Lopez de Lacalle L.N., Lamikiz A. Machine Tools for High Performance Machining

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416 J. Fernández and M. Arizmendi

Fig. 12.14 a DMC 80 FD from DMG

. b Machining example

Figure 12.14b shows a boring operation on an engine housing performed in this

“turning and milling” machine.

Besides the “turning and milling at the same machine” strategy other machine

strategies are appearing for reducing set-up times. One of them is the “milling and

grinding at the same time” strategy that is being applied to blades, turbine discs

and also to housings. These components have milling and grinding features and

therefore they have to visit both a milling and a grinding machine. This is the clas-

sic approach. But it implies an increasing number of set-ups, fixtures and cost.

Some machine builders trying to reduce the machining cost of these components

have incorporated grinding capabilities in their milling machines creating the so

called “milling and grinding at the same time” strategy. One of them is Makino

In Fig. 12.15 the “G5 iGrinder” horizontal machining centre is shown. This is

another hybrid 5-axis machining centre suitable for machining special alloys for

aerospace and engine components such as blades, turbine discs and housings.

Reviewing the manufacturing of aerospace engine components it can be con-

cluded that milling is the principal operation followed by turning and grinding.

But there are also other non-traditional processes such as laser, ultrasounds and

Fig. 12.15 Horizontal machining centre G5 iGrinder from Makino

12 Machines for the Aeronautical Industry 417

electrodischarge machining (EDM), that have their small and very specific niches

of applications in the manufacturing of engine components. In some cases these

processes are the only way to perform certain operations.

One example of this is the Lasertec 80 Powerdrill from DMG

that can drill

holes in difficult-to-cut materials (Fig.12.16) with better tolerances and times than

other more traditional processes.

12.5.3 Machine Tools for Machining Accessories

and Structure Fittings

Accessories and structure fittings are aerospace components, which are smaller

than the aluminium structures. They are never larger than 1000

mm in length.

They are complex in geometry and also require complex fixtures to be fixed to

the machine table. Their tolerances are usually rather demanding, ranging between

0.005 and 0.01

mm, and therefore grinding operations are not unusual. Complex

geometry accessories require a large number of machining operations and to re-

duce cycle times: high-speed tool positioning, small tool changing times and

magazines with a large number of tools are needed.

Because of the expensive fixtures and the demanding precision, it is also very

important to minimise the number of set-ups and hybrid machines are a good solu-

tion because they have been designed to manufacture with fewer and simpler

tools, simple and cheaper fixtures and fewer set-ups. And fewer set-ups means

also more precision.

One representative example of these multi-task machines is the new 5 axis

Integrex Mark IV Series machine from Mazak

(Fig. 12.17). This type of machine is

a mixture of a turning and milling centre designed to produce components in one

Fig. 12.16 a 5-axis laser precision drilling of holes in engine components with Lasertec 80

Powerdrill from DMG

. b Turbine vane made of Inconel. c Compressor ring made of stainless

steel

418 J. Fernández and M. Arizmendi

single set-up. It has a turning spindle (single or dual opposed) and also a milling

spindle head with a linear Y-axis and a rotating B-axis. To shorten cycle times it has

an optional additional tool turret for simultaneous cutting. The machine is very

flexible and, according to the builder, can be competitive with different components

such as: a) round parts with secondary operations, b) fully prismatic parts from

a solid or a casting, c) or sculptured parts such as aerospace components and moulds.

Another example is the Millturn machine from WFL

shown in Fig. 12.18a.

This is a turning-milling machine where the tool can be oriented through a B-axis

to machine the workpiece at any angle. Figure 12.18b and c show two fully ma-

chined components from this turning-milling machine.

Typical batch sizes of accessories are less than 100 units/year for between

8 and 20 accessory types. Airbus is an exception with batches of 2,000 per year

since the components are common for many aircraft models. To cope with small

batches with many variants machine tool flexibility is a necessity. About 70% of

those components (mainly valves and pistons) are made of difficult-to-machine

superalloys and the remaining 30% are made of easy-to-machine materials, mainly

Fig. 12.17 Integrex from Mazak

Fig. 12.18 a Millturn 65 from WFL

and some examples of manufactured parts. b Flap lever.

c Landing gear

12 Machines for the Aeronautical Industry 419

aluminium alloys. For light materials, a very large cutting speed can be used and

a 40,000

rpm spindle would be a good choice, but this same spindle will be too

expensive for machining superalloys since the cutting speed of this material group

is low and a less expensive 6,000

rpm spindle will be sufficient. This problem has

recently been addressed by some builders and they are offering machine tools

equipped with two automatically interchangeable spindles such as the gantry type

machining centre FRF (Q) from the Czech company Tos Kuřim

and the JomaX

265, a mobile gantry milling centre for 3/3

2/4/5 axis machining from the Italian

company Jobs

(Fig. 12.19).

Acknowledgements Our thanks to Fatronik and Invema (Spanish Foundation for Machine Tool

Research) for the information provided, and to all mentioned companies for the pictures.

References

[1] Aerospace and Defence Industries Association of Europe (ASD)

http://www.asd-europe.org/. Accessed 28 March 2008

[2] Aerospace Industries Association. http://www.aia-aerospace.org/. Accessed 28 March 2008

[3] Airbus – Press Release – 7 February 2008

http://www.Airbus.com/en/presscentre/pressreleases/pressreleases_items/08_02_07_Airbus

_forecast_2008.html, Accessed 28 March 2008

[4] Aspinwal DK, Dewes RC, Mantle AL (2005) The Machining of y-TiAl Intermetallic

Alloys. CIRP Ann- Manuf Techn, 54/1:99–104

[5] Ezugwu EO (2005) Key improvements in the machining of difficult-to-cut aerospace super-

alloys. Int J Mach Tools Manuf, 45/12–13:1353–1367

[6] Ezugwu EO, Bonney J, Yamane Y (2003) An overview of the machinability of aeroengine

alloys. J Mater Process Technol 134:233–253

[7] Fatronik (2002) Internal Report: Tendair (Trends in Aircraft Industries)

[8] Invema (2007) Internal Report: Tendencias Tecnológicas y Oportunidades de Negocio

(Business and Technological Opportunities, in Spanish)

[9] Lequeu P, Lassince P, Warner T, Raynaud GM (2001) Engineering for the future: weight

saving and cost reduction initiatives. Aircraft Engineering and Aerospace Technology

73/2:147–159

Fig. 12.19 a JomaX 265 from Jobs

. b Automatically interchangeable spindles

420 J. Fernández and M. Arizmendi

[10] Smith RJ, Lewis GJ and Yates DH (2001) Development and application of nickel alloys in

aerospace engineering. Aircraft Engineering and Aerospace Technology 73/2:138–146

[11] Teti R (2002) Machining of Composite Materials. CIRP Ann-Manuf Techn 51/2:611–634

[12] Weinert K, Biermann D, Bergmann S (2007) Machining of High Strength Light Weight

Alloys for Engine Applications. CIRP Ann-Manuf Techn 56/1:105–108

[13] Williams JC, Starke EA (2003) Progress in structural materials for aerospace systems. Acta

Materiala 51:5775–5799

421 L. N. López de Lacalle, A. Lamikiz, Machine Tools for High Performance Machining,

Chapter 13

Machine Tools for the Automotive Industry

Ciro A. Rodríguez and Horacio Ahuett

Abstract This chapter describes the machine tools used in the automotive indus-

try. The world trends in automotive production are discussed to stress the signifi-

cance of this industrial sector in the global economy. A description of the typical

automotive components with machining operations is also discussed. The use of

flexible machines vs dedicated machines is analysed in the context of current

trends in the automotive markets. Finally, new machine tool and process technolo-

gies of particular relevance to the automotive industry are described.

13.1 World Trends in Automotive Production

The automotive production could be considered the motor of the industrial devel-

opment of the 20th century. Current trends indicate that such a significant influ-

ence will continue in the near future. This section presents the economic impact of

the automotive industry and the corresponding automotive components that utilise

significant amounts of machining operations.

13.1.1 The Economic Impact of the Automotive Industry

The automotive industry is one of the main drivers of the world’s economy. Nearly

70 million cars, vans, trucks and buses were produced in 2006 alone. This level of

output represents a global turnover of €1,900 billion, a figure that exceeds the GDP

_________________________________

Ciro A. Rodríguez and Horacio Ahuett

Centre for Innovation in Design and Technology, Tecnológico de Monterrey,

Av. Eugenio Garza Sada #2501 Sur, Monterrey, N.L. 64849 MÉXICO

{ciro.rodriguez, horacio.ahuett}@itesm.mx

422 Ciro A. Rodríguez and Horacio Ahuett

pan

USA

hina

Sout

Korea

Braz

ico

India

hai

taly

othe

Wolrd Production in 2006 (Munits)

Commercial Vehicles

Cars

Fig. 13.1 World production of cars and commercial vehicles (adapted from [14])

(gross domestic product) of all but the five richest countries. Furthermore, this indus-

try provides more than eight million direct jobs worldwide, or about 5% of the total

manufacturing jobs, and approximately five times more are employed indirectly in

related manufacturing and service supplies. In all, an estimated 50 million people

earn their living from the manufacturing of cars, trucks, buses and coaches [14].

Worldwide, the automotive industry has grown at yearly rate of approximately

4% over the last few years. Furthermore, the production of cars and commercial

vehicles is distributed all over the world. Figure 13.1 shows the top 15 countries in

this industry during 2006. In addition to the top 15 countries, more than 25 coun-

tries contribute to the production of nearly 9 million vehicles [14].

Finally, the influence of the auto industry transcends the mere production of

goods. The auto industry is also a leader in innovation, playing a key role in the tech-

nology level of other industries and of society as a whole. By current estimations, the

industry invests about €85 billion in research and development per year, with several

manufacturers found among the leading top 10 corporations in the world [14].

13.1.2 Machining Processes in Automotive Production

In the automotive industry, the general categories of products with significant

machining operations include: a) engine components, b) transmission and drive

components, c) axles and differential components and d) brakes and wheels.

In all cases, there is a significant amount of hole-making operations such as

drilling, tapping, reaming and boring. There is also an extensive use of milling

operations, such as face milling and pocket milling, and various turning opera-

13 Machine Tools for the Automotive Industry 423

tions. In some components such as crankshafts and camshafts, grinding operations

are needed. Special metal cutting operations such as turn broaching and broaching

are also applied for some components. The typical workpiece materials are forged

steels, cast irons and cast aluminium silicon alloys.

Figure 13.2 presents typical examples of automotive components produced by

first-tier suppliers such as Nemak

[8], Magna Powertrain

, Sisamex

, Delphi

and American Axle and Manufacturing

, among others. The following sections of

this chapter concentrate on machine tools for milling and hole-making operations.

In separate chapters of this book, technology trends associated with turning cen-

tres and grinding machines are discussed in depth.

13.2 Manufacturing System Architecture:

High Volume Production Versus Flexibility

In the automotive industry, there is a constant push to maintain the low unit cost

associated with high volume production, but at the same time to maintain flexibil-

Engines

Transmissions

and Drives

Axles and

Differentials

Brakes and

Wheels

Engines

Transmissions

and Drives

Axles and

Differentials

Brakes and

Wheels

Fig. 13.2 Automotive components that require machining operations

424 Ciro A. Rodríguez and Horacio Ahuett

ity. This need for flexibility comes from both a) the market demand shifts typical

of the automotive sector and b) manufacturing operation changes associated with

new product models. Clearly, the architecture of the machining system is designed

to suit the production demands and ranges from transfer lines to individual ma-

chines in job shop arrangements. The choice of architecture in turn determines the

structure of the machines that constitute the system.

13.2.1 Dedicated Machines

Dedicated machines are divided into linear transfer machines and rotary transfer

machines. The following sections explain and illustrate both types of dedicated

machines.

13.2.1.1 Linear Transfer Machines

The linear transfer machine or transfer line is an automated and interlocked group of

stations that includes machining, deburring, cleaning and inspection operations. The

whole transfer line must be designed and built as a unit. The various stations in the

transfer machine perform manufacturing operations on the product simultaneously.

By interlocking the machine stations and the material handing system, it is possible to

OP 10C

Pre-machine oil pan face and crakcase features,

finish-millin

manufacturin

OP 10

Mill bank faces, mill oil pan face and crankcase

features, drill manufacturin

holes

OP 20C

Pre-machine bank & end faces, core drill cup plug

holes, drill oil gallery holes, de-flash cylinder bores

OP 20 Rough and finish-bore parent metal cylinder bores

OP 30C Washe

OP 30 Preliminary washe

OP 40C Leak test OP 40 Cylinder block heate

OP 50 Cylinder liner assembl

OP 60 Coolin

& stora

e s

stem

OP 70 Finish-mill, drill and tap bearin

cap seats

OP 80 Intermediate washe

OP 90 Bearing cap assembl

OP 100

Semi-finish mill, drill and tap oil pan face, finish

bore manufacturing holes

OP 110 Semi-finish mill, drill and tap end faces

OP 120

Drill and tap deck faces, drill and ream oil feed

and dip stick holes

OP 130

Finish-bore cup plug holes, mill, drill & tap

mounting

OP 140

Rough, semi-finish and finish-bore crank bore,

finish-bore water pump and dowel holes

OP 150

Rough, semi-finish and finish-bore cylinder bores

and finish-mill bank face

OP 160

Finish-mill front, rear & pan faces. Finish-bore

bank face dowels.

OP 170 Hone

OP 180 Final washe

OP 190 Cup plu

assembl

and leak test

Operations Order In Foundry Operations Order in Engine Plant

OP 10C

Pre-machine oil pan face and crakcase features,

finish-millin

manufacturin

OP 10

Mill bank faces, mill oil pan face and crankcase

features, drill manufacturin

holes

OP 20C

Pre-machine bank & end faces, core drill cup plug

holes, drill oil gallery holes, de-flash cylinder bores

OP 20 Rough and finish-bore parent metal cylinder bores

OP 30C Washe

OP 30 Preliminary washe

OP 40C Leak test OP 40 Cylinder block heate

OP 50 Cylinder liner assembl

OP 60 Coolin

& stora

e s

stem

OP 70 Finish-mill, drill and tap bearin

cap seats

OP 80 Intermediate washe

OP 90 Bearing cap assembl

OP 100

Semi-finish mill, drill and tap oil pan face, finish

bore manufacturing holes

OP 110 Semi-finish mill, drill and tap end faces

OP 120

Drill and tap deck faces, drill and ream oil feed

and dip stick holes

OP 130

Finish-bore cup plug holes, mill, drill & tap

mounting

OP 140

Rough, semi-finish and finish-bore crank bore,

finish-bore water pump and dowel holes

OP 150

Rough, semi-finish and finish-bore cylinder bores

and finish-mill bank face

OP 160

Finish-mill front, rear & pan faces. Finish-bore

bank face dowels.

OP 170 Hone

OP 180 Final washe

OP 190 Cup plu

assembl

and leak test

Operations Order In Foundry Operations Order in Engine Plant

Fig. 13.3 Operations sequence for engine block machining in transfer line [1]

13 Machine Tools for the Automotive Industry 425

move a set of in-process products from station to station. As each product reaches the

end of the transfer line, all the manufacturing operations have been performed [11].

The first transfer machines used in the automotive industry date back to the

1920s, both in the US and the United Kingdom. However, it wasn’t until the 1960s

that automobile manufactures started to develop some degree of flexibility through

modularity in the transfer machines [11]. Through the years, transfer machine

developers have increased the modularity of these systems to accommodate the

shortening of product life cycle and market demand changes.

An example is presented in Fig. 13.3, which shows the typical operation se-

quence for engine block machining in a dedicated transfer line (the engine block

picture is for illustration purposes only). In this case, the transfer line is designed

to produce 650,000 engine blocks per year with a cycle time of 27

s. In general,

for the production of large automotive components such as engine blocks and

engine cylinder heads, a dedicated transfer line is recommended for volumes be-

yond 250,000 parts/year.

13.2.1.2 Rotary Transfer Machines

The rotary transfer machine, also known as the dial or carousel transfer machine,

is better suited for small automotive parts. These machines typically handle work-

ing volume envelopes up to 0.027

(300

300

mm). Rotary transfer ma-

chines can produce a large number of small automotive components, ranging from

100 to 550 parts/h. Considering a two-shift operation with a 75% uptime, these

machines can produce between 300,000 and 1,650,000 parts/year (according to

data from Kingsbury and [19]).

A typical design for a rotary transfer machine is presented by Gnutti

, which

produces a rotary transfer machine with a structure that allows 25 stations with up

to 33 high-speed spindles (see Fig. 13.4). This particular machine features 15

m/s

of axis acceleration.

An alternative design for rotary transfer machine is shown in Fig. 13.5. This

machine concept allows for 3 to 6 stations, with various configurations for each

station, such as horizontal, vertical, single spindle, double spindle and multi-head

Fig. 13.4 Modular rotary transfer machine, by Gnutti