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Chapter 15 Lean synchronization 455
is huge demand for special stairs in this region, but also a
lot of competing small joinery businesses which can beat us
on price and lead time. So we go to a lot of trouble quoting
for stairs, but only win about 20 per cent of the business. If
we got the cell idea to work, we could be more competitive
on price and delivery, hence winning more orders.
I know we will need a lot more volume to justify establishing
the cell, so it’s really a case of “chicken and egg”!’
Questions
1 To what extent could (or should) Dean expect to apply
the philosophies and techniques of JIT described in
this chapter to the running of a staircase cell?
2 What are likely to be the main categories of costs
and benefits in establishing the cell? Are there any
non-financial benefits which should be taken into
account?
3 At what stage, and how, should Dean sell his idea to
the Joinery Manager and the workers?
4 How different would the cell work be to that in the
main Joinery Department?
5 Should Dean differentiate the working environment by
providing distinctive work-wear such as T-shirts and
distinctively painted machines, in order to reinforce a
cultural change?
6 What risks are associated with Dean’s proposal?
Problems and applications
These problems and applications will help to improve your analysis of operations. You
can find more practice problems as well as worked examples and guided solutions on
MyOMLab at www.myomlab.com.
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Revisit the worked example earlier in the chapter that analysed a journey in terms of value-added time (actually
going somewhere) and non-value-added time (the time spent queuing etc.). Calculate the value-added time for a
recent journey that you have taken.
A simple process has four stages: A, B, C and D. The average amount of work needed to process items passing
through these stages is as follows: Stage A = 68 minutes, Stage B = 55 minutes, Stage C = 72 minutes and
Stage D = 60 minutes. A spot check on the work-in-progress between each stage reveals the following: between
Stages A and B there are 82 items, between Stages B and C there are 190 items, and between Stages C and D
there are 89 items.
(a)
(b)
Using Little’s law (see Chapter 4) calculate the throughput time of the process.
What is the throughput efficiency of the process?
In the example above, the operations manager in charge of the process reallocates the work at each stage
to improve the ‘balance’ of the process. Now each stage has an average of 64 minutes of work. Also, the
work-in-progress in front of Stages B, C and D is 75, 80 and 82 units respectively. How has this changed
the throughput efficiency of the process?
A production process is required to produce 1,400 of product X, 840 of product Y and 420 of product Z in a
4-week period. If the process works 7 hours per day and 5 days per week, devise a mixed model schedule in
terms of the number of each products required to be produced every hour, that would satisfy demand.
Revisit the ‘Operations in action’ at the beginning of this chapter, and (a) list all the different techniques and
practices which Toyota adopts. (b) How are operations objectives (quality, speed, dependability, flexibility, cost)
influenced by the practices which Toyota adopts?
Consider how set-up reduction principles can be used on the following.
(a) changing a tyre at the side of the road (following a puncture);
(b) cleaning out an aircraft and preparing it for the next flight between an aircraft on its inbound flight landing
and disembarking its passengers, and the same aircraft being ready to take-off on its outbound flight;
(c) the time between the finish of one surgical procedure in a hospital’s operating theatre, and the start of the
next one;
(d) the ‘pitstop’ activities during a Formula One race (how does this compare to (a) above?).