Automatic Sponge Production Line: Raw Material to Finished Product

For sponge manufacturing enterprises, the stability of the foaming process directly determines product qualification rates and production costs. A well-designed, precisely controlled fully automatic continuous sponge production line can minimize raw material ratio errors, temperature fluctuations, and human intervention during uninterrupted operation.

This article briefly outlines the complete process flow of one-shot continuous foaming, with emphasis on the critical control points at each stage that most significantly affect finished product quality.

1. Brief Overview of Foaming Principles

This process involves the one-shot mixing of all raw materials-including polyether polyol (PPG), polymer polyol (POP), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), water, additives, and catalysts-which simultaneously complete chain extension, CO₂ generation, and crosslinking reactions within 7 to 12 seconds, and are directly poured onto the sponge foaming line for molding.

2. Raw Material Storage and Temperature Pretreatment

Bulk raw materials POP and PPG are transported to the plant by tanker trucks and stored in dedicated storage tanks; TDI, MDI, and other drummed additives are kept in the raw material warehouse.

TDI and MDI are highly sensitive to temperature in terms of reactivity and must be pretreated before use:

Winter: Approximately 2 hours before foaming begins, the raw material drums are transferred to an electrically heated pretreatment room. MDI can be used after temperature adjustment in this room; TDI requires further preheating in the metering tank to stably maintain it at approximately 30°C.

Summer: The pretreatment room is switched to air conditioning cooling mode to bring TDI and MDI down to the 30°C usage requirement.

Other materials can be fed directly into the foaming process at room temperature.

3. Metering and Mixing

After temperature pretreatment, each material enters its respective metering tank and is continuously delivered to the mixing head by high-precision metering pumps at the ratios specified by the formulation. The proportioning accuracy of the metering pumps directly affects sponge density uniformity and is one of the most critical control points on this production line.

The materials undergo instantaneous and uniform mixing in the head via high-speed stirring, and are then directly discharged through pipelines onto the foaming conveyor belt-without any residence time in the head, as the materials begin reacting immediately upon mixing; retention would cause premature curing and clogging of the foaming equipment.

4. Continuous Foaming and Curing

The mixed material is poured onto the conveyor belt lined with craft paper and film. The foam body completes initial curing at the end of the conveyor belt, forming a sponge block with specified width and height.

An updraft exhaust collection system is installed above the foaming feed inlet to capture fugitive emissions and reduce fugitive emissions in the workshop.

5. Foam Cutting

The cured sponge blocks are cut into specified dimensions and shapes according to order requirements. Commonly used PU cutting machine includes:

It is recommended to select appropriate PU cutting machines based on product types.

 

6. Foam Making Equipment Cleaning and Maintenance

The foaming head nozzle will accumulate viscous residual material after prolonged operation and requires regular cleaning. The foam making equipment control console features a MC one-touch cleaning function for the mixing head, which is simple to operate and effectively prevents nozzle clogging, reducing unscheduled downtime.

The fully automatic one-shot continuous foaming process has been widely validated in the domestic polyurethane sponge industry. The core advantages of this process route lie in its simple flow, strong equipment versatility, and ease of maintenance, with each step centered around three control objectives: stable proportioning, precise temperature control, and continuous operation.

For more information regarding specific automatic sponge production line configuration solutions or production capacity planning recommendations, please feel free to contact us for technical documentation.

 

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