Your Actionable 7-Point Checklist for Sourcing Custom Heat Sink Extrusions

The effective thermal management of electronic components relies heavily on the thoughtful design and sourcing of heat dissipation solutions. This document examines the multifaceted process of specifying and procuring custom heat sink extrusions, a prevalent method for cooling due to its balance of performance and economic viability. It explores the foundational role of aluminum alloys, particularly the 6000 series, in achieving desired thermal conductivity and manufacturability. The analysis extends to the critical principles of fin geometry, including height, spacing, and aspect ratio, which directly govern the convective heat transfer capabilities of the profile. Furthermore, the manufacturing process, from billet heating to post-extrusion handling, is detailed to illuminate its impact on dimensional accuracy and material properties. The discussion also covers the necessity of secondary operations and surface finishes, such as anodizing, which alter both thermal performance and environmental resistance. The objective is to provide a comprehensive framework for engineers and procurement specialists to make informed decisions, ensuring the final component aligns with both thermal requirements and project constraints.

Key Takeaways

• Select the correct aluminum alloy, as it dictates thermal performance and cost.
• Optimize fin design to maximize surface area without impeding natural airflow.
• Clearly define and communicate dimensional tolerances to your manufacturer.
• Factor in secondary machining and finishing for complete component functionality.
• Partner with a manufacturer who offers design for manufacturability (DFM) feedback.
• Careful planning of heat sink extrusions is vital for project success.
• Consider surface finishing’s impact on both corrosion resistance and thermal emissivity.

Table of Contents

• Understanding the Fundamentals: The Role of Aluminum Alloys
• Designing for Dissipation: The Art and Science of Fin Geometry
• Evaluating the Extrusion Process: From Billet to Profile
• Specifying Tolerances: Precision in a World of Variables
• Considering Secondary Operations: Beyond the Raw Extrusion
• Selecting the Right Finish: Enhancing Performance and Durability
• Partnering with the Right Manufacturer: A Strategic Decision
• Frequently Asked Questions (FAQ)

Understanding the Fundamentals: The Role of Aluminum Alloys

The journey toward an effective thermal solution begins not with a complex shape but with a fundamental material choice. For decades, aluminum has been the cornerstone of heat sink manufacturing, and for good reason. Its properties represent a near-perfect intersection of performance, weight, and cost that few other materials can match. When we approach the task of sourcing heat sink extrusions, the first checkpoint is always an intimate understanding of the aluminum alloy itself. It is the canvas upon which our thermal design will be painted.

Why Aluminum? The Intersection of Thermal Conductivity and Cost

Imagine you need to move a crowd of people out of a building quickly. You could build a few, very wide hallways or many smaller ones. Heat behaves similarly; it needs pathways to escape. A material’s ability to provide these pathways is called thermal conductivity, measured in Watts per meter-Kelvin (W/mK). Copper is an excellent conductor (around 400 W/mK), like a massive, unobstructed superhighway for heat. However, it is heavy and expensive. Aluminum, on the other hand, offers a compelling compromise. Depending on the alloy, its thermal conductivity ranges from about 170 to 230 W/mK. While not as high as copper, it is more than sufficient for a vast range of electronic cooling applications. What truly sets it apart is its low density and significantly lower cost, making complex, large-surface-area designs economically feasible. The process of creating aluminum extrusions allows us to form those many smaller hallways for heat, creating intricate fin structures that would be prohibitively expensive in copper.

Comparing Common Alloys: 6061 vs. 6063

Within the family of aluminum, not all alloys are created equal, especially for thermal applications. The 6000 series, which uses magnesium and silicon as its primary alloying elements, is the workhorse for extrusion. The two most common candidates you will encounter are 6063 and 6061. At first glance, they seem similar, but their subtle differences have profound implications for heat sink extrusions. Click here to view a detailed comparison and differences between 6061 and 6063 aluminum.

Alloy 6063 is often called “architectural aluminum” for its beautiful surface finish and its superb ability to be forced through complex extrusion dies. This extrudability is its greatest asset for thermal management. It allows designers to create profiles with tall, thin, and closely spaced fins, maximizing the surface area available for heat dissipation. Its higher thermal conductivity compared to 6061 is another significant advantage. In contrast, 6061 is a stronger, more structural alloy. While it can be extruded, it resists the process more, making it difficult to produce the very fine features that define a high-performance heat sink. Its lower thermal conductivity also means it is inherently less efficient at conducting heat away from the source. For the vast majority of heat sink extrusions, 6063 provides the superior combination of thermal performance and manufacturability.

The Impact of Temper on Performance and Machinability

Choosing the alloy is only half the story. The “temper” of the aluminum—a designation like -T5 or -T6 that follows the alloy number—describes the heat treatment process it has undergone. This process of heating and cooling alters the metal’s grain structure, profoundly affecting its hardness, strength, and even its thermal conductivity.

The most common temper for 6063 heat sinks is -T5. In the 6063-T5 process, the extruded profile is cooled with forced air from its extrusion temperature and then artificially aged in an oven. This results in a good balance of strength and stress relief. The 6061 alloy is often seen in a -T6 temper, which involves solution heat-treating and then artificial aging. This produces much greater strength but can also introduce internal stresses. For a heat sink, extreme strength is rarely the primary concern. A stable, moderately strong material that machines cleanly and maintains its shape is far more valuable. The -T5 temper provides exactly that, making it the default choice for most custom heat sink extrusions. Understanding this allows you to have a more nuanced conversation with your supplier, ensuring the material properties are perfectly aligned with your application’s needs, not just its thermal load, but also any subsequent machining or assembly steps.

Designing for Dissipation: The Art and Science of Fin Geometry

Once the material foundation is set, our attention turns to form. A heat sink is not merely a block of metal; it is a carefully sculpted object designed to interact with the surrounding air. Its purpose is to take concentrated heat from a small source—like a CPU or a power transistor—and spread it out over a much larger surface area so it can be carried away by convection. The geometry of the fins is the single most important factor in this process. This is where engineering becomes an art form, balancing competing physical constraints to achieve an optimal design.

Maximizing Surface Area: Fin Height, Thickness, and Spacing

The fundamental principle of a heat sink is simple: more surface area equals more cooling. The fins are the primary means of achieving this. Intuitively, one might think that making fins as tall, thin, and numerous as possible would be the best approach. However, the reality is more complex.

• Fin Height: Taller fins certainly add surface area. But as a fin gets taller, the tip becomes progressively less effective than the base. Heat has to travel a longer path to reach the tip, and the fin’s own thermal resistance means the tip will be cooler and thus dissipate less heat to the air. There is a point of diminishing returns.
• Fin Thickness: Thicker fins conduct heat from the base to the tip more effectively, but they also take up more space and use more material, reducing the number of fins you can fit in a given footprint.
• Fin Spacing: Placing fins very close together dramatically increases the surface area within a volume. However, if they are too close, they choke off the airflow. The boundary layer of slow-moving air that clings to each fin surface can merge, creating a pocket of stagnant, hot air that severely hampers convection.

The ideal design is a compromise. The fins must be tall enough to be effective, thick enough to conduct heat well, and spaced far enough apart to allow for robust convective airflow, whether it be natural or forced with a fan.

The Fin Efficiency Equation: A Delicate Balance

Engineers use a concept called “fin efficiency” to quantify this balance. In simple terms, it compares the actual heat transferred by a fin to the ideal heat transfer it would have if the entire fin were at the same temperature as its base. A short, thick fin might have an efficiency of 98%, but a very tall, thin fin might only be 50% efficient. The goal is not to maximize fin efficiency itself, but to maximize the total heat dissipation, which is a product of the efficiency, the total surface area, and the temperature difference. Often, a design with many fins of moderate efficiency will outperform a design with fewer, highly efficient fins (Lee, 1999). This is a critical insight for anyone designing or specifying heat sink extrusions. It’s not just about the shape; it’s about how that shape interacts with the laws of thermodynamics.

Aspect Ratio: Pushing the Limits of Extrusion

The “aspect ratio” of a heat sink fin is the ratio of its height to its width (thickness). A fin that is 40 mm tall and 2 mm thick has an aspect ratio of 20:1. This ratio is a key indicator of manufacturing difficulty. Pushing aluminum through a die to create tall, thin fins is like trying to squeeze toothpaste through a comb. The high pressure can cause the thin steel features of the die to deflect or even break.

Most manufacturers are comfortable with aspect ratios up to 8:1 or 10:1 for standard extrusions. Pushing into the 12:1 to 18:1 range requires specialized tooling, slower extrusion speeds, and a higher level of process control. Ratios beyond 20:1 are exceptionally difficult and costly to achieve with extrusion. When designing custom extruded heatsinks, it is vital to discuss the target aspect ratio with your manufacturer early on. They can provide crucial Design for Manufacturability (DFM) feedback, potentially suggesting a slightly shorter and thicker fin that is 95% as effective thermally but 50% easier and cheaper to produce. This collaborative approach prevents costly redesigns and ensures the final product is both effective and economical. Click here to explore more detailed design considerations for aluminum heat sinks.

Evaluating the Extrusion Process: From Billet to Profile

To truly appreciate the nuances of a finished heat sink, one must understand the journey it takes from a raw block of metal to a complex, finned profile. The extrusion process is a marvel of materials science and mechanical engineering, a dance of heat and immense pressure. Each step in this process leaves its mark on the final product, influencing its dimensions, its structural integrity, and its thermal performance. Having insight into this process transforms you from a simple buyer into an informed partner, capable of understanding the trade-offs and possibilities inherent in manufacturing aluminum profiles.

The Journey of an Aluminum Billet

It all begins with a billet—a solid, cylindrical log of a specific aluminum alloy, typically 7 to 10 inches in diameter and several feet long. This is the raw material.

1. Preheating: The billet is first heated in a large oven to a temperature between 800°F and 925°F (425°C to 500°C). This temperature is critical; it doesn’t melt the aluminum but softens it to a consistency similar to modeling clay, making it malleable. The die through which the aluminum will be pushed is also preheated to prevent it from cooling the billet upon contact.
2. Loading: The heated billet is transferred to the extrusion press. A lubricant is applied to the billet to prevent it from sticking to the ram or the container.
3. Extrusion: A powerful hydraulic ram applies immense pressure (from 100 to over 15,000 tons) to the back of the billet. This pressure forces the softened aluminum through the shaped opening of the steel die. What emerges on the other side is a long, continuous profile with the exact cross-section of the die opening—our heat sink shape.
4. Quenching: As the profile exits the die, it is rapidly cooled, or “quenched,” by a water bath or high-speed fans. This controlled cooling is a crucial part of the heat-treating process, locking in the material’s desired metallurgical properties, which defines its temper (Totten & MacKenzie, 2003).

This process happens continuously, producing a profile that can be over 100 feet long before it is cut to more manageable lengths.

The Critical Role of the Die in Profile Accuracy

The die is the heart of the extrusion process. It is a thick, circular disk of highly durable H13 tool steel with a precise opening machined into it. The design of this die is incredibly complex. It must not only define the shape of the final profile but also manage the flow of the semi-solid aluminum. Different parts of a complex profile, like the thick base and the thin fins of a heat sink, create different levels of resistance. The die designer must compensate for this, ensuring the metal flows at a uniform speed across the entire cross-section. If the metal in the fins flows slower than the metal in the base, the extrusion will warp and twist. Die making is a highly specialized skill, and the quality of the die directly determines the dimensional accuracy and surface finish of the final heat sink extrusion.

Post-Extrusion Cooling and Stretching: Ensuring Dimensional Stability

Even with a perfect die and a controlled quench, the long extruded profiles are not perfectly straight. Natural variations in cooling can cause slight bowing or twisting. To correct this, the profile is moved to a stretcher. Grips on either end of the extrusion pull on it with controlled force, straightening it and relieving some of the internal stresses that built up during quenching. This stretching process is vital for ensuring the profile meets straightness and twist tolerances. After stretching, the long profiles are transferred to a finishing saw and cut to the specified final lengths, ready for any secondary operations or finishing. Understanding this post-extrusion handling helps explain why certain tolerances are standard in the industry and why achieving exceptionally tight straightness can add cost.

Specifying Tolerances: Precision in a World of Variables

In the world of manufacturing, perfection is an aspiration, not a reality. Every process has inherent variability. Acknowledging and managing this variability is the science of tolerancing. When you order heat sink extrusions, you are not just specifying a shape; you are defining an acceptable range of deviation from that ideal shape. Clear, realistic, and well-communicated tolerances are the bridge between your design intent and the manufacturer’s final product. Misunderstandings in this area are one of the most common sources of project delays and cost overruns.

Standard vs. Precision Tolerances: What Your Application Demands

The aluminum industry has established standards for dimensional variation. These are published by organizations like The Aluminum Association and represent the typical process capability of a competent extruder. These “standard” tolerances cover everything from fin thickness and base flatness to the overall straightness of a part. For a great many applications, these standard tolerances are perfectly adequate.

However, some designs require greater precision. Perhaps the heat sink must slide into a tight channel in an enclosure, or a PCB must mount perfectly flat against its base to ensure good thermal contact. In these cases, “precision” tolerances are required. Achieving tighter tolerances than the industry standard almost always involves additional process controls, specialized tooling, slower extrusion speeds, and more rigorous inspection. Consequently, it increases the cost. A critical part of the design process is to perform a “tolerance stack-up” analysis. This means evaluating how the variations in each part of an assembly add up. This analysis will tell you exactly where you need precision and where you can accept standard tolerances, allowing you to spend money on precision only where it truly adds value.

Understanding Twist, Flatness, and Straightness

Beyond the simple dimensions of a cross-section, there are three critical geometric tolerances for heat sink extrusions:

• Straightness: This refers to the deviation from a straight line along the length of the extrusion (bow or camber). It is typically measured as a maximum allowable gap over a given length, such as 0.0125 inches per foot.
• Twist: This is the helical or spiral variation along the length of the extrusion. It is measured in degrees per foot of length. Excessive twist can make it impossible to mount a heat sink correctly.
• Flatness: This applies to a specific surface, most often the base of the heat sink where the heat-generating component will be mounted. It defines how much that surface can deviate from a perfect plane. Poor flatness creates air gaps, which are thermal insulators, drastically reducing the heat sink’s effectiveness (Ellison, 2003). This is often one of the most critical tolerances for a heat sink.

Communicating Tolerances Effectively with Your Manufacturer

The single most important document for communicating your needs is the engineering drawing. This drawing must be clear, unambiguous, and complete. Every critical dimension should be assigned a tolerance. If a standard tolerance is acceptable, it’s often best to note that explicitly. Where a precision tolerance is required, it should be clearly called out on the drawing.

Don’t be afraid to add notes to explain why a tolerance is tight. For example, a note like “FLATNESS OF THIS SURFACE IS CRITICAL FOR THERMAL CONTACT WITH CPU” gives the manufacturer valuable context. It tells them which feature to pay the most attention to during production and inspection. A good manufacturing partner will review your drawings and provide feedback. They might say, “We can hold this flatness tolerance, but it will require a post-extrusion machining step. Is that within your budget?” This kind of dialogue is the hallmark of a successful sourcing relationship and is essential for producing high-quality aluminum extrusions.

Considering Secondary Operations: Beyond the Raw Extrusion

An extruded profile is rarely a finished part. The extrusion process creates a continuous length of a specific cross-section, but most applications require that profile to be cut, drilled, tapped, or otherwise modified to become a functional component. These “secondary operations” are a crucial part of the manufacturing ecosystem for heat sink extrusions. Planning for them from the beginning ensures that your final part is not only thermally effective but also ready for seamless integration into your product assembly. Thinking about these steps early can prevent discovering late in the process that a required feature is difficult or impossible to add.

Machining: Creating Features for Mounting and Assembly

The most common secondary operation is machining. This is typically done using Computer Numerical Control (CNC) mills, which can perform a wide variety of precise cutting operations. Common machining tasks for heat sinks include:

• Cutting to Length: While the extrusion is initially cut by a rough saw, a precision cut on a CNC mill can provide a much tighter length tolerance and a cleaner, burr-free finish.
• Drilling and Tapping: Holes are needed to mount the heat sink to the PCB or enclosure, and to mount the electronic component to the heat sink itself. These holes are often tapped (threaded) to accept screws.
• Fly Cutting / Surfacing: Even with good process control, the base of an extruded heat sink may not be perfectly flat. For applications with high-power-density components, the base is often machined flat in a process called fly cutting. A large, single-point cutter sweeps across the surface, creating a near-perfectly flat and smooth finish that minimizes thermal interface resistance.
• Pocketing: Sometimes, a pocket or cutout is needed in the base of the heat sink to provide clearance for other components on the PCB.

Deburring and Surface Preparation

The cutting and machining processes can leave behind small, sharp edges called burrs. These are not only a safety hazard for technicians handling the parts but can also interfere with assembly. Deburring is the process of removing these sharp edges. It can be done manually with hand tools, but for larger quantities, it’s often automated. Parts may be tumbled in a large drum with abrasive media, which smooths all the edges simultaneously. This step adds a small cost but significantly improves the quality and safety of the finished part. Proper surface preparation is also the first step before any finishing coat, like anodizing or painting, is applied.

The Purpose of Punching and Drilling

While CNC milling is incredibly versatile, for very high-volume production, other methods can be more cost-effective. A stamping press with a custom punch-and-die set can create thousands of holes or other simple features with incredible speed. Punching is generally faster and cheaper per-hole than drilling, but the initial tooling cost is much higher. This makes it a good choice for production runs in the tens or hundreds of thousands. The decision between drilling and punching is a classic manufacturing cost analysis, balancing the non-recurring engineering (NRE) cost of tooling against the per-piece cost of the operation. Discussing your expected production volume with your supplier will help them guide you to the most economical solution for creating the features your design requires.

Selecting the Right Finish: Enhancing Performance and Durability

The final step in fabricating many heat sink extrusions is the application of a surface finish. This is not merely a cosmetic choice; the finish can have a profound impact on the heat sink’s thermal performance, its resistance to corrosion, and its electrical properties. The raw, as-milled aluminum surface is functional, but in many environments, it is not optimal. Choosing the right finish is another critical checkpoint that requires balancing multiple competing requirements to arrive at the best solution for your specific application.

Anodizing: Corrosion Resistance and Electrical Insulation

Anodizing is an electrochemical process that grows a very hard, controlled layer of aluminum oxide on the surface of the part. This oxide layer is much more durable and corrosion-resistant than the thin, natural oxide layer that forms on raw aluminum. It also makes the surface a very good electrical insulator, which can be important in preventing accidental short circuits on a crowded PCB.

However, anodizing has a complex effect on thermal performance. The aluminum oxide layer is a thermal insulator, so it slightly increases the thermal resistance for convection. This seems counterintuitive. Why would you add an insulating layer to a heat sink? The answer lies in radiation. The emissivity of a surface is its effectiveness in emitting energy as thermal radiation. A raw, shiny aluminum surface has a very low emissivity (around 0.05), meaning it is a poor radiator of heat. A black anodized surface, in contrast, has a very high emissivity (around 0.85). Learn more about the impact of anodized finish on heat sinks.

In natural convection environments, where airflow is low, radiation can account for a significant portion of the total heat transfer. In these cases, the large gain in radiative cooling from a black anodized surface far outweighs the small loss in convective cooling. For forced-air applications, where a fan is moving air at high velocity, convection is dominant and radiation is less important. In these cases, a clear (un-dyed) anodize or even a chromate conversion coating may be a better choice.

Powder Coating and Painting: Aesthetics and Protection

Powder coating and liquid painting are primarily used for aesthetics or for color-coding components. They provide a very durable, thick, and uniform coating in almost any imaginable color. From a thermal perspective, however, these finishes are almost always detrimental. They are essentially a layer of plastic, and plastics are excellent thermal insulators. Applying a thick coat of paint or powder to a heat sink can dramatically reduce its ability to dissipate heat. These finishes should only be used when the thermal load is very low and aesthetics are the primary driver, or on non-critical surfaces of the heat sink.

Chromate Conversion Coating: A Pre-treatment for Conductivity

A chromate conversion coating (also known by trade names like Alodine or Iridite) is a chemical treatment that creates a very thin, protective layer on the aluminum surface. It provides good corrosion resistance, similar to a light anodize, but with one key difference: it remains electrically conductive. This makes it an ideal choice for applications where the heat sink needs to be part of an electrical ground plane or provide EMI shielding. The coating is also an excellent primer that promotes adhesion if the part is later to be painted. From a thermal standpoint, its impact is negligible, making it a safe choice when you need corrosion protection without the thermal penalty of anodizing or painting. Understanding the options for custom extruded heatsinks and their finishes is key to a successful project outcome.

Partnering with the Right Manufacturer: A Strategic Decision

The final, and perhaps most consequential, checkpoint in our journey is the selection of a manufacturing partner. All the careful design, material selection, and tolerance analysis can be for naught if the chosen supplier lacks the capability, expertise, or collaborative spirit to execute your vision. Sourcing heat sink extrusions is not a transactional purchase; it is the formation of a strategic partnership. The right partner becomes an extension of your engineering team, providing invaluable feedback and ensuring a smooth path from prototype to production.

Assessing Manufacturing Capabilities and Quality Control

When evaluating potential suppliers, look beyond the price quote. Inquire about their specific capabilities. What is the largest billet size they can extrude? This determines the maximum size of the heat sink profile they can produce. What is the tightest aspect ratio they are comfortable with? This speaks to the level of precision in their die-making and process control.

Equally important is their quality control system. Are they ISO 9001 certified? This provides a baseline assurance of a documented quality management system. Ask about their inspection equipment. Do they have CMMs (Coordinate Measuring Machines) to verify complex dimensions? Do they have profilometers to measure surface flatness and roughness? A capable manufacturer will be proud to discuss their quality processes and show you how they ensure that the parts they ship match the drawings you provide.

The Value of Design for Manufacturability (DFM) Feedback

One of the greatest services a good manufacturing partner offers is Design for Manufacturability (DFM) feedback. This is a collaborative review of your design where the manufacturer’s engineers use their deep knowledge of the extrusion process to identify potential issues or opportunities for improvement. They might point out that a slight change to a fin’s thickness could dramatically improve extrusion speed and lower costs. They might suggest a different alloy that offers similar performance with better machinability. Or they might recommend a change to a corner radius to improve metal flow in the die. This feedback is invaluable. It can lead to a more robust design, a lower unit cost, and a faster time to market. A partner who engages in this kind of dialogue is one who is invested in your success.

Navigating the Quoting and Prototyping Process

The quoting process itself can be revealing. A thorough quote will break down the costs clearly: the one-time tooling (die) cost, the per-piece price at different volume breaks, and the costs for any secondary operations or finishes. Be wary of quotes that are vague or incomplete.

Before committing to expensive production tooling, it is often wise to create prototypes. For heat sinks, this might involve CNC machining the entire profile from a solid block of aluminum. While more expensive on a per-piece basis, it allows you to test the thermal and mechanical fit of your design with a real physical part. Once the design is validated, you can then confidently invest in the extrusion die for mass production. A good partner will help you navigate this process, offering different strategies for prototyping and clearly explaining the cost and lead time implications of launching production tooling. A clear understanding of the quoting process for heat sink extrusions is a fundamental part of a successful partnership.

Sourcing custom heat sink extrusions is an exercise in holistic engineering. It requires a perspective that extends beyond a simple thermal calculation to encompass materials science, manufacturing processes, and supply chain partnerships. The journey from a conceptual design to a functional, cost-effective component involves a series of critical checkpoints. It begins with the foundational choice of an aluminum alloy and its temper, moves through the nuanced art of fin geometry design, and requires an appreciation for the extrusion process itself. Success is found not in maximizing any single variable, but in achieving an intelligent compromise between thermal performance, manufacturability, and cost. By specifying tolerances with intention, planning for necessary secondary operations, selecting the appropriate finish, and, most importantly, fostering a collaborative relationship with a capable manufacturer, an engineer or designer can confidently navigate this complex landscape. The result is not just a piece of metal, but a purpose-built solution that ensures the reliability and longevity of the electronics it is designed to protect.

Frequently Asked Questions (FAQ)

What is the best aluminum alloy for a heat sink?

For most applications, aluminum alloy 6063 is the preferred choice. It offers an excellent combination of high thermal conductivity (around 200-218 W/mK) and superior extrudability, which allows for the creation of complex profiles with thin, closely spaced fins. Alloy 6061 is stronger but has lower thermal conductivity and is harder to extrude into intricate shapes.

How does fin spacing affect cooling performance?

Fin spacing is critical. If fins are too close together, the boundary layers of air on each fin can merge, trapping hot air and preventing effective convection. If they are too far apart, you are not maximizing the available surface area in a given volume. The optimal spacing depends on whether the airflow is natural convection or forced air from a fan.

Can you bend aluminum heat sink extrusions?

Bending extruded profiles is possible, but it is a difficult secondary operation. The process can cause the fins to deform or crack, and it is challenging to maintain a precise angle. If a non-linear shape is required, it is often better to extrude a straight profile, cut it into segments, and weld or mechanically fasten them together.

What is anodizing, and do I really need it for my heat sink?

Anodizing is an electrochemical process that creates a hard, corrosion-resistant, and electrically insulating oxide layer. You need it if your heat sink will be in a corrosive environment or if you need electrical insulation. For thermal performance in natural convection, a black anodized finish is highly beneficial as it significantly improves heat dissipation through radiation.

How much do custom heat sink extrusions cost?

The cost is composed of two main parts: a one-time tooling cost for the extrusion die (typically a few thousand dollars) and a per-piece price. The per-piece price depends on the weight of the profile, the complexity of the shape, the alloy used, the required tolerances, and the order quantity.

What is the maximum size for an extruded heat sink?

The maximum size is determined by the manufacturer’s equipment, specifically the diameter of their extrusion press container. A common large press might have a 10-inch or 12-inch container, meaning the entire heat sink profile must fit within a circle of that diameter. Some specialized extruders can handle larger profiles.