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How Cold Spray is Changing Aerospace

Aftermarket Repair Strategies

Daniel Greving

Agenda

• Honeywell R&O and Aerospace Aftermarket Repair Strategy

• History of Low-Pressure Cold Spray Repairs at Honeywell

• Development of High-Pressure Cold Spray for Structural Repairs

• Summary and Conclusions

• Acknowledgements

Our Mission: Apply State-of-the-Art Technology when Developing Advanced

Repairs thus Providing Maximum Value to Our Customers and Shareholders

Gearboxes

Wheels &

Brakes

Heat Transfer

Electronics

Air Turbine Starters

38 Complete Repair & Overhaul Centers Worldwide

Global Repair & Overhaul Engineering at Honeywell

G05-338-24

Turbomachinery,Valves, and Actuators

Engines/APUs

© 2015 by Honeywell International Inc. All rights reserved.

10,000’s of Engines With Many On 40 Year Old Platforms

Engines Alone Offer Endless Component

Repair Opportunities

Turbofan Engines Turboprop Engines Turboshaft Engines3,000 to 10,000 lb thrust for

commercial and military aircraft575 to 1,600 shp for

commercial and military aircraft500 to 5,000 shp for

tanks, commercial and military rotorcraft

APUs100 to 1400 hp for commercial

and military aircraft

HTF7000

731 Series

CFE738

LF507

F124

ATF3

TPE331-14TPE331-12

TPE331-10/11

TPE331-5

HTS900

LTS101

660 85 Series

131 Series

36 Series

331 Series

700 Series

RE100

RE220

CTS800

Aerospace Repair Methodology

• The aftermarket business model is to re-use the core component

repeatedly until it has reached the end of its serviceable life

• Typical conditions that prevent a part from being repaired

- Cycle/hour limits for certain hardware dictate end of life

- When it is worn out and can not be repaired by any practicable means

- When the repair costs exceed financial targets or takes too long to

repair

• A repair is generally considered economical if it is approximately

80% of the new part cost

- For commercial products, the fabricated new part cost is general much

less than the sale price

• As a repair organization within the OEM, Honeywell has to be

selective when applying repair technologies

- Re-use or repair as many parts as possible

- Watch out for repair costs that exceed the threshold of being

economical

Novel Repair Process Development

Cold Spray Is Reshaping Repair Strategies• Two classes of cold spray repairs on Al and Mg components

- Non-structural is where we are today

- Structural is where we need to go

• Cold spray enables new repair limits

‒ Part can be repaired multiple times during the base material life cycle

‒ Minimal cut-back of base material unlike thermal spray or welding

‒ Ability to maintain minimum wall thickness requirements through multiple

repair cycles

‒ No distortion like welding

‒ Better surface finish

‒ Repaired parts in some cases perform better than the original

• More cost effective and less time consuming

‒ Reduced repair process steps

‒ Potential to eliminate bore sleeves for gear boxes

‒ Eliminates heat treat cycle after welding

‒ Eliminates complete disassembly and full anodize and repaint

Need OEM Aftermarket to Pull the Technology to Mainstream

Typical Gear Boxes

6

Typical Repair Routing For An APU Gearbox

• Current weld repairs often result in multiple rework cycles, in-process scrap,

and can take 100 days to complete

Damaged/Worn

Feature

Machine to

Remove Damage / Cutback

Remove Studs, Liners,

and Paint

Clean and Prep

Surface

Weld Repair

Heat TreatAdjust for Distortion

Finish MachineAnodize/Paint

Install Studs/Liners,

etc.

Damaged/Worn

Feature

Machine to

Remove Damage

Clean Prep

Masking

Cold Spray

Finish Machine

Touchup Alodine/Paint

Weld Repair

Cold Spray Repair

• Cold spray eliminates multiple steps and greatly simplifies routing with

repair cycle reduced to well below 50 days

History of Cold Spray at Honeywell

• Cold spray is a core repair technology for Honeywell Aerospace

• Currently Honeywell Repair and Overhaul (R&O) has over 160

features covered under 60+ approved part repair procedures

• Repairs developed using suppliers and in-house equipment

• All current repairs use low-pressure systems for non-structural

applications

- Dimensional restoration

- Fretting, pitting, corrosion repair

- Seal surface repair

- For APU, propulsion, fuel / oil pumps, air-cycle machines, gearboxes & other

housing components

• Developing structural repairs using high-pressure cold spray

- Structural is a major category repair where the load bearing capability of the

material deposit is required

- Requires FAA approval, design level material data, process control, detailed

structural analysis (FEA), classical methods, and qualification

Background – Development of Cold Spray Repairs

• Honeywell R&O first started production cold spray repair

development in 2007

• First repairs released in 2009 using low-pressure cold spray on

aluminum and magnesium gearboxes and housings

• Repair applications use a blend of aluminum and aluminum oxide

powders

• Essentially all aluminum and magnesium non-structural features can

be repaired with basic low-pressure systems

- Engine, pump, and valve components are now being repaired with cold spray

Al base metal

Al with Al oxide

Background: Cold Spray Repair

Applications at Honeywell

In-Situ Engine Repairs Component Repairs

Machined

• First parts back from service that were cold spray repaired

• Every bore is repaired at first shop overhaul event

• After cold spray

implementation, the

bore did not require

repair at next shop visit

• Tolerance for bore is

.0005 inches

• Cold spray offers

longer service life

Background: Cold Spray Repair

Applications at Honeywell

In-Situ Mount Damage Repair

Damaged Area

Cold Sprayed Repair Prepped

Engine in shipping box

• Customer returned engine that was damaged

en route after overhaul

• Engine was masked/ protected in box

• Cold Spray repair process was performed

with engine still in the shipping box

Substantial Cost and Labor SavingsFinished Repair

Shipped to Customer

• Total repair time from start

to finish 6 hours

Thermal spray vs Cold Spray

Sprayed Sprayed

Machined Machined

Repair Process Benefits Over Thermal Spray

Opportunities for Structural Repair

• Repair of previously un-repairable components due to

distortion associated with weld repair and parent material

cutback

- Structural repair where the load bearing capability of the material

deposit is required

15

Inlet Housings

Front Frames Engine Housing

Novel Repair Process Development

Process for Developing and Qualifying the First

Structural Repairs

Component and Feature List

Requirements

Process, Equipment and Supplier Capabilities

Material Qualification / Design Data Generation

Process Control

Structural Analysis Component Validation FAA Approval

Production Implementation

Initial Component Selection for Structural

Cold Spray Repairs

• Components targeted for first structural cold spray repairs

‒ Cast magnesium and aluminum gearboxes

• Designed for stiffness, subjected to relatively low stress levels

• Low strength cast materials

• Not fatigue life limited

• Locations targeted for structural cold spray

‒ Damaged threaded holes adjacent to tight tolerance bore diameters

‒ Bore ID

‒ Spider carrier mounting pads

‒ Build up undersized casting walls (casting shifts)

‒ Broken bolt ears

‒ Undersized flange thickness

‒ Cracks and damages at locations where welding will cause distortion

and tensile and shear stress levels are below tensile and shear

adhesion strength

17

Low Strength Materials Selected for Structural Repair

High-Pressure Cold Spray Systems Required

to Meet Desired Mechanical Properties

Substrate Material Properties for Powder Selection

• Requirement that the deposited material have similar or better

mechanical properties to the substrate materials

- Magnesium ZE41A-T5

- Aluminum C355-T6

• Aluminum 6061 powder selected due to expected properties relative

to substrates

18

70°F 300°F 70°F 300°F 70°F 300°F

29.96 23.2 41.71 37.58 45.49 37.13

17.97 13.92 25.02 22.54 27.29 22.27

20.26 16.46 33.61 32.66 39.56 35

12.15 9.87 20.16 19.59 23.73 21

15.1 15.1 11.91 12.6 12.44 12.19

UTS (ksi)

Ultimate Shear (ksi)

YS (ksi)

Shear Yield (ksi)

CTE (µin/in*F)

ZE41A C355 6061 Wrought + Aged

Magnesium Aluminum

Collaboration with ARL and MOOG

Production Structural Repair Process Development

• Honeywell started an independent collaboration with ARL to

develop high-pressure cold spray for structural repairs of

aluminum and magnesium gearboxes

• Honeywell recognized that the technical expertise and

equipment required to develop the processes for a high-

pressure structural repair must come from an external source

• ARL is the demonstrated leader in the development of high

pressure cold spray processes and technology

• Coordinated sample preparation and production process

development with MOOG

- Qualify repairs with a commercial third party source

Preliminary Test Matrix

Mechanical Testing to Substantiate Structural Repair

• All spraying done with VRC Gen III system at MOOG

• Cold Spray Metallography and Mechanical Testing at ARL

• Testing on cast material substrates simulating production processes

• Mechanical testing includes:

- Bond strength, shear strength, tensile testing, threaded hole pull test

• Same test matrix for C355-T6 Al and ZE41A-T5 Mg substrates

- Evaluated multiple spray angles on statistically significant quantity of

samples

- Room temp and elevated temp (300°F) testing

• Cold spray coated specimens representative of production process

- Control through process spec, supplier PCC, lot sample evaluation

• Post failure evaluation of tested specimens

• Final demonstration on scrap gearboxes

Bulk Tensile Specimen

• Cold spray deposited on substrate surface

• Substrate milled away

• Tensile specimen machined to drawing

• Tested to ASTM E8 (subsize specimen)

Preliminary Bulk Tensile Results

CS Bulk Material Tensile Exceeds Substrate Properties

• Pooled data for aluminum and magnesium substrates

• Similar trends for ultimate and elongation values at room temperature and 300 ºF

Triple Lug Shear Specimen

• Cold spray deposited on substrate material

• Lugs machined in cold spray coating

• Specimens tested

Machined CS lugs

Applied load

Lug being tested

Specimen holder

Cold Spray coating

Preliminary Triple Lug Shear Strength Results

Shear Strength Results Sufficient for Majority of Proposed Repairs

• Similar trends at 300 ºF

• Cold spray shear strength results exceed the Mg ZE41A-T5

substrate properties

• Shear strength less than Al C355-T5 substrate

Glueless Bond Strength Specimen

• Cold spray applied to substrate bond bar

• Specimen machined to size

• Gauge diameter necked down to force failure in CS

Gauge section

Cold spray coating

Substrate material

As sprayed Machined specimen

Preliminary Glueless Bond Strength Results

Glueless Bond Strength Results Exceed Expectations

• Similar average performance relative to the two substrate

materials

• Higher scatter with Al C355 substrate attributed to higher

hardness of base alloy

Threaded Hole Pull Test

Testing and Analysis is On-going

• Replicate pull load on gearbox flange

• Slot Milled in parent material block (2” x 2” x 1.5”)

• Cold spray to fill machined slot

• Hole drilled/threaded and standard stud inserted

• Tensile load applied on MTS frame until failure

• Compared to parent material

Cold spray wall thickness

Keensert

Rosan

Scrapped Magnesium and Aluminum

Gearboxes for Substantiation Tests

Testing On-going

Gearbox

Al C355-T6

Gearbox

Mg ZE41A-T5

© 2015 by Honeywell International Inc. All rights reserved.

Process Qualification Through Testing and Fixed Processes

Industry And Internal Cold Spray

Specifications

• MIL-STD-3021 is a Department of Defense Manufacturing Process

Standard for “Cold Spray Material Deposition”

• RPS4211 is the internal Honeywell Repair Process Specification for

“Cold Spray Coating”

Future Testing and Process Development• Complete current test matrix and substantiation tests

- Aging of deposited material (tensile/shear)

- Evaluation of isotropic behavior (tensile)

- Compression/physical properties

- Component bench tests

• He-N gas mixing

- DOE for economical coating

- Tensile/shear/bond strength/metallography

• Potential of He recovery systems to improve costs

• Additional substrate coating development (A356.0-T6 and A357.0-T6)

- DOE for alternate substrates

- Tensile/shear/bond strength/metallography

• Explore process variation and optimization

- Develop production process control and specification

- Develop processes to optimize repair requirements versus costs

• Eventual future state is a parametric repair system allowing for

optimization of structural capability to material properties and costs

Summary and Conclusions

Near Term Qualification of First Structural CS Repair

• Cold spray has changed aftermarket repair strategies

‒ Low pressure non-structural repairs are being used extensively

today at Honeywell

‒ Seeing benefits of reduced cost structure and cycle time

• High-pressure cold spray for structural repairs will be the

process that truly transforms the repair process

- Initial test results show tremendous potential

• Challenges for structural cold spray

‒ FAA approval of a novel repair process

‒ Costs (He for maximum properties)

‒ Production capacity/reliable equipment

‒ Process variation/optimization

Acknowledgments

• Vic Champagne and Dan Kaplowitz at ARL for technical leadership,

testing and support of the high-pressure development program

• Chris Howe at MOOG MA for expertise and support

• Christian Widener from South Dakota School of Mines

Questions?