Wednesday, 31 May 2006

Automatic Assembly (7/16)

Any detailed investigation into the design of a product results in a more productive method of assembly. The parts and assembly operations used to put together the parts can be viewed with either manual or automatic assembly in mind.  When designing for automatic assembly, remember that the intricate feedback loop that co-ordinates human motors is not present in economically justifiable automatic assembly systems. For example, parts that are manually picked up the wrong way round can have their orientation corrected. The human assembly worker detects this error through sight or touch and quickly corrects the orientation.    Similarly, defective parts can be detected and discarded by a human assembly worker.

Automatic workheads do not detect rejects without the aid of complex sensor systems.  A defective part arriving at the workhead causes a jam and the workstation is down for a period of time. These events are minimized by having high component quality levels and re­structuring the inspection routines. Most manual assembly systems have three inspection stages - goods inward, during assembly, and upon final assembly of the product.  Parts or assemblies which do not fall within quality bands, at each of these stages, are rejected. Automatic assembly equipment requires higher quality components and, therefore, greater quality control is required at the goods inward stage than for manual assembly. Automatic assembly equipment, fed with high quality parts, gives a higher quality finished product than manual assembly.  The consistency of an automatic system, aided by high quality parts creates a high quality product.

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