Abstract
Computer Numerical Control (CNC) systems are the “backbones” of modern manufacturing industry for over the last 50 years and the machine tools have evolved from simple machines with controllers that had no memory and were driven by punched tape, to today’s highly sophisticated, multiprocess workstations. These CNC systems are still being worked and improved on. The key issues center on autonomous planning, decision making, process monitoring and control systems that can adjust automatically to the changeable requirements. Introduction of CNC systems has made it possible to produce goods with consistent qualities, apart from enabling the industry to enhance productivity with a high degree of flexibility in a manufacturing system. CNC systems sit at the end of the process starting from product design using Computer Aided Design (CAD) tools to the generation of machining instructions that instruct a CNC machine to produce the final product. This process chain also includes Computer Aided Process Planning (CAPP) and Computer Aided Manufacturing (CAM).
TopBackground
The development of an intelligent CNC controller architecture has been one of the main goals for both CNC manufacturers and end users. This new trend comes with a suite of new technologies and concepts. In today’s manufacturing world, understanding the true meaning and implication of these technologies and characteristics is the top priority. Extensibility is the ease with which a third party is able to add capabilities to software or hardware. Interoperability is the ability of two or more systems or devices to exchange information and make use of it transparently. Portability is the ease with which application software can be transferred from one environment to another. Scalability is the ease with which an existing system’s performance can be increased or decreased to suit different applications of different magnitude. The recent CNC controller development includes a digital signal processor (DSP) (Chang, 2007), virtual CNC (Erkorkmaz & Wong, 2007) and CNC system based on STEP-NC and Function Blocks (Wang, Xu, & Tedford, 2007).
STEP-NC (ISO 14649, 2003) is viewed to be an effective means of documenting task-level information in the CAD/CAPP/CAM/CNC manufacturing chain. The new standard of Function Block (IEC 61499, 1999) has the advantages of generating method-level data for the control unit. The kernel software proposed by Park, Kim, and Cho (2006) organized and managed various control software modules dynamically by using process and resource models. It enabled the CNC controller to be easily reconfigurable because the software modules can be plugged-and-played and be built modularly so that new features or number of control axes could be added easily. Bi, Yu, and Li (2006) introduced a new type of CNC, which is based on Sinumerik 840D and STEP-NC. This is a kernel of Intelligent Integrated Manufacturing System (I2MS).
Key Terms in this Chapter
Interoperability: The ability of two or more computer systems to exchange information with no barriers and make use of it transparently.
Interoperable: The ability of two or more computer systems to exchange information and make use of it transparently.
Adaptable: Describes a high level of robustness in dealing with control system or machine’s components changes in a manufacturing environment especially during machining process for future unmanned machining system.
Scalability: The facility which an existing system’s performance can be increased or decreased in the application demand.
Portability: The facility which applications software can be transferred to one environment from another, while maintaining its capabilities.
Extensibility: The facility by which a third party is able to add capabilities to software or hardware.
Distributable: Consists of several components distributed over a network of computers involving Computer Aided Design (CAD), Computer Aided Process Planning (CAPP), Computer Aided Manufacturing (CAM) and Computer Numerical Control (CNC) try to synchronize and coordinate machining activities.
Modular: The degree to which a product of CNC system components is composed of independent modules whose internal functionality is intact without any necessary interactions between them.
Reconfigurable: Is composed of multiple software and hardware, and incorporates basic process components which can be replaced, permitting disassembly, reassembly, rearrangement, or replaced quickly to the main system to allow adding, removing, or modifying specific process capabilities, controls, software, or machine structure.
Open: Having standard hardware and software which permit system scalability, and ensure future performance enhancement; a vendor-neutrality and component-integrability; tool-neutral, and controller-neutral architecture.