■ Weight Reduction Is Extremely Important in Robots
Weight is a major issue for robots.
If an arm becomes 1 kg heavier, the motor supporting that weight must also be made larger.
The motor becomes larger.
Power increases.
The battery becomes larger.
Weight increases further.
In other words,
weight increases cascade.
That is why, in thermal management too,
large copper plates
or thick heat sinks
cannot simply be added.
■ Weight Reduction and Heat Dissipation Conflict
In thermal management, increasing the amount of metal generally makes it easier to spread heat.
In robots, however,
adding metal makes it heavier.
So heat must be released while suppressing weight increase through
● Thin metal foils
● Graphite
● Aluminum
● Integration with the structure
In other words, not only cooling performance per watt,
but the idea of thermal performance per gram is also important.
■ In Robots That Interact with People, Surface Temperature Also Matters
Collaborative robots.
Service robots.
Humanoids.
These move near people.
That is why, if enclosure surfaces become hot, it leads to problems of
● Discomfort
● Burns
● Safety
In other words, it is not enough just to release heat into metal frames.
Heat must not be concentrated where people touch.
■ It Is Necessary to Choose Where to Release Heat
For example,
motor heat is released into the frame.
But people grip that frame.
That is a problem.
So heat is guided to
● Surfaces people do not touch
● Large metal surfaces
● The back
● Internal heat dissipation areas
In other words, in robots, it is necessary to design even
where to release heat.
■ Waterproofing/Dustproofing and Air Cooling Are a Poor Match
Factories.
Outdoors.
Logistics.
Cleaning.
Robots used in such environments need
waterproofing and dustproofing.
However, forced air cooling requires taking in outside air.
Taking in outside air may let in
● Dust
● Water
● Oil
● Mist
In other words, the contradiction arises:
you want to seal it.
But you want to release heat.
■ In Sealed Robots, Enclosure Heat Dissipation Becomes Important
When the enclosure is sealed,
internal heat must be transferred to the enclosure
and released outside from the enclosure surface.
For example, a heat path is created:
Heat-generating component
↓
TIM
↓
Internal frame
↓
Exterior
Here,
● TIM
● Graphite
● Metal foils
● Thermally conductive adhesives
become important.
■ Waterproofing Also Requires Seal Materials
Robots have many openings, such as
joints,
covers,
connectors,
and sensor windows.
Here,
● Gaskets
● Foam seals
● Waterproof tapes
are used.
In other words, in robots, the combined challenge of heat + waterproofing arises.
■ Seal Materials Can Also Trap Heat
Suppose the enclosure is completely sealed to increase waterproof performance.
Then heat generated inside has difficulty escaping.
In other words,
there are cases where the higher the waterproofing, the harder thermal management becomes.
That is why
● Sealing
● Enclosure heat dissipation
● Heat spreading
must be considered together.
■ Robots Also Have Large Vibrations
Motors.
Reduction gears.
Walking.
Driving.
These generate vibration.
Thermal management components are subjected simultaneously to
● Vibration
● Temperature changes
● Repetitive motion
That is why
TIM may shift.
Adhesives may peel.
Thin films may fatigue.
In other words, components for robots need thermal performance + mechanical durability.
■ Adhesives Serve Both to Fix and to Absorb Vibration
Inside robots, adhesives are used to fix
sensors,
films,
heat dissipation materials,
and insulating materials.
A flexible adhesive layer can sometimes absorb vibration.
On the other hand, it may creep at high temperatures.
In other words, what matters is not only being able to fix, but maintaining position even under high temperature and vibration.
■ Insulation Is Also Important
In robots,
● High-voltage batteries
● Motor drivers
● Power supplies
● Metal frames
are close together.
That is why
● Insulating films
● Insulating sheets
● Insulating TIM
are needed.
Here too, there is the challenge that
heat should pass through.
Electricity should be stopped.
■ Higher Voltages Also Raise Insulation Requirements
As robots become higher in output, power supply voltages may also be raised.
Raising the voltage can reduce current for the same power.
On the other hand, requirements for
insulation distance
and
dielectric strength
become higher.
In other words, the higher performance of robots makes not only heat but also insulation design more difficult.
■ Heat and EMI Also Exist at the Same Time
In robots,
motors,
inverters,
high-speed communication,
and AI boards
are in the same enclosure.
That is why EMI countermeasures are also important.
For example, copper foil is used as EMI shielding.
But copper foil also conducts heat.
In other words, a single metal foil may relate to both
noise countermeasures and thermal management.
■ Adding EMI Materials Also Changes the Heat Path
Shielding materials.
Conductive tapes.
Metal foils.
Adding these can make heat flow somewhere else.
Conversely, metal foil for heat dissipation may create electrical coupling.
In other words, there are cases where heat and noise cannot be designed separately.
■ Robots Are a Good Match for Composite Functional Components
Space inside robots is limited.
That is why placing
insulating films,
heat dissipation materials,
EMI materials,
and adhesives
separately increases the number of parts.
Depending on the application, there is great value in
giving multiple functions to a single component.
For example, a structure of
Graphite
＋
Insulating film
＋
Adhesive
■ Integration Can Reduce Assembly Processes
If a customer performs three processes:
applying insulating material,
applying graphite,
and applying fixing tape,
integrating them in advance may reduce this to
a single application.
Because robots have many parts, the value of process reduction is large.
■ However, It Is Important Not to Lose Flexibility
When used in movable parts of robots,
over-lamination makes components stiff.
Then they may
● Not bend
● Peel
● Concentrate stress
In other words, a balance between
multifunctionality and flexibility is needed.
■ Automation Equipment Itself Is Also Made by Automation
As production quantities of robots and automation equipment increase, one also wants to automate their assembly.
So
● Insulating films
● TIM
● EMI materials
● Adhesive components
● Seal materials
are supplied on reels,
and automatically peeled,
automatically picked up,
and automatically applied.
In other words, the robot market is
the side being automated and, at the same time,
the side made by automation.
■ Many Components Are a Good Match for Reel Supply
There are many small, irregularly shaped film components inside robots.
These are
arranged at a constant pitch on a carrier
and supplied in reel form.
This makes it easy to feed them directly into equipment.
In other words, the value of a processing company expands from cutting components
to making them into a form that can be fed directly into the customer’s automated equipment.
■ Shapes That Are Easy for Image Recognition Are Also Needed
In automated application, cameras recognize the components.
However,
transparent films,
black graphite,
and glossy metals
can be difficult for image recognition.
That is why
● Notches
● Recognition holes
● Asymmetric shapes
● Marks
are sometimes provided.
In other words,
shapes that are easy to automate become part of the product design itself.
■ Robot Positional Accuracy Also Changes with Temperature
In precision robots,
dimensional changes due to heat may affect positional accuracy.
Arms.
Frames.
Motors.
Reduction gears.
As these warm up, their dimensions change slightly.
Even if not as extreme as machine tools or semiconductor manufacturing equipment,
it may not be negligible in high-precision applications.
In other words,
the heat problems of robots are not only about preventing failure, but also a problem of positional accuracy.
■ Warm-Up Operation May Be Needed
The body temperature differs between right after start-up and after long operation.
Then
● Friction
● Dimensions
● Sensor states
may also change.
That is why, in precision applications,
there is also the idea of operating for a certain time to stabilize temperature before use.
In the future,
it is also conceivable that AI will predict the temperature state and compensate.
■ Thermal Management by AI Control
A robot knows what it is about to do.
For example,
carrying a heavy load.
Walking at high speed.
Stopping for a long time.
Fast charging.
If these motion schedules are known,
heat generation can also be predicted to some extent.
So control may become possible such as
cooling before high-load motion,
distributing load to other motors,
and lowering AI computing load.
■ Cooling Power Also Affects Operating Time
In battery-powered robots,
fans,
pumps,
and cooling equipment
also consume the battery.
In other words, if cooling power increases,
the time it can move becomes shorter.
That is why, in robots, not only cooling capacity but also how many watts are used for cooling is important.
■ Suppressing Heat May Also Make Batteries Smaller
Reducing cooling power.
Raising motor efficiency.
Raising AI computing efficiency.
If these reduce total power consumption,
the required battery capacity may also be made smaller.
In other words, thermal design also indirectly affects battery weight.
■ In Humanoid Robots, Heat Problems Become Even Harder
In humanoids,
the head,
torso,
arms,
legs,
and joints
each contain
● Motors
● Sensors
● Wiring
Furthermore, the torso tends to concentrate
● AI computers
● Batteries
● Power supplies
In other words,
many heat sources enter a limited, human-sized space.
Moreover, it is used in the same space as humans.
You want it quiet.
You want it light.
You do not want the surface hot.
These are very severe thermal conditions.
■ In the Future, "Thermally Designed Skeletons" May Become Important
The robot’s frame or skeleton is designed
not merely as a structure that supports loads, but as
a structure that carries heat.
For example,
motor heat flows into the arm.
AI board heat flows into the back frame.
Battery heat is released into parts people do not touch.
In other words, it is the direction of integrating structural design and thermal design.
■ The Researcher's Perspective: Robot Heat Problems Are Problems of "Multiple Heat Sources, Movement and Weight"
AI servers are basically fixed.
Robots move.
Moreover, they have the characteristics that
● Heat generation changes over time
● Posture changes
● Heat sources are distributed
● There are weight constraints
● There are battery constraints
That is why, rather than looking only at maximum heat generation,
it is necessary to consider heat across the entire operating scenario.
■ The Shop-Floor Perspective: Finding the Hot Spots Is Not Enough
The motor is hot.
The GPU is hot.
The battery is hot.
If cooling components are added individually for each,
weight increases.
Parts increase.
Wiring becomes complex.
That is why, in robots, not only countermeasures for each heat source,
but how to distribute heat across the whole body must be considered.
■ Things to Check at the Design Stage
In thermal management for robots and automation equipment, at least the following need to be checked.
Motors and drive units
● How much heat is generated at maximum torque?
● Is heat generated even during holding?
● Can heat be released into the frame?
● Does heat affect sensors or reduction gears?
AI and electronic circuits
● How much heat do GPUs and CPUs generate?
● Where are the hot spots?
● Does air cooling work?
● Are graphite or vapor chambers needed?
● Can metal frames be used?
Batteries
● How much heat is generated at high load?
● Is there interference with heat from AI boards or motors?
● What is the temperature during fast charging?
● What insulation and thermal insulation are needed?
Weight reduction
● Is the weight of cooling components acceptable?
● Can structural members be used as heat paths?
● Can metal plates be replaced with thin-film materials?
● Can graphite be used?
Movable parts
● Is there repeated bending?
● Can thermally conductive materials withstand bending?
● Will adhesives shift with vibration?
● Is wiring heat a problem?
Insulation and EMI
● Where are the high-voltage parts?
● Is insulation from metal frames sufficient?
● Do EMI shielding and heat paths interfere?
● Can metal foils be used for multiple functions?
Waterproofing and dustproofing
● Is sealing needed?
● Where will heat go after sealing?
● Can seal materials withstand high temperature and vibration?
● Is the exterior surface temperature safe?
Volume production and automation
● Can small components be supplied on reels?
● Can they be automatically peeled and applied?
● Are shapes easy for image recognition?
● Can multiple functional materials be integrated?
In other words, in robots, it is necessary to consider
heat, weight, insulation, waterproofing, vibration and automation at the same time.
■ OTIS's Perspective: Robots Are a Very Good Match for OTIS's Processing Technologies
OTIS is
not a robot manufacturer.
Not a motor manufacturer.
Not an AI chip manufacturer.
Not a battery manufacturer.
However, inside robots there are many thin-film functional components, such as
● TIM
● Heat dissipation sheets
● Graphite
● Copper foil
● Aluminum foil
● Insulating films
● EMI materials
● Foams
● Adhesives
● Seal materials
● Sensor fixing materials
Moreover, robots have many combined challenges, such as
heat + weight
heat + insulation
heat + EMI
heat + waterproofing
heat + vibration
heat + automation
This easily fits OTIS’s strengths.
■ Where OTIS Should Aim
Not the finished robot itself.
Not the AI chip itself.
Not the motor itself.
What to target are the functional components that exist
between heat sources and structures
between electronic components and metal enclosures
between sensors and fixing parts
For example,
● TIM between motors and metal frames
● Graphite around AI boards
● Insulating heat dissipation components for power semiconductors
● Heat dissipation components around cameras and LiDAR
● Metal foil for EMI + heat dissipation
● Insulating components around batteries
● Waterproof seal materials
● Thin-film adhesives for fixing sensors
● Thin-film functional materials for movable parts
■ Not "Adding Components," but "Giving Multiple Functions to One Component"
Weight reduction is important for robots.
Adding components increases
weight,
thickness,
and assembly processes.
So the idea of
Graphite
＋
Insulating material
＋
Adhesive
or
Copper foil
＋
EMI function
＋
Heat dissipation function
giving multiple functions to a single component
is a good match.
This is an area OTIS can propose in collaboration with material manufacturers.
■ For Robots, "Light Processing Proposals" Become Valuable
For thermal performance alone, there are situations where a thick copper plate would do.
In robots, however,
how many grams it adds
is important.
So unnecessary material is reduced by
● Placing metal foil only where needed
● Partial lamination
● Processing graphite into the required shape
● Placing adhesive only where needed
In other words, precision processing can contribute not only to
miniaturization,
but also to weight reduction.
■ Collaboration with Automation Equipment Manufacturers Is Also Important
When delivering components to robot manufacturers,
if they can be proposed not as mere loose parts but as
reel components that can be applied by automated machines,
their value increases.
OTIS makes the components.
The equipment manufacturer makes the application equipment.
They are proposed to the customer as
components + equipment.
This is a very good match for the robot and automation market.
■ What OTIS Can Do
At OTIS, through
● TIM processing
● Heat dissipation sheet processing
● Graphite processing
● Copper foil processing
● Aluminum foil processing
● Insulating film processing
● EMI material processing
● Foam processing
● Adhesive processing
● Seal material processing
● Sensor fixing component processing
● High-precision die-cutting
● Microfabrication
● Thin-film processing
● High-precision lamination
● Lamination of dissimilar materials
● Partial lamination
● Half-cutting
● Reel-to-reel processing
● Supply formats for automated application
● Integration of multiple functional materials
● Image inspection
● Volume production stabilization
we may be able to contribute to
turning functional materials inside robots into light, thin components that can be assembled automatically.
■ Outside OTIS's Expertise
OTIS is not a company that specializes in
● Robot body design
● Motor design
● Reduction gear design
● AI algorithm development
● GPU design
● Battery cell development
● Thermal analysis of entire robots
● Dedicated CFD analysis
However, by working with
● Robot manufacturers
● Motor manufacturers
● Semiconductor manufacturers
● Material manufacturers
● Battery manufacturers
● Automation equipment manufacturers
we may be able to contribute in the area of
making thin-film components responsible for heat, insulation, fixing, EMI and sealing work in volume production.
■ Markets Where This Technology Will Be Important
★★★★★ Humanoid robots
★★★★★ Industrial robots
★★★★★ Collaborative robots
★★★★★ Autonomous mobile robots (AMR)
★★★★★ AI robots
★★★★☆ Medical and nursing care robots
★★★★☆ Drones
★★★★☆ Automation equipment
★★★★☆ Edge AI devices
■ Summary
Robot thermal management does not work just by “adding cooling components”
In next-generation robots,
motors,
AI computing,
batteries,
power supplies,
sensors,
and communications:
many heat sources enter a narrow body.
Moreover, there are demands to
make it lighter,
make it smaller,
make it quieter,
make it waterproof,
run it for long periods,
and not have it feel hot when people touch it.
That is why, in robot thermal management,
it does not come down to adding large heat sinks.
Using the existing frame as a heat path.
Spreading heat with graphite.
Guiding heat in the required direction with metal foil.
Connecting interfaces with TIM.
Stopping electricity with insulating materials.
Waterproofing with seal materials.
Suppressing noise with EMI materials.
And, if necessary, combining multiple functions into a single thin component.
In other words, in robots, rather than adding more thermal management parts,
the idea of turning the body itself into a thermal management structure is important.
And in volume production, those components must be made
thin,
light,
accurate,
supplied on reels,
and able to be applied automatically.
What OTIS should target is not the robot itself.
It is the common challenges that exist in large numbers inside it:
heat, insulation, EMI, fixing, waterproofing, thin films, weight reduction and automation.
The closer robots come to humans,
the higher AI performance becomes.
The number of motors increases.
Sensors also increase.
Batteries also become larger.
But one does not want to make the body larger.
That is why one of the challenges that remains in the end is
“Within this small body, where should the heat go?”
And what supports the answer is not only huge cooling equipment.
It is thin functional components of just a few tens of μm to a few mm.
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.
