Tablet presses are machines designed to compress pharmaceutical powders and granules into tablets. They must be highly precise in order to create uniform tablets that each contain the same amount of active pharmaceutical ingredients and excipients. This page will cover some key essentials that you need to know about these vital machines.
The pharmaceutical industry manufactures vast numbers of tablets every day, and the safety of patients can depend on the uniformity of each dosage unit. As such, the precision capabilities offered by modern tablet presses are invaluable for pharmaceutical companies.
While most tablet presses function similarly in principle, the method of compression varies slightly depending on the type of press. There are two different classifications of tablet press machines: single punch presses and multi-station/rotary presses.
Single punch tablet presses, also known as eccentric or single station presses, are the simplest form of tablet press. They utilize a single station of tooling that is composed of a pair of upper and lower punches and a die. For this type of press, the lower punch remains stationary while the upper punch exerts the entirety of the compression force to create the tablets. Due to their hammer-like motions, single punch tablet presses are categorized as a stamping process.
Unlike single-punch tablet presses, rotary tablet presses contain multiple tooling stations. As the turret in which these stations are installed rotates, the punches move between a set of upper and lower compression rolls that exert enough compression to form uniform tablets, in large quantities. In this type of press, both the upper and lower punches move and the tablet compression occurs between the two. Rotary presses are thus categorized as a type of accordion compression.
The goal of this type of press is to increase the output of tablets. Depending on the different punch designs, rotary presses can create tablets of different shapes and dimensions.
The two categories of tablet presses are each composed of a number of different parts. Single punch presses contain the following:
Multi-station/rotary tablet presses have a significantly greater number of parts. In addition to the hopper, die cavity, upper and lower cam tracks, and punches, these presses contain:
Each type of tablet press has its own unique advantages that make it well-suited for specific applications.
The single punch press is best for projects where minimal amounts of test material are available, and in cases where the user is simply looking to confirm compressibility and nothing more. They do not allow the user to replicate key principles affecting production-sized presses, such as centrifugal force, mechanical feeder behavior and dwell time. Its biggest advantages are:
Rotary tablet presses are ideal for applications requiring high batch production, as their design allows for significant output and precise control. Advantages include:
Rotary presses can essentially meet most tablet batch requirements in pharmaceutical, nutraceutical, confectionery and veterinary applications. They are also used with surprising frequency to produce catalysts, ceramics, powdered metals and other materials deemed suitably compressible.
Given the sheer capabilities of modern tablet presses, including not only the forces they generate but also the speeds at which they are typically operated, they include many components that require periodic replacement (i.e. “wear” parts). The quality of the parts used when replacing those at the end of their useful life is directly correlated with the machine’s long-term efficacy, and life expectancy.
Parts like punches and dies are particularly important, as they determine not only the size, shape and appearance of the tablets, but also the key attributes referenced earlier: weight, thickness and hardness. High quality tooling, and good preventive maintenance programs ensuring the same, are critical.