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Optimization Case Study

Coating Weight Gain

Problem

For a color coating process, determine the most economical coating process using the development data.  The development data showed that higher weight gain was needed at lower coating uniformity to properly mask the tablet appearance.  Use the following coating integrity data for the analysis:. 

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11.3% wt gain needed at 6% RSD

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16.6% wt gain needed at 10% RSD

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22% wt gain needed at 14% RSD

The cost of coating substrate is $100/kg while the cost of operation is $250/hr.

Problem Categories

Coating uniformity, coating pan, engineering, and PCTSUni

Solution

The base condition at 16.6% wt gain and 10% RSD is shown below.  From this condition, the weight gain is changed to 11.3 and 22% and spray rate is altered until 6% and 14% RSD, respectively are achieved using PCTSUni.  The results are shown in the table below.
Results

Scenario

A

B (Base Case)

C

RSD

6%

10%

14%

Weight gain

11.3%

16.6%

22%

Amount of coating (kg)

30.21 (4% solids)

44.55 (15%)

58.84 (40%)

Cost of coating ($/kg)

100

Cost of coating ($)

3021

4455

5884

Non-coating time (hr)

6

Coating time (hr)

12.59

4.95

2.45

Total time (hr)

18.59

10.95

8.45

Cost of operation ($/hr)

250

Cost of operation ($)

4647

2737

2112

Total cost ($)

~7700

~7200

~8000

The base case results in the lowest cost of manufacturing scenario based on the cost of material and operation cost.