# How to Calculate Blister Machine Foil/ Formula

In Pharmaceuticals Packaging mainly two types of foil (Aluminium and PVC/PVDC) are used in the packaging department. So, Calculating the exact required quantity of foil for a particular lot is quite challenging for Professionals working in the Pharmaceutical manufacturing area.

So, Questions arise How much quantity of printed aluminium foil and base foil is required for a specific lot/ batch?

Below you will learn about a simple calculation for required foil in a particular batch of Pharmaceuticals. Below we will discuss these methods in detail as follows.

1. Theoretical Methods
2. Practical Method

You can apply both methods, Although the results will remain the same.

Table of Contents

## Calculating Formula for Blisters

Suppose, we take the batch size of 10,000 tablets for calculating printed aluminum foil as well as PVC.

Number of tablets = 100,000 Tablets

Tablets/Blister =10 Tabs

Number of blisters = 10,000

So, First, we used the theoretical method to calculate the weight of 10,000 Blisters.

### 1. Theoretical Method

I refer to this method as “theoretical” because it allows us to calculate the required foil for any new product, even if no blister tooling is currently available.

If you have dimensions of the blister (You may check blister drawing), we can easily determine the amount of foil needed.

#### Example

Assume a blister drawing presents the following dimensions:

Length of Blister = 8 cm

Width of Blister = 6 cm

Now, Calculate the foil length for each blister;

8×6 =48 cm²

#### Calculation of Printed Foil

The idea is to cut the printed foil according to the blister’s length and width. In the above example, this results in a 48 cm² piece of printed or lidding foil. For a more precise calculation, we would measure and weigh the foil needed for 10 blisters based on these theoretical dimensions.

48×10 = 480 cm²

So, Now we have dimensions of 10 blisters. Suppose the weight of the printed foil piece for 10 blisters is 1.8 GM and now the calculation for the one foil piece will be:

1.8/10 = 0.18 GM

#### Foil Quantity For 10,000 Blisters

Given that the weight of the printed foil per blister is 0.0.18 grams, the total weight for 10,000 blisters is derived using simple multiplication:

Weight of printed foil for one blister = 0.18 GM

The weight of printed foil for 10,000 blisters is

10’000×0.2 GM = 2,000 GM

Convert grams into kilograms

2,000/1000 = 2.0 kg. (Only required for perfectly cut blisters)

Now Move on important point, Here, we will discuss about scarp method. So what is the Scrap Method?

##### Scrap Factor:

The waste that accumulates as a web (A thread/ Bundle of foil after cutting blister), along with the empty rejected blisters removed during machine adjustments, is referred to as the scrap factor. Depending on the efficiency of the blister machine, we may consider a scrap factor of 1% or 2%. So, in the above calculation, we will add a 1% scrap factor.

After Considering the 1% scrap factor, the total quantity of printed foil for blistering 10,000 blisters will be 2.020 kilograms.

So, Like that we can calculate the foil requirements for base foil also.

Read about the Theoritical method drawback below in Final Thought.

### 2. Practical Method

Practical Method is Performing the process by using a Manual Approach.

#### How To Perform

These calculations are performed by using the original cut pieces of printed and base foil collected from the blister machine. To obtain these samples, the necessary tooling and rolls of printed and base foils are first installed on the blister machine.

Here, we will take a dummy sample by using the cold-forming method (no heat seal and pressure) applied at the sealing station. After the blister is cut, two separate pieces of printed and base foil are collected.

The next step is to separate and weigh the printed foil cut piece, and then do the same for the base foil cut piece. For accuracy, just as in the previous calculation, 10 cut pieces of each foil will be used to determine the precise weight.

#### Calculation

Suppose the weight of 10 pieces of printed foil is 2.0 GM & and the weight of 10 pieces of PVC foil is 7.0 GM.

Take the average weight of each cut piece (both foil) for one blister as below:

2.0/10 = 0.2 GM

7.0/10= 0.7 GM

#### Printed Foil Calculation For 10,000 Blisters

Weight of printed foil for one blister = 0.20 GM

The weight of printed foil for 10,000 blisters is

10’000×0.2 GM = 2000 GM

Convert grams into kilograms

2000/1000 = 2.0 kg. (Only required for perfectly cut blisters)

#### Base Foil Calculation For 10,000 Blisters

Weight of base foil for one blister = 0.7 GM

The weight of printed foil for 10,000 blisters is

10’000×0.7 GM = 7000 GM

Convert grams into kilograms

7000/1000 = 7.0 kg (Only required for perfectly cut blisters)

Note: Don’t Forget to add the scrap factor, While finalizing the quantity. For more details about the scrap factor, Read above.

Related Topic: Blister Defects and Remedies

## Final Thought

As, We have discussed the simple case study with methods to calculate the blister foil required for a particular batch size. Both methods are very useful, it is observed that there is a minor weight variation if we use the first method because of foil shrink, here we taking only foil dimension.

In the 2nd method, We have to do the practical. So this is a more accurate method. we are taking the actual weight of both cut pieces to give more accurate results.