Prevent and Remove J-hook on Punch Tip

J-hooks are the distinctive wear patterns on punch tips that are a cause of such tablet defects as capping, lamination and poor friability. If diagnosed early, a J-hook can be easily and quickly removed thus save costs of purchasing replacement tab tooling. This article focuses on the possible causes of J-hooks as well as corresponding solutions.

A qualified tablet compression machinery operator should have a good understanding of tablet manufacturing process, can promptly response to machine fault, and master more skills to maintain machines and tooling in good condition, so as to minimize cost from various aspects:

  • Increase the service life of tablet tooling as much as possible.
  • Reduce cost on repair and replacement of tablet tooling and operative process..
  • Minimize possibility of defective tablets and improve tablet quality.
  • Eliminate the occurrence of machine downtime, thereby boost productivity.


 Wear causes J-hook   

Before removing the J-hook, we should know the causes and performance.

The punches and dies lose their luster and develop nicks, scratches, and hooks after a certain long time operation. Typically the first area of the punch to wear is the land, the flat and narrow area at the tip’s perimeter. With wear, the tip becomes very thin and more susceptible to damage. Wear from various aspects will cause J-hook.

The materials of particles are rather coarse for making a tablet. In the process of compression, the materials flow into the die and form into tablets, then leave scratches when being ejected and pushed out.

Tooling wear and J-hook may result from worn punch guides, which is possible to cause improper die installation. Tools such as die insertion tool, torque wrenches are all essential instruments to extend die pocket wear and increase tool life, and to improve tablet quality. The upper punch is very susceptible to the development of J-hook, especially when the punch land erodes away. However, J-hook can form on both upper and lower punch tip.


 Regular inspection prevents J-hooks

A clean, smooth surface will release product better, produce better finished tablets, and reduce problems during production. Regular inspection of the possible wear and faults and timely repair are essential points to keep the machine and tool in good condition. Like all the manufacturing tools, compression tools should be inspected in a certain regular period. Visual inspection of punch tip edge and J-hook is important as a direct way to eliminate failures.

The inspector could drag their fingernail to feel whether there is abrasion, scratch, and hooks on, from the inside of the cup out to the outer edge. If the J-hook is not severe, it can be removed by polishing, which will recovers the cup’s mirror luster as well. A well-trained operator should be given responsibility of repairing and refurbishing punches and J-hooks.

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