How pharmaceutical producers can prevent rust in equipment  

If it is not properly dealt with, corrosion might have a negative impact on tablet compression tooling. It may create manufacturing delays, decreased effectiveness, and contamination issues. 

Discoloration, etching, or common red rust are signs of corrosion that can be seen. Acidic components, such as those found in the formulation being compressed or even in the environment, are the primary cause of corrosion. The iron atoms in the metal tooling are in contact with oxygen and moisture, either as vapour or dampness. The iron particles in the steel are lost to the acidic electrolytes of the water when it is exposed to moisture. By oxidising the iron atoms, they create corrosion on the punches and dies. 

Corrosion can happen for a variety of causes, but it can be prevented by using the right steel, coating, or treatment, as well as the right maintenance techniques.  

Moisture in the atmosphere  

The presence of too much moisture and humidity is one of the main causes of corrosion. This is due to the fact that locations with the liquid present frequently experience corrosion. The air we breathe contains oxygen, while wet air carries water. Depending on the temperature, the amount of water vapour in the air can vary from as little as 0.2 percent to as much as 4 percent. 

A major effect on corrosion developing on the tooling can be caused by excessive humidity in the compression chamber, tool storage area, or locations where the drug formulation is stored before compaction. Therefore, it is crucial to maintain environmental control throughout the entire tablet manufacturing process. 

Since steel is used for tooling and we are unable to purge the air of oxygen, environmental controls that manage temperature, humidity, and moisture levels should be in place to avoid corrosion on the punches and dies. 

Formulation information 

All formulations differ greatly in terms of their properties and moisture content, which is frequently required to aid in the binding of the tablet structure. However, too much water inside the tablet might result in sticking and other issues including corrosion. 

Corrosion can occur regardless of the amount of moisture in the formulation. Formulas with corrosive ingredients, like salts, acids, and chlorine, will react with the tooling surfaces and cause oxidation. Additionally, several contemporary tablet presses have wash-in-place systems that expose equipment to water and cleaning agents. If not properly managed, post-compression cleaning methods might also lead to corrosion. Therefore, it's crucial that tools have the required corrosion-resistant qualities through the choice of steel and coating. 

Preventing microbial growth 

Other options, such as tooling material, coatings, and maintenance, should also be taken into account. Improving the environment in which tablet compression and tooling storage take place can significantly effect corrosion prevention. 

Selection of tool steel 

In the production of tablets, tool wear and deterioration are unavoidable. If they are not maintained, the repetitive cyclic action of compression will wear down the tooling. The formulation being compressed has a significant impact on tooling deterioration. Some items, such as some granules that are particularly tough and abrasive, can have negative effects on the punch tips. These have the potential to wear down, impregnate, and scrape steel. Corrosive substances in other granulates may interact with the steel. This deterioration can result in tableting flaws like black spots, which are caused by corroded tooling, and sticking, where the granulation sticks to the punch tip face and results in expensive waste, decreased production, and unwelcome press downtime. 

Although tool steel is hardened and tempered during manufacturing, if the tool material is not adapted to the formulation being compressed, the rigorous procedures could cause deterioration. 

In addition to having a lengthy lifespan, high-quality tooling should also be resistant to wear and abrasion. The danger of damage to the punches and dies from abrasion, corrosion, and impregnation with hard granules can be decreased by making the right material choice. 

For tablet compression tooling to work properly, the right steel is essential. When choosing steel, you should consider the following qualities:  

Strength is the capacity to bear a stress without breaking. 

Resistance to oxidising, staining, and discoloration is referred to as corrosion. 

Toughness: Resistance to breaking of the punch tip, chipping, and cracking 

Resistance to abrasive wear: Protection for punch tips and die bores from abrasive wear.  

Adhesive wear resistance: Protection against welding, galling, and adhesive wear  

Resistance to impregnation by tough, pointy particles 

Compressive strength: Protection against punch tip edges deforming plastically and die bore ringing. 

Fatigue resistance: The ability of a material to withstand the progressive and localised structural degradation brought on by cyclic loads. 

A carefully chosen tool steel is an excellent choice if the tooling being used is susceptible to corrosion either of environmental impacts or because of the formulation's properties. Because they have a stronger resistance to oxidisation, staining, and discoloration of the tablet tooling, specialised martensitic stainless steels with high chromium content ought to be employed.  

Treatments and coatings 

In addition to the tool coating and treatments, selecting the right tool steel is crucial to preventing corrosion. 

The choice of tool coating can have a significant effect on output. Tool coatings are an excellent way to solve issues with tablet manufacture when combined with high-quality tooling steel. By minimising the need for further cleaning and maintenance labour to eliminate troublesome residue, which, if left untreated, may cause possible production concerns, such as corrosion, sticking, and picking, they improve tableting efficiency and output. 

The most common coating historically employed in the tablet tooling business was electro-plated hard chromium, although it has significant drawbacks. A little quantity of hydrogen permeates the substrate when hard chromium is applied to tools, reducing the working load of the steel by up to 20%. The plated instruments go through a de-embrittlement baking procedure to counteract this impact, which lessens but does not completely remove the undesirable property. It can also experience microcracks during plating when the internal tension is greater than the tensile strength of the chromium. These microscopic fissures are dangerous because they offer a permeable pathway to the substrate, allowing granules or cleaning agents to assault the steel below. 

Chromium-rich specialised coatings that are deposited using a sophisticated Physical Vapor Deposition (PVD) procedure have been created. The anti-stick coating produced by the PVD method is exceptionally dense and smooth. None of the problems related to applying hard chromium are present in this procedure. 

Knowing the product being squeezed is essential when selecting a tool coating. For instance, if the mixture contains a lot of corrosive substances like acids and salts, they will eventually interact with the steel and cause oxidation and other types of degradation. In such cases, a suitable corrosion-resistant coating should be chosen, such as one made of chromium or chromium nitride. 

Maintenance of a tool 

The handling, cleaning, polishing, and storage of punches and dies, as well as other improper tool maintenance techniques, can have a significant impact on the manufacturing of tablets. All of these procedures expose the tooling to substances and settings that could potentially oxidise it. Therefore, it's critical that tried-and-true maintenance procedures are in place to increase tool longevity. 

Regular tablet tooling maintenance has the straightforward goal of reducing compression issues and ensuring that it performs at the optimum level of functionality. For efficiency and the general efficacy of the equipment, it is essential to maintain tablet punches and dies in top working order to manufacture high-quality tablets (OEE). Planning frequent audits of operations is necessary to maintain and guard against corrosion problems. Poor tool maintenance and care incur costs in the form of both additional, unneeded tool purchases as well as production issues that could have been avoided. 

When trying to prevent corrosion, the right cleaning techniques are crucial. Granules will be removed from the punch, aiding in the prevention of product contamination and potential production problems like sticking and picking brought on by out-of-date items sticking to the punch tip's surface. 

The best time to accurately evaluate the tooling's condition is right after cleaning. Any visual evaluation of the punch tips and die bores can be impacted by dirty punches. This would imply that issues like wear, damage, or corrosion are not taken into account. 

Tooling must be completely cleaned after being withdrawn from the tablet press to get rid of any oil or product residue, especially in hard-to-reach places like embossing and keyways. Ultrasonic cleaning is one of the best cleaning processes. Consistent cleaning outcomes, less processing and operator time, and a lower chance of tablet contamination are all made possible by ultrasonic baths. Importantly, ultrasonic cleaning enables cleaning of the entire punch, including areas inside and outside of the embossing. A corrosion inhibitor should be introduced to the cleaning cycle at a certain concentration to ensure that the process does not corrode the tooling material. As a result, an oxide film will form on the metal's surface, passivating the steel and preventing corrosion.  

To guarantee that there is no cleaning fluid residue left on the tooling surface that could lead to corrosion, it is also crucial to fully dry the tooling after cleaning. 

Another crucial process to think about while preventing corrosion is appropriate storage. If the storage system is not tidy and dry, tooling may be exposed to moisture. Corrosion on the tooling surface can be avoided with proper storage practises and tooling covered in a coating of non-toxic, FDA-approved oil or grease. Whether oil (short term) or grease (long term) is needed will depend on how long the tooling will be stored. 

Another potential source of anxiety is how the tooling is handled. It is always advised to take up the tooling while wearing gloves. This is due to the fact that human hands contain acids and moisture, both of which can hasten and cause corrosion on tooling. A rusty fingerprint is not unheard of to be left behind! This can be avoided by wearing gloves at all times and using the right maintenance techniques and procedures. 

To get the most life out of punches and dies, a straightforward, standardised tooling maintenance method is necessary. By using these advised best practises, corrosion issues can be avoided, and tool life can be increased. 

 Keep rusting under control 

Corrosion problems brought on by improper tool storage and care, insufficient understanding of the properties of the formulation, and further needless tool acquisitions also result in production issues that could have been avoided. In order to prevent production of tablets from being impacted, it is crucial to manage corrosion at its source.  

Find out if the compressed granule contains hard, abrasive granules or components that contain chlorine, salts, and acids. Does the air where compression and storage occur have a significant moisture content? If the answer is "yes," it is crucial to safeguard tooling to prevent corrosion from setting in.  

Tablet tooling will be more effective and durable if the proper tool steel and corrosion-resistant coatings are used. Pharmaceutical firms may get the most out of tablet punches and dies by following efficient maintenance and tool care methods.