End-to-end solutions from raw materials to production equipments for PU foam and mattress-Sabtech
Sabtech Technology Limited continues to give high priority to developing mattress manufacturing machine in the face of the shifting market. The product is found to be in conformance with the requirement of CE and ISO 9001. Its materials are sourced from the leading suppliers in the domestic market, which have high stablility. Its manufacturing has been monitored by QC personnel who picks up defective semi-finished products.
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From a Continuous Foaming Line Inquiry to an Integrated Foam Production Setup
Project Background
In September 2021, we received an inquiry from Mr Abdullah, a client from Saudi Arabia. He planned to build a new PU foam factory serving the Saudi local market and the Yemeni market, mainly for furniture and mattress flexible PU foam products. He also planned to include downstream processing.
The client had local foaming workers and some basic production conditions in place. As the project moved forward, it required coordinated planning of target products, equipment configuration, factory layout, and the connection between foaming and downstream processing.
How the Project Scope Expanded
The client’s initial inquiry focused on a continuous foaming line. As the discussions progressed, the project scope expanded to include rebonded foam production and the cutting equipment required for downstream processing.
One important consideration was how the factory would handle foam offcuts after production increased. The local market for rebonded foam was relatively strong, while the local selling price for baled foam offcuts was low. As the planned production scale increased, the factory was expected to generate foam offcuts regularly. Processing this material into rebonded foam would provide greater long-term value than selling it directly as low-value scrap.
The client therefore decided to add a complete rebonded foam production line. From a longer-term production and market perspective, combining the continuous foaming line with rebonded foam production was better suited to the planned scale of the factory.
The project also included the required downstream cutting equipment. The CNC foam cutting machine was selected for shaped foam parts used in furniture and mattress products. Two circular foam cutting machines allowed multiple foam blocks to be sliced within the same cutting cycle, while the vertical foam cutting machine was mainly used for trimming block edges and carrying out straight cuts before further processing.
Based on the factory conditions, we also prepared a layout covering equipment placement, production flow, the connection between foaming and downstream processing, and operator working space. Through several video meetings, the client observed an actual flexible foam production process, including the operation of the continuous foaming line and its connection with downstream cutting and processing. The discussions also covered daily operation, practical differences between equipment designs, and the configurations suitable for this project.
The rebonded foam machine purchased by this client
Why the Client Finally Chose Us
The client compared proposals from several equipment suppliers before making the final decision. What distinguished Sabtech was not simply the ability to supply the required machines, but the client’s greater confidence in our communication, understanding of the project, and approach to developing the solution.
1. Responsive Communication with Clear Follow-Through
As the project developed, the client’s questions were answered promptly and directly. Details confirmed during earlier discussions were carried forward into the subsequent planning, allowing the project to progress from the initial inquiry to the final equipment plan without repeatedly revisiting the same issues.
2. Project-Specific Planning Rather Than a Standard Package
The proposed solution was developed around the client’s target products, factory conditions, existing foaming workers, and downstream processing requirements. The equipment plan and factory layout were connected to how the factory was expected to operate, rather than being presented as a standard equipment package.
3. Recommendations Grounded in Actual Foam Production
During several video meetings, the client observed an actual flexible foam production process and discussed daily operation, practical differences between equipment designs, and configuration choices.
After comparing the suppliers, the client had greater confidence in Sabtech’s overall understanding of the project and selected us for the complete equipment order.
Final Procurement Content
Loading rebonded foam line
Loading continuous foam machine and foam cutting machine
Remote Installation and Production Startup
The equipment arrived at the client’s factory in July 2022. Because pandemic-related travel restrictions prevented our engineer from travelling to the site, installation and commissioning support were provided remotely. Commissioning was completed in October, and production started in November 2022.
After the initial setup entered production, the client later placed two additional orders to expand the factory’s downstream processing capacity and product applications. The subsequent development of the factory is covered in How a Saudi PU Foam Factory Expanded Beyond Its Initial Production Lines.
Project Background And Customer Needs
This Malaysian mattress manufacturer previously purchased foam for processing into mattresses and wanted to expand upstream into foam production. Rebonded foam was a practical starting point: the factory already used it in its mattresses, there was demand in the local market, and the production process presented a relatively accessible entry point for the customer.
The initial plan was to supply its own mattress production, with external sales to follow once production was established and capacity expanded. As a newcomer to rebonded foam manufacturing, the customer needed guidance on equipment configuration, raw material preparation, and the production process.
Early Communication And Solution Confirmation
We first discussed the target density and firmness, the customer's mattress applications, and local market requirements. As a first-time producer, the customer had many basic questions and was particularly concerned about whether it could produce foam of the expected quality after purchasing the equipment.
We responded promptly and provided practical explanations of equipment selection, raw material preparation, and production methods, together with the support available during startup. These responses and the proposed support helped build the customer's confidence in Sabtech.
The customer then visited our factory for an on-site evaluation. During the visit, we arranged for the customer to review the actual rebonded foam production process, equipment operating conditions, and different layout approaches under factory conditions. In addition to checking the machine itself, the customer also reviewed several practical issues related to project start-up, including:
The configuration comparison focused on whether to include steam curing and how many mold boxes to use. These choices were evaluated against the target daily output, production efficiency, and available factory space.
Steam curing shortens the time required before demolding, allowing the mold boxes to return to use sooner. This reduces the number of additional mold boxes needed to maintain the production schedule.
The customer selected a rebonded foam machine with steam curing and two mold boxes, allowing two blocks to be produced in one cycle. This configuration matched its target daily output and available factory space.
Installation, Training, And Project Start-Up
After installation, our engineers trained the customer's team in machine operation and the production process, covering:
After installation and training were completed, the customer successfully entered trial production and produced the rebonded foam product required for the project.
Follow-Up Cooperation
Once rebonded foam production was running steadily, the customer decided to add virgin foam production capability and purchased a semi-automatic batch foam machine from Sabtech. The customer also continued to reorder foam chemicals from us.
If you are evaluating a rebonded foam project, you are welcome to discuss machine configuration, factory layout, and start-up planning with us.
Beginners are concerned that if the settling plate is not adjusted properly, the liquid flowing out of the nozzle may cause front surging or back surging, affecting the foaming process. Within two minutes after starting the machine, the reaction speed gradually increases, sometimes requiring adjustments to the settling plate. Adjustments to the settling plate are more critical in low-density and high-moisture-content (MC) formulas.
TDI (Toluene Diisocyanate) flow rate can be calculated to correspond to the scale value, but it is recommended to actually measure the TDI flow rate during the first foaming. Flow rate is too important; if the flow rate is not accurate, everything else will be a mess. It's best to rely on the simplest and most intuitive method of measuring the flow rate.
When mixing powders, the mixed stone powder should be left overnight and production should start the next day. For ingredients containing melamine and stone powder, it is recommended to first mix melamine with polyether for a period of time before adding the stone powder.
Foam machine formulas with long mixing chamber in the machine head or more teeth on the stirring shaft usually have less amine and lower material temperature. Conversely, foam machine formulas with short mixing chamber in the machine head or fewer teeth on the stirring shaft usually have more amine and higher material temperature.
For the same formula, when switching between dual-spray swivel heads and single-spray swivel heads with similar nozzle cross-sectional areas, the requirements for mesh thickness and layers are similar.
For the calibration of minor material flow, one method is to measure the return flow of the minor material, and the other is to calibrate it by dividing the total amount used by the foaming time. When there is a significant difference between the two calibration methods, rely on the data from the second calibration method.
Formulas for high-quality soft foam are usually within an unstable range, such as a low TDI index, low water-to-MC ratio, low T-9 dosage, and low silicone oil dosage.
The production of block-shaped soft foam typically utilizes the batch foam machine foaming process, a gap-type production method. This method evolved from manual foaming in laboratories. The process involves immediately pouring the mixed reaction materials into an open mold resembling a wooden or metal box, hence the name "boxed foam." The molds (boxes) for boxed foam can be rectangular or cylindrical. To prevent the foam block from forming a domed top, a floating cover plate can be placed on the top of the foam during foaming. The cover plate stays closely attached to the top of the foam and gradually moves upward as the foam rises.
The main equipment for boxed foam production includes: 1) Electric-mechanical stirrer, mixing barrel; 2) Mold box; 3) Weighing tools such as scales, platform scales, measuring cups, glass syringes, and other measuring devices; 4) Stopwatch for controlling mixing time. A small amount of mold release agent is applied to the inner walls of the box to facilitate easy removal of the foam.
The advantages of producing soft foam using the boxed foam method include: low equipment investment, small footprint, simple equipment structure, easy and convenient operation and maintenance, and flexible production. Some small and underfunded domestic and township enterprises use this method to produce polyurethane soft foam. Boxed foam molding is a non-continuous production method for soft foam, so the production efficiency is lower than continuous methods, and the equipment is mostly manually operated, resulting in higher labor intensity. Production capacity is limited, and there is a greater loss in cutting foam plastics. The process parameters for boxed foam should be controlled within a certain range because even with the same formula, the foam properties may not be the same when different process parameters are used. The raw material temperature should be controlled at (25±3) degrees Celsius, mixing speed at 900 to 1000r/min, and mixing time at 5 to 12 seconds. The mixing time of the polyether and additives mixture before adding TDI can be flexibly adjusted depending on the situation, and after adding TDI, a mixing time of 3 to 5 seconds is sufficient, with the key being thorough mixing after TDI addition.
During boxed foam molding, attention should be paid to the following aspects:
1) Prepare before production, including material temperature and machine equipment inspection;
2) Measure as accurately as possible;
3) Control the mixing time appropriately;
4) Pour the mixed material liquid quickly and steadily, avoiding excessive force;
5) Ensure the box is placed steadily, with the bottom paper flat, to avoid uneven material flow during pouring;
6) When the foam rises, gently press the cover to ensure the foam rises smoothly;
7) Additives should be used as specified, and pre-mixed materials should not be left for too long.
Three types of foam equipment have emerged in boxed foam molding. Initially, various raw materials were weighed into a container according to the formula, mixed with a high-speed mixer, and poured into the box mold for foaming and shaping. This method often resulted in residue in the mixing container. An improved method used a metering pump to transport the raw materials to the mixing barrel for uniform mixing. A mechanical device automatically closed the bottom of the barrel, and compressed air was used to press the material into the foaming box for shaping. Both of these methods could create eddies due to the rapid influx of materials into the box, which might cause defects or depressions in the foam products. The most reasonable boxed foam device is to place a bottomless mixing barrel directly in the center of the foaming box. A metering pump delivers the various raw materials needed for foaming into the mixing barrel. After mixing for a few seconds, the lifting device raises the mixing barrel out of the foaming box, allowing the foaming material to flow smoothly over the entire box bottom. This prevents foam cracking due to material eddies, and ensures relatively uniform height throughout the foam.
A pressure device can be added to the expanding foam material to produce flat-topped foam, reducing waste during cutting. This device is suitable for the production of polyether-type polyurethane soft foam and high rebound soft block foam. For polyvinyl acetate polyurethane blocks, this method cannot be used due to the high viscosity of the material, and continuous methods are generally employed.
Calculation of foaming distance for continuous foaming machine
Given: Bubble release time for the formula is 108 seconds, conveyor belt speed during foaming is 4.6 meters per minute. Calculate the swinging and trough foaming distances.
Foaming distance when swinging: (108/60) x 4.6 = 8.28 meters
Foaming distance when troughing: [((108-18)/60)] x 4.6 = 6.9 meters
Explanation: For the same formula, continuous foaming machine has a shorter bubble release time than small bubbles. The calculated foaming distance is shorter than the actual foaming distance. This method only provides approximate confirmation of the foaming distance, supporting the adjustment of the settling plate. Troughing: 18" indicates the time in seconds that the raw material stays in the overflow trough.
Calculation of foaming height for continuous foaming machine
Given: Formula flow rate: 80 kilograms per minute for polyether, 20 for white polyether, 60 for TDI, 20 for stone powder, conveyor belt speed 4.5 meters per minute, mold width 1.65 meters, producing foam with a density of 25 kilograms per cubic meter. What is the foaming height in meters?
Total formula weight: 80 + 20 + 60 + 20 = 180 kilograms
Formula volume: 180/25 = 7.2 cubic meters
Base area of conveyor running per minute:
4.5 x 1.65 = 7.425 cubic meters
Foaming height: 7.2/7.425 = 0.97 meters
Explanation: Silicone oil, amine, and tin are not considered here as they offset the amount of carbon dioxide used during the foaming process. Moisture content (MC) is not considered because MC does not increase foam weight when vaporized.
Foaming Daily Operation
Beginners worry that improper adjustment of the settling plate will cause the liquid sprayed from the nozzle to surge forward or backward, affecting foaming. The reaction rate gradually increases within the first two minutes after starting the machine, sometimes requiring corresponding adjustments to the settling plate. Adjustments to the settling plate are more critical in formulas with low density and high MC.
TDI flow rate can be calculated by determining the corresponding scale value for the flow rate, but it is recommended to measure the TDI flow rate during the first foam production. Flow rate is too important; if the flow rate is incorrect, everything else will be a mess. It's best to rely on the simplest and most intuitive method of measuring flow rate.
When powder is being mixed, the mixed stone powder should be left overnight and production should start the next day. For formulations containing melamine and stone powder, it is recommended to first mix the melamine with the polyether for a period of time before adding the stone powder.
Formulas for foam machines with longer mixing chamber or more teeth on the mixing shaft typically have less amine and lower material temperature. Conversely, formulas for foam machines with shorter mixing chamber or fewer teeth on the mixing shaft typically have more amine and higher material temperature.
For the same formula, when switching between dual spray swing heads and single spray swing heads, if the cross-sectional area of the two nozzles is similar, the requirements for the fineness and number of layers of the mesh are similar.
Correction of small material flow rate can be done by measuring the return flow rate of the small material, or by dividing the total usage by the foaming time for correction. When the values obtained from the two correction methods differ significantly, the data from the second correction method should be used.
Formulas for soft foam with better properties are usually in an unstable range, such as lower TDI index, lower water to MC ratio, lower T-9 dosage, and lower silicone oil dosage. Just like in our jobs, there must be effort before reward.
Contact Person: Cynthia Cheung
Contact Number: +86-15687268672
Email: sales@alforu.cn
WhatsApp: +86-15687268672
Company Address: Foshan City, Guangdong Province China