NSRP SP-7 Meeting

Ann Arbor, MI, 13 April 2011

Constructing a Prototype Man-Portable Friction Stir Welding System

Development Team: Fred Callahan, Engineering Consulting Services, NC

George Talia, Wichita State University, KS

NSWCCD Participants: David Forrest, Carrie Davis

NGSB-GC Participant: Lee Kvidahl

� Solid-state process using frictional heat and forging loads.

Uses a non-consumable, rotating pin tool to generate frictional

heat to soften the material, without melting.

Stirring generates highly deformed plasticized material that is

moved around the tool and consolidated in its wake.

1. Tool begins

to rotate.

2. Tool plunges into

the workpiece.

3. Tool dwells to

build up heat.

4. Tool traverses

the joint.

Friction Stir Welding

Navy Interest in FSW

� The Navy already uses FSW in the Fleet for

� New Construction …

LHA-6 America Class,

LCS-1 Freedom Class, and

LCS-2 Independence Class;

� …and portable FSW could be used for assembly and repairs

on Legacy Vessels…

CG-47 Ticonderoga Class, and

Landing Craft, Air Cushion (LCAC).

4

FSW: Great Joining Technology for Aluminum

Greater use of aluminum in Naval vessels →

motivates improving welding technology� Landing Helicopter Assault (LHA-6)

� Littoral Combat Ship (LCS)� Ship to Shore Connector (SSC, LCAC)

� Guided Missile Cruisers (CG-47 class)

FSW: natural fabrication and repair

method for aluminum� Low distortion

� Excellent, consistent weld quality

� Simple—easy to train welders� Less heat input

Arc-weld

Distortion

Large Panel FSW in LCS construction

� Extrusions were welded into sub-panels with FSW by Friction Stir Link

� But the sub-panels had to be arc welded together

5

Low Speed System Size

� High Forces

• 1000-3000 lb. downward500-1000lb. in travel direction

� Large, structurally stiff

� Expensive

� Time Consuming Set-upNSWCCD Research FSW machine, $500k

Panel welder at Navy Metalworking Center, $350k6

High Speed vs. Low Speed

7

� Low Speed FSW:

� High Forces

• 1000-3000 lb. downward

• 500-1000lb. in travel direction

� Extensive, exotic, clamping required to offset large forces

� High Speed FSW:

� Low Forces

• 100-400 lb. downward

• 100-250 lb. in travel direction

� Simple “quick clamps” required

to offset low forces

History of High Rotational Speed FSW

8

Craftsman Router

Proof of Concept

High Speed Spindle attached

to a Fadal CNC Mill NASA Space Station

Leak Repair Module

Lightweight Prototype

Designed for sheet metalCurrent NSRP SP-7 Prototype Machine

MTS FSW Machine, five axis motion

with dynamic controls

Spindle Speeder, capable of

speeds up to 12,000 rpm

High Speed BackgroundFor the past 5 years, laboratory research and data has been conducted and

recorded using the system/set-up shown below at Wichita State University

Typical Welding Forces

Forces generated during HRS-FSW

Dynamic Flash Suppression (DFS) Tooling

Macrograph of bead on plate – DFS Tooling with Pin Length 0.051”

0.125”

0.051”

Induced stir

zones beside

and below the

pinThe ISZ enhances pin “penetration.” This is beneficial for lap welds and Friction Stir Processing

Approximated

Pin Boundaries

AA5456-H116

DFS Tooling -

Joint Efficiency (Average): 95.27%

HRS-FSW

Joint Efficiency

(Average): 91.54%

75-78 78-81 81-84 84-87 87-90 90-93 93-96 96-99 99-102 102-105 105-108 108-111 111-114

0.000

0.063

0

0.063

0.126

0.189

0.252

0.315

0.378

0.441

0.504

0.567

0.630

0.693

0.756

0.819

0.882

0.945

1.008

1.071

1.134

1.197

1.260

1.323

1.386 in

in

0.000

0.063

0

0.063

0.126

0.189

0.252

0.315

0.378

0.441

0.504

0.567

0.630

0.693

0.756

0.819

0.882

0.945

1.008

1.071

1.134

1.197

1.260

1.323

1.386

1.449

in

in

FSW

Conductivity/Exfoliation Tests AA5456-H116

Introduction to High Rotational Speed-Friction Stir Welding (HRS-FSW)

� Rotational speeds, advancing speeds, forging

forces, and flash suppression are the principal

factors contributing to the weld quality.

� Able to increase the rotational processing speed,

reducing the welding forces, and maintaining high

weld quality.

� In HRS-FSW, most of the energy is introduced by

high rotational speeds (above 3000 rpm) of the tool,

reducing the processing forces, and the torque

values.

14

High Speed Background

Development work with NSWCCD since 2008� AA 5456, AA 5083, AA 6082 � Up to 0.25”, mostly 0.125” single and double-sided

� Transverse tensile tests• 95% of base metal strength• Improved ductility (failure in parent metal)

� Good consolidation

� High Speed Forging forces <100 lbs. to 400 lbs.

AA 5456, 0.125” thick

Long Range Objectives

� To develop and implement innovative technologies to allow the friction stir welding and repairs of aluminum Naval structures in situations where standard, stand-alone friction stir welding machines cannot be used.

� The approach must develop uncomplicated, robust measures, which currently do not exist.

� To create a reliable friction stir weld in marine-grade aluminum plates and wrought products for ship assembly/subassembly construction and repair applications.

� Achieving applied welding loads that would permit manual manipulation of the equipment during friction stir weld aluminum plate – is a goal of this project.

16

HRS-FSW Repairs Exploratory Results AA5456-H116

0.000

0.063

0

0.063

0.126

0.189

0.252

0.315

0.378

0.441

0.504

0.567

0.630

0.693

0.756

0.819

0.882

0.945

1.008

1.071

1.134

1.197

1.260

1.323

1.386

1.449 in

in

DFS Tooling

Joining Efficiency (Av.: 89.66%)Repair Efficiency (Av.: 95.77%)

75-78 78-81 81-84 84-87 87-90 90-93 93-96 96-99 99-102 102-105 105-108 108-111 111-114

in

HRS-FSW

DFS Tooling - Joining

Efficiency (Undamaged part) (Average): 93.62%

HRS-FSW Repair Sample

HRS-FSW

Repair Sample

HRS-FSW Trenched Sample

Man-Portable FSW SP-7 Contract

18

NSRP SP-7 2010-609Contract Awarded

12 March 2010

Design May – Part Arrival July – Programming October – Assembly November

Portable HRS-FSW System

Transitioned laboratory work to a demonstration prototype.

Frame rails, transverse member, welding head, controller, and supports and

fixtures are modular and can be separated for ease of transport and configuration.

Frame rails & motor = 50 lbs.Welding head = 60 lbs.Transverse rail & motor = 20 lbs.Controller components = 35 lbs.

* HRS-FSW welds produced in the laboratory are similar in

mechanical properties to conventional FSW welds.

* HRS-FSW has a 10x reduction in Z-force loads for portability.

* Reduction in forces allow for scale down in both size and cost.

Progress

� Contract Awarded 12 March 2010:

� 16 March 2010: Pascagoula• Tour with Lee Kvidahl• Fabrication issues• Finalized target—3/8” plate, 40 foot• Guided the design envelope of 4’ length welds

� 13 July 2010: Panama City• Tour with Glen Campbell• Repair issues

� Design decisions: May

� Programming: October

� Assembly: Mid-November

� Testing: December to present

� Contract ended 31 March 2011

NSRP SP-7 Project

� Design, build, and demonstrate a portable High

Rotational Speed-Friction Stir Welding system.

� Demonstrate Weld at Ingall’s

� Target Demonstration Weld:

AA5456-H116 aluminum

Butt weld

3/8-in. thickness

40-ft length in 4-ft sections

Man-Portable FSW Prototype

� 175 lbs.

� PLC-driven� 24” x 54”+ envelope

� Vacuum hold-down� Position control only

What was learned as a result of the SP-7

� The advantage of the HRS-FSW relies on the ability to input most of the energy by high rotational speed, thereby reducing the size and mass of the machine and the tooling.

� The reduction of the friction forces permits the design and fabrication of small portable machines, which can be used for “in field” or “in-situ” structural assemblies, subassemblies, and/or repairs.

� Preliminary assessment of the design and manufacture of the truly portable HRS-FSW machine(s), does provide a suitable launching platform for the HRS-FSW repair process.

� Developed engineering concepts for a portable prototype friction stir system(s) to weld representative structures.

Prototype Welds Trials

24

January/February Welds March/April Welds

18,000 RPM 1.5”/min. 21,000 RPM 2”/min.

Remaining Tasks

� Develop process parameters for 3/8” plate

� Mechanical/Metallurgical Testing

� Continue Tool research program (April/May 2011)

• 3 different style prototype tools on order

• Varying shoulder diameter and features

• Varying pin dimensions and features

� Demonstration welds

• Invitation to NSRP members

• At Ingalls

Acknowledgements

Lee Kvidahl

– Northrop Grumman Shipbuilding – Gulf

Coast

National Shipbuilding Research Program

– Welding Technology Panel

�This award significantly advanced the

development of this technology.

Video Trials

27

Questions?