Why Compression Machines Have Odd Number Of Punches

Compression machines are used in pharmaceutical industries to compress powders or granules to form Tablets. It is a common observation that mainly Compression Machines have an odd number of punches or odd number of Stations.

Example

If you are working in the pharma industry or you have every chance to visit the pharma Industry you must notice that following numbers of station in a compression machine are present,

So a common question comes to mind: why do odd numbers of punches are used & why don’t we use even numbers of Stations or Punches?

In this article, we will try to remove this confusion but first of all, you have to understand the types of compression machines because the answer to the above questions is directly linked to the type of compression machine.

Types Of Compression Machines

The rotary compression machines are of two types which are given below,

Single Feed Rotary Compression Machine
Double Feed Rotary Compression Machine

Single Feed Rotary Compression Machine

In a single-feed rotary compression machine,one tablet is produced by each punch when the turret revolves & completes its one round.
Single-feed rotary compression machines have one set of main compression rollers, one on the upper side & one on the lower side.
When the machine is in running condition all the Punches pass through the single set of wheels and compress tablets.

Double Feed Rotary Compression Machine

In double-feed rotary compression machines, two tablets are compressed by each punch when the turret revolves & completes its one round.
Double-feed rotary compression machines have two sets of main compression rollers one on the upper side & one on the lower side of the right hand side (RHS) & vice versa.
When the machine is in running condition the punches pass through these wheels or rollers & compress tablets on both sides due to the application of pressure exerted by the wheels installed on both sides.

Even Number Of Compression Stations

Even number of punches may be present in a single feed compression machine because there is no risk of an even number of punches in a single feed Compression Machine. That is why many of you have seen compression machines with an even number of Stations or Punches like 20 punches or stations so why are we discussing this topic?The reason is that an even number of Stations or punches can be installed in single feed Compression Machines but can’t be used in double-feed rotary compression machines where we only use an odd number of Stations due to the following reasons.

Why Odd Numbers Of Compression Stations?

The technical & logical reasoning for double-feed rotary compression machines having an odd number of Stations is to maintain the Dynamic Balancing of the machine.

Dynamic balancing is the balance of a compression machine when it is running.

Explanation

Double-feed rotary compression machines as we discussed earlier have two sets of Compression Rollers so during the motion of the turret, punches on both sides come under both rollers for Compression.

If both side punches come under the both rollers at the same time the dynamic balancing of the machine will be disturbed & the machine will be overloaded,producing heavy noise, vibrations & will be jammed.

Example

To understand dynamic balancing, take the example of Walking or climbing the stairs. For walking, first we lift one feet, place it on the ground & then lift the other feet & so on for smooth walking. We can’t walk if we try to walk by lifting both feet simultaneously or at the same time.

In the same way, if punches on both sides come under the rollers at the same time it will not be possible for the compression machine to run or rotate,& will be jammed.

Due to this reason double feed rotary compression machines have the odd number of punches or punch stations like 39 stations Compression Machine. In the case of 39 stations, the punches are divided as 19/20 meaning 19 punches on one side & 20 on the other side so when the turret of the compression machine revolves there are no chances for punches to come under rollers at the same time.