Furukawa-Sky Aluminum

NewNew Products
ProductsPrecision Extrusion Technology of Aluminum Thin-Walled
Extruded Shapes for Notebook PCs

1.

INTRODUCTION

With the growing diversification of customer needs in theelectronic equipment in recent years, development of newproducts with competitive design is becoming essential.
Under these circumstances, we have developed aluminum thin-walled extruded shapes to be used as the palm
rest of a notebook PC that has been released based on anew design concept. The requirements for the aluminum
extruded shape included: 1) to be thin and lightweightwith a thickness of 0.7 mm, as well as to have high precision as a PC component enabling smooth assembly andmounting, and 2) to achieve appealing surface conditions
with sharp ridgelines.
To meet these requirements, Furukawa Sky Aluminumhas conducted studies including: 1) improvement ofdimensional precision that affects the assembly andmounting accuracy, making full use of a numerical analysis software package that the Company has proprietarily

Figure 1

developed to take various extrusion conditions intoaccount, and 2) optimization of extrusion conditions tosuppressing the generation of defects on the surface ofaluminum extruded shapes which significantly deteriorates design quality. As a result of these studies, we haveestablished a technology of manufacturing aluminum
extruded shapes that meet these stringent requirements,
thereby putting these materials in volume production.
The products shown in Figures 1 and 2 for their appearance have appeared on store shelves since February
2006.

2.

OUTLINE OF PRECISION EXTRUSIONTECHNOLOGY

2.1 Problems of Conventional Extrusion TechnologyFigure 3 shows a schematic of extrusion process, inwhich a billet heated to high temperatures is placed in thecontainer that is also heated, and the material is made toflow into the extrusion die to ultimately yield a product.
Depending on the cross-sectional form of extrusion, it
may happen to be difficult to obtain a desired cross-sectional form due to uneven flow of the material into the die.
Moreover, because extrusion is a kind of hot processing, its dimensional accuracy is generally lower than thatof cold forming such as press forming of plates, under theinfluence of temperature changes during extrusion as wellas due to thermal contraction after extrusion. Accordingly,
even with the dimensional tolerance of special grade
specified in the JIS standards, it has been considered difficult to manufacture extruded shapes applicable to components for electronic equipment of high precision.

Appearance of notebook PC using the product.

Container
Extruded productBilletExtrusion die

Figure 2

Appearance of palm rest.

Figure 3

Schematic of extrusion process.

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Precision Extrusion Technology of Aluminum Thin-Walled Extruded Shapes for Notebook PCs

2.2

Development Subjects in Precision Extrusion
TechnologyTo obtain aluminum extruded shapes of thin-walled, highprecision, and design quality, it is essential to optimize
extrusion conditions as well as die configuration, so as tomake the raw material flow uniformly into the extrusiondie.
We have analyzed the flow of raw material during extrusion, using the Company's proprietary numerical analysis
software that takes various extrusion conditions intoaccount, thereby succeeding in understanding the conditions in designing an extrusion die that ensures uniform
flow of raw material into the die. Analysis examples given
in Figures 4 and 5 show that the material flow near theopening of the extrusion die is fairly uniform. We have fabricated an extrusion die based on the optimum designconditions, and optimized actual extrusion conditions
including extrusion speed, billet temperature and die temperature. In this way, we have established a manufacturing technology of high-precision yet attractive aluminum
extruded shapes that satisfy the stringent requirements
such as dimensional accuracy, sharp ridgeline andappealing surface conditions.

be attractively and uniformly hairline treated. It was therefore required to have aluminum extruded shapes of highprecision free from surface defects such as die mark andstriped pattern, because these can damage the design
quality when hairline treated. And this task of hairline
treatment has been solved by using the aluminum extruded shapes manufactured by the precision extrusion technology developed here by our Company. Figure 6 showsan enlarged photograph of the ridgeline.
Figure 7 shows an appearance of the extruded shape
before and after hairline treatment. The extruded shapewith a wall thickness of 0.7 mm has achieved the dimensional accuracy of 1/2 to 1/5 the special grade specified
in JIS for overall areas, and not greater than 0.35 mm forflat areas in particular, thereby allowing for uniform hairline treatment. Moreover, generation of surface defects on
the extruded shape has been suppressed stringently, sothat the palm rest component made of an aluminum
extruded shape has been accomplished that offers sharp
ridgelines showing characteristic design together withappealing surfaces realized by hairline treatment.

3.

Aluminum extruded shapes enable enhancement of functions by providing metal components with various forms---e.g. ribs to hold mounting circuit boards, screw holes
to fasten other components, etc. It is also possible to offer
a variety of components that present excellent design
quality while taking advantage of metal texture of alumi-

HIGH-PRECISION EXTRUDED SHAPESAND THEIR DESIGN QUALITY

The palm rest component developed here has employed
hairline treatment for the surface, and this has presented
important tasks to be addressed such that blunting of thesharp ridgeline due to grinding during hairline treatment
should be suppressed, and that the entire surface should

4.

TASKS FOR THE FUTURE

Shape of opening
on the extrusion die

Material flow velocity
←Slow

Fast→

Figure 6
Figure 4

Results of numerical analysis of material flow velocity
distribution (Ⅰ).

←Slow

Figure 5

Enlarged photograph of the ridgeline.

Material flow velocity

Fast→

Results of numerical analysis of material flow velocity
distribution (Ⅱ).

Figure 7

Aluminum extruded shape. Upper: As hairline treated.
Lower: As extruded.

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Precision Extrusion Technology of Aluminum Thin-Walled Extruded Shapes for Notebook PCsnum, by combining hairline surface treatment mentioned
here and coloring alumite finish.
In the future, we intend to expand the application ofshaped components to the electronic equipment business field where high-density mounting is required more
and more, thereby promoting the development of diverse
products that meet the customers' needs. If you have acase in need of assistance or a requirement for us, pleasecontact the undermentioned point of contact.

For more information, please contact:
Electronic Products Dept., Processed Goods Div.,
Furukawa-Sky Aluminum
12th Floor, Akihabara UDX, 14-1, Sotokanda 4-chome,Chiyoda-ku, Tokyo 101-8970, Japan		 TEL: +81-3-5295-3530 FAX: +81-3-5295-3766

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