IE 4235 lab 5
Given a production cell description from a local company, develop and evaluate a model for that cell. Report for lab5 is due week 8.
The following pictures show a production cell used to make Rings for mounting riflescopes to firearms:
Nearby is another cell where Bases are produced. Most of the machining in this cell is done using an Imasflex rotary transfer machining center:
After being produced the bases and rings go to the Mount/Ring Packaging area where they are inspected and packaged into complete mounting systems (sets of 2 rings and a base).
A log of processing times was extracted from the manufacturing database. The following table is an extract from the complete data in an Excel spreadsheet that comes with the lab material.
Order / Base Cell / Ring CellArrival Time / Type / Imasflex / Finish / Machine / Drill & Saw / Inspect &
Package / Inspect
Results
16.65 / A3 / 9.73 / N/A / 16.09 / 7.35 / 48.65 / -
33.29 / A1 / 10.75 / 15.64 / 18.85 / 6.53 / 46.74 / -
34.24 / A2 / 11.04 / 15.24 / 17.15 / 5.50 / 54.64 / -
47.96 / A3 / 8.33 / N/A / 21.26 / 7.88 / 50.59 / -
48.03 / A3 / 10.11 / N/A / 20.44 / 7.06 / 57.53 / -
49.83 / A3 / 9.69 / N/A / 17.42 / 10.27 / 51.51 / Rework
All of the above numbers refer to times in seconds. The first order arrives at 16.65 seconds and then the second one arrives at 33.29 seconds (or 16.64 seconds later).
Notice that four of the six jobs were product A3. The Base cell takes thebarstock and machines it into a base with the Imasflex station. Some parts also goes through a finishing process. Notice that the bases that go in the A3 mounting system do not go through the finishing process, so the times are listed as N/A.
In the Inspection & Packaging process, the last product was determined to need rework. In this case, the entire package is sent to the finishing station for cosmetic rework. The package then proceeds back to inspection & packaging. Products can also fail the Inspection entirely, in which case they are denoted in the datafile as a reject. These are considered scrap.
The Ring Cell first machines the barstock to the required dimensions, then drills & taps holes and saws the ring into two halves.
The Base Cell first machines the parts in the Imasflex (which can process 6 parts simultaneously), and then some of them (the large ones) go through an additional finishing process.
Base and ring material is transported quickly from the stock area. It can be assumed to always be available at the machine in the cell.
The part flow looks like this:
/ Machine Rings ---> Drill & Saw Rings ---\
Order Arrival -- -->Inspection & Packaging
\ Machine Bases ---> Finish Bases---/
(for large)
A simplified Bill of Material for the three mounting systems is as follows (ignoring screw kits):
Mounting System / Base / Ring SetA1 / Large / Large
A2 / Large / Small
A3 / Small / Small
Separately from the processing times described above, it also takes time to move parts. Assume that part movement within a cell takes .5 minutes, and movement to operations outside of the cell take 2 minutes.
From / To / Move TimeIMASFLex / Finish / .5 min
Finish / Inspection & Packaging / 2 min
Machine / Drill & Saw / .5 min
Drill & Saw / Inspection & Packaging / 2 min
Inspection & Packaging / Finish / 2 min
Model the current system, and determine how many of each type of machine is needed to keep the mean cycle time (measured from order arrival to finished package leaving the Inspection & Packaging area) to less than 12 minutes.
What sort of buffer stocks is needed (if any)? How much WIP is required to support this rate of production?
Whatwould be the impact on throughput and WIP of bringing the Inspecting & Packaging closer to the Ring and Base cells, such that the move times to and from this area are .5 minutes rather than 2 minutes?
Prepare a writeup that summarizes your model, including: 1) what you decided to model as locations, your entities, arrival events, and operation & routing logic, 2) the key assumptions you had to make, and 3) your results, both the numbers and how you would answer the questions above. Include somewhere in the writeup a screen capture of your model layout, the text file from ProModel that documents the model, and a sample output report (either via screen capture or via the non-3DR output viewer). Finally, discuss your learning experience with this exercise.
ProModel Notes
To combine Ring sets and Bases, it may be useful to use the JOIN logic we experimented with in Lab4.
One challenge is to accomplish the necessary logic with only 5 entity types (the limit in the student version of ProModel if you are modeling with your own computer) since there are two types of Rings and two types of Bases
It may also be useful to use the ORDER command we experimented with in Lab4.
- One entity might be a "workorder" that has an attribute called "Type"
- The other four entities would be the two types each of bases and ringsets
- When a workorder arrives at the orderdesk, it would
- ORDER the correct entities (large or small bases and ringsets) directly into the queues in front of the Imasflex and Machine locations (using IF THEN ELSE logic in the processing logic, based on Type)
- the workorder would go on to the inspectpack area queue using the routing logic
After the parts are completed, they are routed to a staging area
- where the routing logic indicates JOIN 1 (wait for a JOIN request)
Meanwhile, the order (now at the inspectpack area queue)
- issues appropriate JOIN requests in its operation logic to bring the correct ringset and base back together
- using IF THEN ELSE logic based on the Type attribute for the order