately equal tandard deviation. The value of the coefficient will converge to zero if the mean value of the data point in the ampling length are ignificantly different from the mean value of the primary profile. For the econd cae we propoe to introduce a coefficient m which will be calculated a follow: m max min = (6) max where max i the value of the maximal tandard deviation calculated within the ampling length, while min value of the minimal tandard deviation calculated within the ampling length. The value of the coefficient i the m will converge to zero if there are no difference between the value of the tandard deviation determined within the ampling length. If the value of m converge to one, then that mean that there are large difference between the value of the tandard deviation determined within the ampling length. The fact that real primary profile are a combination of the two previouly decribed elementary cae, ugget that the expreion of the cattering of the irregularitie around the mean line, preented uing point in a reference ytem, require the interdependence of the coefficient Baically, the coefficient and. m m complement on two ground. The introduction of m remove the condition that the value of the tandard deviation within a given ampling length are approximately equal to each other. Secondly, the value i a mean value, which mean that if the value of any tandard deviation within a ampling length deviate ignificantly from the other, it real impact will be reduced due to the averaging. It i alo worth emphaizing that the value that the coefficient and may have are inverely proportional, which mean that for a primary profile where m the irregularitie are evenly accumulated around the mean value (mean line), get a value that converge to one, while m get a value that converge to zero, and vice vera. A a conequence of the above, we propoe to introduce a new non-dimenional parameter called parameter of tatitic equality of ampling length, denoted by SE, which will be calculate a: m SE = (7) In cae of a primary profile where the irregularitie are evenly accumulated around the mean value (mean line), or, in other word, the data point within the ampling length have approximately equal tatitic characteritic with each other a well a with the primary profile, then the parameter SE will have the following value:

7 A New Approach in Meauring of the Roughne for Surface 47 Contituted with Machining Proce by Material Removal In the oppoite cae: m m ( will go to zero) ( will go to infinity) The correlation decribe above ugget that the parameter of tatitic equality of ampling length SE i an increaing parameter in the cae of increaing cattering of the data point around the mean line. VERIFICATION OF THE SE PARAMETER The reearch regarding the verification of the SE parameter have been made uing primary profile obtained by meauring etalon urface repreenting: turning (two urface with Ra=.6 and 3. ), face milling (two urface with Ra=.6 and 3. ), circular grinding (two urface with Ra=.4 and.8 ), polihing (two urface with Ra=. and. ), lapping (two urface with Ra=.5 and. ), uper finih (two urface with Ra=.5 and.5 ), and a real urface obtained with honing. The real urface i obtained with the following condition: material EN-GJL-5 (DIN EN 56),n (rotation of honing head)=6 rpm; f (feed of honing head)=4 double motion /min; four honing tone: C5/I9V6 (grain ize 5). The value of the Ra parameter for etalon urface wa ued here olely to ditinguih between different profile from the ame cutting proce. The hape of the primary profile, a well a the calculated value for, and SE are hown on Figure 4, 5, 6, 7, 8, 9,,,, 3, 4, 5, 6. Thee Figure alo how the Gauian filter mean line determined for the repective primary profile uing Matlab (R9b). The weight function for the Gauian filter i the mathematical formulation provided in ISO 56:996 and ISO 66-:. The urface were meaured uing a tylu meauring ytem MarSurf XR, according to the procedure hown in Figure. The nominal form wa removed from the total profile uing the leat quare method. m 4 3 Gauian mean line =.99; m=.5; SE=.5; Gauian mean line =.96; m=.9; SE=,; Figure 4: Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Turning, with Ra =.6. Figure 5. Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Turning, with Ra = 3,

8 48 Mite Tomov, Mikolaj uzinovki &Pavel ovac 6 5 Gauian mean line =.99; m=.46; SE=.47; Gauian mean line =.99; m=.7; SE=.8; Figure 6: Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Face Milling, with Ra =.6 Figure 7: Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Face Milling, with Ra = Gauian mean line =.96; m=.39; SE=.4; Figure 8: Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Circular Grinding, with Ra = Gauian mean line -3 =.9; m=.48; SE=.53; Figure 9: Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Circular Grinding, with Ra = Detail A Gauian mean line =.4; m=.65; SE=.59; Detail B Figure : Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Polihing, with Ra = =.97; m=.4; SE=.4; Gauian mean line Figure : Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Polihing, with Ra = Prim ary profile Gauian mean line -.4 =.87; m=.6; SE=.69; Figure : Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Lapping with Ra = =.97; m=.4; SE=.4; Gauian mean line Figure 3: Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Lapping with Ra =.

9 A New Approach in Meauring of the Roughne for Surface 49 Contituted with Machining Proce by Material Removal Detail C Gauian mean line =.59; m=.93; SE=.58; Detail D Figure 4 : Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Super Finih with Ra = Gauian mean line =.84; m=.67; SE=.8; Figure 5 : Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Etalon Surface Repreentative of Super Finih with Ra =.5 Detail E Gauian mean line =.96; m=.97; SE=.; Figure 6 : Primary Profile, Gauian Mean Line and Value of the SE Parameter for the Real Surface Obtained with Honing The diadvantage of the Gauian mean line can be een on the hape hown on Figure, 4 and 6. Figure (detail A and detail B), and Figure 4 (detail C and detail D) how notable ditortion at the end of the filter mean line, while Figure 6 how that the filter mean line withdraw from the middle of the primary profile due to the deep valley, which i epecially accentuated on Detail E. For the other profile, the form of the filter mean line ha no diadvantage and pae through the middle of the irregularitie. An analyi of the calculated value of the SE parameter will how that it value increae in the event of an increaed cattering of the irregularitie around the mean line. For the conidered primary profile where the mean line have diadvantage, the value of SE i greater than one or cloe to one. Hence, the author think that one i the key value of the SE parameter from the point of view of oftware filtration uing a tandard Gauian filter. For primary profile where the value of SE i le than one, one hould not expect any diadvantage of the mean line determined uing the Gauian filter. The example hown on figure 6 i characteritic. There the application of the filtering procedure precribed in ISO 3565-:996 i jutified due to the deep valley of the primary profile. To recognize uch primary profile the author propoe the ue of the value of the coefficient a an additional criteria.

10 5 Mite Tomov, Mikolaj uzinovki &Pavel ovac IMPLEMENTATION OF SE IN THE PROCEDURES FOR MEASURING SURFACE ROUGHNESS Baed on the value of the SE parameter, thi paper propoe to expand the current procedure for obtaining the primary profile, the roughne profile and the wavine profile, hown on Figure, with the algorithm hown on Figure 7. The propoed algorithm include feedback which facilitate the etablihment of an additional verification of the previouly implemented tep a well a a mechanim for eliminating the poibility of error by the metrologit. For example, the SE parameter can have a larger value if the reference ytem ued for the meaurement i inappropriately etup, which i epecially accentuated in the cae of cylindrical object with mall diameter, or in cae where the nominal hape ha been inappropriately removed. The part of the algorithm hown on Figure 7, marked with dotted line wa introduced to the procedure to facilitate the continuity to ome follow-up invetigation, primarily in the area of oftware filtering, ince, according to the etablihed development framework, the invetigation related to the ISO 66 tandard erie have not been completed by the working group, and alo the part of newly introduced tandard from the ISO 66 erie, until the time of thee invetigation, have not been additionally confirmed. Calculation of SE and SE Ye No Application of tandard Gauian profile filter λc Whether tep and 3 are correct realized No Repetition of the meaurement procedure tarting from tep Ye Whether tep 6 i correct realized No Repetition of the meaurement procedure tarting from tep 6 Ye >. 9 No Ye Application of the filtering procedure ISO 3565-:996 Application of one of the recoendation given in ISO / TS 66-8: Whether filter mean line ha diadvantage No Roughne profile, tep Ye Application of other profile filter (not tandard Gauian) from ISO 66-erie Roughne profile, tep Figure 7: Algorithm for Augmenting Step 9 of the Meauring Procedure Shown on Figure

11 A New Approach in Meauring of the Roughne for Surface 5 Contituted with Machining Proce by Material Removal CONCLUSIONS - Thee invetigation propoe a new approach to the determination of urface roughne, where the choice of the mot appropriate profile filter directly depend on the hape of the primary profile. Thi paper propoe that the hape of the primary profile hould be determined quantitatively, intead of qualitatively (a the current practice), uing the new parameter of tatitic equality of ampling length SE. -The new SE parameter ha been proven a a ucceful attempt to qualitatively determine the tatu of primary profile. The value of one wa hown to be a ignificant value from the point of view of filtration uing a Gauian filter. For primary profile where the value of SE i le than one, one hould not expect any diadvantage of the mean line determined uing the tandard Gauian filter and vice vera. - The propoed algorithm to expand the procedure for obtaining the primary profile, the roughne profile and the wavine profile ugget a new approach to invetigating urface topography, facilitated by the ue of feedback loop, which etablihe an additional verification of the previouly implemented tep a a mechanim to eliminate the poibility of error. REFERENCES. Jiang, X., Scott, P. J., Whitehoue, D. J. & Blunt, L. (7). Paradigm hift in urface metrology. Part I. Hitorical philoophy. Proc. R. Soc. A 7 463, (doi:.98/rpa.7.873). Jiang, X., Scott, P. J., Whitehoue, D. J. & Blunt, L. (7). Paradigm hift in urface metrology. Part II. The current hift. Proc. R. Soc. A 463, (doi:.98/rpa.7.873) 3. Staniław A., Edward M., Franci Č.(9). A model of urface roughne contitution in the metal cutting proce applying tool with defined tereometry. Journal of Mechanical Engineering 55(9), UDC Edward M., Łukaz N. (). Analyi and verification of urface roughne contitution model after machining proce. Procedia Engineering 39 (), ISO 487:997; Geometrical Product Specification (GPS) - Surface texture: Profile method - Term, definition and urface texture parameter. 6. ISO 488:996; Geometrical product pecification (GPS) - Surface texture: Profile method - Rule and procedure for the aement of urface texture. 7. ISO 374:996; Geometrical Product Specification (GPS) - Surface texture: Profile method - Nominal characteritic of contact tylu intrument 8. ISO 56:996; Geometrical Product Specification (GPS) - Surface texture: Profile method - Metrological characteritic of phae correct filter 9. Raja J., Muralikrihnan B., Fu. Shengyu (). Recent advance in eparation of roughne, wavine and form. Elevier, Preciion Engineering. Journal of the International Societie for Preciion Engineering and Nanotechnology. 6 (), -35. ISO 66-:; Geometrical product pecification (GPS)-Filtration: Linear profile filter: Gauian filter. ISO/TS 66-3:; Geometrical product pecification (GPS)-Filtration: Robut profile filter: Gauian regreion filter

12 5 Mite Tomov, Mikolaj uzinovki &Pavel ovac. ISO/TS 66-3:9; Geometrical product pecification (GPS)-Filtration: Robut profile filter: Spline filter 3. ISO/TS 66-:6; Geometrical product pecification (GPS)-Filtration: Linear profile filter: Spline filter 4. ISO/TS 66-9:6; Geometrical product pecification (GPS)-Filtration: Linear profile filter: Spline wavelet 5. ISO/TS 66-4:6; Geometrical product pecification (GPS)-Filtration: Morphological profile filter: Dik and horizontal line-egment filter 6. ISO/TS 66-49:6; Geometrical product pecification (GPS)-Filtration: Morphological profile filter: Scale pace technique 7. ISO/TS 66-8:; Geometrical product pecification (GPS) - Filtration - Part 8: Profile filter: End effect 8. ISO 3565-:996; Geometrical Product Specification (GPS) - Surface texture: Profile method; Surface having tratified functional propertie - Part : Filtering and general meaurement condition 9. John. M.W., & Irwin.M.J., (965): Principle of counication engineering. John Wiley &Son. Inc., New Yorf-London -Sydney. arl V. B., (999). Statitical ditribution in engineering. Cambridge Univerity pre. Taylor J.., Cihon C., (4) Statitical technique for data analyi (Second edition). CRC Pre, LLC