Just like the automobiles many of us drive on a regular basis, pharmaceutical manufacturing machinery needs regular maintenance to keep plugging along. And, similar to those personal autos, failing to keep up with maintenance can lead to frustrating, costly breakdowns.
Alex Bunting, marketing manager for tabletting equipment company I Holland, recently spoke with Outsourcing-Pharma about the vital importance of keeping up with maintenance and offered some tips for getting the job done.
OSP: You brought up an interesting quote from Benjamin Franklin: “The best investment is in the tools of one’s own trade.” How does that quote apply to pharma manufacturing, specifically tablet tooling?
AB: This is particularly true when it comes to the punches and dies used within pharmaceutical manufacturing. Investment should not only be made in the tooling itself, but also in maintaining them so they perform efficiently to maximize tablet production.
The purpose of regular tablet tooling maintenance is simple: to minimize compression problems and ensure that it operates at its highest functionality. Ensuring tablet punches and dies are kept in optimum condition to produce high-quality tablets is critical for productivity and overall equipment effectiveness (OEE). The reality is however that tablet compression tools are often viewed as disposable items, therefore, maintenance can be seen as an unnecessary and time-consuming process. This can be a costly mistake and will directly affect production.
OSP: Could you please talk about some of the ways in which neglecting tooling maintenance can come back to haunt an operation (i.e. impact to quality, efficiency, safety considerations, costly breakdowns)?
AB: The cost of poor tool care and maintenance not only results in additional unnecessary tool purchases but also in production problems that could have been avoided.
The repetitive cyclic action of compression will take its toll on tooling, particularly if they are not maintained. A substantial influence on tooling deterioration is the formulation being compressed. Some products can cause adverse effects on the punch tips, for example, certain granules are extremely hard and abrasive. These can scratch, wear and impregnate the steel surface.
Other granulate can contain corrosive elements which react with the steel. Demanding processes are applied throughout manufacturing and despite using hardened and tempered tool steel materials, punches and dies will be affected if not maintained regularly. This deterioration can lead to tabletting defects like sticking where the granulation adheres to the punch tip face causing costly wastage, reduced yield, and unwanted press downtime. This degradation in the tool’s surface can be identified during proper assessment and rectified by cleaning granules from the surface and through polishing.
Die bore wear
Die bore wear or ringing is another defect that can occur if maintenance processes are not put in place. Ringing is caused by abrasive wear of the granule under compression and continuous forces acting on the face of the die bore. This can lead to problems such as tablet capping where the top or bottom of the tablet separates horizontally from the main body resulting in reduced tablet output.
This type of wear can be mitigated by utilizing different zones in the die bore where the tablet is compacted or by the selection of a harder more wear-resistant die material. However, unless maintenance procedures are put in place to identify and monitor wear through early diagnosis and assessment measures, the negative effect on tablet output will be costly.
Tooling damage through careless handling can be another significant problem. About 80% of damage to punches and dies is caused accidentally when handling the tooling.
There are several stages of the tablet manufacturing process where damage can take place, including unpacking the tooling, loading and unloading the tools in or out of the tablet press, during tool maintenance procedures and storage and transportation. If damage occurs, usually in the form of nicks or burrs to the delicate punch tip land area, it can lead to the production of poor-quality tablets, and even further damage to both the tooling and worst of all, the tablet press.
It is important to understand the delicate nature of the tooling and exercise good tool care, maintenance, storage, and handling procedures, to keep this problem to a minimum. This should be done by adopting a planned process for tooling maintenance and storage with the incorporation of a management system to monitor all tooling.
Careless handling during loading and unloading the tooling in or out of the tablet press can also cause damage to punch keys. The punch key is used when producing non-round tablets and punches with multiple tips, usually on the upper punches, to facilitate accurate alignment of the upper punch tip into the die bore.
The key is designed as a sacrificial part and is typically manufactured from a softer material than the body of the punch which can make it more prone to damage if not handled correctly during loading and unloading. Key damage can lead to other issues such as punch tightness or other alignment issues. Damage to keys can be reduced by having a good understanding and appreciation of its function and by taking extra care during the handling, maintenance, and setting processes.
The punch heads are subjected to high cyclic loadings, and if they are out of specification or conformity there will be resistance between the punch heads, the cams, and rollers, increasing the high frictional force. This will lead to premature wearing and eventual fatigue and total breakdown of the tool material.
The result is contamination in the tablet press due to metal particles, and expensive damage to tooling, press cams, and compression rollers. This type of damage can be avoided by close monitoring of the tooling condition and good tooling and tablet press maintenance procedures.
OSP: If a neglectful operation wants to change its ways, how can it start? Please share advice or steps it should follow.
AB: Effective solid dose manufacturing practices are critical to producing a quality tablet quickly, efficiently, and economically. One of the most important procedures to implement is appropriate tool care, maintenance, storage, and handling procedures, to optimize tooling life. This can be achieved in seven simple steps. Applying specific procedures will ensure tooling is clean, serviceable, and within specification when required for production, resulting in a better product for longer, reducing costs, and increasing profitability.
Cleaning is the first and most important step to undertake within the process. This will remove granules from the punch and help to avoid product contamination and potential production issues such as sticking and picking caused by old product adhering to the surface of the punch tip.
This step is also the ideal time to accurately assess the condition of the tooling. If this step is not carried out effectively it can affect the other steps within the process. For example, if punches are not clean any visual assessment of the punch tips and die bores can be affected. This would mean that problems like wear, damage, or corrosion are missed.
Using a precise and detailed cleaning method, such as ultrasonic cleaning, provides a very reliable method to remove any contaminants. Ultrasonic cleaning can deliver an extremely clean surface within a few minutes with a cleaning process that is repeatable and effective. It is only once the clean has been executed that all other steps may be followed effectively and efficiently.
Following a comprehensive clean of all punches and dies, they then need to be visually inspected. This step should be conducted thoroughly on a regular basis to avoid any build-up of residue.
Tooling inspection should take place under magnification to identify any defects that may cause tabletting issues and interrupt production. High magnification lenses and microscopes are recommended to offer precise and clear high-quality imagery to identify any signs of damage, wear or corrosion, and to validate the cleaning process. Assess every part of the tooling including punch tips and cups, die bores, tablets, embossing, and land, and the punch key.
By carrying out an assessment it will establish if the production process is working satisfactorily and highlight if any tooling maintenance is required. Remember that identifying damage off the tablet press is far less costly and time-consuming for the tablet manufacturer and far better than letting the tablet press identify it.
Tooling that has experienced light surface wear, corrosion, and minor damage, can be manipulated and repaired back to a useable condition. Equipment such as a motorized chuck and double-ended polishing motor is used together with abrasive polishing accessories.
However, it is vital that the repair is accurately and extensively completed by skilled technicians to ensure that the tooling does not exceed tolerance limits. Importantly, repair should not be carried out on coated tooling as this may remove the surface treatment from the punch.
This step of the process must follow repair as it analyzes the critical working length of the punch. This controls tablet thickness, weight, and ultimately, dosage. It also ensures that relevant measurement data has not been influenced by extraneous variables, such as oil or compacted granule, and therefore presents an accurate observation and analysis of the process equipment.
Measuring should also be carried out consistently at regular intervals for signs of natural wear during compaction using simple hand-held micrometers, Vernier calipers, and height gauges to semi-automatic, computerized digital gauging systems.
Modern tooling is often supplied with coatings, therefore automated polishing is essential to ensure punches are evenly polished to a consistent finish so the coating is not removed prematurely.
This step also helps to produce the optimum and consistent tooling condition which creates maximum productivity, reduces sticking, and reduces labor costs related to the amount of time spent on polishing.
Lubrication is necessary as it serves to protect, preserve and support continuous press tooling operations. For lubrication purposes, a non-toxic, FDA-compliant oil or grease is recommended. Choose a product that offers machine component protection and lubrication performance with a wide temperature range, to ensure it can be used in all machines.
Tooling storage and transportation should be specifically designed and developed with high security and safety handling considerations a priority as this reduces the probability of damage and deterioration. Custom-built storage cabinets and storage containers are just one solution that provides this protection. Also, ensure the tooling is separated to ensure it avoids contact with other punches and so that the tooling condition does not deteriorate during storage.
OSP: Anything to add?
AB: Take care of your investment. To protect tooling investment and obtain the maximum life from punches and dies, a planned, professional maintenance and storage program should be adopted.
The availability and condition of tools are of primary importance for uninterrupted production, this is especially important in the pharmaceutical solid-dose manufacturing environment where productivity is key. Application of the seven-step process will have a direct impact on the reduction of many common tablet and tooling problems, resulting in a better quality end product and direct time and cost savings for the tablet manufacturer.
Take care of your tools and your tools will take care of you.