1

Laser Drilling of Cylindricaland Shaped Holes

NCMS/CTMA Symposium: Track 1bTerry L. VanderWert

PRIMA North America, Inc.

2

Outline

Laser drilling technology overview Capability Applications Recent developments – benefits of integration

Repair applications Potential benefits

Potential projects

Summary

3

Customers

Serving Turbine Engine Manufacturers

4

• Incremental improvements have led to substantial increases in the number of cooling holes in new engine designs.

• Laser drilling is fast relative to competing methods for small holes – translates into substantially lower cost.

• No tooling means lower cost, faster turnaround – the ‘tool’ is a focused beam of light

• Flexible – single part lot sizes• Easily interfaced with CAD/CAM

Laser Drilling - An Enabling Technology

• Drills/machines a wide range of materials• At shallow angles• Complex shapes

5

Laser Drilling of Cylindrical Cooling Holes

• Typical applications – Cooling holes in blades, vanes, combustors, and afterburners

• 0.3 to 1 mm diameter holes at 15-90° in cast, sheet, and machined components, uncoated and with TBC

• Rates – 0.25 to 5 holes per second

Airfoil

Air flow

Film cooling holes

6

Laser Drilling of Shaped Cooling Holes

0.8 - 1.2mm

0.8 - 1.2mm

10-30 degrees

‘Wine Glass’ Shape

(Fan in, Fan out)

‘Race Track’ Shape

(Fan in, straight out)

Top View

1. Pierce undersized through hole2. Trepan fan shape- through hole3. Finish through hole to size (trepan to exit hole diameter)

Top View

1. Pierce undersized through hole2. Trepan fan shape- through hole3. Finish through hole to size (trepan to exit hole diameter)

• Film cooling holes increase efficiency of cooling air by 30%, reducing the amount of air required for cooling.

• Used sparingly today because of their cost when produced using EDM.

0.4-1.2 mm

1.5-3.0 mm12-20 degrees

7

Recent Developments by PRIMA North America for New Part Manufacturing and Repair

• Process control for improved airflow consistency• Optimum laser process parameters for cylindrical shaped

holes• Drill at focus

• Breakthrough detection

• Optical focus control (for TBC)

• ‘Simple’ shaped hole drilling

The bottom line? More consistent holes

Distribution of Exit Hole Diameter

0.50 0.60 0.70 0.80 0.90Hole Diameter, mm

Without Breakthrough Detection

Breakthrough Detection

8

Repair Applications for Laser Drilling

• Re-drilling of cooling holes. • Some cooling holes become blocked during repairs by

welding or brazing• Holes must be re-drilled to restore component airflow.

Blades and vanes repaired by welding or

brazing.

Cooling holes become blocked and component

suffers some distortion

Cooling holes re-drilled by laser

9

Repair Applications for Laser Drilling

• Removal of TBC overspray • Coatings must be removed before any repairs can take

place. • Re-coating partially fills cooling holes and this must

be removed to restore component airflow.

Coating must be stripped from components

before repair.

Repaired components must be re-coated. The new coating covers existing cooling holes

Coating overspray removed by Laser

Issue: Amount of new coating in the hole varies

10

Potential benefits of laser drilling for repair depots

Reduced costs

Reduced turnaround time - keep aircraft flying

Provides a method for producing engines having increased engine performance

Thermal barrier coatings Film cooling – shaped and cylindrical

11

Potential Projects

• Laser source technology for combined machining and drilling

• in uncoated as well as thermal barrier coated (TBC) components

• Automation of set-up and drilling• Probe repaired components to compensate for

deviations in shape and position• Identify actual hole locations

• In process gauging - improve process efficiency and quality by automating part inspection

12

Laser source technology for combined machining and drilling

• Objective - Develop laser source capable of both pulsed drilling of cylindrical holes and ablative machining of shaped holes.

• Challenges – Produce laser source having both ms (deep hole drilling) and µs (machining) pulse widths, with high beam quality.

• Potential return – Improve productivity and reduce cost for laser drilling by taking advantage of the speed of laser machining and producing complete shaped holes in a single setup.

13

Laser Drilling Capability is Source Dependent

• Throughput holes/second minutes/hole

• Feature size f (wavelength, lens focal length, beam diameter, beam quality)

• Debris 10’s µm negligible

• HAZ/recast tens to hundreds µm less than 10 µm

• Depth control inversely related to removal rate

4 FBeam Ø = M2

D

4 FBeam Ø = M2

D

CW fs

Melt expulsionVaporization Ablation

“Cold Ablation”

PulsedNd:YAG(ms/µs)

Q-switchedNd:YAG

(ns)

Ti:Sapphire(fs)

Nd:YVO4(ps)

Cu vapor(ns)

Excimer(ns)

“Coarse” to “fine”

CW fs

Melt expulsionVaporization Ablation

“Cold Ablation”

PulsedNd:YAG(ms/µs)

Q-switchedNd:YAG

(ns)

Ti:Sapphire(fs)

Nd:YVO4(ps)

Cu vapor(ns)

Excimer(ns)

“Coarse” to “fine”Mechanism

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+01

1.E-12 1.E-09 1.E-06 1.E-03 1.E+00

Pulse duration, sec

Rem

ova

l ra

te,

mm

^3/

sec

14

Automation of Setup and Drilling

• Objective – Develop vision and probing tools to gauge the shape and hole location of repaired components.

• Challenges - Parts are deformed; shape will not match that of the new component. However, the ‘repair holes’ must be coincident with the original holes.

• Potential return – Improved productivity by automating time-consuming setup steps.

15

In Process Gauging

• Objective – Actively monitor component airflow to determine which holes should be re-drilled.

• Challenges – Integration of gauging tools with laser machines.

• Potential return• Higher quality components.• Greater machine utilization by

avoiding inefficiencies of removing/resetting the part into the drilling system.

16

Summary

• Improvements in laser drilling technology for modern, new component manufacturing can benefit repair – whether at the repair depot or commercial partner.

• Additional technology development is needed to improve productivity, reduce dependence on skilled operators, and improve consistency in repair operations.

• PRIMA North America’s 20+ years history of innovation in lasers for turbine engine manufacturing and repair will reduce risk and cost of these developments.