What is production automation?
Automation means machines do the work of making things, and humans plan, set up and watch. Why do it? Machines are fast, never tired and repeat a job exactly. They can also do dangerous jobs. Costs: machines are expensive, need skilled people, and jobs change.
CAD/CAM
CAD (computer-aided design) is drawing and testing a product on a computer. Sizes are exact and easy to change. CAM (computer-aided manufacturing) takes that drawing and plans how a machine will make it: which tool, how fast, and the path. The result is a program. See the full lesson on CAD/CAM.
Numerically controlled (NC and CNC) machine tools
A numerically controlled (NC) machine moves its tool by following numbers. In early NC machines the numbers came from punched tape. A CNC (computer numerical control) machine has its own small computer, so the program can be stored, edited and run again.
The program is usually G-code. A line like "G01 X40 Y20 F100" means: move in a straight line to x = 40 mm, y = 20 mm at a feed speed of 100 mm per minute. The machine moves along axes: X (left-right), Y (front-back) and Z (up-down). A motor on each axis turns exact steps, and a sensor checks the position (closed loop).
Good points: accurate, repeatable, makes complex shapes. Examples: lathe, milling machine, laser cutter.
Automation systems in industrial production
An automated line joins machines with conveyors, sensors, actuators (motors, cylinders) and a controller such as a PLC (programmable logic controller). The pattern is: sensor reads, controller decides, actuator acts. For example, a light sensor sees a part, the PLC stops the belt, a press comes down, then the belt starts again.
Types: fixed automation (one product, very fast, like a bottling line), programmable automation (batches, program changes for a new product) and flexible automation (changes product with almost no stop). Robots often load parts and weld or paint.
Networking production
In a networked factory each machine is connected by cable or wireless to a main computer. Orders go down: what to make and how many. Reports come up: parts made, faults, temperatures. Managers see the whole factory on one screen. This is the idea of the smart factory (Industry 4.0).
Benefits: less waiting, faster fault finding, less waste. Risks: if the network fails, work may stop, and hackers could attack it, so networks need passwords, updates and backups.
Key formulas and definitions
- Output per hour = 3600 s / cycle time (s)
- Feed time = distance / feed speed
- Efficiency (%) = good parts / total parts x 100
- Axes: X left-right, Y front-back, Z up-down
Worked examples
1. A CNC machine makes one part in 30 s. How many parts in one hour?
Parts = 3600 / 30 = 120 parts.
2. The tool moves 60 mm at a feed of 120 mm per minute. How long does it take?
Time = 60 / 120 = 0.5 min = 30 s.
3. What does "G01 X40 Y20 F100" tell the machine?
Move straight to x = 40 mm, y = 20 mm, at 100 mm per minute.
4. A line makes 500 parts and 25 are faulty. What is the percentage of good parts?
Good = 475. 475 / 500 x 100 = 95 per cent.
5. A belt carries parts 3 m in 12 s. What is its speed?
Speed = 3 / 12 = 0.25 m/s.
6. Line A makes 90 parts per hour. After automation the cycle time is 20 s. How many more parts per hour?
New output = 3600 / 20 = 180 per hour. Gain = 180 - 90 = 90 parts per hour more.
Common mistakes
- Thinking CAD and CAM are the same. CAD is the drawing, CAM is the manufacturing plan.
- Thinking a CNC machine thinks by itself. It only follows the program, so a wrong program makes wrong parts.
- Saying automation means no humans. People design, program, set up and repair.
- Forgetting that sensors are what tell the machine where the part is.