Construccion De Aviones

Introduction
This paper airplane folding exercise demonstrates the push vs. pull aspect of lean manufacturing.
The goals of this exercise are to illustrate the significant reduction in WIP and throughput time using the pull system, to explain and illustrate the concepts of push, pull, kanban, bottleneck, cycle time, idle time, line balance, and to illustrate worker behaviour in anoperational setting.
This exercise utilizes four assembly operators in an assembly line to build a paper airplane. The work centre tasks are assigned in such a way as to place the bottleneck at the third workstation. The students first work in a standard push approach: each student works at their own comfortable pace as long as inventory is available, and they do not worry about inventory build-up.The second run requires a pull of one unit at a time. The reduction in inventory and throughput time is readily evident to all, providing a powerful learning experience. In addition, student discussion of a multitude of lean concepts and behavioural issues is easily elicited.
This exercise can be completed in about 20 minutes, using 100 sheets of blank, standard A4 paper and 2 coloured sheetsof Coloured Paper. A white board / flip chart can be used to record key data.
The basic folds are easily explained, as shown in Figure 1.
The four work centres are set up as below:

Figure 2 Push Production Line Set-ups

Table length ~12 feet
Student Student Student Student
Raw
Material
(Paper) Work Centre
1
WIP Work Centre
2
WIP Work Centre
3
WIP Work Centre4 Finished goods
(Airplanes)

Material Flow
Participants
Personnel required are as follows:
4 Assembly Operators
1 QA Person
Since the objective of this exercise is the push and pull concepts, the quality is monitored by the QA person to insure that the operators are not rushing improperly to try to balance the line. Workers need to be instructed to “work at a comfortable pace, this isnot a contest for maximum output, but quality will be monitored by the QA person,” students will work accordingly.
The objective is to complete 20 airplanes at the Finished Goods Station. The Instructor monitors the time it takes to complete the 20 units. Dividing by 20 will give the average cycle time
The remaining participants should gather around and be instructed to keep an eye on theworkers and the action, with knowledge that they are to provide insightful discussion at the conclusion.
Exercise
PUSH RUN
The first run is the push run: let them make inventory as fast as they want and push to the next work centre.
At an opportune time, insert the coloured sheet onto the top of the raw material paper. Insist on a FIFO type of process between work centres so that the planewith the coloured paper doesn’t jump ahead of the queue. The Instructors tracks the throughput time: the time from when the first worker takes the sheet from the raw material pile, to the time when the last worker completes the plane and places it in the finished goods inventory. This throughput time is recorded. The task is completed once 20 planes are placed in finished goods.
A discussionat this point should result in the identification of the bottleneck, the piles of inventory, and observation that work centre 4 is idle some of the time while the other work centres worked continuously. This is a good time to reinforce the concepts of bottleneck, cycle time, throughput time, push, line balance and worker behaviour.
PULL RUN
The second run is a pull system. Designate a spacebetween each work centre as an imaginary kanban box where inventory will be held as shown in Figure 3.
Place 1 unit of WIP in each of the 3 kanban areas. Indicate that one worker’s in box is the previous worker’s out box.
A worker can start work at their work centre only when
1) there is 1 unit in the incoming Kanban area (except for work centre 1, which is pulling from the raw material...