Statistical Analysis of the Quality of Fe-Zn Coated

Statistical Analysis of the Quality of Fe-Zn Coated Sheets
for Automotive Industry
Jozef Vyboch, Jozef Kmec, Emil Evin
Abstract
The demands of the automobile industry for the formability, weldability and lacquering of galvanized steel sheet for
exterior body panels are constantly growing. To meet these requirements "tailored production of galvanized sheets" can be
achieved by sophisticated optimization procedures not only mechanical properties but also the phase composition of
coatings, coating thickness and surface microgeometry of sheet metal. In evaluating the capacity (suitability) of Fe-Zn
galvanized sheets type "galvanneal" on the surface body parts the principles of Six Sigma methods were applied. The
character of used sheet metals has been assessed from the perspective of requirements required for microgeometry surface
parameters (Ra and Pc).
Keywords: statistical methods, coated sheets, quality, optimalization
1 Introduction
Increasing demands on the anticorrosion behavior of
steel plate stampings in the automotive industry to support
the development of various types of coated sheets. Among
the coated steel sheets are given the ratio between quality
(meeting the requirements of customers) and the price of its
irreplaceable galvanized sheets. Unlike conventional steels,
the evolution of galvanized sheets has for the automotive
industry own characteristics. Requirements must be met not
only the mechanical properties, but also to ensure a perfect
surface zinc coating and his adhesion to base materials. To
achieve the desired surface appearance of body parts after
pressing and after painting, customers require very close
tolerance parameters (Ra) with a uniform microgeometry
plate surface. Customer requirements microgeometry surface galvanized sheets designed for surface parts are mainly
focused on the parameters of roughness Ra [μm] (roughness), Pc [cm-1] (number of peaks) .
Increasingly demanding customer requirements can be
met using sophisticated technology for the production of
galvanized sheet metal body parts. Passes from roughening
the surface of the work rolls by blasting a mechanical finegrained granules (SBT-Shot Blast Texturing) to roughing
work rolls by sparking (EDT-Electric Discharge Texturing,
laser beam (LBT-Laser Beam Texturing), electron beam
(EBT Electron Beam-Texturing) and electrolytic chromium
(PRETEX Preussag Texturing) [1]. In applying EDT (Electo Discharge Texturing) is a good reproducibility of results
and transfer parameters microgeometry surface rolls on the
sheet surface. In the production of cylinder manner EDT
applies: higher values of Ra mean fewer Pc. From tab. 1,
shows that customer requirements for roughness parameters
Ra and Pc are different.
Tab. 1 Customer requirements microgeometry sheet metal
surface [1]
For experimental research have been used extra deepdrawing galvanized steel sheets of IF steel (interstitial-free
steel according to EN 10327). By annealing after galvaniczing sheet metals of IF steels (GA1) were obtained from
sheets of Fe-Zn films like "galvanneal" with varying
degrees of alloying coating (low alloyed-GA1, the optimum
alloyed - GA2 and prealloyed - GA3). Annealing after galvanizing is changing the parameters Ra and Pc. Meeting
specific customer requirements were evaluated for changes
in the parameters Ra and Pc and paint adhesion. Adhesion
of Fe-Zn coating depends % Fe content in the coating [1].
Fe content in the coating in the investigated materials was
determined titration and phase composition of coatings was
determined scanning electron microscopy (SEM) with
EDXanalyzer. Individual phases were identified on the basis
of the percentage of Fe and Zn, which is intended the
stoichiometric composition phase - tab. 2 [1].
Tab. 2.Properties of Fe-Zn coating materials
Microgeometry parameters (arithmetic mean deviation
of profile Ra [μm] and the number of peaks Pc[cm-1]) the
surface of the metal were detected on the device Hommel
Tester1000 in the direction of 90 ° to the direction of
rolling. Statistical methods are becoming a common tool for
quality control of production. Statistical methods provide a
rea-sonable input and output data necessary for decisionma-king [3]. Results of regression analysis of measured
values of the microgeometry parameters Ra and Pc studied
mate-rials are listed in Table 3.
3 Achieved results and discussion
2 The methodology and experimental
research
2.1 The methodology and experimental
research
44
From tab.3shows that annealing procedures applied after
galvanization led to a decrease of roughness parameters Ra
and Pc. As an example application of the method of Six
Sigma how you assess the competence oft he manufacturing
process of Fe-Zn coated sheet on the requirements of Skoda
Auto and Renault to the roughness parameters Ra and
Pc(Table 3). If a customer specified lower and upper limit
value of the parameter Ra, then the capability indexis
calculated:
USL     LSL 
(1)
C pk  min 
,
  min C pL , C pU 
3. 
 3.
and if the Pc is specified by the customer on lythe lower
limit value, capability indexes calculated:
  LSL ;
(2)
C pL ( lower ) 
3.
Where μ is the mean parameter value achieved by metal
producers,
T-mean value of the required customer
USL, upper specification limit
LSL, lower specification limit
σ- standard deviation
Tab. 3Customer requirements for roughness parameters Ra,
Pc and the calculated index value for individual materials
In view of the stamping of paint abrasion coating is
closely related to the tool contact surfaces. As a result of
abrasion damage occurs to the surface coating on the
stamping. Abrasion resistance of the coating can be quantified by microhardness of the surface phases (= 52-72,
=240-300) coating. η phase is essentially pure zinc, which
is abrasion (formation of micro weld deposits coating cold)
quickly transferred to the contact surfaces of the holder and
pulling the edge(low-abrasion 2 points). Abrasion was observed to a lesser extent in the coatings materials GA2 and
GA3, which coatings are formed  phase (FeZn10, respectively. FeZn7) with microhardness about 300HV(very good abrasion resistance-4body) [2].
Galvanized steel coated with Fe-Zn type "galvanneal"
represents the most progressive material .Effective use of
the unique characteristics required to optimize the choice in
terms of requirements for specific body parts. Based on assessment of compliance requirements can write the following objective function:
n
I
i j
ij
(3)
 Cpk1, j Cpk 2 , j Hf 3,e
HW4 , j
HV5, j
HC 6 , j 



.q j 
.q j 
qj 
q j   max
 Cpk

Cpk 2,e Hf 3, j .
HW4,e
HV5,e
HC 6,e 
1, e

n
, where
I
ij
analysis reflects performance car parts,
i j
Process capability indices are bilateral and unilateral
specification listed in Table. 4. From comparison of the Cpk
for Ra and Pc according to the requirements of Skoda Auto
is clear that if material GA1, which is normally in the
indices cpk Ra=1.85 and cpk Pc=3.03 , is greater than 1.33
respectively. 1.25. This means that the number of nonconforming products from the million units would be
around1.Int he case of material lGA2 is a new product.
Reliability index value of its production process was1.32
respectively. 1.4 .This means that the number of nonconforming products could move at about 60- 70. In the
case of material GA3, the index values were cpk Ra= 0.64
and cpk Pc= 1.76, which means that the process to the
requirements of Skoda car on the parameters Ra and Pc
would be unreliable. Required value Ra work rolls. Today's
modern rolling mills enable to level parameters could be
achieved by increasing the removal or increasing roughness
of work rolls. Renault's requirements for roughness parameters Ra and Pc would be met by reducing or removing mean
arithmetic adjust the removal rate.
Tab. 4 cpk values
In terms of adhesion the coating to the basic material
results of work [3] that the optimal Fe-Zn alloyed coatings
containing 8 to 14% Fe. On the base of the degree exponent
body parts that can be divided into finer range. For example,
on a scale from 1 to 5can be unalloyed respectively. low
alloyed coatings containing 0-8% Fe rate5 points, because
they have excellent adhesion to base material, alloyed
coatings containing 8 to 11% Fe4points because they have
very good adhesion to the base material, alloy coatings
containing 10 to 14% Fe have good adhesion to the base
material- 3points, with coatings containing more than 14%
Fe have lower adhesion to the basic material-2 points.
Hij is the value of the i-th parameter (i = 1-adhesion
coating to the base material, i =2-abrasion resistance on
the coating microhardness HV, i = 3-look paint on the
base cpk Ra, i = 4-look paint on cpk Pc,) j-th analyte,
Hie- the value of the i-th parameter of the standard
material(GA1)
qj-significance weight of j-th analyte.
4 Conclusions
This paper presents a comprehensive approach to
assessing consumer demand for galvanized sheet metal
body parts for the surface. Galvanized sheets were evaluated for the required parameters microgeometry surface Ra
and Pc, the phase composition of Fe-Zn coatings, their
adhesion and abrasion resistance. Galvanized steel with FeZn coating of the type "galvanneal" represents the more
progressive material sites for the best use of its properties, it
is still necessary procedures to optimize the rolling and
pressing. Based on these results has been described objective function, which would help to optimize the process
of producing galvanized sheets as to meet the most demanding customers in the parameters roughness Ra and Pc, abrasion, friction coefficient, etc. ..
Acknowledgement
This article was created by implementation of the project
"Centre for Management Research technical, environmental
and human risks for sustainable production and products in
engineering" (ITMS: 26220120060), by supporting operational program Research and development program financed from the European Regional Development Fund. The
authors the work gratefully acknowledge for the financial
support of the Scientific Grant Agency of the Slovak
Republic (VEGA 10890/09).
45
.Vyboch Jozef, M.Sc.,
Prof. Evin Emil, M.Sc., PhD.,
Faculty of Mechanical Engineering
of the Technical University of Kosice,
Street Mäsiarská 74, 040 01 Kosice,
E-mail: [email protected]
E-mail: [email protected]
Kmec Jozef, RNDr., PhD.,
Faculty of Manufacturing Technologies of the
Technical University of Kosice with a seat in Presov,
Street Bayerova 1, 080 01 Presov,
E-mail: [email protected]
References
[1] EVIN, E. a kol.:Vplyv fázového zloženia povlakov FeZn na charakteristiky trenia pri lisovaní. Metal 2008,
Ostrava, Tanger, 2008, ISBN 9788025419878.
[2] LINDSEY, J.H.,PALUCH, R.F. , NINE, H.D.: The
interaction between electrogalvanized zinc deposit
structure and the forming properties of sheet steel.
Plating and Surface Finishing, 76, s. 62-69, 1989.
[3] SEMIATIN, S.L. at all: Metals Handbook. Forming
and Forging, Vol. 14, ASM International, 1993.
Continued from page 43
References
[9] Bełz W., Jak powstał CRM? – przyczynek do historii
pewnego standardu, [w:] Informatyka w zarządzaniu
logistycznym, pod red. J. K Grabary, Polskie Towarzystwo Informatyczne–Oddział Górnośląski, Katowice
2006
[10] Buchnowska D., Wybór systemu wspierającego zarządzanie relacjami z klientami, [w:] Komputerowo Zintegrowane Zarządzanie, pod red. R. Knosali, Oficyna
Wydawnicza Polskiego Towarzystwa Zarządzania
Produkcją, Opole 2010
[11] Co warto wiedzieć o CRM?, MCX Telecom Spółka z. o.
o., Warszawa, maj 2011:
http://www.eclix.pl/assets/Uploads/Co-warto-wiedzieo-CRM-2011.pdf
[12] Cichosz M., Lojalność klienta, a logistyka firm usługowych, Wydawnictwo SGH, Warszawa 2010
[13] Filemonowicz K., Jędrzejek Cz., Radziulis P., Organizacyjno-finansowe bariery przy wdrażaniu systemów
CRM w Polsce:
http://www.ploug.org.pl/konf_01/materialy/pdf/filemon
owicz_jedrzejek_radziulis.pdf
[14] Gabryelczyk R., Architektura zarządzania procesami
wiedzy o klientach, [w:] Informatyczne wspomaganie
procesów logistycznych, pod red. J. K. Grabary, WNT,
Warszawa 2004
[15] Grabara I., Znaczenie wprowadzenia w Polsce programów klasy CRM, [w:] Efektywność zastosowań systemów informatycznych, T. I., pod red. J. K. Grabary, J.
Nowaka, Wydawnictwo PTI, Warszawa-Szczyrk 2002
[16] Horovitz J., Strategia obsługi klienta, PWE, Warszawa
2006
[17] Kijewska K, Iwan S., Znaczenie technologii internetowych dla efektywności zarządzania relacjami z klientami, [w:] Komputerowo Zintegrowane Zarządzanie,
pod red. R. Knosali, Oficyna Wydawnicza Polskiego
Towarzystwa Zarządzania Produkcją, Opole 2010
[18] Kmieciak R., Systemy CRM a funkcjonowanie małych i
średnich przedsiębiorstw w dotychczasowych badaniach empirycznych, [w:] Komputerowo Zintegrowane
Zarządzanie, pod red. R. Knosali, Oficyna Wydawnicza
Polskiego Towarzystwa Zarządzania Produkcją, Opole
2010
46
[1] Logistyka. Teoria i Praktyka, pod red. S. Krawczyk,
Wydawnictwo DIFIN, Warszawa 2011
[2] Modrak V., Dima I. C., Conceptual Framework for
Corporate Sustainability Planning. International Business Management. 2010, Vol. 4 (3 ), pp. 139-144.
[3] Największe ryzyka wdrożeń systemów CRM – raport –
K2 Consulting sp. z. o. o., 2009, dostępny na stronie
http://www.k2c.pl/index.php?option=com_content&view
=article&id=267%3Araport-najwiksze-ryzyka-wdroecrm&Itemid=2
[4] Paliszkiewicz J. O., Budowanie trwałych związków z
klientami dzięki wykorzystaniu możliwości zintegrowanych systemów zarządzania na przykładzie Micro-soft
Business Solutions – Naision, [w:] Informatyczne
wspomaganie procesów logistycznych, pod red. J. K.
Grabary, WNT, Warszawa 2004
[5] Peppers D, Rogers M, The one to one future: Building
relationships one customers at a time, Dobuleday, New
York 1993
[6] Śmigielska A., CRM – w trosce o klienta, [w:] Systemy
informatyczne zastosowania i wdrożenia, pod red. J. K.
Grabary, J. S. Nowaka, WNT, Warszawa-Szczyrk 2003,
T. III
[7] Szydłowska A., Śmigielska A., Partnerstwo – krok ku
CRM, [w:] Informatyczne wspomaganie procesów
logistycznych, pod red. J. K. Grabary, WNT, Warszawa
2004
[8] Wykorzystanie technologii informacyjno-(tele)komunikacyjnych w przedsiębiorstwach i gospodarstwach domowych w 2010
http://www.stat.gov.pl/gus/5840_wykorzystanie_ict_
PLK_HTML.htm