MACHINE TOOLS and MACHINES
Post 297 ⇒ by Gautam Shah →
Machine tools are power driven utilities, and are of two basic types: Hand held or mobile tools and Stationary tools. Hand-held tools are apparently small, and lightweight. Whereas stationary tools often called, Machine tools, are large, fixed to a position. The large size requires stationary positioning. Both types of machine tools are classifiable into home or hobby machine tools and Industrial or Engineering machine tools.
Machines and machine tools both are automated entities, and so have slightly overlapping categorization. A machine is a specific product entity which can be conducting several sequential or concurrent processes. A machine tool is a multi-purpose entity, and used for several processes. It can have attachments of (non-machine) tools, or it may be part of a machine. All machine-tools are a type of machine, but conversely all machines may not be called machine tools. To use a tool or machine tools some form adaptation, recognised as craftsmanship is required. Machines do not need personal creativity or craftsmanship except basic technical knowledge.
Machines and machine tools are powered by human, animal, kinetic, hydraulic and pneumatic power, wind mills, steam and electric power. Machine tools need to be manipulated or the feedstock requires positioning, adjustment, etc. When this input processes are guided or automated, a machine tool becomes a machine. The guidance or automation may be to free the hands, other limbs and sensory nodes. So, in this sense a machine can have several machine tools, each of which has time-space feeds mechanisms. Advance machines have feed-forward and feed back systems to reduce or correct errors.
A machine-tool can take up various types of tools. Such as a drill can take different types of bits or a potter uses different shapes of spatulas to shape and finish the turned-clay item. A CNC machine, has predefined set of feed-guide processes controlled by the computer input. A machine tool that is handy will have to be very quite and vibration free. Very fine work tools like a dentist or orthopaedic surgical drills are operated through pneumatic or compressed air, rather then electric motors. The pneumatic technology offers vibration free and noiseless movement at very high speeds. Similarly Air-jet looms working on suction reduce the nominal noise associated with yarn bobbin shuttles.
Machines were stationary entities due to the robust size, stability and power needs. This created batch production system, creating lots of cross traffic within the plant. Batch production with fixed machines required power locally. This was difficult proposition when steam or a large electric motor generated power was transferred through shafts and belts to the machine. Batch based products tended to be holistic in nature. The need for faster production forced rethinking of product design into component-based entities. Components were produced by machine tools or machines and brought to the assembly line. The assembly line was operated through handy machine tools.
Assembly lines had many grey areas. A slowdown or stoppage affected the entire production systems. Processes, tasks, etc., were carefully apportioned in terms duration, speed and space. All these studies provided opportunities for automation of assembly processes. The automation allowed multiple operation at a station which drastically reduced the length of assembly lines. The automation is now seen in use of robots handling several processes at a station. A human assembler cannot go into narrow spaces, take difficult body postures and require rest or diversion, but a robot is beyond these difficulties. A robot is a machine with several machine tools.