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News Release from: CECIMO | Subject: MANTYS machine tools aerospace
Edited by the Manufacturingtalk Editorial Team on 06 October 2005

How aircraft design may affect machine
tools

Changes in the way future aircraft may be designed may well begin to affect future demand for machine tools, reports Mike Page in the second part of a paper presented at a MANTYS public session.

In the second part of a paper presented at the second CECIMO MANTYS public session at the EMO 2005 machine tool exhibition in Hannover Germany, 'Product Innovation by end users' examines how the future design trends in aircraft construction could affect the demand for machine tools, in type and quantity * To re-state the objects of MANTYS C.1: - to establish the likely timing in which new technologies and products are to be progressively implemented by the automotive and aerospace industries

To assess the relative economic importance to manufacturing equipment suppliers of design and manufacturing innovations in the automotive industry.

The initiative will also attempt to establish a quantitative relationship between product innovations and manufacturing equipment specification.

A number of interviews were carried out by IWB Muenchen, SYMAP, Paris, UCIMU, Milan and Michael Page, Cambridge during 2002.

Difficulties were experienced in gathering data owing to the reluctance of many OEMs and Tier 1s to discuss, in any kind of detail, as the timing of any product innovation is considered to be 'highly sensitive marketing information'.

The few interviews carried out with the aerospace industry, where similar, but more historic concerns and developments over weight saving continue.

The aerospace industry also revealed some reluctance to talk about future product innovation, but some idea has been gleaned about future changes likely to take place.

Both topics have been recently updated where time permitted.

Also in the presentation at EMO, Page looked at the European mould and die industry, where recent competition from the Far east and Eastern Europe has accelerated European mould and die makers' wish to reduce direct labour costs and 'time-to-market'.

In consequence, some Western European mould and die making companies have gone out of business - up to 30%.

This will be published on the web shortly.

* Aerospace - traditionally, airframe components are monolithic - machined from billets, forgings or castings.

Airframe assembly has, for many years, used riveting, involving extensive drilling, countersinking and finishing.

Some OEMs have developed automatic and robotic drilling and riveting systems to speed up assembly and achieve greater process consistency.

Turbine engine construction has relied primarily on TIG, automatic TIG and high temperature brazing and furnace brazing.

The 1960s saw the advent of high-power electron beam welding (EBW) that allowed the welded assembly of finish-machined components.

Some of the less dimensionally critical, low-penetration work, performed by EBW, TIG, Plasma-arc and brazing, has been taken over, in the 1990s by high-power laser welding.

In this century, even higher power lasers will be available; including solid-state fibre lasers (that provide a narrower heat-affected-zone and deeper penetration than C02 or Nd:YAG systems, but will not equal the characteristics of EBW) will be available.

Also friction stir welding (FSW) and linear friction welding (LFW) - essentially 'machine tool' systems - are proving themselves as extremely reliable joining techniques.

The availability of high-power laser, FSW and LFW systems has generated a 're-think' about the way in which future engines and airframes will be manufactured.

Lasers have also encouraged the development of 'fast prototyping' systems using a laser beam to selectively sinter - or latterly - to melt metals and alloys to 'grow' complex shapes.

Components produced by these processes can be very 'near-net-shape', and so require only finish machining.

'Rapid Manufacturing' (RM) or 'Production Rapid Prototyping' (Production RP) offer enormous potential to reduce or eliminate conventional die and mould forming and drastically reduce machining.

* Turbine engines - there are changes taking place in the ways in which turbine engine components will be manufactured in the future and materials that will be used: * Materials changes, such as the use of composites and plastics in engine parts.

* Manufacturing lead times.

* Further standardisation of CNC systems In military gas turbine engines, the role of the blade-integrated disk - or BLISK - is expected to increase, over the next 20 years owing to the weight saving it offers.

BLISKs do not come cheaply, and latest fabrication technologies - using LFW and FSW, with some forming - offer an attractive route when compared with machining from a solid billet.

Even so, after fabrication, a BLISK still needs to be finish machined, requiring 'special' high-speed simultaneous continuous path six-axis milling machines that are currently only available from one supplier, says an OEM.

Simultaneous continuous path five-axis milling is required for the machining of BLISKs from a solid billet.

Civil and military engine life can be 10 to 30 years; therefore manufacturing equipment tends to have an operating life of 10 to 15 years.

There is a high population of older machines; many having been retrofitted with up-to-date CNC systems or up-to-date software upgrades.

Companies have tried to standardise - and continue to standardise - on one CNC controller supplier, where possible.

Another step in rotor development is the manufacture of the 'Blade Integrated ring' or BLING.

Again the attraction is to reduce engine weight and centrifugal forces.

An idea is to embed fibres along a rotor to form a metal-matrix-composite (MMC) structured ring to increase its tensile strength.

The MMC is formed by coating ceramic fibres with a titanium-aluminium alloy.

These fibres are then coiled and melted together under high pressure.

The process involves presswork and more milling and turning, when compared with conventional rotor ring forging and machining.

It is generally felt that the fibre-reinforced BLING will become economically applicable within the next 10-20 years.

On the topic of reducing manufacturing lead times, engine builders wish to reduce the 'door-to-door' time.

Typically, a civil gas turbine production engine takes 100 days or more from the placing of material orders to leaving the factory through the door.

Ideally, it could be reduced to 40 days.

This trend is creating more demand for multi-function machining.

Applying 'lean manufacturing' concepts may also reduce the number of machine tools required, while increasing the utilisation of those that remain.

The 'lean' concept, introduced by Toyota, Japan in the 1950s, is making a big change at methods of working at Boeing, USA, and Broughton in Wales.

At Boeing, the steady introduction of 'lean' concepts has reduced rework, scrap and waste by some 61%, reports Boeing's director of the 'Lean Enterprise Office', Mike Hescher.

Similarly at Broughton, senior lean consultant, Chris Taber, reports quality defects down 62% in 4 years.

(Aerospace America, June 2005).

Leaner factory operations can mean greater utilisation/more efficient utilisation of machine tools - implying a slightly reduced demand for machines to achieve 'right first time' work.

There is already the growing usage of 'mill/turning' centres capable of carrying out continuously interpolated turning, milling and drilling.

There is growing interest in adding on operations like grinding and gear cutting, or combining hard turning and finish grinding.

Generally, the idea is to perform as many operations as possible in one or two workpiece set-ups.

The required reduction in 'door-to-door' time will also demand more from the machine tool supplier in terms of diagnostics, tele-servicing, internet/extranet-capability and the concept of the 'digital factory'.

Machine tools will be more intensively used, and companies like RR and MTU will be making greater demands in this respect.

* Rapid prototyping (RP) or rapid manufacturing (RM) - by progressively laying and selectively laser-sintering or laser-fusing layers of metallic powders, a structural component can be 'grown' into shape.

Carl Dekker, president of Met-L-Flow, Geneva, Illinois, USA, said: "While the majority of RP is for design validation, it is starting to get into actual final products." (Aerospace America, January 2005).

He said that present limitations are in testing and available long-term materials' characteristics data.

SLS - Selective laser sintering - parts are being built from glass-filled nylons.

In metals, parts such as F/A-18 (fighter aircraft) ducts are being produced, where formerly 22 parts comprised an assembly, SLS can produce one complete duct.

Dekker added: "Design change? Just modify the CAD file and 'go'." President of Mydea Technologies, USA, Michael Siemer said; "Five years from now, I see more 'jumps' in (SLS) materials, leading to more diverse applications - but more importantly, there will be more 'proven' materials that can be used for RM.

'RP' will, in future, mean 'rapid production' - and not just 'rapid prototyping'." He added: "For example, a wing is made of extruded titanium and parts that have to be riveted".

"But what if you could just 'grow' the whole wing in a single process (such as RP/RM) that incorporates an optimum design?" Siemer said that the biggest impact would be in building very complex objects - but that will require far better 3D CAD/CAM software.

SLM - selective laser melting - Aeromet in Eden Prairie, Minnesota, USA, has produced titanium alloy products directly from CAD renderings.

The company uses an 18kW CO2 laser to fuse deposited titanium powder metal - a process that eliminates moulds and dies.

The company has a laser melting unit with 5-axis manipulation and working envelope of 3000 x 3000 x 950mm.

It claims the process 'cuts months' off processing times and can be used to 'grade' alloys (in-process alloying) across a geometry.

Alloying ingredients worked with have included niobium and rhenium.

The Engineering Department of the University of Liverpool (Eureka, April 2005) began SLM work in 1998 on 316 stainless steel powders, conducting full fusion melting with laser.

Fockle and Schwarz, Germany, is also developing the process, initially producing complex structures for micro heat exchangers and also aerospace components.

Northrop Grumman Air Combat Systems has been using SLR/RP systems since the 1980s and has concentrated on: * SLR - models and simulation parts.

* SLS - direct manufacturing with on going studies in titanium.

* FDM - (filament deposition material) a process that involves squeezing high temperature resistant thermoplastics through a large, hot 'glue' gun to produce parts that can withstand heat generation from 'nearby engines' at up to 400 deg F (about 205 deg C).

* Laser fused titanium deposition - depositing laser-fused titanium through a small orifice to built up a shape onto base material (similar to surface weld deposition).

The company said that these processes will see an impact in the next 5-10 years in aerospace components manufacture - though it will represent a relatively small percentage of overall aircraft construction - maybe 5-10% - and all involving small components.

Siemer said that in that time (next 5-10 years) we should see the applications of rapid tooling (RP, RM) double, or even triple.

About RM, Siemer said that there might be some applications funded to look at critical components in the next 10 years, but aircraft companies will be very hesitant to accept the potential liability for critical RM parts.

So the risk factor needs to be minimised before engineers will specify RM materials and processes for critical components, Other changes foreseen in the next 10-15 years include: * Greater use of reconfigurable fixturing to avoid the current practice of using dedicated fixturing, which is scrapped at the end of a project.

* More use of the direct manufacture of prototypical parts from CAD models, using low cost laser technology and MIG/TIG welding.

* Closer integration of modelling systems with machine tool systems - e g, modelling to predict stress-induced distortion, optimum clamping, etc - and so reduce non-conformance and NC programming time.

* Deburring 'on the machine' - expected to be in demand over the next 5-10 years, to eliminate manual dressing of parts after machining.

* Significant developments in hot forming and super-plastic forming are expected over the next 5-15 years - say to make fabrications more competitive against castings.

* Aero structures - in conversations with OEM and SME representatives at various conferences, there is the growing interest in the all-welded civil aircraft fuselage (using FSW, laser and plasma-arc techniques) and in the 'jigless' riveted fuselage construction.

Perhaps the most startling development is the production of a small executive jet plane in the U.S., featuring a fuselage construction making extensive use of FSW.

Military aircraft wing structural parts are now being regularly fabricated using combinations of FSW and laser or laser+MIG welding.

The reduction in machining, when comparing a fabricated component with a monobloc component machined from a single billet is in the order of 60%-plus.

Spars and stringers can also be fabricated in this way.

In civil aircraft, the next generation following the Airbus A380, will see considerable advantage being taken of progress with welding techniques.

The industry is also expected to make considerable more use of fibre-reinforced composites - in wing and tail fin structures for example.

These changes would occur from 2010 onwards.

Jigless assembly places the requirement on the machine tool manufacturer to provide a greater degree of in-process temperature sensing and dimensional measurements on the machine tool and the workpiece during the skin milling and drilling/countersinking operations.

Significantly, perhaps, BAe and Boeing, for example, have very successfully modified existing machine tool installations to produce skin panels for jigless assembly.

* Composites materials in engines and structures - the GENX (GE Next Generation) 10-stage engine being built by General Electric for Boeing's 7E7 'Dreamliner' passenger aircraft will be making greater use of composite materials.

To achieve weight savings in the fan blade design, General Electric will employ 'third generation' composites and an all-composite fan casing.

This development is described by GE's marketing general manager Mike Wilking as the 'first commercial development away from metals.

He reports a 350lb (146kg) weight saving plus noise enhancements when compared with the existing GE CF6 family.

It would mean, for example on the Boeing 777 a 3-4% increase in fuel efficiency compared with the existing GE90.

(Aerospace America, Feb 2005).

Overall, GE would realise a 20% 'advantage' in fuel efficiency on the 7E7 versus competing aircraft.

Carbon fibre composites are 20-30% lighter than aluminium alloys and 15-20% lighter than 'advanced' aluminium alloys.

President of Engineering at Boeing, Walt Gillette said that the 7E7 is the "biggest carbon fibre project ever".

The wing box, wing centre section and fuselage pressure vessel are carbon fibre structures - resisting fatigue and corrosion.

Previously, carbon fibre structures were considered to be too expensive, but Boeing figured production cost levels are "Very, very competitive with aluminium." In traditional designs, the wing and fuselage are in composite materials - but carbon fibre uses a new structural concept for the empennage, Research into metals-composite 'hybrid' materials began at the Delft University in the mid-1970s.

7E7 wings may include TiGr composite.

The Airbus A380 uses GLARE composite in the fuselage.

TiGr - the composite consists of titanium foil of 0.12-0.24mm thick alternating with graphite-polymer layers to give high strength.

GLARE - the composite is glass fibre reinforced aluminium laminate alternating with layers of aluminium foil and glass fibre reinforced polymer.

The material is able to take a 20-25% higher load than 'conventional' aluminium, so save up to 20% weight in upper fuselage skins.

TiGr and GLARE are fabricated with composite tape placement and compaction systems using a hot blending process.

In the 7E7 carbon fibre laminates are used in the tail rudder and a sandwich for the aerolons.

The wings are a mix of carbon laminate, carbon sandwich (box) with aluminium leading edges.

The engine nacelles are fabricated from carbon fibre sandwich.

The pylons are fabricated from aluminium, steel and titanium.

Metal matrix composites - Professor of Engineering, Richard Butter (Engineer, Jan 12, 2005) reports the production of near-net-shape metal matrix composites structures that can be formed and machined using diamond tipped tooling.

Structural parts, for example for use in wings, and engine parts are currently undergoing aerospace approvals * Conclusion - with some 60% of current machine tool supply taken by the world's automotive industries, it has to be noted that there will be a steady reduction in the demand for production metal-cutting machine tools associated with IC engine, steering and braking.

Ongoing is the steady reduction of 'rough machining' through the use of 'near-net-shape' castings, forgings and extrusions.

The advent of 42V vehicle systems - possibly before 2010 - could bring major changes.

Use of 'camless' IC engines could be relatively sudden in the truck industry and at a steadier pace in the volume car industry, dependent on new models introductions and environmental legislation.

Though the fuel cell as a prime mover is generally considered to be some way off - 2020 - some OEMs consider 2010 as viable.

In general, a 'camless' IC powered vehicle with 'drive-by-wire' features could require some 20-40% less metal cutting content when compared with a vehicle using the classic camshaft IC engine and hydraulic braking and hydro-mechanical/servo-mechanical steering systems.

A vehicle with a fuel cell/digital motor as prime mover, coupled with 'drive-by-wire' systems may need as much as 70% less metal cutting machining content, when compared with a 'classical' IC engine + transmission+ hydraulic systems vehicle.

Any major materials change in volume-produced vehicles could occur in 2010 or so - whether all-aluminium/magnesium alloy or a combination of non-ferrous and plastics.

Materials pricing and materials recycling considerations will determine any such change.

Loss of volume production metal cutting markets will be offset - to an as yet undefined extent - by continued growth in mould and die manufacture.

The advent of the fuel cell and digital electrical drive will significantly reduce the demand for metal cutting machine tools in volume production.

Conversely, there could be a 'balancing' in terms of increased requirements for machine tools dedicated to mould and die manufacture.

In the immediate future, the desire of turbine engine builders to reduce 'door-to-door' times, that is from when materials are received to when the finished engine leaves for testing and despatch, has focussed builders' attentions on the amount of time machined and welded components and sub assemblies are spending in waiting.

Very typically, waiting for inspection.

Consequently, one way of reducing time is to perform as many operations as possible in one set-up.

The result is a growing demand for 'multi-tasking' or 'multi-function' machine tools.

Not only combining cylindrical and prismatic machining functions, but also finishing and deburring.

Also of importance is a demand for even more diagnostics and in-process control and quality monitoring systems at the machine tool, and greater machine tool reliability.

The next 10-15 years will see a general 're-think' on the way turbine engines are manufactured and constructed, as near-net-shape casting and forging technologies are developed and non-metals become used in the 'cooler' parts of the engine.

As regards structures, the greater use of welding technologies and wider use of composite structures, will have an effect on the types of machine tool required.

Certainly, concerning engines and machined aerostructure components, the desire is there to reduce or eliminate 'rough' machining (milling, routing, etc).

Assuming all the changes take place, based only on the availability of the technology developments mentioned in the report for commercialisation, then it can be speculated that the demand for volume metal cutting machining requirements will reduce by 2020.

There will be greater demand for mould and die machining systems, or 'total packages'.

A 'total package' is a single sourcing of CAD/CAM/VR/fast prototyping systems that are easily interfaceable with IT/Internet/machine tools.

* About the author - Mike Page (Michael Page), editor of www.manufacturingtalk.com website was the Leader of the Task Force C.1 (4.3.1) Product innovations by end-users.

* Comments or queries - please contact Mike Page on mikepage@freeuk.com.

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