Automation an Introduction

Role of automation in industry

•         Manufacturing processes, basically, produce finished product from raw/unfinished material using energy, manpower and equipment and infrastructure.

•         Since an industry is essentially a “systematic economic activity”, the fundamental objective of any industry is to make profit.

•         Roughly speaking,

                      Profit = (Price/unit – Cost/unit) x Production Volume

So profit can be maximized by producing good quality products, which may sell at higher price, in larger volumes with less production cost and time.

Automation can achieve all these in the following ways; Figure shows how overall production time for a product is affected by various factors. Automation affects all of these factors. Firstly, automated machines have significantly lower production times. For example, in machine tools, manufacturing a variety of parts, significant setup times are needed for setting the operational configuration and parameters whenever a new part is loaded into the machine. This can lead to significant unproductive for expensive machines when a variety of products is manufactured. In Computer Numerically Controlled (CNC) Machining Centers set up time is reduced significantly with the help of Automated Tool Changers, Automatic Control of Machines from a Part Program loaded in the machine computer. Such a machine is shown in Figure 1.3. The consequent increase in actual metal cutting time results in reduced capital cost and an increased volume of production.

•         Similarly, systems such as Automated Guided Vehicles, Industrial Robots, Automated Crane and Conveyor Systems reduce material handling time.

•         Automation also reduces cost of production significantly by efficient usage of energy, manpower and material.

•         The product quality that can be achieved with automated precision machines and processes cannot be achieved with manual operations. Moreover, since operation is automated, the same quality would be achieved for thousands of parts with little variation.

•         Industrial Products go through their life cycles, which consist of various stages.

•         At first, a product is conceived based on Market feedbacks, as well as Research and Development Activities.

•         Once conceived the product is designed. Prototype Manufacturing is generally needed to prove the design.

•         Once the design is proved, Production Planning and Installation must be carried out to ensure that the necessary resources and strategies for mass manufacturing are in place.

•         This is followed by the actual manufacture and quality control activities through which the product is mass-produced.

•         This is followed by a number of commercial activities through which the product is actually sold in the market.

•         Automation also reduces the overall product life cycle i.e., the time required to complete

(i) Product conception and design

(ii) Process planning and installation

(iii) Various stages of the product life cycle

Types of production systems

•         Continuous flow process: Manufactured product is in continuous quantities i.e., the product is not a discrete object. Moreover, for such processes, the volume of production is generally very high, while the product variation is relatively low. Typical examples of such processes include Oil Refineries, Iron and Steel Plants, Cement and Chemical Plants.

•   Mass Manufacturing of Discrete Products: Products are discrete objects and manufactured in large volumes. Product variation is very limited. Typical examples are Appliances, Automobiles etc.

•       Batch Production: In a batch production process the product is either discrete or continuous. However, the variation in product types is larger than in continuous-flow processes. The same set of equipment is used to manufacture all the product types. However for each batch of a given product type a distinct set of operating parameters must be established. This set is often referred to as the “recipe” for the batch. Typical examples here would be Pharmaceuticals, Casting Foundries, Plastic molding, Printing etc.

•     Job shop Production: Typically designed for manufacturing small quantities of discrete products, which are custom built, generally according to drawings supplied by customers. Any variation in the product can be made. Examples include Machine Shops, Prototyping facilities etc.

Types of Automation Systems

Automation systems can be categorized based on the flexibility and level of integration in manufacturing process operations. Various automation systems can be classified as follows:--

•    Fixed Automation: It is used in high volume production with dedicated equipment, which has a fixed set of operation and designed to be efficient for this set.

•     Programmable Automation: It is used for a changeable sequence of operation and configuration of the machines using electronic controls. However, non-trivial programming effort may be needed to reprogram the machine or sequence of operations.

•      Flexible Automation: It is used in Flexible Manufacturing Systems (FMS) which is invariably computer controlled. Human operators give high-level commands in the form of codes entered into computer identifying product and its location in the sequence and the lower level changes are done automatically.

•         Integrated Automation: It denotes complete automation of a manufacturing plant, with all processes functioning under computer control and under coordination through digital information processing. It includes technologies such as computer-aided design and manufacturing, computer-aided process planning, computer numerical control machine tools, flexible machining systems, automated storage and retrieval systems, automated material handling systems such as robots and automated cranes and conveyors, computerized scheduling and production control.

Limitations to automation

1.       Current technology is unable to automate all the desired tasks.

2.       Many operations using automation have large amounts of invested capital and produce high volumes of product, making malfunctions extremely costly and potentially hazardous. Therefore, some personnel are needed to insure that the entire system functions properly and that safety and product quality are maintained.

3.       As a process becomes increasingly automated, there is less and less labour to be saved or quality improvement to be gained. This is an example of both diminishing returns and the logistic function.

4.       As more and more processes become automated, there are fewer remaining non-automated processes. This is an example of exhaustion of opportunities. New technological paradigms may however set new limits that surpass the previous limits.

Current limitations: -

5.       Many roles for humans in industrial processes presently lie beyond the scope of automation. Human-level pattern recognition, language comprehension, and language production ability are well beyond the capabilities of modern mechanical and computer systems.

6.        Tasks requiring subjective assessment or synthesis of complex sensory data, such as scents and sounds, as well as high-level tasks such as strategic planning, currently require human expertise.

7.       In many cases, the use of humans is more cost-effective than mechanical approaches even where automation of industrial tasks is possible. Overcoming these obstacles is a theorized path to post-scarcity economics.

Effects of automation on people: -

One of the main reasons for the introduction of automated systems was and remains the desire to be able to produce goods less expensively than the competition. Automation technology can do this in several ways:

1.       Fewer staff is needed for automated production.

2.       Production can run round the clock, except for a few maintenance interval periods.

3.       Machines generally make fewer mistakes, which mean the quality of the produced products is consistently high.

4.       The processing times are shortened, which means that larger quantities can be shipped faster.

5.       Automation relieves people of boring, physically heavy or hazardous work (humanization of the world of employment).

1.       On the other hand, there are also less positive effects associated with automation technology, such as:

6.       The loss of jobs, in particular those with a low skill level (one highly qualified service technician takes the place of 10 unskilled assembly workers).

7.       The automation of production demands that employees occasionally make decisions, however the complexity of the system structure is such that they cannot fully decipher their consequences.

8.       The expenditure for an automated system of this type increases each individual's responsibility for the success of the company as a whole.

Industrial Automation with time : -

Manual Control :-  All the actions related to process control are taken by the operators

Drawbacks:- 

1. Likely human errors and consequently its effect on quality of  final product
2. The production, safety, energy consumption and usage of raw material are all subject to the correctness and accuracy of human action.

Pneumatic Control:- Industrial automation, with its machine and process control, had its origin in the 1920s with the advent of "Pneumatic Controllers". Actions were controlled by a simple manipulation of pneumatic valves, which in turn were controlled by relays and switches. 

Drawbacks:- 

1.    Bulky and Complex System
2.    Involves lot of rework to implement control logic
3.    Longer project time 

   

Hard wired logic control:- The contactor and Relays together with hardware timers and counters were used in achieving the desired level of automation.
Drawbacks:-

1.      Bulky panels
2.     Complex wiring 
3.      Longer project time
4.      Difficult maintenance and troubleshooting

Electronic Control using Logic Gate:- In 1960s with the advent of electronics, the logic gates started replacing the relays and auxiliary contactors in the control circuits. The hardware timers & counters were replaced by electronic timers
Advantages:- 

1.    Reduced space requirements and Energy saving
2.    Less maintenance & greater reliability

Drawbacks:- 

1.    Changes in control logic not possible            
2.    More project time

Questions                  

1.  Can you explain the Control system definition in the context of a common control system, such as temperature control in an oven? Is the definition applicable to open-loop as well as closed loop control?

2.  Can you give an example of an automated system, which contains a control system as a part of it? What are the other parts of the system?

3.  What kind of automation would you recommend for manufacturing:-  Light bulbs, Garments, Textile, Cement, Printing, Pharmaceuticals, Toys?

4.  For what kind of a factory would you recommend computer integrated manufacturing and why?

5.  Why does an automated system achieve superior performance compared to a manual one? Can you give an example where this happens?

6.  During a technical visit to an industry how can you identify the type of automation prevailing there from among the above types?