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Home / Case Study: Injection Molding of Rice Cooker Shell Using a 260-Ton Injection Molding Machine

Case Study: Injection Molding of Rice Cooker Shell Using a 260-Ton Injection Molding Machine

2025/11/03 By le zhan

Injection Molding of Rice Cooker Shell Using

Unstable plasticization, inaccurate demolding, and excessively long production cycles lead to significant losses in production efficiency. On average, each factory loses tens of thousands of dollars annually due to PP material waste and failure to meet production targets. As product managers at Topstar, we’ve heard many clients raise these issues. One large home appliance brand approached us seeking solutions for rice cooker shell production, as they needed an injection molding machine capable of handling the unique flowability of PP material, maintaining a 30-second production cycle, and seamlessly integrating with their automated systems. We provided them with a 260-ton injection molding machine from the Topstar TMll series. Therefore, we will use this case study to demonstrate how to enhance production, achieve stable quality, reduce production cycles, and minimize waste.

Why equip a rice cooker shell with a 260-ton injection molding machine?

Rice cooker shells are typically 3-4 mm thick and 30-40 cm in diameter. Injection molding has specific requirements: sufficient clamping force to prevent flash, precise plasticization of the PP material, and compatibility with automated systems for mass production. Topstar’s 260-ton injection molding machine fully meets these requirements:

Clamping Force: The 260 ton clamping force is sufficient to maintain a tight seal in the single-cavity mold during the injection molding process. This is crucial for low-viscosity PP materials, as insufficient clamping force can easily lead to flash.

Injection Volume: The injection molding machine‘s injection volume can easily accommodate 180-200 grams of PP material, which is typically used for the outer shell of a rice cooker.

Size Compatibility: The tie rod spacing of the TMll 260 ton injection molding machine is ideal for accommodating large, shallow molds required for rice cooker shells.

rice cooker shell

Precision PVD alloy screw head, with superior PP plasticizing technology

PP is the preferred material for rice cooker shells due to its heat resistance, durability, and cost-effectiveness. This 260 ton injection molding machine’s precision PVD alloy screw head assembly solves the material adaptability problem. The PVD coating on the screw head reduces friction, allowing PP to melt evenly and flow smoothly into the mold. Unlike standard screw heads, it can handle the low melting point of PP (160–170°C) without degradation.

Simultaneously, the screw’s 22:1 L/D ratio ensures complete melting of PP granules, eliminating unmelted particles and preventing surface defects on the casing. This high precision reduces the brand’s defect rate from 2.1% to 0.3%. Furthermore, by optimizing the plasticizing process, material waste is reduced by 60%. The TM260’s PVD screw head changes this, resulting in a smooth and uniform casing surface that eliminates scrap due to deformation or uneven melting.

Automatic Mold Opening Position Compensation in the 260-ton Injection Molding Machine

In the mass production of rice cooker shells, injection molding robots play a crucial role in demolding. Inaccurate mold opening positions can lead to robot gripping failures, thus extending the production cycle. The automatic mold opening position compensation function of the 260-ton injection molding machine effectively solves this problem. Guided by a unified control system, this function can automatically adjust the mold opening position (with an accuracy of ±0.1mm) based on real-time feedback from the injection molding robot, thereby ensuring perfect alignment between the injection molding robot’s clamp and the shell demolding point.

Consistent mold opening positions eliminate the need for manual adjustment, ensuring timely completion of the 30-second cycle. The injection molding robot now completes demolding in just 2 seconds, without any delay. Furthermore, the compensation function prevents collisions between the robot and the mold, extending mold life by 30% and providing better protection for the mold.

260-ton Injection Molding Machine

The integrated control system of the 260-ton injection molding machine enables coordinated production

The true advantage of the 260-ton injection molding machine lies in Topstar’s independently developed integrated control system. This system integrates the machine, auxiliary equipment, and automation systems into a unified and coordinated workflow. Through real-time communication, the system synchronizes data between the dryer, injection molding machine, and injection molding robot. For example, if the dryer detects moisture in the PP, it signals the machine to extend the plasticizing time, thus preventing plastic expansion. Additionally, step-by-step optimization is implemented, with each stage of production finely tuned: material pretreatment, plasticization, injection molding, and demolding. The system adjusts these parameters in real time based on production data. Finally, all process parameters are recorded and accessed via touchscreen or the factory ERP system, ensuring traceability of quality control. Customers can use this data to identify bottlenecks and further optimize production processes.

Case Study Results

After using the Topstar TMll series 260 ton injection molding machine for six months, this appliance brand achieved significant results in rice cooker shell production:

Cycle time: Consistently maintained at 30 seconds, with a 16% increase in daily output.

Defect rate: Reduced from 2.1% to 0.3%, saving tens of thousands of dollars in material waste annually.

Automation efficiency: Clamping failure rate reduced from 8% to 0.5%, with a 94% reduction in unplanned downtime.

Mold life: Extended by 30%, saving $15,000 in mold replacement costs.

This customer told me, “We set high goals for the TM260, and it exceeded them. A 30-second molding cycle, consistent quality, and seamless automation make this injection molding machine the core of our rice cooker shell production.”

Key Considerations for Rice Cooker Shell Manufacturing

We hope this case study will provide manufacturers looking to purchase and use a 260-ton injection molding machine, or for rice cooker shell production, with several key considerations:

Prioritize Material-Specific Components: For PP, PVD alloy screw heads are essential as they ensure consistent plasticization and reduce waste.
Invest in Automation Integration: Automated mold opening compensation eliminates manual adjustments and robot malfunctions, keeping production cycles on track.
Choose Integrated Controls: Unifying the injection molding machine, auxiliary equipment, and automation systems reduces bottlenecks and ensures traceability.

Higher Standards in Rice Cooker Shell Production

Topstar The TM260 series 260 ton injection molding machine precisely controls PP plasticization through its precision PVD alloy screw head. Its automatic mold opening compensation function enables seamless integration with injection molding robots, and the integrated control system coordinates every production step. All of this achieves a rapid molding cycle of 30 seconds. For the appliance brand in this case study, the TM260 not only solved their immediate problems but also brought long-term value by reducing waste, increasing output, and extending equipment lifespan.

 

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