Workpiece automated

IS) no mechanical stresses are produced in workpiece surface (6) no thermal effects are produced in ihe workpiece because of the relatively low temperature ol the operation (7) tough metals often can he removed faster by ECM than conventional methods (8) good tolerances and repeatability are produced in complex as well as simple shapes and (9) the process is easily automated. The basics of this process are also applied in deburring. grinding, and polishing operations,... 

The type of automated assembly system is essentieilly determined by the workpieces to assemble. The most influential factors are the workpiece s total weight, size, amoimt, and mnnber of types euid variants. 

The various types of automated assembly systems euise due to the combination of the different t5rpes of assembly stations and work transfer devices, which, in turn, ate dependent on the requirements of the workpieces to assemble. HexibUity, that is, being adaptable to different conditions euid assembly tasks, should also be a characteristic of assembly systems. An adequate configuration of the assembly station as well as respective work transfer devices will help meet the different flexibility requirements. 

Particularly for small annual workpiece amounts, it is economically necessary to assemble several different products or components in one flexible automated assembly system in order to maintain a high level of system utilization. Because sometimes very different assembly processes must be realized, a linking structure (flex-link sequence), independent from certain assembly processes, is necessary. Assembly systems of this type are able to meet the increasing demands for more flexibility. 

The greatest market potential among the different types of rivets is forecast for bUnd rivets. Access to the workpieces being joined is required from only one side, thereby offering the ideal conditions for automation. A bhnd riveter for industrial robots has been developed based on a standard tool that, apart from its size and weight, is also notable for its enhanced flexibility. With the aid of a changeover device, for example, different rivet diameters and types of blind rivet can be handled. 

Sorting and feeding devices are tm important component in the automated assembly of products. Their task is to sort out the often unsorted supplied workpieces and to deliver the tight amount to the assembly station at the tight time. The most commonly used feeding systems are vibratory bowl feeders, capable of sorting nearly 90% of all components automatically. 

Fixtures are the bases that securely position workpieces while the assembly system performs operations such as pick-and-place and fastening. They are generally heavy and sturdy to provide the precision and stability necessary for automated assembly. They carry a variety of sirbstructures to hold the particular workpiece. While each fixture is different, depending on the workpiece it handles, several commonsense rules for their design are suggested ... 

The collaboration between human and machine normally is synchronized, so that interaction is efficient. The synchronization can be controlled by the human, the machine, or both. Machine generally means an automated system, such as a robot. The common goal normally is a complex task where human and automated system can fulfill synchronized subtasks. Subtasks of the human are typically those where complex sensory-motor control abilities are required and the need for adaptation to changing conditions in the process is high. Subtasks of the machine are normally very repetitive with low complexity in handling of workpieces. Due to the combination of adaptivity... 

Machinery should be built in such a way as to minimise the exposure of workers to the cutting fluids. Manual feeding of workpieces, oil contact when machines are shut off and hands are placed into the machines, and the need to hold workpieces under the flow of oil when it is being machined are machine-design problems which will increase the risk of development of dermatitis. Increasing automation with computer-controlled machines which are enclosed to prevent oil contact will reduce the incidence of dermatitis. 

The use of CNC machine tools has radically changed the manufacturing industry. Curves are as easy to machine as straight lines, as well as parts with complicated contours and complex 3D shapes. The increased automation has resulted in improvements in consistency and quality together with a reduced frequency of errors. CNC also allows for more flexibility in the way workpieces are held, often avoiding the use of expensive jigs or fixtures required on conventional machines. Dimensional modifications can be done quickly and the time required to change over to a different part is reduced. Small batches or short production runs as well as parts needed in a hurry can be easily accommodated. 

Stud Arc Welding (SW) for welding pins and stud bolts to structures for subsequent fastening operations. Uses the pin or stud as a consumable electrode to join to the workpiece at one end. Portable semi-automatic or static automated equipment available. 

Automated production requires a workpiece carrier that can be used all the way along the production line. Consequently, the design is such that the carrier can be conveyed by the printed-circuit board conveyor to all the machines in the process chain. The appropriate number of workpiece carriers is required if production is to be continuous. An interface for energy supply and communication between the automatic machines and the workpiece carrier is necessary, particularly for the dispensing unit and the automatic placement machines. The electronics built into the workpiece carrier render it unsuitable for reflow soldering, so a handling step has to be included so that the MID can be lifted on to a separate, passive workpiece carrier for this process. This transfer can be manual or by means of an industrial robot such as the Scara robot. 

FIGURE 4.20 Automated workpiece carrier in an SMD pick piace machine... 

TABLE 4.7 Properties of the Kinematics of the Automated Workpiece Carrier... 

FIGURE 4.21 Automated workpiece carrier in SMD pick place machine Siplace HF... 

Carrier thermal mass or, more accurately, capacity becomes important when work-piece carriers (Fig. 4.22) are used along the entire production line. The soldering proces s in particular is very much affected by this thermal capacity. The temperature profile has to be adapted to ensure dependable electrical and mechanical interconnecting that will also result in the requisite reliability. If the choice is going to be in favor of an automated workpiece carrier, it is important to bear in mind that the integrated drives and the electronics are not suitable for the soldering process. 

It may well be necessary to adapt an optical inspection system to accommodate the three-dimensional layout of MID process surfaces. Class 2l D MID can be inspected without additional kinematics and adaptation of the optical inspection system. This holds true only if the process surfaces are plane-parallel in the inspection plane of the sensor array. Classes n x 2D and 3D call for changes to the AOI system if the electronic components are widely spaced. This could well mean integrating an extra handling and positioning unit for MID, for example an automated workpiece carrier. 

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