Thermal Conductivity of Materials and Their Role in Modern Manufacturing

Understanding the thermal conductivity of materials is crucial for engineers, designers, and procurement teams working in product development and precision manufacturing. Whether you're designing a heatsink, choosing a polymer for insulation, or selecting a metal for a CNC-machined component, knowing how heat moves through different materials can directly impact performance, production speed, and quality.

This guide breaks down everything you need to know about the thermal conductivity of materials with practical insights tailored to CNC machining, 3D printing, injection moulding, and sheet metal fabrication.

What is Thermal Conductivity?

Thermal conductivity is the property of a material that indicates its ability to conduct heat. It’s usually denoted by the symbol k and measured in Watts per meter-Kelvin (W/m·K).

Formula (Fourier's Law of Heat Conduction):

The following expression represents Fourier’s Law, which describes how heat transfers through a material. It states that the rate of heat conduction is proportional to the negative temperature gradient and the cross-sectional area through which heat flows.

Where:

q = heat transfer per unit time (W)

k = thermal conductivity (W/m·K)

A = cross-sectional area (m²)

dT/dX = temperature gradient (K/m)

Materials with high thermal conductivity (like copper) quickly transfer heat, while those with low thermal conductivity (like plastics) act as insulators.

Factors That Impact Thermal Conductivity of Materials

Several intrinsic and extrinsic factors influence the thermal conductivity of materials:

• Atomic structure: Materials with highly ordered atomic lattices, like metals, tend to conduct heat more efficiently due to the free movement of electrons.
• Phase of matter: Solids generally conduct heat better than liquids and gases because their atoms are more closely packed.
• Material density: Denser materials may facilitate better heat transfer depending on their bonding and structure.
• Moisture content: In porous or hygroscopic materials, trapped moisture can significantly alter conductivity.
• Temperature: Thermal conductivity often changes with temperature. Some materials, like metals, exhibit reduced conductivity at higher temperatures, while others may increase.
• Alloying and impurities: The presence of other elements in a material can scatter heat-carrying electrons or phonons, lowering thermal conductivity.
• Microstructure: Grain size, porosity, and defects within a material all affect how heat travels through it.

Understanding these variables is essential when evaluating materials for thermally sensitive applications in manufacturing.

Comparing the Thermal Conductivity of Materials

Below is a bar chart visualizing the thermal conductivity values of commonly used metals and polymers, including popular 3D printing materials in manufacturing processes. This chart highlights the significant range of conductivity across different materials and reinforces how critical these differences are in application-specific decisions.

Different materials exhibit a wide range of thermal conductivities, including the varying thermal conductivity of metals and polymers frequently used as CNC machining materials. This is essential to consider in manufacturing, especially when thermal management or temperature sensitivity is involved.

Thermal Conductivity Chart of Materials

Below is a material thermal conductivity chart comparing various materials used across Geomiq's manufacturing services:

Thermal Conductivity of Metals in CNC Machining

The thermal conductivity of materials has significant implications in CNC machining. High-conductivity metals, like aluminum and copper, quickly dissipate heat generated during cutting, which helps reduce tool wear and maintain part tolerance. On the other hand, low-conductivity materials such as stainless steel can trap heat near the cutting zone, increasing thermal expansion and reducing dimensional accuracy.

Engineers using Geomiq’s CNC machining services can specify materials based on thermal behavior, with access to real-time DFM feedback and tolerance control.

Best Practices:

• Use flood coolant for low-conductivity metals.
• Adjust feed rates and speeds based on heat transfer properties.
• Opt for high-conductivity materials when dimensional stability is critical.

How the Thermal Conductivity of Materials Impacts 3D Printing

Thermal behavior directly affects 3D printing accuracy and structural performance. In Geomiq’s metal 3D printing services, for example, materials with very high thermal conductivity (like copper) can result in poor fusion due to rapid cooling, while low conductivity materials can cause excessive heat buildup.

Impact by Technology:

• DMLS/SLM: Higher conductivity metals need precise power control and layer timing.
• SLS/SLA/FDM: Thermal conductivity of polymers influences warping, delamination, and surface finish.

Using materials like titanium, aluminum, and nylon enables consistent thermal performance for applications from aerospace to medical prototyping.

Injection Moulding and Thermal Conductivity of Materials

The cooling rate of both tooling and injected parts is largely governed by the thermal conductivity of materials involved in injection moulding.

This is particularly important when working with different types of injection moulding materials, as their ability to transfer or resist heat can directly influence part quality and production speed. Thermoplastics such as ABS, PC, and PEEK all have distinct thermal profiles that require customized cooling strategies.

Injection moulding services utilize aluminum or steel tooling, chosen for their thermal performance. High conductivity reduces cycle times, while the chosen plastic affects how evenly parts cool and cure.

Tips for Better Moulding:

• Use high-conductivity aluminium moulds for prototypes.
• Choose PC or PEEK for thermal insulation applications.
• Optimize cooling channel layout based on part geometry and material.

Sheet Metal Fabrication and Thermal Behavior

In sheet metal, thermal conductivity influences not just cutting efficiency but also forming reliability.

With Geomiq’s advanced sheet metal services, parts cut from copper or aluminum require tuned laser parameters to avoid burn marks, while stainless steel often needs slower cutting due to poor thermal dissipation.

Practical Insights:

• Higher conductivity = faster heat spread = cleaner cuts
• Lower conductivity = slower cooling = better for insulation or containment

Designing for Thermal Performance

When designing for high or low thermal conductivity, engineers need to balance thermal behavior with structural, economic, and manufacturing constraints. The heat conductivity of different materials affects not only heat flow but also tolerance stability, production time, and part durability, especially in thermally demanding applications.

Consider:

• Desired heat dissipation rate
• Operating temperature range and ambient conditions
• Compatibility with the chosen manufacturing process (e.g. CNC, 3D printing, injection moulding)
• Availability and cost of materials with desired thermal properties
• Integration with surrounding components, for example, thermal mismatches can lead to expansion or warping.
• Mechanical requirements such as strength, stiffness, and wear resistance

Example:

• A housing for electronics might use aluminum (fast dissipation, lightweight, machinable)
• An insulating mount or handle might be better made from ABS or PC (low conductivity, mouldable)
• Medical implants might combine titanium's moderate conductivity with biocompatibility and corrosion resistance
• For layered assemblies, designers may combine high- and low-conductivity materials to achieve specific thermal zoning

By analyzing the thermal conductivity of materials early in the design stage, engineers can ensure optimal part performance in real-world environments, improving efficiency, safety, and lifespan while avoiding thermal failures or production delays.

Diagram: Heat Flow in High vs. Low Conductivity Materials

This simple diagram shows how quickly heat moves through metals versus polymers, which is a crucial difference in designing thermally managed parts.

Future Considerations for Engineers Working with Thermal Properties

As materials science advances, the ability to control and predict the thermal conductivity of materials will become increasingly valuable. Engineers will need to consider not only how heat moves through parts but how it interacts with evolving technologies like thermal interface materials (TIMs), hybrid composites, and embedded cooling systems. In applications such as electric vehicle battery enclosures, high-frequency electronics, or space-grade enclosures, the thermal conductivity of materials becomes a mission-critical factor.

Moreover, sustainability goals and lightweighting strategies will push the demand for thermally optimized alternatives to traditional metals, such as carbon-based conductive polymers or metal-matrix composites. Designers and procurement teams should stay up to date with these emerging solutions and integrate thermal analysis earlier in the development process to minimize costly revisions.

Unsure About Material Selection? Geomiq Can Help You Choose the Right One

The thermal conductivity of materials plays a key role in design, prototyping, and production. From CNC-machined heat sinks to 3D-printed structural components and injection-moulded housings, selecting the right material based on thermal behavior can lead to better product performance, reduced costs, and faster time to market.

Geomiq’s quoting platform, material database, and engineering team help you make these decisions with confidence - ensuring every part is optimized not just for form and function, but for thermal performance as well.