Question: This problem is concerned with the design of a GT cell to machine the components for a family of parts. The parts come in several different sizes, and the cell will be designed to quickly change over from one size to the next. This will be accomplished using fast-change fixtures and distributed numerical control (DNC) to download the NC programs from the plant computer to the CNC machines in the ceil. The parts are rotational type, so the cell must be able to perform turning, boring, facing drilling, and cylindrical grinding operations Accordingly, there will be several machine tools in the cell, of types and numbers to be specified by the designer To transfer parts between machines in the cell, the designer may elect to use a belt or similar conveyor system. Any conveyor equipment of this type will be 0.4 m wide. The arrangement of the various pieces of equipment in the cell is the principal problem to be considered. The raw workparts will he delivered into the machine cell on a belt conveyor. The finished parts must be deposited onto a conveyor that delivers them to the assembly department. The input and output conveyors are 0.4 m wide, and the designer must specify where they enter and exit the cell. The parts are currently machined by convention-al methods in a process-type layout. In the current production method, there are seven ma-chines involved, but two of the machines are duplicates. From-To data have been collected for the jobs that are relevant to this problem.
The From- To data indicate the number of workparts moved between machines during a typical 40-hr week. The data refer to the parts considered in the case. The two categories -parts in-and 'vans out- indicate parts entering and exiting the seven-machine group. A total of 400 parts on average arc processed through the seven machines each week. However, as indicated by the data, not all 400 parts are processed by every machine. Machines 4 and 5 are identical, and assignment of parts to these machines is arbitrary. Average production rate capacity on each of the machines for the particular distribution of this parts family is given in the table below Also given are the floor space dimensions of each machine In meters Assume that all loading and unloading operations take place in the center of the machine.
Operation 6 is currently a manual inspection operation. It is anricipated that this manual station will be replaced by a coordinate measuring machine (CMM). This automated inspection machine will triple throughput rate to 15 parts/hr from 5 parts/hr for the manual method. The floor apace dimensions of the CMM arc 2.0 m × 1.6 m. All other machines currently listed arc to be candidates for inclusion in the new machine cell.
(a) Analyze the problem and determine the most appropriate sequence of machines in the cell using the data contained in the From-To chart.
(b) Construct the flow diagram for the cell, showing where and how many parts enter and exit the cell.
(c) Determine the utilization and production capacity of the machines in the cell as you have designed it.
(d) Prepare a layout (top view) drawing of the GT cell, showing the machines, the robot(s), and any other pieces of equipment in the cell, (c) Write a one-page (or less) description of the cell, explaining the basis of your design and why the cell is arranged as it is.