What is a Batch Foam Machine?

A batch foam machine is a primary non-continuous device used for producing polyurethane foam blocks. It typically comprises essential units such as raw material tanks, metering systems, mixers, mixing barrels, and foaming boxes.

The main raw materials—TDI and polyether polyol—can be delivered into the tank or mixing barrel by metering pumps or manually weighed and poured. Catalysts, water, surfactants, and foaming agents can either be pre-mixed with polyether polyol or added separately into the mixing barrel, and finally mixed with TDI for foaming.

Types of Batch Foam Machines by Mixing and Feeding Methods are showed on the following picture.

(1)Lifting Type Mixing Barrel
The mixing barrel and mixer are integrated, with the bottom open. During feeding, the barrel is sealed tightly to the bottom of the foaming box. After mixing, the barrel is lifted, and the material flows into the box, foaming to fill it and forming a rectangular foam block under the floating cover.

(2)Movable Bottom Cover Type
The barrel and mixer are integrated with a movable bottom cover. When feeding, the cover is closed. After mixing, the cover opens and the liquid pours into the box. The box is then removed and the barrel cleaned.

(3)Bottom Stirring Type
The mixer is located at the bottom of the barrel and connected to the motor with a detachable coupler. Materials are added from the top. After mixing, the barrel is removed manually and the mixture is poured into a prepared foaming box.

Common stirrer types include disc and tri-blade, and speed is adjusted based on mixer type, volume, and desired foam cell structure. Advanced machines use variable-speed motors for flexible adjustment.

Large machines can mix up to 150 kg per batch, producing foam blocks of 2000mm×2500mm×1000mm. Manual machines usually mix under 60 kg and produce 2000mm×1500mm×1000mm blocks. Using cylindrical boxes, they can also create cylindrical blocks for thin foam slicing.

Batch foaming can produce various densities of polyether foam, including high-resilience, high-load-bearing, and flame-retardant foams. Its flexibility makes it ideal for small foam factories.

However, due to its batch-mixing nature, batch foaming can trap air bubbles, leading to uneven cell structure and inferior mechanical properties compared to continuous foaming machines. This limits its application in some fields.

Due to high viscosity, polyester polyols are not suitable for batch foaming.