Common Tablet Defects Explained: Capping, Sticking, Lamination and Dusting
Tablet defects are rarely random. Issues such as capping, sticking, lamination or dusting usually indicate underlying formulation or process problems. This article explains the most common tablet defects encountered in food supplement manufacturing and what typically causes them from a CMO perspective.
In tablet manufacturing, visual defects are often the first visible signal that something in the formulation or compression process is out of balance. While tablets may still appear acceptable at first glance, unresolved defects can lead to production instability, packaging issues and customer complaints after scale-up.
For contract manufacturing organizations (CMOs), understanding why tablet defects occur is essential for preventing repeat failures and ensuring scalable production.
For contract manufacturing organizations (CMOs), understanding why tablet defects occur is essential for preventing repeat failures and ensuring scalable production.
Why tablet defects occur
Tablet defects are usually caused by an interaction between:
Formulation properties
Powder flow behavior
Compression parameters
Tooling condition
Environmental factors
(e.g. humidity)
In many cases, defects only become apparent when moving from pilot to larger-scale production, making early detection and interpretation critical.
Capping: separation of the tablet crown
What is capping?
Capping occurs when the top or bottom portion of a tablet separates from the main body, either during ejection from the die or shortly after compression.
This defect is often sudden and can affect entire batches if not addressed quickly.
This defect is often sudden and can affect entire batches if not addressed quickly.
- Typical causes of capping.Common contributing factors include:
- Excessive air entrapment in the powder blend
- Insufficient binding between particles
- High elastic recovery after compression
- Overly rapid decompression during ejection
- Formulations containing brittle or poorly compressible ingredients are particularly prone to capping.
- Manufacturing perspective.Capping often indicates that the formulation is not releasing compression stress evenly. Adjustments usually involve optimisation of compression speed, formulation balance or tooling geometry rather than simply increasing compression force.
Sticking: material adhering to tooling
What is sticking?
Sticking occurs when tablet material adheres to the punch faces, leading to rough surfaces, logo damage or incomplete tablets.
It is one of the most disruptive defects during continuous production.
It is one of the most disruptive defects during continuous production.
- Typical causes of sticking.Sticking is commonly associated with:
- Hygroscopic or moisture-sensitive ingredients
- Insufficient lubrication
- Low melting-point components
- Excessive fines in the powder blend
- Certain botanical extracts and sugars increase sticking risk, especially under elevated humidity.
- Why sticking escalates quickly.Once material begins adhering to tooling, surface roughness increases, accelerating further adhesion. If not controlled, sticking can rapidly lead to downtime, rejected batches and tooling damage.
Lamination: internal layer separation
What is lamination?
Lamination occurs when a tablet splits into two or more horizontal layers, either during compression or shortly after ejection.
Unlike capping, lamination may not always be immediately visible.
Unlike capping, lamination may not always be immediately visible.
- Typical causes of laminationSticking is commonly associated with:
Common causes include:- excessive compression force
- high air entrapment
- uneven density distribution
- formulation heterogeneity
- Lamination is often linked to formulations that compress unevenly or release internal stress inconsistently.
Dusting: a common issue in amino acid tablets
What is dusting?
Dusting refers to fine powder release from tablets during handling, packaging or transport. While tablets may retain their shape, material loss occurs over time.
- Why dusting is common in amino acid tabletsAmino acids often exhibit:
- Poor compressibility
- Crystalline structures
- Low binding affinity
- High brittleness
- As a result, amino acid tablets are especially prone to surface abrasion and dust generation, even when hardness values appear acceptable.
- Practical consequences of dustingDusting can lead to:
- Contamination of packaging lines
- Inaccurate tablet counts
- Visual quality complaints
- Increased cleaning requirements
How tablet defects are identified early
CMOs rely on a combination of:
- Visual inspection
- Hardness and friability testing
- In-process monitoring
- Controlled pilot runs
Preventing tablet defects in contract manufacturing
Rather than addressing defects individually, CMOs aim to:
- Balance formulation compressibility
- Optimize compression profiles
- Select appropriate tooling geometry
- Control environmental conditions
Summary: understanding defects reduces production risk
- Capping indicates stress release issues
- Sticking signals adhesion and lubrication imbalance
- Lamination reflects internal density inconsistencies
- Dusting, especially in amino acid tablets, points to abrasion sensitivity
FAQ: Common Tablet Defects in Food Supplement Manufacturing
In most cases, tablet defects are caused by an interaction between formulation properties and compression parameters rather than the tablet press itself. Issues such as capping or lamination often originate from powder behavior, air entrapment or binding balance rather than equipment malfunction.
During scale-up, changes in compression speed, dwell time and material handling can amplify small formulation weaknesses. Defects that are not visible in pilot batches may become pronounced when production throughput increases.
Sticking is typically managed by optimizing formulation moisture, lubrication levels and compression conditions. Environmental control and tooling surface condition also play a key role in preventing material adhesion to punches.
Many amino acids have poor compressibility and brittle crystalline structures. This makes tablets more susceptible to surface abrasion, resulting in dust generation during handling and packaging even when mechanical strength appears acceptable.
Some defects can be mitigated through compression parameter adjustments or tooling optimization. However, persistent defects often require formulation changes to achieve long-term production stability, especially in contract manufacturing environments.