1. **Problem Statement:** Isaacson Dental Inc. has a manufacturing process with 4 steps and batch sizes of 50 units. We need to calculate value-added time, non-value-added time, total lead time, and value-added ratio for both the present and proposed lean production approaches. 2. **Definitions and Formulas:** - Value-added time (VA) is the sum of processing times. - Non-value-added time (NVA) is the sum of waiting, moving, and inventory times. - Total lead time (TLT) = VA + NVA. - Value-added ratio (VAR) = $\frac{VA}{TLT} \times 100\%$. 3. **Given Data:** - Processing times per step: Step 1 = 6 min, Step 2 = 12 min, Step 3 = 9 min, Step 4 = 3 min. - Batch size present = 50 units, proposed = 2 units. - Move times present = 6 min between steps and inventory, proposed = 1 min. --- ### (a) Present Production Approach 4. **Calculate Value-Added Time (VA):** $$VA = 6 + 12 + 9 + 3 = 30 \text{ minutes}$$ 5. **Calculate Non-Value-Added Time (NVA):** - Move raw materials to Step 1: 6 min - Move between steps (3 moves): $3 \times 6 = 18$ min - Move finished goods from Step 4: 6 min - Total NVA: $6 + 18 + 6 = 30$ min 6. **Calculate Total Lead Time (TLT):** $$TLT = VA + NVA = 30 + 30 = 60 \text{ minutes}$$ 7. **Calculate Value-Added Ratio (VAR):** $$VAR = \frac{30}{60} \times 100\% = 50.0\%$$ --- ### (b) Proposed Production Approach 8. **Value-Added Time (VA) remains the same:** $$VA = 30 \text{ minutes}$$ 9. **Calculate Non-Value-Added Time (NVA):** - Move raw materials to Step 1: 1 min - Move between steps (3 moves): $3 \times 1 = 3$ min - Move finished goods from Step 4: 1 min - Total NVA: $1 + 3 + 1 = 5$ min 10. **Calculate Total Lead Time (TLT):** $$TLT = VA + NVA = 30 + 5 = 35 \text{ minutes}$$ 11. **Calculate Value-Added Ratio (VAR):** $$VAR = \frac{30}{35} \times 100\% \approx 85.7\%$$ --- **Final answers:** - Present approach: VA = 30 min, NVA = 30 min, TLT = 60 min, VAR = 50.0%. - Proposed approach: VA = 30 min, NVA = 5 min, TLT = 35 min, VAR = 85.7%.