Calculate Lead Time

Williams Optical Inc. is considering a new lean product cell. The present manufacturing approach produces a product in four separate steps. The production batch sizes are 45 units. The process time for each step is as follows:

Process Step 1	5 minutes
Process Step 2	8 minutes
Process Step 3	4 minutes
Process Step 4	3 minutes

The time required to move each batch between steps is 5 minutes. In addition, the time to move raw materials to Process Step 1 is also 5 minutes, and the time to move completed units from Process Step 4 to finished goods inventory is 5 minutes.

The new lean layout will allow the company to reduce the batch sizes from 45 units to 3 units. The time required to move each batch between steps and the inventory locations will be reduced to 2 minutes. The processing time in each step will stay the same.

Determine the value-added, non-value-added, total lead times, and the value-added ratio under the present and proposed production approaches. If required, round percentages to one decimal place.

	Present Approach		Proposed Approach
Value-added time		min		min
Non-value-added time		min		min
Total lead time		min		min
Value-added ratio (as a percent)		%		%

Feedback

In this exercise for Present: Value-added processing time = Add together Process steps 1-4 Non-value-added time = Total within-batch wait time + Move time, where Total Within-Batch Wait Time = (Total Time to Perform Operations) x (Batch Size - 1) Add value-added processing time + non-value-added processing time to obtain total processing time. Calculate Value-Added Ratio = Value-Added Process Time Total Process Time In this exercise for Proposed: Value-added processing time = Add together Process steps 1-4 Non-value-added time = Total within-batch wait time + Move time, where Total Within-Batch Wait Time is obtained by multiplying the process time by the remaining units in the batch (waiting their turn) Add value-added processing time + non-value-added processing time to obtain total processing time. Calculate Value-Added Ratio = Value-Added Process Time Total Process Time

Learning Objective 1.

Present Approach Proposed Approach Value-added time Non-value-added time Total lead time Value-added ratio (as a percent) 20 min 905min 925min 2.161 X % 20 min 50 min 70 min 281 X %