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1 Laboratory Testing to Identify Permanent PVD Coatings to Minimize Lubricant Use During Forging T. Kehe, S. Midson, A. Korenyi-Both, K.D. Clarke Forging Technical Conference, Sept. 11, 2018, Long Beach, CA. 1

Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

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Page 1: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

1

Laboratory Testing to Identify Permanent

PVD Coatings to Minimize Lubricant Use

During Forging

T. Kehe, S. Midson, A. Korenyi-Both,

K.D. Clarke

Forging Technical Conference,

Sept. 11, 2018, Long Beach, CA.

1

Page 2: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

22

Project Goals

• Utilize permanent PVD thin-film coatings

Apply to forging dies

Minimize friction coefficient

Reduce use of lubricants

Reduce lubricant overspray

Improve die life

Improve cycle times

Improve quality of forgings

Page 3: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

• Leverage the recent CSM “Lube Free” die casting

die coating project

New PVD coatings reduced lubricant use significantly

Apply similar coating technologies to forging dies

• Develop a flexible testing methodology

Evaluate relative friction coefficients of PVD surface

coatings during aluminum forging (die temperatures

<400°C)

33

Project Approach

Page 4: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

44

Project Tasks

1. Perform literature review of coatings used in

forging and metals fabrication

2. Design and fabricate tooling for laboratory

forging test

3. Set up laboratory testing procedure and procure

coated die test samples

4. Perform plant trial of best PVD coating

identified during laboratory testing

5. Reporting

Page 5: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

55

Today

• Literature review of PVD coatings

• Die design and fabrication

• Validation of friction testing procedures

and initial friction test results

• PVD coating test matrix

Page 6: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

66

Literature review of PVD coatings

Page 7: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Literature review of PVD coatings

•Coating thickness is typically <10 m

Thicker coatings will spall

•Substrate temperature needs to be less than 550°C (1,000°F) during application

To avoid over-tempering of hardened tool-steel substrate

•PVD coating meets these criteria

Page 8: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Literature review of PVD coatings

• PVD coatings are not common on forging dies

More common on die casting dies

• Most studies focused on wear resistance and die life

Not on improving lubricity

• Coatings examined include: CrN, TiN, TiC, TiCN, TiAlCN, AlCrN, TiAlN

• Data from Leskovsek et al. showed that TiCN did reduce coefficient of friction

Source: Leskovsek et al., Wear, 2009

H11 plasma nitrided, PECVD

Page 9: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Literature review of PVD coatings

Several hard coatings have

the potential for improving

lubricity• Diamond like carbon (DLC)

• CrN/SiC

• TiCN

Sources: Mulligan et al., Mat. & Man. Proc., 2014

Donnet and Erdemir, 2008

CoatingCoefficient of

Friction

CrN 0.28

CrN/DLC 0.07

CrN/SiC 0.07

Cutting applications

Page 10: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Literature review of PVD coatings

MoS2 is an excellent lubricant

• Due to its layered structure

MoS2 can be directly deposited

• Deposited structures are very soft

• Easily detach from substrate

MoS2 has been deposited as part

of a harder coating

• Titanium

• AlCrN

• Coefficient of friction values were

reducedSource: Bobzin et al., Ad. Eng. Mat., 2016

Cold-forging

(a) Uncoated substrate (M2)

(b), (c) & (d) utilizing (Cr1-XAlX)N/

MoYSZ-type coatings

Page 11: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Literature review of PVD coatings

For applications at high

temperatures

• Unreasonable to expect

materials to resist

oxidation for long periods

Utilize oxide materials

with low interfacial shear

strengths

• V2O5

• MoO3

• Layered structure of V2O5

• V atoms as grey balls

• O atoms as red balls

Source: Mulligan et al., Surf. & Coat. Tech., 2010

Page 12: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

PVD coatingsType of Coating Specifics Supplier Temperature

Single-layer hard

coatingsTiCN

Tribologix, Dayton,

Ionbond<400°C

Multi-layer hard

coatings

Super MoS2 Tribologix 375°C

Ti-MoS2 (MOST) Teer in UK, Ionbond <350°C

AlCrN-MoS2 Tribologix

TiCN-TiMoS2 Teer

CrN-DLC Phygen <300°C

CrN-SiC Phygen

i-Kote Tribologix 350°C

Noble MetalsHard coating plus noble

metal

Voevodin, Scharf &

Samir at UNT<500°C

Highly lubricious

oxide-- None identified

Plasma Sprayed PS400 NASA

Laser Textured Laser texture a TiCN coating Tribologix/CSM

Page 13: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

1313

Test methodologies and die design

Page 14: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Test methodologies and die design

Page 15: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Test methodologies and die design

Page 16: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Test methodologies and die design

• Easy installation and removal

• Trials of multiple coatings

• Ability to quickly switch die faces

• Room temperature to ~500°C capability

• Fit on available 100 kip hydraulic press

• Measure load and displacement

Page 17: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Test methodologies and die design

Design tooling with

removable inserts

• In-house surface

preparation of

uncoated die sets

• Coat smaller pieces

• Send sets of tooling

to various vendors

for coating

• Allow for elevated

temperature testing

• Easily replaceable• Aluminum ring 1” OD, ½” ID

• 0.2 in/s compression velocity

• Applied to a 100 kip force

Effective stress, ksi

Page 18: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Test methodologies and die design

25 mm

Page 19: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Test methodologies and die design

Page 20: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

2020

Validation of friction testing procedures and

initial friction test results

Page 21: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Friction testing results: 6061 Al @ RT

Left to right: Increasing reductions in height

Top to bottom: Increasingly effective lubricants

No lubricant

MoS2 grease

Dry graphite

spray

Page 22: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Fri

ctio

n c

oeffic

ient

Test number

Friction testing results• Die inserts ground to 1200 grit and polished from 6μm to

3μm to 1μm

• Friction coefficient responds to multiple tests

• Surface conditioning performed on dies

• No lubricant, room temperature

Page 23: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Friction testing results – lubricant amountD

ecre

ase in insid

e d

iam

ete

r

% height reductionFriction factor

No Lubricant

CRC Graphite

Molykote MoS2

0.8 0.3

0.12

Page 24: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Friction testing resultsD

ecre

ase in insid

e d

iam

ete

r

% height reductionFriction factor

No Lubricant

CRC Graphite

Molykote MoS2

0.8 0.3

0.12

No lube, 200°C

Page 25: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

2525

PVD Coating Test Matrix

Page 26: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

6 die sets (uppers + lowers)

• 1 H13 set used for no-coating baseline

• 4 H13 sets are at vendors for coating• Can be re-coated

• Surface imaging, tribology, and metallographic

examination of coating performance also possible

• 1 W303 set will be used to validate no-

coating baseline values and coating

effectiveness on a different substrate

PVD coating test matrix

Page 27: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Type of Coating Specifics Supplier Temperature

Single-layer hard

coatingsTiCN

Tribologix, Dayton,

Ionbond<400°C

Multi-layer hard

coatings

Super MoS2 Tribologix 375°C

Ti-MoS2 (MOST) Teer in UK, Ionbond <350°C

AlCrN-MoS2 Tribologix

TiCN-TiMoS2 Teer

CrN-DLC Phygen <300°C

CrN-SiC Phygen

i-Kote Tribologix 350°C

Noble MetalsHard coating plus noble

metal

Voevodin, Scharf &

Samir at UNT<500°C

Highly lubricious

oxide-- None identified

Plasma Sprayed PS400 NASA

Laser Textured Laser texture a TiCN coating Tribologix/CSM

PVD coating test matrix

Page 28: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

PVD coating test matrix

• Friction testing on uncoated dies and four initial

PVD coatings selected (5)

• Temperature will be varied from RT to 300°C (4)

• Tests will be performed with and without

lubricant…MoS2 and Graphite (3)

• Three sets of rings at three deformation levels (9)

Page 29: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Summary

• Flexible forging tooling has been designed and built

• Room temperature to 500°C

• Loads up to 100 kip

• 6 sets of interchangeable die inserts

• Ring-compression friction tests have been validated

• Polished as-heat treated (uncoated) dies

• Room temperature to 300°C

• Forging die coatings

• Literature review complete

• List of promising coatings compiled

• Four initial coatings selected for application to dies (underway)

Page 30: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Acknowledgements

• FIERF – stage gated grant, “Laboratory Testing to

Identify Permanent PVD Coatings to Minimize

Lubricants Use During Forging”

• FIERF board – stage gate reviews and guidance

• NSF REU program grant through the Center for

Advanced Non-Ferrous Structural Alloys

• CSM undergraduate research support

• Die materials

• Bohler-Uddeholm (Patricia Miller), H13 and W303 inserts

• Hitachi (Tom Bell), H13 inserts

• Finkl (Al Underys), 4340 die blocks

Page 31: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Test methodologies and die design

Trevor Kehe

• Currently a senior at CSM

• Pursuing a degree in metallurgical and materials engineering

• Started on Forging Coatings project in August, 2017

• Designed die sets

• Oversaw manufacturing/machining

• Initiated testing program

• Interested in pursuing a graduate degree at CSM

• Interests

• Mines Baseball

• 2017: 1 out away from CWS

• 2018: 2nd in RMAC

Page 32: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Thank you!

Page 33: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Literature review of PVD coatings

Mechanism Material Examples Temp. Range

Traditional liquid lubricants Oils and greases <~250°C

Atomic structures that can

easily shearMoS2, graphite <300°C

PVD hard coatings

(can contain softer lubricating

phases)

Diamond like carbon,

TiCN, CrN/SiC, i-Kote

<300-500°C

depending upon

coating

Soft metals within hard

coatings that diffuse to

contact surfaces

Ag, Au, Cu encapsulated

in TiN, CrN, VN, YSZ,

CrAlN

300 – 500°C

Lubricious oxides V2O5, MoO3 500 – 1000°C

Source: Adapted from Voevodin et al., Surf. & Coat. Tech., 2014

Page 34: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Friction testing results: 6061 Al @ RT

Lubricant application conditions – did not affect room

temperature friction factor

Page 35: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Friction testing results: 6061 Al @ RT

Left to right: Increasing reductions in height

No lubricant

Page 36: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Literature review of PVD coatings

PS400• Nickel-molybdenum

binder for strength

• Silver and barium–calcium fluoride are added for lubrication

Layered microstructure

Source: DellaCorte & Edmonds, NASA Report, 2009

Page 37: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Literature review of PVD coatings

• Ag-Ta-O

• Sputtered from Ta

and Ag targets in

reactive oxygen

atmosphere

• Exhibit extremely low

coefficient of friction

at 600 – 700°C CoF for four silver tantalate

coatingsSource: Stone et al., Surf. & Coat. Tech., 2013

Page 38: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Friction testing results

• Identification of lubricants to be used for further tests

(Graphite, MoS2)

• Four trials run at three different deformation amounts for

each condition

• At max load, a greater % deformation is achieved with

lubrication

Page 39: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Literature review of PVD coatings

Noble metals are dispersed

in hard coatings

• Ag in CrN

• Ag in CrAlN

• Ag in TiC

Noble metal diffuses to

surface

• Provide lubricity at

temperature greater than

300oC

Source: Voevodin et al., Surf. & Coat. Tech., 2014

Page 40: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Test methodologies and die design

• Cooling of dies during test set up recorded

• Heat higher than target test temperature

• Test is run when goal temperature is reached

• Al samples reach same temperature as dies quickly

50

100

150

200

250

300

0 50 100 150 200 250 300

Tem

p (˚C

)

Time (sec)

160 ˚C

230 ˚C

300˚C

Page 41: Laboratory Testing to Identify Permanent PVD …...Test methodologies and die design Design tooling with removable inserts • In-house surface preparation of uncoated die sets •

Literature review of PVD coatings

Traditional Surface TreatmentsHard Thin-Film Coatings

Weld Overlay