Fette Training

Tablets, a common form of oral medication, may develop visible or internal defects as a result of improper manufacturing processes and equipment or suboptimal formulations. Catching these tablet defects — whether manually or via an automated visual inspection system — helps ensure high product quality and consumer confidence. This article will highlight common tablet defects, their causes, and how to eliminate them.

Tableting Process: Eight Visual Defects

The tableting process can lead to several potential surface defects, such as:


The separation of a tablet’s top from its main body is often the result of air entrapment, poorly finished or shaped dies and punches, incorrect take-off blade adjustments, or unnecessarily high turret speeds. As for formulation causes of capping defects in tablets, multiple fines in granulation during pressing, improper binding material, and low moisture content can lead to capping.


This defect involves the breakage of a tablet into multiple layers. Excessive turret speeds, rapid decompression, and elevated pressure force can cause it. Lamination can result from the same formulation issues as capping, in addition to the rapid relaxation of a tablet’s peripheral regions due to the lack of a material’s compactness.


Chipping, or the breakage of small bits of tablet edges, can occur when there are substandard die shapes or conditions. Wet material, insufficient lubricant, and improper binders that lead to sticking are potential issues in formulations.


This defect is the presence of scored or rough tablet edges resulting from improperly finished or sized dies with incorrect clearance or extreme pressure in the tablet press. Formulation-related challenges include excessive moisture and other granular factors, as well as insufficient lubrication.


When a portion of a tablet sticks to a punch face, the leading process-related cause is the free rotation of lower and upper punches during the tablet’s ejection or abraded punch faces. Picking’s formulation-related causes include high moisture in the granules, an excessive binder amount, and improper lubrication.


Improper or inconsistent tablet thickness may result from poorly cleaned or maintained tablet presses and varying lengths in punch tooling. The primary formulation-related cause is inconsistent die filling.

Black Spots

Contaminated material, scorched material from within the die bore, and improper feeder setup or adjustment are process-related sources of visible spots or contaminants in tablet material. The leading formulation-related cause is contamination during any process preceding tableting. Black spots can also be caused by unique combinations of certain products, machine component materials and lubricants.


The primary process-related causes for variations in tablet shape are extreme press speeds or short pre-compressions. In formulation, the most likely origin of shape inconsistencies is highly soft or damp tablets.

Coating Process: Five Visual Defects

As for defects that operators can detect by sight in the coating, these include:


Fractures in surface coating result from improper tablet coating conditions such as low pan speeds and excessive heating effects. Conversely, the formulation-related causes are poor coating elasticity or insufficient mechanical strength.


When a tablet’s coating becomes stuck to press components, causes include over-wetting during the coating application, high spray rates, low pan speeds, and poor spray gun alignment. In formulations, low glass transition temperatures in coating formulations or low tablet cap curvature can cause these defects.

Color Deviation

Inadequate coating distribution uniformity is a process-driven cause for this inconsistency in tablet color within a batch. Formulation-related problems include insufficient tablet coating coverage properties, high solid content of the suspension, and low batch quantity.

Dark Spots

Spotting on the coating surface may be due to prolonged coating and low pan speed. Alternatively, the coating formulation may have a high material concentration that’s harder than the stainless steel pan walls.

Damaged Print

Incorrect tablet alignment with the punch, excessive ink on the punch, uneven ink flow, clogged inkjets, and improper ink viscosity are process-related origins of smudged or otherwise deformed print. The leading formulation cause for damaged print is improper ink formulation blending with a tablet’s coating ingredients.

How to Eliminate Capping and Lamination Defects

While a range of solutions exists for each individual defect, the procedures for remedying capping and tablet lamination are basically the same. To curb these defects of tablets specifically, operators should:

  • Consider the use of tapered dies
  • Decrease punch penetration depth
  • Reduce press speed to increase dwell time
  • Carefully analyze blending, formulation, and production processes

When eliminating tablets’ defects, manufacturers ultimately want to minimize friability, or the likelihood that a tablet will fracture, chip, or otherwise crumble during handling or product transportation so that consumers won’t question tablet integrity.

Tableting Solutions at Fette Compacting

At Fette Compacting America, Inc., we provide quality tableting solutions, including tooling, presses, and other tablet equipment, to assist tablet manufacturing operations. Our team is committed to providing comprehensive support services to our customers. Contact us to learn more about our capabilities, or request a quote today.

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