Perform successive rollups with Product Report

Suppose you want to use Product Report to perform successive rollups in order to determine the overall performance measures for a complex product. In this example, assume you have a product composed of the following assemblies:
  • Assembly 1 requires 2 units of subassembly 1-1 and 1 unit of subassembly 1-2.
  • Assembly 2 requires 4 units of subassembly 2-1, 2 units of subassembly 2-2, and 1 unit of subassembly 2-3.
  • Assembly 3 requires 1 unit of subassembly 3-1, 1 unit of subassembly 3-2, and 6 units of subassembly 3-3.

The end product requires 4 units of assembly 1, 2 units of assembly 2, and 1 unit of assembly 3.

Assembly 1, subassembly 1-1
Assembly 1, subassembly 1-2

Combine the data from subassembly 1-1 and subassembly 1-2 to make the report for assembly 1.

C1 C2 C3 C4 C5
Sub-assembly Defects Units Opps/Unit Z.Shift
 1-1 61 140 26040 / 140 = 186 1.24
 1-2 26 162 6156 / 162 = 38 1.23
Entire assembly 1

In the process of making 70 units of assembly 1, there are 72 defects. Overall, assembly 1 has a Z = 4.044 and YRT = 0.3558. Thus, the probability of making one unit of assembly 1 with 0 defects is ~ 36%.

Assembly 2, subassembly 2-1
Assembly 2, subassembly 2-2
Assembly 2, subassembly 2-3

Use the following data to make the report for assembly 2.

C1 C2 C3 C4 C5
Sub-assembly Defects Units Opps/Unit Z.Shift
 2-1 69 241 16147 / 241 = 67 1.42
 2-2 30 307 7675 / 307 = 25 1.26
 2-3 36 162 10692 / 162 = 66 1.36

Entire assembly 2

In the process of making 60 units of assembly 2, there are 94 defects. Overall, assembly 2 has a Z = 4.035 and YRT = 0.2089. Thus, the probability of making one unit of assembly 2 with 0 defects is ~ 21%.

Assembly 3, subassembly 3-1
Assembly 3, subassembly 3-2
Assembly 3, subassembly 3-3

Use the following data to make the report for assembly 3.

C1 C2 C3 C4 C5
Sub-assembly Defects Units Opps/Unit Z.Shift
 3-1 26 203 7308 / 203 = 36 1.39
 3-2 47 210 13440 / 210 = 64 1.41
 3-3 45 160 7680 / 160 = 48 1.42

Entire assembly 3

In the process of making 60 units of assembly 3, there are 136 defects. Overall, assembly 3 has a Z = 3.984 and YRT = 0.1034. Thus, the probability of making one unit of assembly 3 with 0 defects is ~ 10%.

Entire product

You would expect to see 162 defects in 17 products. The entire product has a Z = 4.023 and YRT = 0.000073. Thus, the probability of producing an entire product with 0 defects is essentially 0. Considering the large opportunity count (48620 total opportunities divided by 17 products is 2860 opportunities per product) and the Z of 4, this result is expected.

The three assemblies are almost identical in capability, with Z values very close to 4.

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