End-to-end solutions from raw materials to production equipments for PU foam and mattress-Sabtech
Sabtech Technology Limited promises to global customers that every mattress compression machine has undergone rigorous quality testing. Each step is strictly monitored by the professional quality inspection department. For instance, the feasibility analysis of the product function is carried out in the design; the incoming material adopts manual sampling. Through these measures, the quality of the product is guaranteed.
We rely on Sabtech to promote our products. Since they are launched, the products have been highly appraised by the market for bringing value to customers. Gradually, they shape the brand image into a reliable one. Customers prefer to choose our products among other suchlike. When the new products are marketed, customers are willing to try them. Therefore, our products gain continuous sales growth.
We know that short delivery times are important to our customers. When a project is set, the time of waiting for a customer to reply can affect the final delivery time. In order to maintain short delivery times, we shorten our waiting time for the payment as stated. In this way, we can ensure short delivery times through Sabtech Technology Limited.
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.
When using a batch foam machine for polyurethane soft foam foaming, have you encountered the following situations?
1.Uneven and numerous foam pores,
2. Rough foam texture.
3. Chaotic pore sizes across the entire foam surface, with slight signs of large pores.
Issues like these are quite common. The main reason for the first issue is that the distance between the mixing impeller of the foam machine and the bottom of the mixing barrel is too great; the second issue is that the mixing blades are too short and narrow: the third issue is that the angle of the mixing blades is too large.
Many manufacturers who design and produce foam machines only understand the principles during the design process, without understanding the significant relationship between a different design in foam production and product quality. A reasonable and perfect mechanical design can only be gradually improved in actual work, and only experienced foamers can achieve this.
Here are some experiences we have had with machine modifications and upgrades, hoping they will be helpful:
First, the installation position of the mixing wheel should be as low as possible, closer to the bottom of the mixing barrel is better. In general, the distance between the lowest point of the mixing blade and the bottom of the mixing barrel should be around two centimeters
Second, the shape of the mixing blade should be fan-shaped, with a moderately wide edge. The advantage of being wide is that it increases the contact area with the liquid material, providing sufficient power and also balances the liquid material.
Third, the length of the mixing blade should also be as long as possible, leaving about three to four centimeters from the baffle inside the mixing barrel.
Fourth, the two edges of the mixing blade should be sloped, with the angle of inclination based on the width of one end and two centimeters difference on both sides. After the mixing blade is modified, proper operation is also crucial, especially the mixing speed. Most batch foam machines nowadays are equipped with high-speed timing frequency conversion devices. However, in actual production, this device is often unnecessary. The operating speed mainly depends on the amount of material in the mixing barrel. If there is a lot of material, the speed should be appropriately faster, and if there is less material, then the speed should be lower.
The compressive resistance of a foam is related to many factors such as the structure of various chain segments composing the foam, the chemical bonds between molecules, the crystallinity of polymers, the degree of phase separation, the structure of isocyanates, and the proportion of isocyanates used.
1. Slow rebound foam is formed by the reaction of high molecular weight polyols and low molecular weight polyols with isocyanates. The soft segments formed by high molecular weight polyols have large volumes, low crosslink densities, and high activity. They are easy to compress and quickly recover after pressure is removed. The hard segments formed by low molecular weight polyols have small volumes, high crosslink densities, and low activity. They are difficult to compress and also difficult to recover after external forces are removed. This characteristic gives foams their slow rebound feature and is the basis for manufacturing slow rebound foams.
Because the properties of the soft and hard segments in slow rebound foams are different, there is a certain degree of phase separation between them. If there is no phase separation between the segments, the foam body is a tightly bound whole on a macro scale, leading to the phenomenon of "move one hair and the whole body moves," meaning it shrinks as a whole when compressed and expands when pressure is released. However, the microstructure of the foam determines that this situation cannot be achieved completely. Especially in slow rebound foams, various chain segments have different molecular structures, uneven molecular weight distributions, and unavoidable phase separation. Slight phase separation causes some hard segments, due to their low activity, to have difficulty recovering during the recovery process after external forces are removed. These "escapees" more or less restrain the recovery of soft segments, ultimately leading to shrinking.
2. The crystallinity of hard segments, which is stronger than that of soft segments, is also a reason for poor recovery. Materials have similar compatibilities, which also apply in slow rebound foams. Because the hard segments have closer cross-linking points and higher crosslink densities, the small molecules formed are more likely to aggregate together. Due to the presence of hydrogen bonds, these aggregated hydrogen-containing substances enhance the crystallinity of the material, leading to greater cohesive forces. After compression, external forces change the aggregation state of the chain segments, making it easier for polar groups to fuse together. When the external force is released, the new aggregation state, due to strong cohesive forces, is difficult to return to the pre-stressed state, resulting in shrinkage of slow rebound foams.
3. The structure of isocyanates is also a factor affecting the compression resistance of slow rebound foams. TDI is usually used to produce slow rebound foams. Because the two NCO groups in the TDI molecule are at the 2,4- and 2,6- positions, they have a certain angle between them, making them prone to deformation under stress. Especially under hot pressing conditions, significant deformation and heat loss occur, particularly evident in bra cup foams, making recovery from these deformations difficult.
4. The low NCO index of isocyanates used in the preparation of slow rebound foams is also a reason for poor recovery. The NCO index of ordinary foams is usually above 100, while in slow rebound foams , the NCO index is generally between 85-95. This means that 5-15% of the hydroxyl groups do not participate in the reaction. Therefore, although the surface of the foam appears to be a single entity, internally there is a considerable portion of chain segments that are independent of each other.
Solutions for Improving Compression Resistance of Slow Rebound Foams:
1.Use high EO polyether (so-called blowing agent polyether) to replace some slow rebound polyether.
A. High EO polyether has a low hydroxyl value and a large molecular weight. After reacting with isocyanates, the segments formed have molecular weights greater than or close to those formed when ordinary polyether reacts with isocyanates, reducing the degree of phase separation and crystallinity.
B. High EO content polyether has soft and smooth segments, which can provide good slow rebound effects. Additionally, the addition of high EO polyether can effectively improve the low-temperature resistance of slow rebound foams.
2.Add a small amount of polyether-modified polyester to increase the material's cohesive force.
The polyester segments, due to the presence of ester groups, have high internal cohesive forces and good tensile and compressive properties, significantly improving the compressive resistance of slow rebound foams.
3.Use a small amount of high-functionality and high molecular weight polyether as a crosslinking agent, and replace some ordinary polyether with high-activity polyether for slow rebound.
This disrupts the distribution of chain segments, reduces the degree of phase separation, and increases the reaction degree, reducing crystallinity.
4.Use MDI or add MDI to TDI.
MDI has a different structure from TDI and produces foams with better compression resistance and less heat loss. If using MDI, it is best to use modified MDI (with high branching and easy closure of cells); liquid MDI can also be used, as it is intramolecular cyclization and more resistant to compression. Slow rebound foams made with all MDI have much better compression resistance than pure TDI, and many manufacturers are already using this.
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