Working with Per-Piece Quantities in Premixes

Per-piece calculations place special constraints on how premix ingredient levels are calculated for per-piece target levels. You have the choice between allowing changes to the per-piece ratios of premix ingredients, or locking the per-piece ratios of premix ingredients.

See Also
Creating a Standard Phase
About Phases
Creating a Premix Phase and Linking to It
Viewing and Editing Phase Properties
Phase Properties

You can conceive of a premix in two ways:

  • As a phase in a formula whose ingredient ratios can be changed.

  • As a separate, premade subformula whose composition cannot be changed.

In the first case, you select Phase composition changes to accommodate Per Batch and Per Piece changes. Links to Phase remain unaffected in the premix's properties. This enables you to change the relative per-piece amounts of ingredients in the premix phase, while keeping the amount of the premix link in the main formula unchanged.

In the second case, you select Phase composition is LOCKED for Per Batch and Per Piece changes. Links to Phase are altered in the premix's properties. If you change the per-piece amount of an ingredient in the premix, the per-piece amounts of the other ingredients also change, so that the ratio of the ingredients stays the same. The total amount of the premix link in the main formula increases automatically to reflect the new per-piece total.

Example

Consider a formula for a tablet with a blue coating. The coating is defined in a premix phase called Coating, which includes the coloring ingredient Blue Dye.

You want to make the tablet darker by increasing the amount of blue dye. How you achieve this depends on whether or not you can alter the composition of the Coating premix. If you can alter it, you can select Phase composition changes to accommodate Per Batch and Per Piece changes. Links to Phase remain unaffected in the premix phase's properties. You then increase the amount of Blue Dye in the premix (Method 1 below). The amount of the coating, specified in Link to Coating, stays the same, but the tablet is darker because the per-piece level of blue dye has increased from 10 mg to 16 mg.

If you cannot alter the composition of the Coating premix, you can instead make the tablet a darker blue by increasing the thickness of the coating. Select Phase composition is LOCKED for Per Batch and Per Piece changes. Links to Phase are altered. Now, when you increase the per-piece amount of Blue Dye to 16 mg, the amounts of the other premix ingredients increase proportionately. The per-piece dry weight of the premix increases from 60 mg to 96 mg (Method 2 below).

Original Composition:

# Material ID Material Name Wet % Wet Wt Processing Loss Dry Wt Per Piece Dry Wt Units
P1 PI-00000049
Main Phase 100.00% 1000.00 10.00% 900.00 400.00 mg g
1 0000000001 Ingredient A 25.00% 250.00 10.00% 225.00 100.00 mg g
2 0000000002 Ingredient B 60.00% 600.00 10.00% 540.00 240.00 mg g
3 Link to Coating 15.00% 150.00 10.00% 135.00 60.00 mg g
Coating 100.00% 400.00 10.00% 360.00 60.00 mg g
4 0000000003 Blue Dye 16.67% 66.67 10.00% 60.00 10.00 mg g
5 0000000004 Coating Ingredient X 35.00% 140.00 10.00% 126.00 21.00 mg g
6 0000000005 Coating Ingredient Y 48.33% 193.33 10.00% 174.00 29.00 mg g
TOTALS: 100.00% 1000.00 10.00% 900.00 400.00 mg g

Method 1: Use Phase composition changes to accommodate Per Batch and Per Piece changes. Links to Phase remain unaffected. Make the tablet darker by increasing the per-piece amount of Blue Dye in the premix from 10.00 mg to 16.00 mg. Reduce the amounts of the other premix ingredients, to keep the premix total at 100%. The level of Blue Dye in the premix is now 26.67%:

# Material ID Material Name Wet % Wet Wt Processing Loss Dry Wt Per Piece Dry Wt Units
P1 PI-00000049
Main Phase 100.00% 1000.00 10.00% 900.00 400.00 mg g
1 0000000001 Ingredient A 25.00% 250.00 10.00% 225.00 100.00 mg g
2 0000000002 Ingredient B 60.00% 600.00 10.00% 540.00 240.00 mg g
3 Link to Coating 15.00% 150.00 10.00% 135.00 60.00 mg g
Coating 100.00% 400.00 10.00% 360.00 60.00 mg g
4 0000000003 Blue Dye 26.67% 106.67 10.00% 96.00 16.00 mg g
5 0000000004 Coating Ingredient X 30.00% 120.00 10.00% 108.00 18.00 mg g
6 0000000005 Coating Ingredient Y 43.33% 173.33 10.00% 156.00 26.00 mg g
TOTALS: 100.00% 1000.00 10.00% 900.00 400.00 mg g

Method 2: Use Phase composition is LOCKED for Per Batch and Per Piece changes. Links to Phase are altered. Make the tablet darker by increasing the total amount of the premix in the main formula:

# Material ID Material Name Wet % Wet Wt Processing Loss Dry Wt Per Piece Dry Wt Units
P1 PI-00000049
Main Phase 109.00% 1090.00 10.00% 981.00 410.00 mg g
1 0000000001 Ingredient A 25.00% 250.00 10.00% 225.00 100.00 mg g
2 0000000002 Ingredient B 60.00% 600.00 10.00% 540.00 240.00 mg g
3 Link to Coating 24.00% 150.00 10.00% 216.00 96.00 mg g
Coating 100.00% 400.00 10.00% 360.00 96.00 mg g
4 0000000003 Blue Dye 16.67% 66.67 10.00% 60.00 16.00 mg g
5 0000000004 Coating Ingredient X 35.00% 140.00 10.00% 126.00 33.60 mg g
6 0000000005 Coating Ingredient Y 48.33% 193.33 10.00% 174.00 46.40 mg g
TOTALS: 109.00% 1090.00 10.00% 981.00 436.00 mg g

Note that the total percentage of the formula increases to 109%. To correct the ingredient levels, use Scale Ingredient Weights to Batch Size (see Rescaling Ingredient Weights).