Introduction:
How are softgels made? By rotary-die encapsulation: two ribbons, fill injected, capsules cut and sealed in one motion, then dried and conditioned. A softgel manufacturer runs that one-piece oil or suspension path. It is not empty two-piece shell dipping, and it is not powder filling into purchased hard capsules.
This guide covers the rotary-die encapsulation stage of softgel manufacturing, from gel mass and fill preparation through forming, sealing, drying, and inspection. Searchers mix three factories. This page is only the rotary-die softgel line. Empty two-piece shells are molded elsewhere; powder is filled into those shells on a different machine. Format choice sits on softgel vs hard capsule.
Quick answer: The encapsulation process starts with formulation feasibility, not at the encapsulation machine. If the fill cannot meter, seal, and dry on a production-relevant die, the rotary-die sequence will not rescue it.
Key takeaways
- A softgel is form-fill-seal. You do not buy empty softgels and fill them.
- Each stage creates the conditions required by the next. The chain is not seven independent steps.
- Freshly encapsulated units are not yet in commercial mechanical state. Drying and equilibration sit in the chain.
- Sample feasibility is not commercial manufacturability.
- The RFQ is a starting screen. Trial still decides the window.
What Is Rotary-Die Softgel Encapsulation?
Rotary-die encapsulation is a form-fill-seal process. Two continuous ribbons of gelatin or vegetarian / plant-based shell systems (often called plant gel) meet on a pair of dies. Fill is delivered between them. Each cavity is filled, cut, and sealed in the same rotation. Fresh units then go to drying and equilibration, then to the inspection gates named in the specification.
In scope: gel-mass preparation, ribbon formation, fill delivery through the wedge, die forming and sealing, drying and equilibration, post-drying handling, and inspection. Pack is named on the RFQ; this page does not walk a packaging line.
Out of scope: empty two-piece shell molding; powder encapsulation into purchased capsules; specialty nested or delayed-release systems except as a pointer.
The commercial question is not “list every machine motion.” It is whether this fill and this ribbon can run that chain on a production-relevant die.
This page publishes process sequence, process purpose, and the variables that matter. Machine settings, ribbon parameters, drying endpoint, die-specific conditions, and acceptance criteria stay in the product-specific manufacturing record. They are confirmed on a production-relevant trial. That is why this page does not publish factory set-points.
Why the manufacturing process looks different from hard-capsule filling:
Rotary-die softgel
The shell is formed during encapsulation. Fill and shell formation occur together. Liquid or semi-solid fill is common. The seam is formed during encapsulation.
Hard-capsule filling
An empty shell is supplied before filling. Filling is a separate operation. Powder or granule fills are common. Body and cap are joined after filling.
That comparison is process logic only. Format selection remains on the softgel vs hard capsule page.
Rotary-Die Softgel Process at a Glance
Gel mass → ribbon → fill → wedge → die → drying / conditioning → inspection
Each stage creates the conditions required by the next. A non-uniform gel mass becomes a ribbon problem; an unstable fill becomes a metering problem; poor ribbon or fill behavior becomes a seam problem; incomplete drying becomes a handling and storage problem. Softgel manufacturing is a chained process, not seven independent steps.
Gel mass
Main input: polymer, water, plasticizer
Process output: homogeneous gel mass
Next stage depends on: ribbon formation
Ribbon
Main input: gel mass
Process output: continuous films
Next stage depends on: die sealing
Fill
Main input: active and carrier
Process output: metered fill
Next stage depends on: wedge delivery
Wedge
Main input: fill and ribbons
Process output: controlled cavity filling
Next stage depends on: die closure
Die
Main input: ribbons and fill
Process output: sealed softgel
Next stage depends on: drying
Drying / conditioning
Main input: fresh softgels
Process output: conditioned shell
Next stage depends on: inspection and release
Inspection
Main input: conditioned units
Process output: accepted or rejected units
Next stage depends on: release
Set-points stay in the batch record.
How Each Stage Works
The logic is sequential. Each stage exists to create the input condition for the next.
Gel-mass preparation
The shell polymer, water, and plasticizer are combined into a homogeneous mass suitable for casting. Composition identity sits on what softgels are made of; this page only needs the mass to be uniform enough to run.
Input: shell materials and water
Process purpose: a consistent, castable gel mass
Failure carried forward: non-uniform ribbon or inconsistent seam behavior
Ribbon formation
The gel mass is cast into two continuous ribbons that feed the rotary dies.
Input: homogeneous gel mass
Process purpose: continuous, uniform films with enough mechanical and sealing properties to meet at the die
Failure carried forward: weak weld, appearance rejects, or a seam the next stage cannot close
Fill preparation
The bulk is mixed and held so it can be metered. Solution and suspension do not behave the same way through the vessel, pump, and transfer. For suspensions, the formulation must remain sufficiently uniform during holding and transfer so that the material entering the wedge remains representative of the intended fill. Particle size and solids loading sit on the formulation page.
Input: active and carrier
Process purpose: a fill that arrives at the wedge in a workable, representative state
Failure carried forward: metering scatter or a cavity that does not match the intended fill
Wedge injection
The wedge is the feed assembly positioned between the two moving ribbons near the die cavity; it introduces the fill immediately before the ribbons close around it. It is therefore where fill flow behavior and ribbon movement meet.
Input: prepared fill and two ribbons
Process purpose: placing a controlled dose inside the forming cavity
Failure carried forward: incomplete fill, squeeze-out at the weld, or an unstable cavity
Die forming and sealing
The dies form the capsule, cut it from the ribbon, and seal the seam in one motion. Die geometry determines capsule shape and nominal cavity volume; the sealing interface must close around the intended fill without compromising the seam. Size screening is a separate file.
Input: ribbons plus fill at the cavity
Process purpose: a closed one-piece unit
Failure carried forward: incomplete weld or a unit that cannot be dried and released
Drying and equilibration
Freshly encapsulated softgels are not yet in their commercial mechanical state. Drying changes the mechanical state of the shell after encapsulation: moisture, flexibility, tackiness, brittleness, and dimensional stability. Equilibration may still be required before the units match the handling and release state in the file. There is no universal day-count on this page.
Input: freshly encapsulated units
Process purpose: a conditioned shell the specification can handle and release
Failure carried forward: a unit that is not yet in the mechanical state the next stage and the pack assume
Inspection and post-drying handling
After drying: sorting, visual defect removal, polishing or surface cleaning if the file requires it, named inspection, and release. Packaging is outside the scope of this page.
Input: conditioned units
Process purpose: accepted or rejected units against the specification
Failure carried forward: a lot released without the checks the commercial file named
Fill rheology affects both metering and seam formation, so it belongs in formulation feasibility rather than being treated as a final visual issue.
What the Rotary Die Needs From the Formulation
The rotary die does not decide the path. Formulation feasibility does. This page only asks what the machine needs from the fill and ribbon.
Meterable
The fill has to be delivered through the wedge at a controlled rate on this die.
Seal-compatible
The ribbons have to weld around that fill without a wet or incomplete seam.
Stable during the encapsulation hold
The material entering the wedge has to remain representative of the intended fill through mixing, holding, and transfer.
Compatible with the intended shell and drying process
Gelatin and vegetarian / plant-based ribbons are different shell systems. A process developed for one should not be copied to the other without a new qualification.
The encapsulation process starts with formulation feasibility, not at the encapsulation machine. Path selection — solution vs suspension vs another dosage form — sits on oil fill vs suspension softgels. When to choose the shell family sits on gelatin vs vegetarian softgels.
If the fill cannot run within the qualified process window, the next decision may involve the carrier system, concentration, fill weight, serving count, shell, or dosage form — not simply machine speed.
Why Drying and Seam Integrity Matter
Cut-and-seal is where the commercial leak file often starts. The two ribbons must actually weld around the fill. Ribbon uniformity, fill delivery through the wedge, die closure, shell–fill compatibility, and later drying all affect whether that weld holds.
Drying changes the mechanical state of the shell after encapsulation. It moves moisture, flexibility, tackiness, brittleness, and dimensional stability. The endpoint has to be named for that ribbon and fill.
Leak, weep, crack, and pack-oil diagnosis belongs to why softgels leak. This page only names drying, equilibration, and seam as process controls. It does not publish a leak-test SOP.
Why Lab Feasibility Does Not Equal Commercial Manufacturability
A bench unit is not a commercial die. Sample feasibility is not commercial manufacturability.
Buyers often ask whether a laboratory capsule that “worked” will run stably at volume. The honest answer is: only after the same fill and ribbon are checked under continuous encapsulation, then dried, equilibrated, and inspected on production-relevant equipment.
The scale-up file usually has to show:
- lab formulation that can be described
- pilot encapsulation on a relevant die
- commercial equipment that can repeat the window
- fill-weight consistency
- appearance
- seam integrity
- drying endpoint and equilibration
- packaging compatibility
Fill-weight evenness and seam/leak checks are related files, not one number. That split is covered in softgel fill weight and seam integrity. This page does not publish a weight formula or a sampling clock.
A successful sample is not a production-ready SKU. The commercial judgment is: production-relevant trial → qualified process window → documented specification → repeatable commercial production. A pilot that passes without a recorded window is not a commercial control file.
What to Include in a Softgel Manufacturing RFQ
Send what you have. You do not need a finished process SOP to start a feasibility review.
Product / fill
- Ingredient and form
- Fill type: oil solution or suspension (or “not sure”)
- Target dosage per serving
- Target fill weight or serving count, if known
Shell / size
- Shell preference: gelatin or vegetarian / plant-based
- Vegetarian or vegan requirement, if any
- Softgel size preference, if already chosen
Pack / market
- Packaging format: bottle or blister
- Destination market
- Any climate or barrier notes that affect drying or pack
Program
- Whether a pilot is required
- Estimated annual or initial volume
Target dosage, fill type, shell preference, and market are a useful starting screen. Final rotary-die feasibility still depends on the actual fill, target concentration, fill weight, shell system, and trial results. Size, if frozen too early, is a common rework — die volume is confirmed on the trial.
If fill weight or shell size is not known, leave it blank. It can be screened during feasibility review.
Need a Softgel Manufacturing Feasibility Review?
Send the ingredient and form, target dose, preferred softgel type, shell preference, destination market, and estimated annual or initial volume. Add fill weight if you already have it. If fill weight or shell size is not known, leave it blank — we can screen it during the review.
KS Nutripharma can review whether the formulation fits a standard rotary-die process and whether a production-relevant pilot is the next step — then quote softgel manufacturing from that file.
Submit your softgel process brief
Related Softgel Manufacturing Guides
- What Are Softgels Made Of?
- Gelatin vs Vegetarian Softgels
- Oil Fill vs Suspension Softgels
- How to Choose Softgel Size
- Why Softgels Leak
- Softgel Fill Weight and Seam Integrity
- Softgel vs Hard Capsule
- How to Read a COA
Two ribbons of shell film meet on a rotary die. Fill is delivered between them. Each capsule is formed, filled, cut, and sealed in one rotation of the dies, then dried and conditioned.
Neither in the hard-capsule sense. Unlike hard capsules, the softgel shell is formed and sealed around the fill during encapsulation. You do not buy empty softgels and fill them.
Oil-based solutions and designed suspensions that can meter and seal on a rotary die. Many dry powders, highly aqueous fills, and alcohol-rich systems require a different formulation or dosage-form assessment rather than being treated as standard oil-filled softgels. Path selection sits on the oil-fill vs suspension page.
Die cavity volume and fill density — not hard-capsule size 00. Screening and trial lock sit on how to choose softgel size.
Usually a process-chain failure: fill, ribbon, seam, drying, or pack — not pack-line inspection alone. Diagnosis and RFQ language sit on the leak page.
Until the endpoint for that ribbon and fill. Drying time is a process outcome, not a universal fixed number of days.
FDA dietary-supplement CGMP describes specifications, testing against those specifications, and batch records for finished lots. It does not publish a rotary-die SOP, drying-day count, ribbon thickness, or daily capacity for nutraceutical softgels.
- U.S. Food and Drug Administration. Dietary Supplements.
- U.S. Food and Drug Administration. Current Good Manufacturing Practice in Manufacturing, Packaging, Labeling, or Holding Operations for Dietary Supplements, 21 CFR Part 111. Specifications, testing against those specifications, and batch records.
- Gullapalli RP. Soft gelatin capsules (softgels). J Pharm Sci. 2010;99(10):4107-4148. Rotary-die process context: plasticized gelatin films formed, filled, and sealed. Not a KS batch SOP.
Disclaimer: Wholesale / brand manufacturing and product-development reference only. Not intended to diagnose, treat, cure, or prevent any disease. Dietary supplements are not drugs. Ribbon, wedge, die, and drying parameters are batch-record items. They are confirmed on a production-relevant trial. This page does not publish factory set-points, drying-day counts, or daily capacity. Brand owners remain responsible for finished-label compliance with local counsel. KS Nutripharma provides manufacturing feasibility and documentation support — not legal approval. [1][2]
Written by: KS Nutripharma Formulation Team
Reviewed by: KS Nutripharma Director of R&D (PhD, Food Science | 19+ years nutraceutical development)
Last updated: August 2026
