A single station assembly machine is to be considered as an alternative to the dial indexing…
A single station assembly machine is to be considered as an alternative to the dial indexing machine in Problem 19.4. Use the data given in the table of Problem 19.3 to determine: (a) production rate, (b) yield of good product (final assemblies containing no defective components), and (c) proportion uptime of the system. Handling time to load the base part and unload the finished assembly is 7 sec and the downtime averages 1.5 min every time a component jams. Why is the proportion uptime so much higher than in the case of the dial indexing machine in Problem 19.4?
Problem 19.3
A synchronous assembly machine has eight stations and must produce at a rate of 400 completed assemblies per hour. Average downtime per jam is 2.5 min. When a breakdown occurs, all subsystems (including the feeder) stop. The frequency of breakdowns of the machine is once every 50 cycles. One of the eight stations is an automatic assembly operation that uses a feeder-selector. The components fed into the selector can have any of five possible orientations, each with equal probability, &manly one is correct for passage into the feed track to the assembly workhead. Parts rejected by the selector are fed back into the hopper. What minimum rate must the feeder deliver components to the selector during system uptime to keep up with the assembly machine?
Problem 19.4
A dial indexing machine has six stations that perform assembly operations on a base part. The operations, element times, q and in values for components added are given in the table below (NA means q and m are not applicable to the operation). The indexing time for the dial table is 2 sec. When a jam occurs, it requires 1.5 min to release the jam and put the ma-chine back in operation. Determine: (a) production rate for the assembly machine, (b) yield of good product (final assemblies containing no defective components), and (c) proportion uptime of the system.
