Page 285 - How To Implement Lean Manufacturing

262 Cha pte r S i x tee n

elements, performed. These work elements included burning the leads, straightening
the leads, cleaning the leads, connecting to the Hipot machine, cycling the machine,
disconnecting from the machine, and passing to the next station.) Since most of the
work elements could not really be transferred to another work station, this was not a
good tool for us as we tried to internally synchronize the flow. (Recall that this was a
key element in balancing the Zeta Cell so efficiently. Unfortunately, it just wouldn’t
work here).
Table 16-10 shows the results from the time study, with the data segregated into
large and small rotors.
The data for the time study was then used to create the line balance chart, Fig. 16-7,
showing both the large and small stator cycle times compared to the takt of
7.09 minutes. This was then converted to a balancing chart to show operation with a
line that is balanced with 50 percent large stators and 50 percent small stators, shown
in Fig. 16-8.
Evaluation of the Balance Chart
As we evaluate this line balance chart, we can see there is lots of waiting and that the
process stations are not well balanced. However, the critical problem is the bottleneck
of the CNC lathe. Not only is it a bottleneck but the cycle time exceeds takt. This shows
clearly why a great deal of overtime is required. It is obvious that to meet customer
demand we will need to improve the cycle time at the CNC lathe.

Large Stator Small Stator Ave C/T Based on
Work Time Work Time Present Present Staffing
Process Step (Min) (Min) Staffing Large/Small (Min)
Weld Stator 14 11 2 7.0/5.5
Coil Insert. 105 65–90 16 ∗ 6.5/5.0
Lace&Press 36 26 9 4.0/2.9
Hipot 3.5 3.5 1 3.5/3.5
Preheat 7.5 3.75 1 7.5/3.75
Varnish 6.7 3.3 6.7/3.3
Bake 8.75 4.38 8.75/4.38
Polish 3.5 3.5 4.5/3.5
CNC Lathe 9.5 8.5 2 ∗∗ 9.5/8.5
Final Ass’y 13 12 4 ∗∗∗ 6.5/6.0
Final Insp. 6 6 1 6.0/6.0
Packaging 2.5 2.5 1 2.5/2.5

∗ Four cells of four people each
∗∗ Lathe personnel operate in parallel
∗∗∗ Two cells of two people each
TABLE 16-10 Time Study