Proceedings of the International Conference on Mechanical Engineering and Renewable Energy 2013 (ICMERE2013) 24- 27 December 2013, Chittagong, Bangladesh ICMERE2013-PI-208 © ICMERE2013 1. INTRODUCTION It is the era of science and technology. People are making new inventions for their day to day uses. They love comfort, but not in the cost of quality. So man thinks of something new which is easy to use but in the same time it can prove itself useful. Nowadays industries are playing a vital role in the national economy .So it is very important for an industry to maintain the quality of the product they produce. At the same time it is also a disgrace for an industry if their product is not accepted by the customers. Many industries need to produce various types of product at various types of range. Taking this matter under consideration this paper proposed a method which would be very useful for industries. The scope of this method is huge in modern manufacturing industries. It gives knowledge about the different branches of science and technology. Two sectors of engineering science are widely used to materialize this idea. They are- 1. Mechanical Engineering 2. Electrical and Electronic Engineering 2. AUTOMATION Automation is the use of control systems such as numerical control, programmable logic and other industrial control systems, in concern with other application of information technologies such as computer aided technologies CAD, CAM, to control industry or industrial machineries and industrial process or processes, reducing the need for human intervention. 2.1 Automation Tools Engineers now can have numerical control over automated devices. Computer-aided technologies (or CAx) now serve the basis for mathematical and organizational tools used to create complex systems. Notable examples of CAx include Computer-aided design (CAD software) and Computer-aided manufacturing (CAM software).The improved design, analysis, and manufacture of products enabled by CAx have been beneficial for industry. Together information and technology with industrial machinery and processes, can assist in the design, implementation, and monitoring of control systems. One example of an industrial control system is a programmable logic controller (PLC). PLCs are specialized hardened computers which are frequently used to synchronize the flow of inputs from (physical) sensors and events with the flow of outputs to actuators and events. Human-machine interfaces (HMI) or computer human interfaces (CHI), formerly known as man-machine interfaces, are usually employed to communicate with PLCs and other computers. In industrial process and manufacturing environments, they are called operators or something similar. In boiler houses and central utilities departments they are called stationary engineers. Different types of automation tools exist:  ANN - Artificial neural network  DCS - Distributed Control System  SCADA - Supervisory Control and Data Acquisition  PLC - Programmable Logic Controller etc. 2.2 Advantages of Automation Compared to Manual  It is used to avoid human errors.  By using automation it reduces the testing lifecycle with respective to time.  We get more reliable test result.  It reduces man power. Abstract - The goal of this paper is to propose an automatic system to assert the dimensional (length) accuracy of a product and the rejection of the defective products. An IR sensor is being used which will ensure the presence of object. When a product is arrived then the motor starts running and so as the conveyor belt. A Laser is used which cut the product and a counter start to count. The time is calculated and is compared with the time which was set earlier knowing that how much time a defect less product will be in contact with the laser. From this, a decision comes whether the length of the product is right or wrong. Keywords: Dimensional accuracy, Automation, Motor, Micro Controller, IR Sensor and Conveyer belt. AUTOMATIC DIMENSIONAL ACCURACY ASSERTION ON CONVEYOR BELT AND REJECTION OF DEFECTIVE PRODUCT Sheikh Ziaur Rahman 1 , Mohammad Kamrul Islam 2 and Md. Mehdi Masud Talukder 3 1 Student, Department of Business Studies, DU, Bangladesh. 2 Senior CAD Engineer, Bangladesh Japan Information Technology (BJIT), Dhaka, Bangladesh. 3 Lecturer, Department of Mechanical Engineering, CUET, Bangladesh.*