introduction to the merlin project - lortekrolls-royce-introduction... · copyright © twi ltd 2014...

Copyright © TWI Ltd 2014

Introduction to the MERLIN Project

Carl Hauser, Principal Project Leader and MERLIN Project manager

www.merlin-project.eu


OUTLINE

• Concept

• Industrial Pull

• Technology Push

• Project Outputs

• Summary


MERLIN Concept

“MERLIN will seek to develop the state-of-the-art by producing higher performance additive manufactured parts in a more productive, consistent, measurable, environmentally friendly and cost effective way”


Concept

”To reduce the environmental impact of air transport using Additive

Manufacturing (AM) techniques in the manufacture of civil aero engine

components”

Develop AM techniques, at the level 1 stage, to allow environmental

benefits including (reduction in life cycle emissions):

– near 100% material utilisation

– no toxic chemical usage

– no tooling costs

– impact the manufacture of future aero engine components (current buy to

fly ratios result in massive amounts of waste)

Additional in-service benefits from the design freedom from AM

techniques

– Light-weighting and the performance improvement of parts will result in

reduced fuel consumption and reduced emissions


Technology Selection

• A wide range of processes exist, with varying attributes in terms of

precision, cost, integrity, etc.

• As with subtractive manufacture, there is no single “best process”;

selection needs to consider application, including material, size, shape

type and complexity, access, inspection and validation.

Heat Source

Material Form

Powder Stream

(various types)

Powder Bed

Wire

Laser (various types)

Electron Beam

X

Electric Arc X


Laser Metal Deposition

• Use of powder/wire material

• Material blown/fed into melt pool

• Complete melting of

material • Materials (Powder):

- Titanium alloys - Steel Alloys - CoCr alloys - Nickel alloys - Carbides


Selective Laser Melting

Courtesy of Fraunhofer ILT

• Use of powder material

• Material preplaced in layers • Complete melting of the

powder particles • Materials:

- Titanium alloys - Aluminium alloys - Steel - CoCr alloys - Nickel alloys


Industrial Pull

• Reduced time to market

- Simple/minimal tooling,

• Reduced material cost

- Reduced waste material + powder recycling (lower buy to fly ratios)

• Reduced ‘removal’ operations

- No roughing, minimal finishing, reduce use of cutting fluids

• Materials Processing

- Nickel and Titanium super alloys. e.g. MAR M 247

• Repair capabilities to support aftermarket opportunities

- Lower total life cycle cost

• Enhanced products

- Light weighting, performance increase > reduced emissions and fuel consumption.


But…..

Rapid Prototyping Development parts

• Short Lead time

• Ability to change design until the last minute

• Material properties not always important

• Expect to pay a premium on price

OEM Metal Parts by Additive Manufacture

• Have to compete with established processes

• High cost of Qualification

• Need Powder Supply Chain

• Need Parts Supply Chain

• Control Material Properties

• Control thermal distortions…………..


Grand Challenges

Cost to deposit material

• Assumes a self checking, self controlling, serialised, production system

for shop floor use

• Specific cost of deposited material is primarily a function of build rate

and powder cost

• Ideally turn key solution with capability to flag an inline failure

Material Properties

• UTS - Between Cast and Forged

• Fatigue - Dependent on level of micro cracking

• Creep - Fine grain structure tends to lower creep performance

• Anisotropy - Deposition Parameters can be optimised to minimise

anisotropy

• Fracture Toughness (Hot Creep Rupture) - Can be problematic if the

resulting grain structure exhibits epitaxial grain growth


Grand Challenges

Component size and complexity

• Limited by chamber size in SLM.

• Complexity limited through lack of support structure in LMD.

Powder

Limited number of sources approved for powder supply into Aerospace

(Expensive)

Powder variability can be large between suppliers

Use of recycled powder is an unknown quantity.

Residual Stress

Material structure is defined when the deposit is hot

Thermal contraction must take place during cooling: Residual stress

Distortion in the part

Cracking


Grand Challenges

Process Window

• Fully dense parts limited by heat input

(power, speed, spot size etc)

(hypothesised)

Superalloy

Process Window

Pow

er

density (

incre

asin

g a

s a

function o

f

incre

asin

g s

pot ra

diu

s. Lin

ked to

consum

able

feed r

ate

and local

dyn

am

ic h

eat sin

k.

Travel speed, linked to location

Liquation

Excess segregation Solidificatio

n cracking

Lack of inter-run fusion

Adapted (After Reed)

Dilution Porosity

No fusion P

ow

er

density (

incre

asin

g a

s a

function o

f

incre

asin

g s

pot ra

diu

s.

Consumable feed rate

Bead

profile

aspect

ratio

Energy per

unit length –

related to

velocity

(After Steen)


Grand Challenges

Material Integrity

• There are many claims with regard to

density and forged properties

• What do they mean?

• Usually that the porosity is often

acceptable……but not necessarily

homogenous.

Flaws

• The maximum flaw-size is significant for

component life.

• Flaws of various sizes will randomly

intersect test bars.

• Scatter in performance and tight

acceptance thresholds show the

importance of control

Schematic (not to scale) of flaws dispersed through a mechanical test block .


Identification of Progression

Productivity increase (Optimisation)

• Systems with economically competitive deposition

rates

Deposition Parameters for High specification

materials

Topology optimised designs for AM

Powder qualification and recycling validation

In-process NDT development for flaw detection.

In-process geometrical validation

Post processing methods to give acceptable Surface

Finish & Materials Properties

The MERLIN consortia have identified the following areas where a

progression of the state-of-the art is needed to take advantage of AM:


MERLIN Work Packages

WP1 - Project Definition and Specification

WP2 - Shape - Topology optimisation, modelling and validation

WP3 - Process Development - Process development, process

monitoring and control, and thermal management

WP4 - In-Process NDT development and integration, geometrical

measurement and control

WP5 - Post Processing - Mechanical testing, analysis, recycling

validation and heat treatment

WP6 - Technology Demonstration - Environmental and through

lifecycle evaluation

WP7 - Management

WP8 - Dissemination and Exploitation


Demonstration Activity

Part designation Process Material Challenging issue

Features on hot structural casing

LMD-wire and powder

Inconel 718 Cost, weight, reproducibility, quality

Blade shielding case SLM Inconel 625 / Inconel 718

Rapid manufacturing associated with topologic optimisation will allow to optimize design of the part and to decrease mass

Combustion chamber LMD powder

Hastelloy X/ Inconel 718

Testing of many part design during engine design process

Turbine Support Case LMD wire Inconel 718 Quality, cost, lead time

Extension of blade root

LMD powder

Inconel 718 No current method of manufacture

Vane trailing edge of tail bearing housing

LMD powder

Inconel 718 Simplify manufacturing process/ Lead time

Low Pressure Turbine Hard Facing

LMD powder

TiAl lead time and cost

High Pressure Turbine Repair

SLM Single crystal

Alloys current repair locations are restricted

NGV’s SLM Inconel 738 / MAR M 247

Testing of many part design during engine design process


• “AM is currently to slow for Aero Applications”

• How slow?

• Can we Benchmark productivity against „traditional‟

manufacturing?

• Build rate is a significant factor affecting productivity.

• However, build rate is strongly affected by:

• Part Complexity

• Resolution

• Substrate geometry

• There is no holistic solution to define AM productivity – it

has to be component specific.

• Topology optimisation >>> Design for AM manufacture.

WP3: Build rate and Productivity


WP3: Productivity

.Laser Metal Deposition:

• Current Build Rate: 60-130cm3/h (~1Kg/h)

• MERLIN Target Build Rate: 400cm3/h (~3Kg/h)

• Commercial Laser Cladding Systems: up to 20kg/h (wire)

• Constraints: >99.5% Density and suitable Metallurgical Properties

• Proposed Solution: High powder LMD powder and wire systems (hybrid

manufacturing?)


WP3: Productivity – Combustion Chamber Demonstrator

• Component: helicopter combustor casing (Turbomeca)

• Material: Inconel 718

• Size: 300mm diameter x 90mm tall.

• Weld track: 0.9mm wide x 0.2mm deep x 0.5km long.

• Dimensional variance from CAD: 0.16mm (average)

• Surface finish: 15 microns RA (average)

• Deposition rate – 0.1kg/h (Manufacturing time reduced from 8 weeks to 7.5 hours


WP4: IN-Line Laser Ultra Sonic NDT

In-Process Inspection of LMD-p Manufacturing.


1. Pulsed laser generates surface waves.

2. Detection beam reflects off surface to record surface displacement information.

3. Interferometer compares the reflected beam with a reference beam.

4. AC signal output gives surface displacement as a function of time (A-scan).

Generation

Beam

Detection

Beam Surface waves

Laser Ultrasonic Testing:

WP4: IN-Line Laser Ultra Sonic NDT


WP4: Flaw Detection

No flaw present. Surface wave is unaffected.

Sub-surface hole. 500 µm diameter 100 µm depth

Flaw Detection (Task 4.2):


LUT Flaw Detection on a LMD thin wall

In-Process NDT on Circular Wall:

17.5 mm/s

140 mm


Task 4.4 │ Results & Analysis

Limited Dynamic Performance:

4 mm/s

2 mm/s



8 mm/s

6 mm/s




10 mm/s

Stepped



Acknowledgements and Contact

Dr Carl Hauser

Joining Technologies Group

TWI Technology Centre Yorkshire

Advanced Manufacturing Park, Wallis Way, Catcliffe Rotherham. S60 5TZ, UK

Tel: +44 (0)114 269 9046 E-mail: [email protected]

Web: www.twi-global.com

www.merlin-project.eu

mailto:[email protected]

http://www.twi-global.com/



introduction to the merlin project - lortekrolls-royce-introduction... · copyright © twi ltd 2014...

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