ALUMINUM EXTRUSION PROCESSES EXPLAINED

The aluminum extrusion process produces a single bar with a unique uniform engineered “cross-sectional profile” for the entire length of the aluminum extruded bar. The most significant consideration when considering aluminum extrusions are, design, logistics, and cost. There are two distinctly different aluminum extrusion “markets”; architectural and components (such as heat sinks, heat pipes and extruded enclosures). The requirement in manufacturing, finishing, and logistics and especially the customer requirements are significantly different for these markets. On this page, we are going to discuss:

  • First, how the aluminum extrusion process works
  • Second, the requirements for architectural and components (heat sinks and heat pipes) to allow you to consider who is best to manufacture “your” unique products.
  • Additional Thermal Management Options:
    1.  Heat Pipes
    2. Liquid Cooled Heat Plates
    3. Spreader Bars
    4. Folded Fin Heat Sink
    5. Bonded Fin Heat Sinks
    6. Skived Heat Sinks
    7. Stamped Sheet Metal Heat Sinks
Aluminum Extrusion Process

Aluminum Extrusion Process

First, let us discuss the aluminum extrusion process. This process is fundamentally simple and has a quick turnaround. Especially when you compare it with forging and casting since it is designed to produce just a 2-dimensional profile. To produce this male profile, a simple die is manufactured with the female profile to produce the extrusion. This die is designed to push a round cylindrical log or billet using a large hydraulic ram against the die extruding the aluminum profile thus forming the extrusion

For more detail, step by step on the extrusion process, please see the below:

  1. A cylindrical bar is cut into a pre-defined length to produce a billet
  2. This billet is then put into a gas or induction furnace to heat it to 900°F. Note that aluminum retains its nominal color even at these temperatures.
  3. The billet is then transferred to the extrusion press.
  4. The press uses a hydraulic ram that pushes the profile into the die.
  5. As the ram pushes the billet into the die. The extrusion profile is produced continuously from the other side and then is either air or water-cooled.
  6. Once the extruded bar reaches the maximum length, it is cut to a manageable length.
  7. When the extrusion is cooled, it is put in a “puller” that pulls the part to straighten the bar. This also relieves any stress withing the aluminum extrusion.

Aluminum Extrusion Markets

Second, now let us talk about the two markets. If you are a buyer or engineer, you need to consider these markets in selecting a supplier that will meet their unique requirements.

Architectural:

Extrusions that fit the architectural category are in long lengths. These “finished aluminum extrusions” are typically from 1ft to 20 ft ++ length. They are used for items such as window & door frames, curtain walls, window louvers handrails, structures for the building and construction industry, or guide rails for the manufacturing process or a simple leveraged component. The very minimal secondary processes that are required are processes such as cutting powder coating, anodizing, or plating.

For this market, the cost is driven by material, large quantities, and especially LOGISTICS. Due to the sizable order requirements, logistics is the most significant cost factor to consider. The more competitive suppliers set up manufacturing facilities close to the consumer of their products to reduce the logistics cost. What this means to the consumer of architectural type of extrusions is you should be looking for a near-source manufacturing company or an “off the shelf” products to get the lowest possible cost.

Components:

When considering components, heat sinks or heat pipe, these parts could be from ¼” to 24” in length with a unique OEM profile.

First architectural extrusion manufacturers will want to produce a minimum of a few thousand feet. This puts most component manufacturers beyond the reach of an architectural extrusion manufacturer unless they want to purchase 2000+++ parts.

Second, architectural extrusion manufacturers do not focus on detailed machining.  This includes matching cavities, faces, drilled, and reamed holes, and finishing complicated machined shapes. These processes take a multitude of different specific machines to produce to each unique customer requirement.

Third, architectural extrusion manufacturer usually does powder and wet coating, simple black and clear anodizing. However, not a multitude of anodized colors, Alodine, nickel, chrome, and other plating’s, thermal Pad Installation, EMI bead installation, Fastener, and PEM installation. Also, some aluminum extrusion customers are looking for heat sinks that incorporate heat pipes that are a combination of a heat pad and heat sink or require friction welding or high thermal conductivity thermal epoxy.  For these processes, customers need to be looking at a custom aluminum extrusion manufacturers that focuses solely on custom extruded components, extruded housings and Heat Sink/heat Pipes.

These contract manufacturers normally also run much shorter extrusion runs. This is to meet the customer lower quantity requirements. Last, since these types of extrusion customers have smaller parts, the cost of shipping is insignificant, so a near location is not necessary.

Heat Sink Green Anodized Aluminum Extrusion
Green Anodized Aluminum Extrusion
Black anodized with a brushed finishExtrusion with Machined Windows
Extrusion with Machined Windows
HEAT SINK THERMAL PAD and pressed in
Heat Sink with Thermal Pads and Pressed-In Fastners
Machined 5G Aluminum Extrusion
Machined 5G Aluminum Extrusion
Powder Coated and Extruded Aluminum Extruded Enclosure
Powder Coated and Extruded Aluminum Extruded Enclosure
Extruded Black Anodized Face Plate with PEM Fasteners and Machined Stand-Offs
PEM Fastener Installation in Sheet Matal
PEM Fastener Installation
Liquid Cooled Copper Heat Sink-Pipe & Aluminum Heat Sink Combo
Copper Heat Pipe & Aluminum Heat Sink Combo

Conclusion /Aluminum Extrusion Processes

If you have an architectural aluminum extrusion, look for extrusion manufacturer that can meet your requirements with the lowest logistics cost to your required delivery point. If you require a specialized aluminum extruded component, look for an extrusion contract manufacturer that can perform all your unique requirements IN HOUSE at your required manufacturing QUANTITIES. Do not be force-fed something less than you require or be force-fed to outsource secondary processes beyond a single-source control of your aluminum extrusion supplier.

Ionthis is a FULL-SERVICE contract manufacturer specializing aluminum extruded components, extruded enclosures, heat sinks, and heat pipes. Being a FULL-SERVICE contract manufacturer means that Ionthis can provide you with a finished part. We are a one-stop-shop including machining, PEM/Fastener installation, surface finishing (brushed aluminum and beaded aluminum), Plating (Anodizing, Chromate, Alodine, nickel and so on) & silk screening and engraving, thermal pad installation, silver solder, friction welding, thermal epoxy and more. This eliminates having to resend out your part for secondary processes to multiple vendors. The significant advantage to this is you now only have one source responsible for your quality and on-time delivery needs.

Ionthis is also a “Cradle to Grave” manufacturer, which means we produce smaller quantities to meet your initial market needs. As your product matures, we continually give you suggestions (process changes, material changes, sub-assemblies) to reduce your cost giving you an improved sales advantage.  Ionthis can do both!

For a DFM/Analysis of your Extrusion Heat Sink, Enclosure or Component or assembly, feel free to contact Ionthis at engr@ionthis.com

 

Additional Thermal Management Options

On the page above, we discussed traditional Aluminum Extruded Heat Sink manufacturing.  Depending on our customer’s thermal management requirements, the below thermal management components might be more suitable. We will discuss the design and manufacturing of the advantages of using

Heat Pipes

Heat Pipes are a heat transfer component that utilizes a sealed copper tube with deionized water at a vacuum. By doing a Vacuum, it a lower boiling point of the deionized water. The water at the heat source, the evaporator, turns to vapor and travels through the heat pipe to the cooling source, the condenser. This cooling source is like a traditional heat sink that is in a better location to be cooled.

The vapor then turns back to a liquid and travels back to the heat source, and the cycle repeats itself. One advantage of using Heat Pipes is that the design is very flexible and easy to adapt to the user’s requirements while being one of the most efficient ways to transfer heat

Nickel-Plated-Heat-Pipes
Nickel Plated Heat Pipes

Liquid Cooled Plates

Liquid Cooled Cold Plates utilizes copper tubes that are pressed in and either brazed or thermo-epoxy into place into an extruded plate. These copper tubes are pressed flat on top to allow the most amount on the surface for thermal heat transfer. These tubes can be in a serpentine loop back and forth or a manifold pattern.  The liquid is circulated to a downstream radiator to cool the liquid. Liquid-cooled cold plates are used with high heat electronics that require a high heat transfer coefficient.

Liquid Cooled Cold Plate
Liquid Cooled Cold Plate

Spreader Bars Heat Sink

Spreader Bars are used if there is a high concentration of heat in a small area and just Aluminum will not allow enough heat transfer, Spreader Bars are a possible economical solution. Spreader Bars utilize solid copper bars or plates inserted into an aluminum plate or traditional heat sink to move heat rapidly away from the heat source than just plain Aluminum can provide.

Heat Copper Spreader Bars
Heat Copper Spreader Bar

Folded Fin Heat Sink

Folded Fins utilizes thin metal folded sheet metal and brazed or thermal epoxied on a plate. There are many advantages in using Folded Metal Heat Sink Designs.  First, there are the many materials that can be used. These materials include but not limited to Copper, Copper Alloys, Steel, Stainless Steel, Nickel Alloys, Inconel, and Aluminum. Second, many different configurations can be manufactured since they are manufactured by folding a continuous strip of sheet metal. Examples of these configurations are flat or round crested, louvered, wavy and many more to improve thermal performance. Third they are much lighter than traditional extruded heat sinks. Last the NRE cost are low compared to other designs. Last by being folded metal you extend you cooling surface area within a small amount of usable area.

Copper Finned Heat Sink
Copper Finned Heat Sink

Bonded Fin Heat Sinks

Bonded Fin Heat Sinks are usually forced air cooling and the key benefit of this design is fin height to the space between the fins is very high, as much as 40:1, significantly higher than traditional extruded heat sinks.  This is because the fins are cut out of sheet metal and then boded perpendicular to the mounting plate. The material can be either copper or Aluminum

Bonded Fin Heat Sink
Bonded Fin Heat Sink

Skived Heat Sinks

Skived Heat Sinks are manufactured from a Skive Machine. This particular Skive machine that takes a thick plate of Aluminum or copper and utilizes a special “V” shaped tool that shaves a fin off the surface then bends the fin to be perpendicular leaving a small curved end at the fin to base interface to the surface and then repeats. The advantages of this design are first the high fin height to the fin space ratio. Second, very thin fins can be produced. Third, since the Skive tool is used over numerous designs, thus NRE is very low. Last, since there is no solder or epoxy used, this is a single piece material, the thermal is low.

Copper Skived Heat Sink
Copper Skived Heat Sink

Stamped Sheet Metal Heat Sinks

Stamped Sheet Metal Heat Sinks are economicaly stamped from sheet metal either from a CNC, Laser, or traditional mold stamping process. This process produces a very economical heat sink were heat dissipation required is minimal.  Materials that can be used are Copper, Steel, Stainless steel, and Aluminum.

To discuss which thermal management option best suites your  needs or for a DFM/Analysis of your thermal management component or assembly, feel free to contact Ionthis at engr@ionthis.com