level switch
wants to know level of fluid
proximity switch
- non contact
- three kinds: inductive (ferrous objects), ultrasonic, and capacitance (non-ferrous)
off delay timer switches
delay only when they are deenergized
cushion spear/sleeve
tiny flow control valves inside of a cylinder
emergency switch
- keeps circuit safe
- will stop circuit in middle of cycle
- cycle stop will wait until cycle has ended
flow control valves need to be as close as possible to cylinder:
difficult to control air because air is very compressible
pressure switch
- turns compressor on/off
- if it fails, safety relief valve kicks in and sends air to the atmosphere
pressure regulator
usually set around 120 psi because it doesnt need very high pressure
pneudraulics
smooth movement of hydraulics with cheapness of pneumatics
determining compressor size
- add up all airflows needed for all cylinders and motors
- have some stand by capacity
- be ready for future expansion
sizing of volume or receiver tank for compressor
use a nomograph
dryers
- water is the enemy
- volume tank has manual/automatic drain
3 types of dryers
- absorption: uses chemicals that absorb water (LiCl2, Al2O3)
- adsorption: keeps water on surface, uses silicon gel
- refrigerant type dryer (heat dryer)
FRL
filter, regulator, lubricator
Bernoulli’s law
velocity goes up so pressure goes down
max vacuum pressure
30” Hg
air motor types
- radial/axial piston
- sliding vane
- gear
couple
two forces that are equal and opposite but not in line
types of non-contact sensors
- photo eye
- proximity: inductive, capacitance, ultrasonic
- pressure switch/temperature switch
- level switch
contact sensor
limit switch
photo eye scanning methods
- opposed scanning: one side is a transmitter, one side is a receiver, they must line up perfectly
- reflective scanning: transmitter sends beam to reflective surface and reflective sends back to receiver
- diffused scanning: transmitter sends beam to object and object acts as reflective to send beam back to receiver
receiver side: how does it work
- photo resistor: when light hits it, resistance changes
- photo diode: when light hits it, it conducts
- photo transistor: when light hits base, it conducts
- photo voltaic: has voltage when light hits it
detent
a small spring that prevents spool from accidentally shifting
relay
a transfer device for electrical energy, consists of a coil and contact(s)
holding relay principle
coil relay is locked in through its own contact
manual mode
- operator can control certain components without circuit automatically operating
- beneficial for troubleshooting
- operator must push jog buttons to turn on certain devices
- if on auto, these buttons are locked out
guard door
put around circuit, if guard door is open = circuit wont work
rules for electrical circuit design
- push buttons and contacts always go on the hot side (left)
- solenoids, relays, lights, etc. always go on the cold side (right)
center drill vs regular drill
center drill drills a hole into the object and then regular drill drills the rest of it
5 ported valves
use 5 ported valves to control speed
venturi suction cup
creates a vacuum which creates a suction cup grip = picks up/lets go of part
hydraulic servo valve
- directional and flow control valve
- can position spool anywhere in stroke
desirable features of pneumatic systems
cleanliness, high speeds, temperature stability, and overload safety
undesirable features of pneumatic systems
cost, force, compressibility, and lubrication
3 types of compressors
reciprocating piston, diaphragm, and slide vane rotary