Inductive Sensors
• Inductive sensors use magnetic fields to find metal things.
These sensors see only metals 🧲
• They work at very short distances.
The closer the metal gets, the stronger the signal becomes ⚙️
• When metal enters the field, the sensor feels it.
This happens because the magnetic field changes ✨
• The change reduces the electric flow in the sensor coil.
This drop sends a signal to other machines ⚡
• The coil has a ferrite core to make the field stronger.
The field looks like a cone ⛰️
Correction Factors for Inductive Sensors
• Each metal changes the field in a different way.
This means the sensor sees them at different distances 🧪
• A table shows how much each metal reduces the range.
Copper and aluminum reduce it a lot 🧯
• Steel (ASTM A240) gives the best results.
Stainless steel can be magnetic or not 🛡️
Capacitive Sensors
• Capacitive sensors use electric charge to feel materials.
They detect things that hold electric charge well ⚗️
• They have two plates with space between them.
This space holds a charge when something gets close ✋
• When an object comes near, the charge changes.
This change tells the sensor something is there 🧼
• They can detect solids, liquids, and even powders.
Water and alcohol are easy to detect because they hold lots of charge 💧
Dielectric Constant (εr)
• Different materials hold charge in different ways.
This ability is called dielectric constant (εr) 🔢
• Air holds almost no charge (εr = 1).
Water holds a lot (εr = 80) 💦
• Wood changes depending on how wet it is.
Wet wood is easier to detect than dry wood 🌳
Optical Sensors
• Optical sensors use light to see objects.
They shine a light and wait to see it bounce back or get blocked 💡
• A small LED sends the light out.
If something gets in the way, the light changes 🚦
• A photodetector sees the light and sends a signal.
This signal tells machines that something is there 📸
• They work without touching anything.
That makes them very fast and clean 🧼
Ways Optical Sensors Detect Things
• Light barriers use two parts far apart.
The object blocks the beam between them 🚧
• Reflected light sensors have one part.
The object bounces light back to it 🔁
• Polarized sensors use a special reflector.
It only reflects light in one direction 🪞
• Perfect Prox (Perfect Proximity) sensors ignore the background.
They focus on one short area and skip everything else 🔍
Sensor Applications in Machines
• Sensors help machines know if bottles are present.
Even clear bottles can be detected with special sensors 🍼
• Sensors check if metal parts arrive on time.
This is key in machining processes 🛠️
• Capacitive sensors measure how full a tank is.
They work through tank walls or windows 🛢️
• Thru-beam sensors know how high something is stacked.
They count layers by seeing when a beam breaks again 📦
Other Useful Jobs for Sensors
• Carton sensors make sure boxes are filled right.
If the level is too low, they stop the line 📤
• Lid sensors check if cans are closed.
They look from above or from the side 🥫
• Vehicle sensors open toll gates.
They work even in rain or snow 🚗
• Sensors inside bins count plastic pellets.
They keep bins from overflowing 🧃
• Assembly sensors know if parts are in place.
They ignore reflections and bright lights 🧩
• Paper sensors measure filter length.
They cut at the right moment ✂️
• Speed sensors read turning shafts.
They help keep motors safe 🔄
• Valve sensors show if something is open or closed.
This helps avoid leaks 🧯
• Web sensors find breaks in thin films.
They stop the machine before damage spreads 🎞️
• Paper sensors work in tight spots.
They still see the paper clearly 📃
• Forklift sensors prevent damage.
They warn drivers when a beam breaks 🚨
What We Learn from All Sensors
• Inductive sensors love metal.
They are strong and very exact 🛠️
• Capacitive sensors love change.
They find nearly everything 🧃
• Optical sensors love light.
They see from far away without touching anything 🔦
• Each sensor has a perfect job.
Knowing which one to use makes machines smarter 🧠
My Diary - Leonardo Cardillo 