Cables for custom automation can withstand certain temperatures or they can cause system failures when the temperature reaches a certain threshold. Often engineers find that the standard “90°C cable” is not suitable for radiant heat from a nearby oven or that a standard flexible cable is too brittle to withstand the cold of the wintertime installations or freezer applications. Using appropriate temperature ratings, materials and constructions to manage extreme heat, cold and thermal cycling minimizes insulation degradation, conductor fatigue, cracking of jacket materials and expensive downtime in robotics, drag chains, machine tools, outdoor equipment.
For more than twenty years, Hulk Electric has been manufacturing high-flex and high-temperature silicone industrial cables, assisting OEMs and system integrators to specify cables which can be relied upon from extreme temperature variations. This guide provides practical advice on understanding ratings, material behavior, design strategies, and best practices in specifications, to help avoid common pitfalls and ensure long service life.
What Temperature Ratings Really Mean – Installation vs Operating Conditions
Numbers listed for temperature on cable datasheets shouldn’t be taken at face value, they’re not always a one size fits all figure. It is quite common for people to misinterpret their cables, resulting in premature failures despite the fact that they may be paper rated.
Installation Temperature vs Operating Temperature
Installation temperature is the range of temperatures at which the cable may be safely bent, routed and terminated when first installed. Operating temperature is the range of temperature that the installed cable can endure continuously under normal running condition of the machine. Not all cables can be bent at the same temperatures as they can be operated at—e.g., a cable that is rated for -40°C to +90°C operating temperature may only be able to be bent during installation to -15°C. Sharply curving in very cold conditions can form hidden microcracks that can start to grow when flexing or temperature changes.
Continuous vs Peak Temperature Ratings
Continuous Ratings – the temperature that the cable can withstand continuously throughout its expected life. Short-term or peak ratings are for short-time trips (startup or cleaning, for example). Design always based on continuous ratings of actual cable location temperature including ambient air temperature, radiant heat from hot surfaces and internal heat rise due to current flow. This difference is often ignored which leads to softening around hot machinery or brittleness during outdoor winter conditions.
Material Behavior Under Heat, Cold and Thermal Cycling
Insulation and jacket compounds have different temperature stress reaction. When using silicone industrial cables or silicone flexible cables for high temperature, or low temperature outdoors or in the freezer, the selection of material is very important.
How PVC, PE/XLPE, PUR, TPE and Silicone Respond to Temperature
PE and XLPE are good electrical properties and have higher thermal stability than PVC but are less flexible in extreme temperatures and in high temperature for long time. PUR and TPE provide excellent mechanical toughness and flexibility over a wider moderate temperature range and there are grades available for colder applications.
Silicone is a special extreme application material, with flexibility and electrical property from -60℃ to +200℃. High temperature silicone cables are resistant to cooling down in the cold and softening in the hot, and have excellent resistance to thermal aging. However, silicone may require additional mechanical protection in high-abrasion areas.
Thermal Cycling – Expansion, Contraction and Fatigue
Repeated heating and cooling stresses cause materials to expand and contract at differing rates, generating internal stresses, delamination between layers and increased fatigue, particularly in motion applications. The life of industrial cables can be shortened further by thermal cycling combined with torsion in drag chains or torsion from robot arms.
Low-Temperature Brittleness and High-Temperature Softening
Standard jackets crack when moving in cold storage or in the winter out of doors. Insulation may melt or flow in the vicinity of hot engines or near ovens. These can be reduced by choosing the right industrial cables, as silicone cables that are suitable for high temperatures or special low-temperature types.
Designing for Extreme Heat – Cables Near Ovens, Furnaces and Hot Machinery
Special care is required for mapping on-site cable exposure in high-temperature environments.
Mapping Heat Sources and Real Cable Temperature
Measure not just ambient air but radiant heat from hot surfaces, convective airflow, and self-heating from current. Cables routed close to heating elements experience far higher effective temperatures than the room reading.
Material and Construction Choices for High-Temperature Cables
When exposure temperatures are likely to be above 90°C, consider silicone rubber insulation and jackets. Other features such as heat resistant braids, thick walls or other conductors enhance performance. Our custom high temperature silicone industrial cable has been designed to meet these challenging environments in the food processing, metal and automation industries.
Routing and Mechanical Protection in Hot Areas
Minimize cable exposure to heat sources as much as possible, use protective material around cables (conduits or shields) and keep proper bend radius. Correct installation methods can greatly prolong cable life.
Designing for Extreme Cold – Outdoor, Freezer and Cold-Climate Applications
Cables must be flexible and tough in sub zero conditions.
Low-Temperature Limits and Flexibility Requirements
Always test for both installation and operating low temperatures, especially for flexing applications. Most cables become less flexible at temperatures below -20°C, causing cracks to occur when in motion.
Material Choices for Cold Environments
PUR, TPE and silicone based compounds remain supple in extreme cold. These materials are used in low-temperature flexible cables for outdoor and freezer applications, offering a good performance in the fields of cranes, wind turbines, and refrigerated facilities.
Handling, Installation and Storage Considerations
Pre-warm cables for cold installations and never bend a cold cable into a tight bends on the cold material. Be sure to store cables in temperature controlled areas before deployment.
Thermal Cycling in Motion Applications – Drag Chains, Robots and Repeated Start-Stop Duty
Compound stress is caused by the combination of motion and temperature fluctuations.
Combined Mechanical and Thermal Fatigue
The metabolic stress on cables in drag chains is compounded by temperature swings, which can cause the conductor to break and/or cause wear to the jacket.
Selecting Flex-Rated Materials and Constructions for Thermal Cycling
Use fine stranded conductors, high flex designs and thermally stable compounds such as silicone. These are all demands to which our robot and torsion cables are designed to withstand.
Testing and Life Expectancy Under Real Duty Cycles
Collaborate with manufacturers to validate in a realistic flex and thermal cycling test similar to your application.
Integrating Temperature Ratings into Custom Cable Specifications
Present clarity results in best fit custom solutions.
How to State Temperature Requirements in RFQs and Drawings
Give accurate ranges of: installation temperatures, continuous operating temperatures, peak excursions, cycle frequency, duty type. Do not use “generic” words — be specific and reference measured conditions at cable routing points.
Coordinating Temperature Specs with Other Requirements
Consider temperature requirements, flex life, chemical resistance, voltage and certification. There are always compromises to be made, and expert manufacturers assist in optimizing.
Common Mistakes in Temperature Design—and How to Avoid Them
- Assume that the ratings for indoor conditions are satisfactory near hot processes: Measure the actual cable temperature instead.
- Failing to account for low temperature limits when installing in the colder weather: Plan and pre-warm accordingly.
- Thermal cycling as an afterthought: Embed it in design reviews and testing.
Practical Temperature Design Checklist for Custom Cable Projects
Questions to Answer Before Finalizing Temperature Requirements
- What are the real ambient, radiant and cable-location temperatures?
- What are the installation and operating ranges and are there any extremes and cycling?
- Is the cable in static, flexing or torsion?
- Do there exist chemical or mechanical stresses as well as temperature?
What to Ask Your Custom Cable Manufacturer About Temperature Performance
- The range of materials that are available and the temperature ranges in which they have proven themselves.
- The test data includes the following:The following test data is provided:
- Comparing to reference applications in similar environment.
- The District should provide recommendations for routing and protection.
The correct choice of temperature ratings for custom cables will depend on the application, temperature, and stresses from heat, cold and movements. Engineers can benefit from these issues addressed early for greater reliability and lower total ownership costs.
Our engineers are experts in providing high flexible cables, servo motor cables, robot torsion cables, and high temperature silicone cables for extreme conditions at Hulk Electric. Just provide us with the application information: temperatures, motion profiles, process conditions, etc, and we’ll provide you with customized solutions tailored for long-term performance.