Caso práctico integración en fabricaciónDepartamento de Ciencias de los Materiales e Ingeniería Metalúrgica, Expresión Gráfica en la Ingeniería, Ingeniería Cartográfica, Geodesia y Fotogrametría, Ingeniería Mecánica e Ingeniería de los Procesos de Fabricació

López, Roberto

Mahíllo Isla, Raúl

Martín Llorente, Óscar

San Juan Blanco, Manuel

Santos Martín, Francisco Javier

Suárez Sánchez, Raquel

Tiedra Frontaura, María del Pilar

Repositorio Documental de la Universidad de Valladolid

Proceedings	of	the	6th	Manufacturing	Engineering	Society	International	Conference	–	Barcelona	–	July	2015	 An	experience	in	integrated	knowledge	about	Manufacturing	Technologies	for	Students	of	the	Grades	of	Industrial	Engineering		M.	San‐Juan(1),	M.	del	P.	de	Tiedra(2),	O.	Martín(2),	F.	J.	Santos(2),		R.	López(2),	R.	Suárez(2),	R.	Mahillo–Isla(2)		(1)	University	of	Valladolid‐	Department	of	CMeIM‐EGI‐ICGM‐IM‐IPF‐	Escuela	de	Ingenierías	Industriales,	Paseo	del	Cauce,	59,	47011,	Valladolid	(Spain)	mansan@eii.uva.es	(2)	University	of	Valladolid‐	Department	of	CMeIM‐EGI‐ICGM‐IM‐IPF‐	Escuela	de	Ingenierías	Industriales,	Paseo	del	Cauce,	59,	47011,	Valladolid	(Spain)		ABSTRACT	In	the	development	of	the	specific	skills	in	the	field	of	industrial	engineering,	the	transversality	 of	 the	 contents	 of	 each	 area	 of	 knowledge	 must	 be	 considered.	This	paper	shows	how	the	integration	of	the	contents	of	different	areas	(such	as	materials,	manufacturing,	design,	etc.)	is	performed	in	order	to	allow	students	to	enhance	 their	 transversal	 skills.	 For	 this,	 a	 specific	 product	 is	 proposed	 as	“learning	 object”.	 The	 analysis,	 to	 be	 made	 by	 the	 students,	 includes	 all	 the	aspects	 regarding	 technical	 and	 economic	 feasibility,	 and	 manufacturing	optimization	 of	 the	 product.	 	 The	 article	 also	 shows	 the	 analysis	 of	 the	 work	environment	 and	 methodology	 established	 by	 an	 interdisciplinary	 group	 of	university	 teachers	 from	 different	 areas:	 materials,	 manufacturing	 and	 design	who	have	contributed	with	their	knowledge	in	the	specific	problem.		Keywords:	 Interdisciplinarity;	 Industrial	 Engineering;	 Manufacturing	Technology	Teaching.				1.	Introduction		Nowadays,	 engineering,	 broadly	 speaking,	 and,	 particularly,	 extensive	 research	 activities	 cannot	 be	conceived	and	projected	without	a	multidisciplinary	approach	 in	which	different	 areas	of	 expertise	 are	integrated.	 Education	 at	 universities	 should	 not	 escape	 from	 integration	 as	 a	 key	 concept	 since	departments	of	human	resources	of	the	companies	recognize	the	integrated	education	as	an	added	value	in	the	curriculum	vitae	of	the	applicants	[1,	2].	Nonetheless,	 in	the	context	of	higher	education	institutions,	the	development	of	 lecturing	of	science	and	technology	in	the	industrial	framework	has	been	traditionally	treated	as	a	set	of	independent	disciplines	in	 which	 the	 departments,	 sometimes,	 fight	 for	 finding	 their	 working	 scope.	 The	 same	 skills	 to	 be	developed	by	the	students	are	treated	by	different	areas	of	expertise	and,	consequently,	different	scopes,	different	universities	or	simply	because	of	pure	availability	needs	of	lecturers	[3,	4].		Coordination	between	teachers	of	different	subjects	 is	a	key	milestone	 in	teaching	of	 the	manufacturing	technologies.	 This	 fact	 allows	 us	 to	 improve	 the	 educational	 programs	 of	 the	 grades	 of	 industrial	engineering	in	the	matters	of	manufacturing.	The	main	aim	is	to	achieve	a	better	quality	in	the	skills	of	our	students.	For	that,	we	perform	an	integration	of	the	contents	as	a	whole	in	the	programs	of	the	subjects	by	highlighting	the	joints	between	the	different	matters	regarding	manufacturing.	The	development	of	skills	 in	manufacturing	 technologies	has,	as	a	key	point,	 the	 transversal	connection	between	subjects.	Design,	materials	and	processes	are	 interconnected	by	some	key	factors	that	must	be	carefully	chosen	in	order	to	achieve	the	specified	quality.	The	contrast	between	student	and	professional	activities	are	very	high.	Students	tend	to	perceive	the	contents	of	different	subjects	as	independent	topics	but,	 nevertheless,	 in	 the	 professional	 activity	 of	 an	 engineer	 the	 problems	 are	 complex	 and	 require	 a	global	knowledge	to	be	not	only	solved	but	also	tackled.	With	regard	to	manufacturing	technologies,	the	skill	 to	be	 included	 in	 the	program	of	 the	different	 subjects	 can	be	 stated	as	 follows:	Knowledge	of	 the	relations	between	materials,	shapes,	processes	and	costs.		Even	though	each	subject	deals	with	a	specific	part	of	the	manufacturing	problem,	our	programs	account	for	the	connections	with	other	subjects.	Proceedings	of	the	6th	Manufacturing	Engineering	Society	International	Conference	–	Barcelona	–	July	2015	  This	work	arises	in	the	framework	of	a	Learning	Innovation	Project	of	the	University	of	Valladolid.	Among	the	 objectives	 of	 the	 project,	 some	 topics	 such	 as	 the	 statement	 of	 the	 basis	 of	 an	 interdisciplinary	workgroup	of	teacher	of	different	areas	of	the	Industrial	Engineering,	and	the	development	of	transversal	skills	of	the	teachers,	are	included.		In	order	to	carry	on	the	proposed	work,	the	learning	objects	[5]	were	defined	and	each	teacher	gave	the	perspective	 regarding	 some	 projects.	 Those	 projects	 deal	 with	 very	 significant	 forming	 processes:	Traditional	processes	such	as	casting,	machining	and	plastic	deformation;	and	nontraditional	processes	as	electrical	 discharge	machining	 and	 laser	 cutting.	 The	 project	 explained	 in	 this	 paper	 regards	 with	 the	manufacturing	of	a	rigid	overhead	catenary	with	its	extrusion	die.		2.	Methodology	and	used	resources	The	 techniques	mainly	used	within	 the	workgroup	have	been	brainstorming	and	case	method.	This	has	favored	 the	 use	 of	 interdisciplinarity	 in	 the	 process	 of	 decision‐making	 when	 looking	 for	 a	 solution.	Previously	 to	 the	 beginning	 of	 work	 meetings,	 the	 teamwork	 was	 propitiated	 by	 having	 research	 line	presentations,	 visiting	 laboratories	 and	 companies,	 and	 organizing	 specific	 formation	 courses	 (mainly	about	CAD/CAM/CAE/CAQ	tools).					Figure	1.	Specific	formation	and	tools.	Integration	of	CATIA	and	PC‐DMIS	CAD++		In	 the	 following	 step,	 the	 topics	 to	 be	 worked	 were	 defined	 by	 finding	 the	 common	 and	 particular	elements	of	the	problems.	The	result	was	the	elaboration	of	a	so	called	“scope	statements”	of	the	different	aspects	that	should	be	considered	for	the	work	with	the	students.		In	 the	 example,	 a	 problem	 involving	 different	 areas	 of	 the	 industrial	 engineering	 is	 proposed:	 the	manufacturing	of	an	aluminum	alloy	rigid	overhead	catenary	that,	in	contrast	to	a	conventional	one,	has	a	better	 behavior	 in	 terms	 of	 efficiency	 and	 a	 reduction	 in	 the	 total	 height	 of	 tunnels	 among	 other	advantages	[6].	The	main	features	of	the	caternary	are	summarized	in	Table	1.	Table	1.	Characteristics	of	the	rigid	overhead	caternary	Profile	section	 2220mm2	Height	 110mm	Length	 10–12m	Weight	per	meter	 6.1Kg	Moment	of	inertia	Ixx	 338·104	mm4	Moment	of	inertia	Iyy	 113.7·104	mm4	Copper	equivalent	section	 1400mm2	Coefficient	of	thermal	expansion	(long.) 24·10‐6	Shear	modulus	 69000N/mm2			The	profile	sustains	a	copper	wire	that	contacts	the	pantograph	of	the	train	(see	Figure	2).	Proceedings	of	the	6th	Manufacturing	Engineering	Society	International	Conference	–	Barcelona	–	July	2015	  		Figure	2.	Rigid	overhead	catenary.	It	clamps	the	copper	wire	that	contacts	the	pantograph		The	proposed	solution	will	have,	in	this	case,	two	main	objectives:	the	manufacturing	of	a	rigid	overhead	catenary	and	its	extrusion	die.	For	each	problem,	as	standard	problems,	we	try	to	resolve	and	document	all	aspects	regarding	to:	 Denomination	 of	 the	 material	 (in	 terms	 of	 chemical	 composition	 and	 material	treatments)	 Dimensions	and	tolerances	 Main	properties	and	characteristics	 Planes	and	3D	models:	how	to	put	all	the	aforementioned	information	 Manufacturing	problems			3.	Learning	objects:	the	case	The	 integration	 of	 the	 solutions	 proposed,	 from	 the	 view	 point	 of	material	 science	 and	manufacturing	processes,	 is	quite	significant	for	the	students.	It	cannot	be	conceived	one	without	the	application	of	the	other.	Let	us	see,	promptly,	some	of	the	most	important	points.	2.1	Rigid	overhead	catenary	Material	The	rigid	overhead	catenary	made	of	an	aluminum	alloy	named	6063	in	the	UNE	norm	that	is	equivalent	to	the	Al	Mg	0.5	Si	in	the	ISO	denomination.	Its	chemical	composition	is	plotted	in	Table	2.	Table	2.	Chemical	composition	of	aluminum	alloy	6063	(%wt.)	Si	 Fe	 Cu	 Mn Mg	 Cr	 Zn	 Ti	 Al	0.20–0.60	 0.35	 0.10 0.10 0.45–0.90 0.10 0.10 0.10 rest		The	 catenary	 is	 formed	 by	 hot	 extrusion	 at	 520°C.	 At	 this	 temperature	 the	 alloy	 also	 experiments	solubilizing.	After	this	process	the	mechanical	characteristics	of	the	catenary	are	improved	by	performing	an	artificial	age	hardening.	Therefore	the	state	of	the	alloy	is	designed	as	a	T5	[7].	Manufacturing	process	The	forming	of	the	profile,	that	are	presented	in	a	sequential	way	in	which	forming	processes	and	thermal	treatments	alternate,	is	made	as	follows:	Extrusion	of	the	alloy,	cut,	stretch,	age	hardening,	finishing.	1. Extrusion	of	the	alloy:	The	aluminum	alloy	is	previously	heated	up	to	a	temperature	in	between	400–460°C.	Boron	nitride	(BN)	is	applied	in	the	surface	of	the	ingot	to	avoid	the	adherences	to	the	extrusion	chamber.	By	controlling	the	pressure	of	the	press,	the	extrusion	speed	is	controlled.	The	way	out	of	the	material	 is	helped	by	applying	a	light	traction.	The	temperature	at	the	out	of	the	press	is	in	between	510–550°C	and	the	cooling	is	about	50°C/min.	2. Cutting:	By	using	a	circular	saw	the	pieces	are	cut	in	a	length	that	allows	the	transportation.		Proceedings	of	the	6th	Manufacturing	Engineering	Society	International	Conference	–	Barcelona	–	July	2015	  3. Stretching:	A	stretching	bank	is	used	to	get	rid	of	the	curvature	of	the	profile	and,	due	to	the	cold	work,	the	material	will	present	enhancement	of	the	strength.	4. Age	hardening:	This	treatment	consists	in	heating	at	205°C	for	one	hour	followed	by	a	non‐forced	air	cooling.	5. Finishing:	 Anodizing	 of	 the	 profile	 is	 performed.	 The	 procedure	 is	 an	 electrochemical	 one	 that	consists	in	generating	a	layer	of	oxide	in	the	surface	of	the	piece	to	enhance	the	behavior	against	corrosion.	2.2	Extrusion	die	Material	The	material	chosen	to	make	the	extrusion	die	must	meet	the	requirements	of	a	steel	for	hot	work	tools	[7],	 designated	as	F.5318	 in	 the	UNE‐EN	norm,	 equivalent	 to	 the	 SAE/AISI	H13	 steel.	H13	 steel,	whose	chemical	composition	is	depicted	in	Table	3,	is	widely	used	in	the	production	of	forming	tools:	extrusion	dices	for	light	alloys,	blanking	dies,	etc.	The	use	of	H13	steel	gives	a	good	balance	in	terms	of	toughness,	resistance	against	fissure	forming	due	to	thermal	shocks,	quenching	resistance	and	wear.		Table	3.	Chemical	composition	of	SAE/AISI	H13	steel	(%wt)	C	 Si	 Cr	 Mo V	 Fe	0.40	 1.00 5.20 1.30 0.95 rest	After	tempering	with	non‐forced	air,	hardness	in	between	44	and	52	HRC	are	obtained.	High	temperature	quenching	 (below	 540°C)	 allow	 the	 material	 to	 keep	 the	 hardness	 obtained	 by	 tempering	 and	 its	resistance	to	be	used	at	high	temperatures:	tools	made	with	H13	steel	can	be	used	with	temperatures	up	to	 540°C,	with	 short	 exposures	up	 to	 595°C.	 It	 is	 a	 first	 choice	 for	making	hot	 extrusion	dices	 for	 light	alloys	such	as	the	aluminum	alloy	of	the	rigid	overhead	catenary.	Besides,	it	accepts	nitriding	to	enhance	surface	wear	resistance.		Manufacturing	process			The	 forming	 of	 the	 extrusion	 die	 is	 made	 following	 these	 steps:	 Forging,	 annealing,	 initial	 machining,	stress	relaxing	procedures,	tempering,	quenching,	wire	electrical	discharge	machining	and	nitriding.	1. Forging:	The	process	is	made	at	1000°C	and	after	that,	slow	cooling	is	performed	in	a	furnace.	It	is	recommended	to	heat	the	press	up	to	720°C	to	avoid	high	thermal	contrast	and	consequently	the	wear	of	the	press.	2. Annealing:	After	forging,	an	annealing	process	is	performed.	It	consists	in	heating	maintaining	for	two	hours	870°C,	then	six	hours	at	760°C	and,	finally,	non‐forced	air	cooling.	The	annealing	must	provide	a	material	whose	hardness	is	in	between	192	and	235	HBN	that	could	be	easily	machined.	3. First	machining:	By	turning	and	milling	the	general	shape	of	the	dies	is	obtained.	The	thickness	of	the	 die	 at	 the	 output	must	 be	 taken	 into	 account	 to	 reduce	 torsions	 and	 other	 problems.	 The	output	profile	is	not	obtained	in	this	step.	If	wire	electrical	discharge	machining,	as	is	the	case,	is	considered	to	provide	the	 final	profile,	 the	hole	must	be	done	 in	order	 to	 introduce	the	wire.	 If	other	procedure	is	considered	(for	instance,	laser	or	abrasive	water	jet	machining)	the	hole	is	not	necessary.	4. Stress	 relaxing	 procedures:	 After	 the	 intense	machining	 process,	 it	 is	mandatory	 to	 anneal	 the	material	in	order	to	get	rid	of	inner	stresses	above	all,	as	in	this	case,	when	the	specimen	is	going	to	 be	 tempered	 and	 quenched.	 Such	 stresses	 can	 be	 the	 origin	 of	 defects	when	 different	 local	contractions	 and	 expansions	 are	 added	 in	 the	 tempering	 process.	 The	 procedure	 consists	 in	heating	and	maintaining	for	two	hours	the	temperature	at	520°C.	Then,	a	long	cooling	in	a	furnace	is	made.	5. Tempering:	 Tempering	 is	 made	 by	 heating	 the	 piece	 in	 between	 995	 and	 1025°C.	 Such	 a	temperature	is	maintained	for	30–45min	and	later	oil	cooling.	Cooling	is	interrupted	at	650°C	and	cooling	 speed	 must	 be	 around	 25°C/min	 until	 650°C	 is	 reached.	 Thus,	 impact	 and	 quenching	resistance	is	improved	but	strength	is	lightly	worse.	6. Quenching:	 It	 is	mandatory	to	quench	the	specimen	after	tempering.	This	procedure	consists	 in	heating	 at	 540°C,	maintaining	 this	 temperature	 one	 hour	 per	 25mm	 thickness	 and,	 finally,	 air	cooling.	The	hardness	obtained	is	52	HRC	and	the	estimated	resilience	with	a	Charpy	impact	test	Proceedings	of	the	6th	Manufacturing	Engineering	Society	International	Conference	–	Barcelona	–	July	2015	  is	14J.	This	procedure	can	introduce	a	very	small	size	increment	of	about	0.06%.	Variations	in	the	quenching	 procedure	 also	 give	 rise	 to	 different	 results.	 To	 compensate	 for	 the	 dimensional	variations	of	the	die,	polishing	and	grinding	should	be	considered.	7. Wire	Electrical	Discharge	Machining	(WEDM):	An	electrode	of	electrolytic	copper	wire	is	used	to	obtain	the	final	extrusion	profile.	Note	that	at	this	point,	traditional	machining	processes	are	not	recommended	 due	 to	 the	 lack	 of	machinability	 of	 the	material	 after	 tempering	 and	 quenching.	This	procedure	allows	it	to	obtain	complex	profiles	and	sharp	edges,	and	it	is	widely	used	in	the	manufacturing	of	dies.		It	can	be	used	in	tempered	materials	because	material	hardness	does	not	have	any	influence	(there	is	not	physical	contact	between	the	wire	and	the	piece)	and	the	heat‐affected	 zone	 can	 be	 neglected.	 High	 accuracy	 machining	 can	 be	 obtained	 but	 some	 manual	trimming	could	be	used	[8].		8. Nitriding:	 The	 procedure	 is	 performed	 by	 heating	 the	 die	 at	 about	 500°C	 in	 a	 furnace	 with	 a	controlled	 atmosphere	 of	 ammonia	 (NH3);	 then	 air	 cooling.	 If	 the	 process	 is	 well‐done,	dimensional	 changes	 are	 not	 expected	 because	 structural	 transformation	 of	 the	 steel	 does	 not	take	place	at	those	temperatures	[9].			4.	Conclusions	The	work	between	different	areas	of	expertise	on	the	same	problem	to	be	treated	in	different	subjects	can	improve	 the	 communication	 of	 transversal	 knowledge	 in	 engineering	 problems,	 especially	 in	manufacturing	technologies.		This	experience	has	allowed	the	authors	to	consolidate	a	workgroup	and	to	start	the	creations	of	what	we	call	 “learning	 objects”	 as	 an	 instrument	 for	 teachers	 in	 their	 respective	 subjects.	 The	 interrelations	 of	solutions	 are	 enhanced	 even	 with	 other	 areas	 of	 expertise	 different	 from	 the	 workgroup	 [10].	 The	material	 is	 mainly	 aimed	 to	 seminars	 and	 practice	 where	 the	 students	 can	 promote	 the	 discussion	 of	different	solutions.		Figure32.	Integration	of	the	project	with	other	disciplines.	Finite	elements	analysis	of	the	static	problem	[10]		Even	 though	 the	 experience	 and	 teacher	 viewpoint	 is	 quite	 positive,	 these	 kinds	of	 innovation	projects	have	troubles	when	trying	to	know	what	students	exactly	learn	about	transversal	knowledge.	Students	are	receptive	to	this	kind	of	method	but	we	have	not	been	able	to	account	for	the	improvements	in	their	skills	regarding	interdisciplinarity.			5.	Acknowledgements	We	would	like	to	thank	Antonio	Alonso	Moreno,	Honorific	Collaborator	of	the	Universidad	de	Valladolid	who	 passed	 away	 few	months	 ago;	 and	 Ismael	 de	 la	 Cruz,	 who	 works	 with	 SAFRAN	 Engineering	 and	Hexagon	Metrology.		Proceedings	of	the	6th	Manufacturing	Engineering	Society	International	Conference	–	Barcelona	–	July	2015	  6.	References	[1]	H.L.	 Yustos	 et	al. Enseñanza	 Integrada	 de	 “Diseño	 y	 fabricación	 con	materiales	 plásticos”. Primeras	Jornadas	de	Innovación	Educativa	de	la	Escuela	Politécnica	Superior	de	Zamora.	2006.		[2]	C.O.	Cañizares	Luna,	C.	Sarasa	Muñoz,	C.	Labrada	Salvat.	Enseñanza	integrada	de	las	Ciencias	Básicas	Biomédicas	en	Medicina	Integral	Comunitaria.	Educación	Médica	Superior,	vol.	20,	no.	1,	2006.		[3]G.	 Bengu,	 W.	 Swart.	 A	 computer–aided,	 total	 quality	 approach	 to	 manufacturing	 education	 in	engineering.	IEEE	Transactions	on	Education	vol.	39,	no.	3,	p.	415–422,	1996.		[4]	 J.D.	 Orjuela–Méndez,	 J.M.	 Arroyo–Osorio,	 R.	 Rodríguez–Barakaldo.	 Actualidad	 y	 Perspectivas	 En	 La	Enseñanza	Del	Área	De	Manufactura	a	Estudiantes	De	Ingeniería.	 Ingeniería	Mecánica,	vol.	16,	no.	1.	pp.	59–71,	2013.		[5]	S.	Aguirre,	C.	Fuqueme,	G.	Zambrano.	Desarrollo	De	un	sistema	de	manufactura	virtual	y	su	Integración	con	un	sistema	ERP	para	la	educación.	Tecnología	Informática	,	2009.		[6]	R.R.	López–López,	A.	Pecharromán,	A.	Fernández–Cardador,	P.	Cucala.	Transportation	Research	Part	C	vol.	38	p.	85,	2014.		[7]	 S.D.	 Henry,	 S.E.	 Frueh,	 R.	 Boring,	 D.	 Levicki,	 L.	 Harrision.	 ASM	 Specialty	Handbook.	 Aluminium	 and	Aluminium	Alloys,	ASM	International,	Materials	Park,	OH,	1993.		[8]	K.H.	Ho,	et	al.	State	of	the	Art	in	Wire	Electrical	Discharge	Machining	(WEDM).	International	Journal	of	Machine	Tools	and	Manufacture,	10,	vol.	44,	no.	12–13.	pp.	1247‐1259,	2004.		[9]	D.	Bombač,	et	al.	The	Progress	of	Degradation	on	the	Bearing	Surfaces	of	Nitrided	Dies	for	Aluminium	Hot	Extrusion	with	Two	Different	Relative	Lengths	of	Bearing	Surface.	Wear,	9/30,	vol.	307,	no.	1–2.	pp.	10‐21,	2013.		[10]	 SEAP	 “Proyecto	 de	 instalación	 de	 catenaria	 rígida	 y	 actuaciones	 complementarias	 en	 los	 túneles	urbanos	 de	 cercanías	 de	 Barcelona”.	 Secretaría	 de	 Estado	 de	 Administraciones	 Públicas.	 Ministerio	 de	Hacienda	y	Administraciones	Públicas.	(2008)		http://www.seap.minhap.gob.es/dmsweb/es/ministerio/delegaciones_gobierno/delegaciones/catalunya/actualidad/notas_de_prensa/notas/2008/12/2008_12_15a/parrafo/00/PRESENTACI‐NCATENARIAR‐GIDA‐definitiva‐.pdf	[last	visited	23/02/15]		

An experience in integrated knowledge about Manufacturing Technologies for Students of the Grades of Industrial Engineering

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An experience in integrated knowledge about Manufacturing Technologies for Students of the Grades of Industrial Engineering

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