Engineering Systems 2025 - Topic 2: Equipment with Simple Control Systems

Equipment with Simple Control Systems

Defining Control Systems

  • A control system processes an input to produce an output.

  • Process: What must be controlled.

  • Controller: Manages the behavior of another device.

  • Input: A signal applied to control a system for a specific output.

Identifying Equipment with Simple Control Systems

  • Engineering: Surface grinders, compressors, CNC machines, capstan lathes, refrigeration units, presses, turbines, woodworking machines.

  • Mining

  • Textiles: Spinning machines, Weaving machines, Knitting machines.

  • Food Industry: Bottling machines, Packing machines.

  • Other: Traffic lights, washing machines, security alarms.

Control System Functions: Examples

  • Change the speed of motion.

  • Change the direction of motion.

  • Change the direction of rotation.

  • Increase or decrease the force of the machine.

  • Convert to a different type of motion.

Different Robotics Movements - Actuators

  • Linear

  • Rotary

  • Reciprocating

  • Oscillation

  • Hydraulics

  • Pneumatics

  • Electric induction motors

  • Microprocessor

  • Computer software

Classes of Control Systems

Open-Loop Control Systems

  • Utilize a controller or control actuator to obtain the desired response.

  • No feedback mechanism.

  • Diagram:

    • Desired output response -> Actuating device -> Process -> Output

Closed-Loop Control Systems

  • Utilize feedback to compare the actual output to the desired output response.

  • Diagram:

    • Desired output response -> Comparison -> Controller -> Process -> Output -> Measurement

Multivariable Control System

Abbreviations

  • DC: Direct Current

  • AC: Alternating Current

  • CNC: Computer Numeric Controller

  • CAM: Computer Aided Machines

  • CAD: Computer Aided Design

  • PLC: Programmable Logic Controller

  • CPU: Central Processing Unit

  • IO: Input/Output

  • IC: Integrated Circuits

CNC Machine Programming

  • Actions required: (M Codes)

  • Direction of movement: (X+, X-, Y+, Y-, Z+, Z-)

  • Dimensions: Example: X67,369X67,369

  • Movements: (G-codes)

  • Absolute programming: All coordinate values are relative to the origin.

  • Incremental: Movement does not take your part zero point into consideration.

Electronic Control Systems

Input (Sensor):

  • Temperature gauges

  • Pressure gauges

  • Switches

  • Thermostats

  • Proximity switches

Process:

  • Decision taken by microprocessor

Output:

  • Output signal

Electronic Control Systems - Examples & Applications

  • PLC

  • Servo-motors

  • Stepper motor

  • Conveyor belts

  • Traffic lights

  • Electrical generation plants

  • Railway switching

  • Bottling plants

  • Motor vehicles

Electrical Control Systems

  • Use switches and micro-switches

  • Micro-switch: Semi-automatic control

  • Tripping devices: Automatic control

Control Systems - Hydraulic & Pneumatic

Hydraulic motion can be controlled by:

  • Stop valves

  • Reverse valves

  • Pilot valves (large applications)

  • Throttle valves (cater delay)

  • Sequence valves to hold back motions

  • Relief valves (uniform pressure)

Pneumatic spool valve operating an actuator

  • When the valve button is not pressed, the piston moves out, and when it is pressed, it moves back.

Control Systems - Mechanical

Brakes and clutches

  • Principal types of clutches in control systems are:

    • Electrically operated friction disc type

    • Eddy current type clutches

    • Magnetic fluid type clutches

      Pneumatic

  • Cams

  • Screw thread

  • Backlash

  • Digital readout

Safety Precautions When Setting or Operating SCS

  • Study the machine before operating.

  • Start and Stop switch must be protective to the machine.

  • Know where to start and stop the machine in case of emergency.

  • Levers which cause rapid movement should only cause movement if held by the operator.

  • Hand wheels should automatically disengage when not being in use.

  • It is very important to read the manufacturer’s guide carefully.

    General safety rules

  • Avoid loose clothing.

  • Remove jewelry.

  • Do not wear gloves when operating.

  • Wear hearing protection.

  • Keep all guards in position.

  • Keep material away from moving materials.

  • Keep area around the machine clean.

  • Never leave the machine unattended, isolate and lockout the machine.

Implications of Non-Conformance with Manufacturer’s Specifications

  • The machinery will wear out sooner.

  • The machinery will be less efficient.

  • The chances of breakdowns will increase.

  • The machinery will become unsafe to use.

  • Using unsafe machines and unsafe equipment will increase incidents and accidents.

Unit 3: Setting and Operating Equipment with SCS

The importance of setting the machines and equipment correctly:

  • One machinery can be used for different operations.

  • Machine set-up increases production.

  • Set-up times can be reduced by a number of methods.

  • Keeping tools in their proper places and getting tools and equipment ready beforehand would save time.

Plan of Operation - Isolating the Machine

  • The name of the equipment.

  • The title of the manual of the machine.

  • Name of the operator.

  • Name of setter

  • Date

  • List of tools required.

  • Safety equipment that is needed.

  • Sequence of operation of setting the machine and equipment.

  • The starting time.

  • The setting end time.

  • Stop the machine.

  • Isolate the machine from the power source.

  • Locking out and tagging out the energy source.

  • Letting off energy stored.

  • Putting up a notice to inform people of the reason for disconnection.

  • Double checking with a tester making sure there are no live conductors.

Setting the Drilling Jig and Machine / Starting Operating Equipment

  • Gather all tools and equipment you are going to need.

  • Clean the machine table.

  • Clean the jig and remove sharp edges.

  • Set the correct speed and feed for machining 8 mm and drill bit.

  • Mount a sharpened drill bit.

  • Place the jig onto the table of the machine.

  • Tighten the bolts holding the jig on the table.

  • Set the depth stop as per the piece, in this case, 15 mm.

  • Switch on the drill machine and the correct coolant.

  • Drill and measure if the size is correct.

  • Insert another work piece and repeat all the steps.

  • Remove all tools and equipment you may have used to adjust the machine.

  • Ensure all bolts and nuts are well tightened.

  • Ensure all guards are in place and well secured.

  • Follow all safety procedures before starting.

  • Make sure the work piece is securely clamped.

  • Set the correct cutting tool for the specific material.

  • Allow the machine to warm up first.

During Operation

  • As it starts operating, keep an eye, checking if everything is working properly.

  • Monitor gauges like temperature, pressure, and electrical meters.

  • Monitor accuracy of machined components.

  • Re-adjust the cutting tools if necessary.

Maintaining Equipment with SCS

Caring and Maintaining

  • Lubrication

  • Inspection

  • Practical skills

  • Theoretical skills

  • The right attitude

  • Troubleshooting skills

Starting the Equipment After Maintenance

  • Inspect the machine or equipment if it is working as expected.

  • Notify all employees who are affected that the machine will be returned to service.

  • Checking all operations are easily accessible and safe.

  • Double check if all bolts and nuts are well tightened.

  • Check if all tools were removed on top of the equipment.

  • Remove the lock-out device.

  • Energize the machine.

  • Make sure there are no strange noises and overheating.

Service and Maintenance Report

  • Example report includes details such as:

    • Machine name (XYZ Milling machine)

    • Model (Vera 365)

    • Serial number (14692 A-2004)

    • Department (Toolroom Machine)

    • Dates (Service, Start, End)

    • Times (Start, End)

    • Service Technician, Operator, Operator Number

    • Spares used (e.g., V-belts, ball bearings)

    • Consumables used (e.g., Shell Tellus oil, bearing grease, soluble oil, paraffin)

    • Comments on machine condition, potential issues, and operator care.