What filling machine is best for high-viscosity products?

For high-viscosity pastes, sauces with particles and sticky products, a servo-driven rotor pump filling machine is the proven choice. The rotor pump acts as the metering element, handles 50–300,000 cSt, achieves ±0.5% accuracy and does not crush solids.

Why use a rotor pump instead of a piston pump for thick products?

A piston pump uses a narrow valve seat and cylinder that can block or crush solids in thick products. A rotor pump has no such restriction: the pumping chamber passes particles freely, which is why it is used for chilli sauce, bean paste, jam and large-particle fillings.

What viscosity range can rotor pump filling machines handle?

Grounton Pak metering-grade rotor pump filling machines cover approximately 50 cSt (milk-like liquids) up to 300,000 cSt (bean paste and thick pastes), with fill volumes from 5 ml to 300,000 ml.

How to Choose a Filling Machine for High-Viscosity Products

The pump is the metering element. Here is how to match the right pump technology to your product's viscosity, particle content and fill volume.

Why high-viscosity filling is different

Thick products change the rules of filling. A liquid filler can rely on gravity or a simple valve, but a paste at 50,000–300,000 cSt will not flow the way a beverage does. The product is sticky, it can trap air, and if it contains particles — chilli flakes, meat pieces, fruit chunks — the filling element must push it without crushing or blocking.

For this reason, the most reliable filling machines for thick and particle-containing products use a positive-displacement pump as the metering element. The pump determines both accuracy and product integrity.

Compare the four pump technologies

Which pump technology fits which product (typical guidance, always verify with a product sample)
Technology	Best for	Key strength	Watch out for
Rotor pump	Pastes, sauces with particles, high-viscosity, shear-sensitive products	Handles 50–300,000 cSt, passes particles without crushing, ±0.5% accuracy	Rotor pump needs metering-grade design for accurate dosing
Gear pump	Thin liquids — milk, beverages, edible oil	Stable, high-speed volumetric filling of low-viscosity liquids	Not ideal for large particles or very thick pastes
Piston pump	Simple liquids and some creams (non-particle)	Common, low initial cost	Valve seat and cylinder can block or crush solids
Screw down-press	Products needing a different discharge principle	Gentle discharge for special products	Assessed against your product sample

The rotor pump advantage: the pump is the metering element

Grounton Pak builds metering-grade rotor pumps specifically for filling — a different standard and design intent from the conveying-grade rotor pumps common in the industry. Because the pump itself doses the product:

Filling accuracy of ±0.5% with an error of 1 g or less, container after container;
No piston, no narrow valve seat — particles pass freely, from chilli flakes to fruit chunks;
Viscosity coverage from 50 cSt to 300,000 cSt on one technology platform;
Fill volumes from 5 ml to 300,000 ml across the GTX series;
Modular build: pump head (three-lobe, single-lobe, waist, twin-lobe, five-lobe) × hopper (standard, agitated, heated, square-mouth) × filling valve (blow-spray, full-immersion, sauce cut-off).

Six questions to answer before you buy

What is the product and its viscosity? This decides the pump technology more than anything else.
Does the product contain particles, and how large? Particle-friendly pumping (rotor) may be mandatory.
What is your fill volume range? From 5 ml single-dose sachets to 300,000 ml bulk packs, the GTX series covers it.
What output do you need? Containers per hour determines whether a single head or a multi-head line is right.
What container and cap type do you use? This shapes the conveyor, capping and labelling stages of a complete line.
Do you need CIP or hygiene certification? CIP-capable rotor pump production has been validated in dairy projects since 2020.

From a single machine to a complete line

High-viscosity filling rarely stops at the filler. Grounton Pak engineers custom filling lines that combine the filling machine with bagging, capping, labelling, coding and conveying — matched to your container and line speed. OEM and private-label projects are supported.

40,000+ units have been delivered since the company entered the rotor pump field, with more than 10,000 fluid application profiles accumulated and customers among major dairy and food groups in China.

Selection guidance: viscosity, particle size and fill volume are the three parameters that matter most. Send your product details (product type, viscosity, fill volume, containers per hour, container and cap type) to Grounton Pak and you will receive a configuration proposal, usually within one business day.