FAQ

1. Why use aluminum? Why use aluminum in its extruded form?
Few commercial metals can be extruded in as wide a variety of configurations with desirable combinations of physical properties as can aluminum. Aluminum extrusions provide a high strength-to-weight ratio, close tolerance, ease of joining, seamless manufacturing, uniform quality, excellent corrosion resistance, high electrical conductivity, excellent thermal properties, sustained recyclability, and suitability for a wide range of finishes.

2. How is the cost determined?
Production cost in aluminum material is concerned with the dimension (size), quantity, wall thickness, weight, alloy/temper, length, packing, classification of shape (solid, semi-hollow or hollow), marking and shipping quantity tolerance. When possible, follow the design suggestions of the manufacturer to generate the lowest production cost.

3. Can I save production costs by designing with aluminum extrusion?
The tools required for aluminum extrusion - dies and related elements - are relatively inexpensive compared with those necessary for other production methods. Initial investment may be quickly amortized and even a fairly small production run may pass the "bread even" point, thus economically justifying the use of extrusion.

4. Why is the length such an important factor in determining the price of extrusions?
The extrusion process is designed to be a combination of heat, die and pressure, which forms an extruded shape from an aluminum billet. The extruder's goal is to increase recovery from the billet by reducing scrap and obtaining the optimum amount of quality extruded material from each push (cycle of the extrusion press). Therefore potential cost savings exist when extrusions are purchased in their know end-use lengths, or length multiples, as the best means to reduce scrap generated in the extrusion process.

5. How do I determine which is right aluminum alloy for my part?
It is possible that several alloys and tempers would be suitable for your part. Selection is usually made on the basis of structural or fabrication requirements. It's a good idea to look for the most economical alloy among several that may be suitable to you specific application. The choice of alloy is best arrived at by consultation with your extruder.

6. I'm in the market for some extruded aluminum heat sinks. Which alloy is best for this type of application?
The purpose of any heat sink material is the dissipation of heat. Although all aluminum is capable of this, the specific alloy 6063 works best, when all aspects of aluminum in this application are considered. This alloy finishes well, and is machinable to most user needs. It is one of the most cost-effective alloys for this purpose. This alloy's characteristics lend themselves well to the sharp corners and tight spaces of some heat sink designs.

7. What is the difference between a sulfuric acid anodize, hard anodize, and conversion coating?
In the sulfuric acid anodizing process, the aluminum workpiece is placed in an acid-based electrolyte. An electric current is then passed through the part. During theoxidation process, the workpiece is coated with a hard, porous oxide layer. Organiccoatings or dyes of various colors can thus be applied to the aluminum outside surface.
The primary difference between the sulfuric acid anodize and hard anodizing processes are the operating temperature and the current density at which the process occurs. Hard anodizing produces a heavier coating with better wear properties than a sulfuric acid anodize.
The conversion coating, also know as chrome phosphate or chrome oxide (yellow chrome), is a process that treats the metal surface as a result of chemical attack occurring when the metal is immersed in. or sprayed with, various solutions. This finish provides protection and good adhesion, but would typically be used as a based for another final finish.
　
8. What advantages is there to using an aluminum extrusion over an aluminum casting?
The integrity of an extrusion is much more consistent than that of a casting. Castings are inherently more porous due to their manufacturing process, and this results in more material used for structural applications. In result, the aluminum extrusion is inexpensive(dies) and take shorter time than casting manner. 　

Reported by: Caiping Enterprise Co., Ltd. (In Taiwan)

Dated: 1997.11.10 　

Information reference
1. Aluminum Extrusion Council(AEC) in U.S
2. The Aluminum Association in U.S