The Importance of Volumetric Machine Tool Accuracy

in Making Precision Aerospace Parts

Presented by

Koichi "Ken" Iwakura

President, Mitsui Seiki Kogyo Co., Ltd.

Presentation Outline

• What is Volumetric Accuracy?

• Why is it needed?

• How is it achieved during Machine Tool Construction?

• How is it measured?

• What are the results?

What is precise?

What is precision in a volume?

A machine tool has six deviations that contribute to the TCP (Tool Center Point) positioning error

• Linear positioning

• Vertical straightness

• Horizontal straightness

• Roll

• Pitch

• Yaw

How does that impact motion?

Why is high Volumetric accuracy needed? Because expensive AEROSPACE

manufactured parts require: • High precision dimensional accuracy

• Stability of accuracy during 24/7 production

• Longevity of accuracy for the life of an aircraft model

What is the global market? LIMITED DUE TO MACHINE TOOL COST AND EXPORT CONTROL

Price Complexity Automation Complexity

How is High Volumetric Accuracy achieved? High Precision Production Machine Requirements

• Construction environment

• Construction methodology

• Designed for stable thermal characteristic’s

• Hand scraped for straightness of travel

• High tolerance pallet flatness and wobble

• Spindle thermal control for Z axis

• Ball screw drunkenness control

• Scraping to fit mating surfaces precisely

Construction Environment

Ultra Precision Machine Tool Factory

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Unit Assembly A/C

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Head Assembly

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A/C control Room

Measuring Room

•Room temperature is controlled 20℃±0.4℃ •Dispatch is also temperature controlled utilizing air lock •Foundation piles every 10m2 to ensure a solid floor •Machining and Assembling is all under same temperature

Complete Temperature Control Room

• Air temperature controlled to 20℃±0.4℃ • The dual structure ceiling with conditioned air down through number of small holes • No temperature difference in vertical direction •

Multi-ceiling panels

Flow of air

Return duct

Solid Foundation (Machine Tool Factory)

• 1m deep foundation on 1700 pillars concrete • Foundation for building and floor is completely separated. • The vibration from the cranes both large and small is isolated.

Designed for thermal stability

Mass and symmetry for thermal control

Video: 5Xproject Start 0:34 Finish: 1:21

Hand Scraping

Process of scraping

Highly skilled Technicians scrape to micron tolerance

Confirm scraped component by using the Autocollimator

If not as achieved, scrape again

Ultra high accuracy is completed by repeating scraping and measuring

Accuracy by Scraping is repeated until Specified tolerances are achieved

How is it measured?

• Precision measurement of machine tool components

• Measurement of machine tool geometry at finished assembly

• Test Cutting • Production tolerance results

Precision measurement of machine tool components

• To produce high precision machines, it requires a measuring accuracy more than the produced machine itself

• The means to accurately measure below 1μm under controlled environment is available

• Facilities are 3 dimensional measurement Systems consisting of; Leitz, Carl Zeiss, and our original Laser Tool Measurement System.

Example Geometry Test Procedure for Horizontal Jig Bore

Procedure: Measure from the spindle with 2 dial indicators as shown against a precision cylinder. At the Z positions Z1, Z2, Z3 calculate the difference in indicator readings for both indicators from Y1 to Y2 and note the values. Record the total difference of the 3 measurements for each indicator.

Setup Data: X= center of pallet Y1= min. dist. from pallet top Y2= Y1 + 500mm Z1= min. dist. from pallet center Z2= (Z axis travel) / 2 Z3= max. dist. from pallet center Maximum Error: A= 8 micron / 500mm B= 8 micron / 500mm

Taper Cone Test Cutting

What are examples of production aerospace components?

James Webb Space Telescope Rotor Hub

About James Webb Space Telescope

Sample deep space program

Next Generation Space Telescope

present

(+137millyrs.) 1st galaxy

(+9.5mill yrs)

1stplanet

(+3mill yrs)

Big bang

(0yr.)

man

• It is the core of “Origin Program”, a plan of which NASA propels.

• Will be launched by Aliane5 of ESA (European Space Agency ) in June 2013.

• Research birth and evolution of the galaxy, cosmic size and shape, and the mysterious life cycle of materials.

• It is a next generation space telescope which will take over the position of Hubble Space Telescope.

JWST searching for space origin

James Webb Space Telescope

Hubble Space Telescope

JWST( James Webb Space Telescope)

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Test piece machining by 8 HS6As • Margin of bore pitch error is within 5μm, and parallelism of φ100 boss is within 5μm. • 7 holes machined on a individual basis to duplicate exact cutting conditions. • A few mutual errors between the 8 machines.

size：800×900×80 material：A5052P unit：μm

穴 座標 0 1 2 3 4 5 6 X 0.0 -0.7 -1.6 -3.7 -1.2 4.5 4.0 Y 0.0 4.5 3.5 -0.6 -3.6 -0.9 3.0 X -0.3 0.0 -0.2 -2.7 0.0 4.8 4.2 Y 2.1 3.7 2.8 -1.4 -3.9 -1.4 2.1 X 0.0 0.0 -1.1 -2.1 -0.8 2.1 0.2 Y 0.0 4.0 3.5 -2.6 -4.9 -4.6 1.5 X -1.0 -0.8 -2.2 -3.2 -1.2 1.7 -0.6 Y 1.5 4.2 4.5 -1.4 -4.4 -3.8 2.7 X 0.0 0.0 0.6 -2.4 -3.7 1.1 1.3 Y 0.0 0.1 0.0 0.6 0.3 1.7 0.5 X 0.7 0.8 1.5 -2.2 -4.5 0.1 1.1 Y 1.6 0.7 0.9 2.2 2.0 2.7 1.2 X 0.0 0.0 4.7 2.4 -4.3 -3.5 -3.1 Y 0.0 -2.0 -1.9 0.3 3.2 1.8 -1.0 X -0.3 -2.0 4.0 1.9 -4.5 -3.6 -3.3 Y 1.9 -2.0 -0.2 1.9 4.5 2.8 1.3 X 0.0 0.0 -1.3 -3.8 -3.7 -0.1 -3.5 Y 0.0 -4.2 -3.5 -1.6 0.8 3.3 0.3 X -0.4 -1.2 -1.2 -4.1 -4.2 -1.5 -4.1 Y 1.2 -2.7 -1.7 -0.1 2.3 4.7 2.3 X 0.0 0.0 -1.2 -4.7 -4.5 -2.6 0.4 Y 0.0 1.6 3.7 -4.3 -3.5 -4.1 1.8 X 0.2 0.8 -1.1 -4.6 -4.1 -1.6 1.0 Y 1.5 3.7 4.5 -4.9 -2.2 -3.3 3.6 X 0.0 0.0 3.2 1.6 -4.1 -3.7 -3.8 Y 0.0 1.8 3.7 4.0 1.3 1.2 1.0 X 0.3 0.5 2.7 1.6 -3.5 -3.8 -3.6 Y 1.3 3.3 4.1 4.4 2.3 1.5 2.1 X 0.0 0.0 -2.2 -0.7 -4.1 -3.4 -3.6 Y 0.0 0.7 -2.3 -2.0 -1.3 1.3 1.5 X -0.5 -1.1 -1.8 -0.6 -4.2 -3.4 -3.9 Y 0.2 1.2 -2.1 -1.9 -0.6 1.8 1.6

squareness

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穴ピッチ精度 Parallelism

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JWST( James Webb Space Telescope)

Primary mirror of JWST (back)

About JWST primary mirror machining

Machine with 8 HS6A HMCs, delivered to Axsys Technologies Inc.

A mirror with 6.5m diameter is made of 18 hexagonal parts with opposite sides of 1.39m.

Material is beryllium. Weight of raw material is 250kg. When machining is done, the finished weight is 21kg.

Repeat ‘machining’→ ‘warp correction→’machining’. This process takes about a year to complete 1 mirror.

Parallelism of 9 bosses, across the back of the mirror, are 3μm.

A plant for Primary mirror

HS6A, Hi-precision HMC

JWST

JWST( James Webb Space Telescope)

Sample 5 Axes Project Application Putting Things In Perspective

Large 5 Axis Trunnion Saddle

9/21/2012

New Product Development Team

25

Large 5 Axis Machining Center Table

9/21/2012

New Product Development Team

26

Timing Slot

Sikorsky Heavy Lift Rotor Hub Forging

9/21/2012 27

Material is titanium

Finished Sikorsky Heavy Lift Rotor Hub

Critical tolerances to 25 microns!

THANK YOU