Developing an electric pressure cooker prototype requires precise CNC machining to validate design rationality, test functionality (e.g., pressure sealing), and evaluate appearance—critical steps before mass production. Unlike regular kitchen appliances, electric pressure cookers have strict requirements for sealing performance and structural strength, which shape every stage of the CNC process. This guide breaks down the full workflow, from design to post-processing, with key parameters, material choices, and practical tips to ensure prototype success.
1. Preliminary Preparation: Design & Data Processing
The foundation of a high-quality prototype lies in accurate design and optimized data. This stage focuses on creating a detailed 3D model and preparing it for CNC machining.
(1) 3D Modeling with CAD Software
Use professional CAD tools (e.g., SolidWorks, UG) to design a model that reflects every critical detail of the electric pressure cooker. The model must include both external and internal structures, plus process features to simplify machining.
| Structure Category | Key Design Details | Precision Requirements | Purpose |
| External Structure | Lid (curved top), pot body (cylindrical shape), handle (ergonomic grip), control buttons (凸起 height ≥2mm) | Lid-body alignment tolerance ±0.1mm; handle mounting hole position error ≤0.05mm | Ensure assembly accuracy; meet user ergonomics |
| Internal Structure | Sealing ring groove (width 5mm ±0.05mm), pressure valve mounting seat, sensor fixing holes | Sealing groove depth tolerance ±0.03mm; valve seat hole diameter error ≤0.02mm | Guarantee pressure tightness; fit internal components (e.g., sensors) |
| Process Features | Draft slope (3°~5° on lid/pot body), rounding corners (R2mm on handle edges), parting lines | Draft slope ensures easy demolding; rounding prevents stress concentration | Simplify CNC machining; avoid prototype damage during testing |
(2) Model Repair & Format Conversion
Raw 3D models often have defects that can ruin machining—fix these issues before exporting:
- Defect Checking: Use software like Magics to identify broken surfaces, overlapping geometry, or missing features (e.g., incomplete sealing grooves).
- Repair Steps: Fill gaps, merge overlapping surfaces, and smooth uneven edges to ensure the model is “machinable.”
- Format Export: Convert the repaired model to STL format (the standard for CNC machining), with a mesh density of 0.1mm (balances detail and file size).
2. Material Selection & Processing Process Planning
Choosing the right materials and processes is critical—materials must mimic the performance of mass-produced parts, while processes need to balance precision and cost.
(1) Prototype Material Selection
Different components of the electric pressure cooker require materials with specific properties (e.g., heat resistance, wear resistance). Below is a detailed comparison:
| Material Type | Applicable Parts | Key Properties | Machinability Tips | Surface Treatment |
| ABS | Pot body, lid (appearance parts), control button housings | Easy to mill, smooth surface, low cost | Use high-speed spindle (10,000–15,000 rpm) to avoid melting | Spray matte black paint (adhesion ≥4B standard) to simulate plastic texture |
| Nylon (PA) | Internal structural parts (e.g., sensor brackets, pressure valve covers) | High strength, wear resistance, heat resistance (up to 120°C) | Use carbide tools; add cutting fluid to prevent overheating | No treatment needed (naturally wear-resistant) |
| Aluminum Alloy (6061) | Metal handles, lid holders | Lightweight, high rigidity, corrosion-resistant | Use high spindle speed (18,000–22,000 rpm) to reduce burrs | Anodizing (silver-gray, 8–10μm thick) for anti-oxidation + wire drawing |
| Transparent Acrylic | Observation windows (if included) | High light transmittance (≥90%), clear appearance | Precision cutting with Φ3mm ball-head tool; avoid chipping edges | Polishing with abrasive paste (from coarse 400# to fine 1200#) |
(2) Core CNC Machining Processes
The process combination depends on the part’s shape and function. Below are the key processes and their applications:
| Process Name | Application Scenarios | Key Parameters & Tips |
| CNC Milling | Pot body cavity (depth ≥80mm), lid curved surface, sealing ring groove | Use “layered cutting” for deep cavities (0.5mm per layer); use ball-head tool for curved surfaces (Ra ≤1.6μm) |
| CNC Turning | Round components (e.g., pressure valve knobs, handle shafts) | Spindle speed 20,000 rpm; feed rate 1,000 mm/min (ensures smooth surface) |
| Drilling & Tapping | Sensor mounting holes (M4 threads), handle fixing holes | Drill Φ3.3mm bottom holes first, then tap (avoids thread stripping); use pecking drilling for deep holes |
| Wire EDM | Special-shaped parts (e.g., acrylic observation window frames) | Achieves accuracy ±0.02mm (critical for transparent, visible parts) |
3. CNC Machining Execution: Key Steps & Parameters
Precise execution is essential to avoid defects like poor sealing or structural weakness. Focus on programming, tool selection, and process monitoring.
(1) Programming & Tool Selection
Use CAM software (e.g., Mastercam, PowerMill) to convert STL models into G-code, and select tools based on material and feature:
| Machining Stage | Tool Type | Tool Size | Key Settings |
| Roughing | Flat-bottom end mill | Φ10mm (ABS/nylon), Φ8mm (aluminum alloy) | Remove 90% of material; leave 0.3mm finishing allowance |
| Semi-Finishing | Ball-head end mill | Φ6mm | Smooth curved surfaces; reduce allowance to 0.1mm |
| Finishing | Small ball-head end mill | Φ3mm (ABS/nylon), Φ2mm (acrylic) | Machine fine features (e.g., sealing grooves); achieve Ra ≤1.0μm |
| Drilling | Twist drill | Φ2–Φ5mm | Pecking drilling (drill 3mm, retract 1mm) to clear chips |
(2) Machining Parameter Setting
Parameters vary by material to ensure quality and efficiency. Below is a practical reference:
| Material | Machining Stage | Spindle Speed (rpm) | Feed Rate (mm/min) | Cutting Depth (mm) |
| ABS | Roughing | 10,000–12,000 | 1,500–2,000 | 0.5–1.0 |
| ABS | Finishing | 15,000–18,000 | 800–1,200 | 0.1–0.3 |
| Aluminum Alloy | Roughing | 12,000–15,000 | 1,200–1,800 | 0.5–0.8 |
| Aluminum Alloy | Finishing | 18,000–22,000 | 800–1,000 | 0.1–0.2 |
| Nylon | Roughing | 8,000–10,000 | 1,000–1,500 | 0.4–0.8 |
| Nylon | Finishing | 12,000–15,000 | 600–800 | 0.1–0.2 |
(3) Machining Process Monitoring
The first prototype (first piece) requires strict monitoring to catch issues early:
- Dimensional Checks: Pause after roughing to measure critical features (e.g., sealing groove width, lid-body gap) with calipers or a micrometer. Adjust the program if tolerance exceeds ±0.1mm.
- Surface Quality Checks: Inspect for tool marks, burrs, or melting (common in ABS/nylon). If tool marks are visible, increase spindle speed by 2,000 rpm.
- Clamping Stability: Ensure the part doesn’t shift during machining—use vacuum suction cups for flat parts (e.g., aluminum handles) or custom fixtures for curved parts (e.g., pot lids).
4. Post-Processing & Functional Testing
Post-processing enhances appearance and performance, while functional testing validates if the prototype meets design goals—especially critical for pressure cookers.
(1) Surface Treatment
Tailor the treatment to the part’s role and material:
| Part | Surface Treatment Steps | Expected Outcome |
| ABS Pot Body/Lid | 1. Grind with 600# → 1000# sandpaper (remove tool marks); 2. Spray primer (30μm thick); 3. Spray matte paint (50μm thick); 4. Oven cure at 60°C for 2 hours | Paint adhesion ≥4B; no peeling or fading |
| Aluminum Alloy Handle | 1. Degrease with isopropyl alcohol; 2. Anodize (form oxide film); 3. Hand-wire draw along the length | Uniform silver-gray color; no scratches |
| Acrylic Observation Window | 1. Polish with 400# abrasive paste (remove cutting marks); 2. Polish with 1200# paste (achieve transparency); 3. Clean with lens cleaner | Light transmittance ≥90%; no visible defects |
(2) Functional Testing
Assemble internal components (sealing ring, pressure valve, sensor) and simulate real usage:
| Test Type | Test Method | Pass Standard |
| Tightness Test | Fill the pot with 500ml water, close the lid, and pressurize to 100kPa (simulate working pressure). Hold for 30 minutes. | No water leakage; pressure drop ≤5kPa in 30 minutes |
| Button Feel Test | Press control buttons 1,000 times (2 presses/second). Measure stroke (2mm ±0.2mm) and feedback force (5–8N). | Consistent stroke and force; no button jamming |
| Structural Strength Test | Apply 5kg load to the lid (simulate accidental pressure). Hold for 10 minutes. | No deformation; lid-body gap remains ≤0.1mm |
| Heat Resistance Test | Heat the pot to 100°C (simulate cooking) and hold for 2 hours. Cool to room temperature. | No material warping; sealing groove tolerance remains ±0.05mm |
5. Inspection & Optimization
Inspect critical dimensions and iterate on the design to fix defects—this ensures the prototype is ready for mold opening.
(1) Critical Dimension Inspection
Use a Coordinate Measuring Machine (CMM) to check key dimensions:
- Lid-body mating gap: ±0.1mm (ensures sealing)
- Sealing ring groove width: 5mm ±0.05mm (fits standard sealing rings)
- Threaded hole position (sensor mounting): ±0.05mm (avoids assembly interference)
- Handle mounting hole alignment: ≤0.03mm (ensures handle stability)
(2) Design Iteration & Cost Optimization
If defects are found (e.g., leakage, button jamming), modify the 3D model and reprocess. Use these tips to reduce costs:
- Split Complex Parts: Machine the lid and its holder separately instead of as one piece—cuts machining time by 30% and reduces tool wear.
- Use Hybrid Processes: 3D print small internal parts (e.g., pressure valve covers) with SLS nylon, then CNC machine appearance parts (e.g., pot body) with ABS—lowers material waste by 25%.
- Batch Machining: For 10+ prototypes, use aluminum profile blanks (pre-cut to approximate size) instead of full blocks—reduces material removal by 40%.
Yigu Technology’s Perspective on Electric Pressure Cooker Prototype CNC Machining
At Yigu Technology, we believe sealing performance and structural strength are the core of electric pressure cooker prototype machining. Many clients overspend by using high-cost materials for non-critical parts—e.g., aluminum alloy for internal brackets that only need nylon. Our team selects materials strategically: ABS for appearance parts (cost-effective, easy to finish) and nylon for internal structures (heat-resistant, wear-resistant). We also optimize machining for sealing: our “layered finishing” of sealing grooves ensures Ra ≤0.8μm, and we test tightness three times during production to avoid leakage. For cost savings, we use hybrid CNC + 3D printing and batch processing, cutting prototype costs by 20–30%. Our goal is to deliver prototypes that accurately validate design and function, accelerating clients’ path to mass production.
FAQ
- Why is nylon (PA) used for internal structural parts instead of ABS?
Nylon has better heat resistance (up to 120°C) and wear resistance than ABS—critical for internal parts near heating elements or moving components (e.g., pressure valves). ABS melts at ~90°C and wears faster, making it unsuitable for parts that need to withstand high temperatures or repeated use.
- How do you ensure the lid and pot body have a tight seal after CNC machining?
We focus on two key steps: 1) Machining the sealing groove with a Φ3mm ball-head tool to achieve Ra ≤0.8μm (smooth surface reduces leakage risk); 2) Inspecting the lid-body gap with a CMM to ensure tolerance ±0.1mm. We also test tightness with 100kPa pressure—only prototypes with ≤5kPa pressure drop pass.
- How long does it take to CNC machine a single electric pressure cooker prototype?
Total time is ~4–6 days: 1 day for design/data processing, 1–2 days for CNC machining (varies by part complexity), 1 day for post-processing (painting/anodizing), and 1–2 days for assembly/functional testing. Batch production (10+ prototypes) can be shortened to 3–4 days with parallel processing.