pressure cooker moulding

Through our rich experience and perfect supply chain, our company can provide customers with high-quality customized pressure cooker moulding products to meet their specific needs. At the same time, we have 10 years of professional foreign trade service experience, understand the foreign trade process, and better serve our customers. For pressure cooker moulding products, we can make corresponding plastic parts, which is mainly done through injection molds.

Pressure cookers are kitchen appliances characterized by high temperatures, high pressures, and stringent safety requirements. Although their plastic components do not come into direct contact with the high-pressure environment inside the pot, they are constantly exposed to a harsh environment involving high-temperature radiation, steam condensation, thermal cycling, and frequent mechanical stress. Key plastic components include handles, lid knobs, pressure-limiting valve covers, float valve buttons, sealing ring retainers, side covers, switch sliders, base decorative covers, and similar parts. These components demand exceptionally high levels of heat resistance, creep resistance, steam aging resistance, mechanical strength, dimensional stability, and non-toxic safety. Consequently, the injection molding process must prioritize four core control objectives: resistance to high-temperature deformation, resistance to steam-induced cracking, reliable structural integrity under load, and food-contact safety compliance. The specific molding guidelines are outlined below.

Material selection prioritizes heat resistance, steam resistance, high mechanical strength, and food-grade safety. For components subject to prolonged mechanical stress—such as handles and knobs—and situated in close proximity to heat sources, the preferred materials are heat-resistant ABS, glass-fiber reinforced PP, or PA66. These materials must possess a heat resistance threshold exceeding 130°C to withstand continuous high-temperature steam exposure and repetitive mechanical loading (e.g., during assembly and disassembly) without softening, deforming, or exhibiting creep. Standard PP is generally unsuitable for primary load-bearing components due to insufficient heat resistance; it is typically reserved for non-critical parts such as bases and outer covers. Precision transmission components—such as float valve buttons, sliders, and interlocking mechanisms—typically utilize POM or reinforced PA66, which offer excellent self-lubrication, wear resistance, and dimensional stability, thereby ensuring smooth and reliable lid opening and closing operations. Components that may come into indirect contact with steam or food products must be fabricated using food-grade PP, food-grade ABS, or food-grade PA. These materials must comply with food-contact safety standards, remain free of odors, exhibit no toxic leaching, and withstand boiling water exposure without releasing harmful substances. Additionally, high-stress components—such as handles—must possess high impact resistance to prevent cracking in the event of accidental drops. Regarding raw material pretreatment: ABS, PA66, and POM exhibit significant hygroscopicity; therefore, they must be dried at 80–90°C for 3–4 hours to reduce moisture content to below 0.03%. This prevents the formation of silver streaks, air bubbles, or flow marks during high-temperature molding. Conversely, PP exhibits low hygroscopicity and does not require extensive drying; a brief low-temperature preheating for one hour is sufficient, particularly in humid environments. The primary focus of the mold design lies in addressing structural strength under load, precision fitting, dimensional stability within a steam-rich environment, and reliable demolding. Plastic components for pressure cookers typically feature thick-walled transitions, intricate snap-fit mechanisms, deep-cavity structures, and dense reinforcing ribs. Consequently, the mold parting lines must be positioned to avoid load-bearing and mating surfaces; furthermore, the mold-closing clearance must be controlled to within 0.02 mm to prevent flash or burrs from compromising assembly integrity and sealing performance. The mold cavities and cores are fabricated using wear-resistant, pre-hardened steels—such as 718 or S136—and polished to a surface finish of Ra 0.02–0.05 μm to ensure a smooth exterior that is resistant to oil stains and easy to clean. Load-bearing components, such as handles and grips, require the design of appropriately reinforced ribs; the rib thickness should be maintained at 50%–60% of the main wall thickness to prevent stress concentration. The dimensional accuracy of mating holes, positioning slots, and snap-fit features is controlled within a tolerance of ±0.05–0.1 mm to ensure a tight, secure fit with the metal pressure cooker lid, thereby preventing looseness or steam leakage. The mold design must incorporate precise compensation for material shrinkage rates—specifically 0.5%–0.7% for ABS, 1.2%–1.8% for PP, and 1.0%–1.4% for PA66—to prevent dimensional deviations caused by exposure to high-temperature steam from resulting in jamming or component failure.

The gating system typically employs side gates or submarine gates; for elongated components such as handles, a dual-point gating strategy is utilized to ensure uniform melt filling and minimize the impact of weld lines on structural strength. The cooling system is distributed uniformly throughout the mold cavity, with increased water channel density in thick-walled sections and around rib structures; mold temperature fluctuations are controlled within ±3°C to prevent uneven cooling, which can lead to internal stresses and warping. Venting design is of critical importance, as the molten material is prone to trapping air at the ends of ribs, at corners, and within deep cavities—a risk compounded by the material's susceptibility to thermal decomposition at high temperatures. Consequently, venting grooves with a depth of 0.02–0.03 mm must be incorporated to prevent short shots, burning, and porosity. For features involving undercuts—such as those found on handles or snap-fit mechanisms—sliding cores or angled ejector pins are employed to ensure smooth demolding, preventing surface drag marks or "whitening" (stress marks) that could lead to the propagation and cracking of microscopic fissures under high-temperature load conditions. The core objectives of the injection molding process are low internal stress, high strength, dimensional stability, and thermal stability. Equipment selection involves 120–300 ton injection molding machines, with an injection volume set at 1.2 to 1.5 times the product weight to ensure thorough plasticization and stable injection. Temperature settings are segmented as follows: for heat-resistant ABS, the barrel temperature is 230–265°C and the mold temperature is 60–80°C to enhance surface quality and reduce internal stress; for reinforced PP, the barrel temperature is 190–230°C and the mold temperature is 40–65°C to balance crystallinity and improve heat distortion resistance; and for PA66, the barrel temperature is 250–280°C and the mold temperature is 60–85°C to ensure adequate flowability and strength. Injection speed employs a three-stage control strategy: an initial low speed to prevent jetting, a mid-stage high speed to fill the main body, and a final low speed for pressure holding to avoid air entrapment and flash.

Injection pressure is set between 85–140 MPa based on wall thickness and structural design, with appropriately higher pressures applied for thick-walled, load-bearing components. Holding pressure is set at 60%–80% of the injection pressure, with a holding time of 10–25 seconds; the primary focus here is to compensate for shrinkage in thick-walled areas—such as the handle base and assembly points—thereby eliminating sink marks and depressions. Back pressure is maintained at 3–8 MPa to improve melt homogeneity and prevent color variations or uneven mixing. Cooling time is controlled between 20–40 seconds, depending on wall thickness, to ensure the product is fully solidified before ejection, thereby preventing deformation or sticking to the mold. Ejection utilizes a combined ejector plate and pin system to ensure uniform force distribution, preventing "ejector whitening" or cracking—particularly avoiding the appearance of ejection marks on load-bearing surfaces.

Post-processing and quality inspection are conducted in strict compliance with safety standards for cookware. After molding, gates, flash, and burrs are meticulously removed; aesthetic components are inspected for color variations, scratches, and weld lines; while structural components are checked for dimensional accuracy, snap-fit strength, and mounting hole spacing. Key reliability tests include: High-temperature resistance testing—withstanding exposure to an environment of 120–135°C for 2–4 hours without softening, deformation, or yellowing; Steam aging testing—remaining free of cracks, discoloration, or stress whitening under continuous steam exposure; and Mechanical impact testing—ensuring the handle remains uncracked and unbroken after drop tests and repeated compression cycles. Additionally, food-contact components undergo odor and extractable substance testing to ensure the absence of off-odors and the non-release of toxic or harmful substances.

Regarding the prevention and control of common defects: Handle cracking is often caused by excessive internal stress or insufficient weld-line strength; this requires optimizing the gate location, increasing mold temperature, and extending the cooling time. Sink marks and depressions result from insufficient holding pressure or overly thick ribs; solutions involve increasing holding pressure and optimizing the structural design. Silver streaks and matte surface finishes are caused by moisture in the raw material; strict drying protocols must therefore be enforced. Deformation and jamming issues stem from uneven cooling or improper dimensional compensation; these require adjustments to mold temperatures and shrinkage compensation parameters. Flash and burrs are caused by insufficient clamping force or mold wear; remedies involve increasing the clamping force and repairing the mold's parting line. Finally, issues involving high-temperature creep and loosening necessitate switching to a material grade with higher heat resistance and optimizing the design of the reinforcing ribs.

We are a pressure cooker moulding manufacturer, providing high-quality pressure cooker moulding manufacturing. As long as you want to customize/develop pressure cooker moulding products, you can find us. We have professional injection mold design and mature manufacturing technology, providing you with one-stop service, from product design-mold making-product production-product packaging-product transportation, we can help you in every link. As long as you come to us, we will provide you with the ultimate service and satisfy you in terms of product quality, production time, information dialogue, etc.

Plastic Injection Mould making

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We are Custom Plastic Mold factory. Our factory is plastic injection mold maker. we has 17 years of experience in professional custom plastic mold and 10 years of foreign trade experience. We are custom Plastic Mold supplier. We can provide custom Plastic Mold service. Our factory can make the Injection molded plastic parts, and the quality of the products will satisfy you.

We have more than 50 high-end machines and hundreds of engineers and designers. We can provide one-stop service, from product design - mold making - product production - product packaging - transportation. We have a complete production chain. We can meet all your requirements.

Services we provide:

Professional custom mold service, Plastic mold design and manufacturing .plastic product production, product design, mold design, blow mold customization, rotational mold customization, die-casting mold customization. 3D printing services, CNC manufacturing services, product packaging, customized packaging, shipping services.

We always adhere to the principles of quality first and time first. While providing customers with the highest quality products, try to maximize the production efficiency and shorten production time. We are proud to tell every customer that our company has not lost any customer since its establishment.If there is a problem with the product, we will seek a solution actively and take responsibility to the end.

FAQ

Q1: Are you trading company or manufacturer ?

A: We are manufacturers.

Q2. When can I get the quotation?

A: We usually quote within 2 days after we get your inquiry.

If you are very urgent, please call us or tell us in your email so that we can quote for you first.

Q3. How long is the lead-time for mold?

A: It all depends on the products' size and complexity. Normally, the lead time is 25 days.

Q4. I have no 3D drawing, how should I start the new project?

A: You can supply us a molding sample, we will help you finish the 3D drawing design.

Q5. Before shipment, how to make sure the products quality?

A: If you don't come to our factory and also don't have the third party for inspection, we will be as your inspection worker.

We will supply you a video for production process detail include process report, products size structure and surface detail, packing detail and so on.

Q6. What is your payment terms?

A: Mold Payment: 40% deposit by T/T in advance, 30% second mold payment before sending out the first trial samples, 30% mold balance after you agree the final samples.

B:Production Payment: 50% deposit in advance, 50% before sending out the final goods.

Q7: How do you make our business long-term and good relationship?

A:1. We keep good quality and competitive price to ensure our customers benefit for best quality products.

2. We respect every customer as our friend and we sincerely do business and make friends with them, no matter where they come from.