■ Robots Contain Many Heat Sources
Robots have many heat sources.
● Motors
● Gears
● Reduction gears
● Batteries
● Control boards
● Sensors
● AI computing chips
● Communication modules
● Power supply circuits
These all operate at the same time.
In particular, robots are different from stationary electronic devices.
They move. They bend. They stop. They accelerate. They carry loads. They come into contact with people.
Each time, they use energy and generate heat.
■ The Most Difficult Part Is the Joints
What is especially important in robot heat problems is the joints.
Motors, reduction gears, sensors, wiring, and control components are concentrated in the joints.
Moreover, to make them move as naturally as humans, joints must be small, light, and high-output.
In other words, the joints end up in a state in which heat sources are densely packed into a small space.
This is the core of the robot heat problem.
■ Higher Output Means More Heat
Robots need power.
Carrying heavy objects.
Moving quickly.
Controlling finely.
Operating for long periods.
Trying to achieve these raises the load on motors and control circuits.
As the load rises, heat generation also increases.
In other words, improving robot performance tends to go hand in hand with increased heat generation.
■ Miniaturization Keeps Heat from Escaping
On the other hand, robots are also required to be smaller.
If they are too large, they cannot enter human living spaces.
If they are too heavy, power consumption increases.
If they are too thick, their range of motion becomes narrower.
That is why robots are made as small and light as possible.
However, miniaturization reduces the space for releasing heat.
In other words, in robots, wanting high output and wanting to make it small collide head-on.
■ The Closer to People, the More Difficult Heat Problems Become
With large robots in factories, even if they get somewhat hot, situations in which people touch them directly are limited.
With collaborative robots and humanoid robots, however, things are different.
They move near people.
They work in the same space as people.
In some cases, they touch people.
At such times, a hot robot surface becomes a problem.
It may lead to
● Discomfort
● Risk of low-temperature burns
● Reduced safety
● Reduced trust
In other words, in robots close to people, a temperature at which internal components do not break is not enough.
It must be a temperature at which people can touch it with peace of mind.
■ It Must Be Cooled Quietly
In robots, there are also constraints on cooling methods.
Using a large fan might cool it.
However, there are problems such as
● Noise
● Added weight
● Increased power consumption
● More moving parts
● Increased risk of failure
● Reduced dustproofing and waterproofing
Especially in robots for homes, medical care, nursing care, and offices, noise becomes a major problem.
In other words, in robots, cooling quietly is important.
■ Robots Are a Combined Problem of Heat × Light Weight × Safety
Heat problems in robots are not simple heat dissipation problems.
In reality,
● Heat
● Weight reduction
● Quietness
● Safety
● Flexibility
● Durability
● Dustproofing and waterproofing
● Mobility
● Volume production stability
are all intertwined at the same time.
In other words, in robots, just cooling it does not make it work.
Being able to move.
Being light.
Not breaking.
Being safe for people.
Being mass-producible.
Only with all of this included does it become thermal management.
■ Wiring, Sensors, and Boards Are Also Affected by Heat
Robots contain many wires and sensors.
Each time a joint moves, the wiring bends.
It is also subjected to vibration.
It is also subjected to temperature changes.
Heat may cause materials to harden, adhesive materials to degrade, or insulating properties to change.
In other words, robot heat problems are not a problem of the motors alone.
They also affect the films, tapes, insulating materials, cushioning materials, and fixing materials inside.
■ Adhesion and Fixing Change with Heat
Inside robots, tapes and adhesives are sometimes used to fix components.
However, when heat is applied,
● Reduced adhesive strength
● Peeling
● Shifting
● Hardening
● Deformation
● Lifting
may occur.
And when lifting or peeling occurs, the escape route for heat also changes.
In other words, in robots, a relationship arises in which heat changes adhesion, and changes in adhesion also change heat.
This is quite important.
■ Points of Contact Between Dissimilar Materials Become Heat Problems
Various materials are used in robots.
● Metals
● Resins
● Rubber
● Films
● Tapes
● Sensors
● Boards
● Insulating materials
● Heat dissipation materials
These differ in how they expand with heat.
When the temperature changes, each moves separately.
As a result,
● Lifting
● Peeling
● Stress concentration
● Poor contact
● Abnormal noise
● Deformation
can occur.
In other words, in thermal management for robots, interfaces between dissimilar materials are important.
■ AI Will Increase Heat Problems Further
From now on, robots will carry even more AI.
Image recognition.
Speech recognition.
Posture control.
Autonomous movement.
Dialogue with people.
Work decisions.
Doing these requires computation.
As computation increases, heat generation also increases.
In other words, in future robots, heat from motors and heat from AI computation will exist at the same time.
Robots are becoming beings whose muscles and brains both generate heat.
■ Batteries Also Get Hot
For robots to move cordlessly, batteries are needed.
Batteries generate heat both when charging and when discharging.
Especially in robots that run at high output for long periods, battery thermal management also becomes important.
In other words, in robots,
● Motor heat
● Control board heat
● AI chip heat
● Battery heat
must be considered at the same time.
■ Heat Accumulates During Long-Term Operation
It is not enough for a robot to move for just a moment.
In factories and logistics, long-term operation is required.
In nursing care and medical care, continuing to operate stably is required.
When operating for long periods, heat accumulates.
Even if there are no problems in short-term tests, the temperature may keep rising during long-term operation.
In other words, in robots, rather than momentary performance,
thermal stability during continuous operation is important.
■ The Researcher's Perspective: A Robot Is a Machine That Moves While Carrying Heat
In research and development,
● High-efficiency motors
● Lightweight heat dissipation materials
● Flexible heat dissipation materials
● Compact cooling mechanisms
● Highly heat-resistant insulating materials
● Temperature control by AI
● Battery thermal management, and so on become important.
In robots, it is required not just to cool, but to control heat while moving.
■ The Shop-Floor Perspective: Because Robots Move, Contact Conditions Change
The difficulty with robots is that they move.
Even if components are in contact when stationary, the state of contact may change during operation.
● Bending
● Vibration
● Impact
● Repetitive motion
● Cable routing
● Component shifting
● Thermal expansion
These change the state of heat dissipation and insulating materials.
In other words, in robots, thermal management that works in a stationary state is not enough.
Thermal management that also works during operation is needed.
■ Lamination and Supply Format Become Important
Inside robots, many components must be placed in narrow spaces.
That is why heat dissipation materials, insulating materials, fixing materials, cushioning materials, and so on are required to be
● Small
● Thin
● Complex in shape
● Compatible with curved surfaces
● High-precision
Furthermore, in volume production, they must be made into a form that can be supplied stably in automated processes.
In other words, in thermal management for robots, not only the materials themselves,
but also how to process them, how to apply them, and how to supply them is important.
■ OTIS's Perspective
From OTIS’s perspective, what matters in robot heat problems is
● Thin-film processing
● High-precision die-cutting
● Heat dissipation material processing
● Insulating material processing
● Adhesive material processing
● High-precision lamination
● Lamination of dissimilar materials
● Processing of components that conform to curved surfaces
● Reel supply
● Support for automation
● Volume production stability
In robots in particular, it is important that they are small, thin, and light, and work even while moving.
■ What OTIS Can Do
At OTIS, through
● Heat dissipation sheet processing
● Insulating sheet processing
● Adhesive tape processing
● Film processing
● High-precision die-cutting
● Microfabrication
● High-precision lamination
● Stacking of irregular shapes
● Support for reel supply
● Designing supply formats for automated processes
and more, we may be able to contribute to making functional components for robots work in volume production.
In robots in particular, many components are used in joints and narrow spaces, so
high-precision processing, flexible supply formats, and volume production stability are important.
■ Outside OTIS's Expertise
On the other hand, OTIS is not a company that specializes in
● Robot body design
● Motor development
● Reduction gear development
● Robot control software development
● AI algorithm development
● Battery cell development
However, in the area of making thermal management components, insulating materials, and fixing materials used inside robots work in volume production processes,
we may be able to play an important role.
■ Industries Where This Technology Will Be Important
★★★★★ Industrial robots
★★★★★ Collaborative robots
★★★★★ Humanoid robots
★★★★☆ Logistics robots
★★★★☆ Medical and care robots
★★★★☆ Automation equipment
■ Summary
The more robots move, the more heat they carry
Robots have motors, control boards, sensors, AI chips, and batteries.
In other words, a robot is a moving heat source.
Moreover, from now on, robots will become smaller, higher-performance, and closer to people.
As a result, heat problems will become even more difficult.
In thermal management for robots, just being able to cool it is not enough.
Light, quiet, safe, stable even during operation, and workable even in volume production.
Only when all of that is achieved does it become true thermal management.
Column Supervisor: Koji Kakumoto (President, OTIS Co., Ltd.)
After studying abroad and working in planning and development at a trading company, he joined OTIS Co., Ltd. in 2011. While primarily working in the Corporate Planning Department, he has also served concurrently in manufacturing and technical divisions, and since 2018 has served as President, working to drive business growth and strengthen the organization.
This article is a general technical explanation intended for educational purposes and does not refer to any specific company, product, or technology.
