Sandblasting deburring machine

4 month ago

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Dongguan YingSiDa Intelligent Technology Co., Ltd.

4 month

Product details

Comprehensive Process and Technical Advantages of Removing Flash and Burrs from Plastic Parts with Cryogenic Deflashing Machine

In the field of plastic part processing, the precise removal of flash and burrs is crucial for enhancing product precision and surface quality. Cryogenic deflashing technology, leveraging the composite process of low-temperature embrittlement and kinetic energy spraying, offers an efficient solution for plastic part deflashing. This article details the standard process of removing flash from plastic parts using a Liquid nitrogen flash machine and deeply analyzes the technical advantages of Sand blasting machine and small sand blasting machine in fine processing.

I. Pretreatment: Dual Preparation of Parts and Equipment

1. Initial Inspection and Fixing of Plastic Parts

Flash Positioning: Flash distribution is identified via a visual inspection system (precision ±0.02mm), commonly found on injection molding parting surfaces, gate areas, and thread hole edges. Record burr thickness (typically 0.05–0.3mm) and plastic type (e.g., ABS, PC, POM).

Flexible Fixture Design: Parts are fixed with silicone-padded aluminum alloy fixtures. For thin-walled structures (wall thickness ≤1mm), multi-point supports are designed to avoid cracking from stress concentration at low temperatures. Fixture surfaces undergo insulation treatment to prevent static adsorption from plastic-metal contact.

2. Parameter Setting for Liquid nitrogen flash machine

Cryogenic Embrittlement Threshold: Equipment temperature is adjusted based on plastic type:

ABS plastic: −80℃–−100℃, holding for 10–15 minutes (embrittlement threshold −70℃);

PC plastic: −120℃–−140℃, holding for 15–20 minutes (embrittlement threshold −110℃).

This ensures flash areas are below their glass transition temperature while maintaining mechanical properties of the main part.

Spray Media Preparation: 0.1–0.2mm nylon sand (Shore D 70–80 hardness) is used, pre-dried at 50℃ for 2 hours to avoid moisture affecting spraying performance.

II. Liquid Nitrogen Cryogenic Deflashing: Flash Embrittlement and Batch Removal

1. Gradient Cryogenic Embrittlement

Staged Cooling: After starting the Liquid nitrogen flash machine, parts are pre-cooled at −40℃ for 5 minutes, then gradually cooled to the target temperature to prevent deformation from sudden temperature changes. Liquid nitrogen atomization particle diameter in the chamber is controlled at 30–80μm, with a circulating fan (wind speed 8–12m/s) ensuring uniform flash cooling and surface temperature difference ≤2℃.

Temperature Field Monitoring: Infrared sensors monitor heat dissipation blind spots like grooves and bosses. Airflow deflectors are added if necessary to optimize cold air circulation for consistent flash embrittlement.

2. Low-Pressure Sandblasting for Flash Removal

Kinetic Energy Matching: After freezing, the equipment drives nylon sand with 0.3–0.5MPa compressed air at 60–100m/s. "Parallel spraying" (15°–30° angle) is used for thin flash below 0.1mm, while cross-spraying paths are applied to thick flash (>0.2mm), with single-pass removal ≤0.05mm to avoid over-blasting (control tolerance ±0.03mm).

Automated Trajectory: For complex-structured parts (e.g., automotive air vent grilles), CNC-generated contoured spraying trajectories ensure no flash residue in delicate areas like blades and clips, protecting snap structure precision.

III. Sandblasting Finishing: Surface Quality Optimization

1. Coarse Sandblasting with Sand blasting machine

Batch Processing: For small-to-medium plastic parts (e.g., electronic connectors), a turntable-type Sand blasting machine is used. Parts are loaded with 0.2–0.3mm glass beads (roundness ≥98%) and sandblasted at 30–50rpm for 5–8 minutes to reduce surface roughness from Ra 6.3μm to 1.6μm.

Process Parameters: Sandblasting pressure 0.2–0.4MPa, spraying distance 10–15cm. The turntable angle is adjusted via servo motor for uniform sand exposure.

2. Fine Trimming with small sand blasting machine

Local Micro-Processing: For high-precision plastic parts (e.g., medical catheter connectors), a small sand blasting machine is used with 0.03–0.08mm corn starch sand. Under a 10–20x microscope, secondary sandblasting eliminates 0.01mm-level burrs on critical areas like thread holes and O-ring grooves.

Static Control: An ion air bar (wind speed 8–12m/s) is activated during sandblasting to prevent static adsorption of sand particles, ensuring assembly accuracy.

IV. Post-Processing and Quality Verification

1. Cleaning and Stress Relief

Ultrasonic Cleaning: Parts are placed in an ultrasonic tank with neutral detergent (40kHz) for 3–5 minutes, then rinsed twice with deionized water. Medical-grade parts require additional pure water spraying (conductivity ≤1μS/cm).

Stress Relief: Parts are kept in a thermostatic chamber (60–80℃) for 1–2 hours to eliminate internal stress, preventing cracking in subsequent use.

2. Full-Dimension Inspection

Visual Inspection: Under 3000lux lighting, flash removal is checked via visual inspection equipment (resolution 0.01mm), requiring no visible burrs on sealing/mating surfaces and non-functional surface burr height ≤0.02mm.

Precision Verification: Key dimensions (e.g., addendum circle diameter of plastic gears, tolerance ±0.05mm) are measured using an image measuring instrument to ensure no dimensional out-of-tolerance.

V. Analysis of Cryogenic Deflashing Technical Advantages

1. High Precision and Consistency

The Liquid nitrogen flash machine achieves selective flash embrittlement through precise temperature control, combined with CNC sandblasting trajectories, enabling ±0.01mm-level deflashing precision. Consistency is improved by 90% compared to traditional manual methods, suitable for high-precision medical and aerospace applications.

2. Efficiency and Cost Advantages

Single equipment processes 300–800 parts per hour, 15–20 times more efficient than manual deflashing. Nylon sand can be reused 50–80 times, with liquid nitrogen consumption only 0.3–0.8L/part, reducing costs by 40%.

3. Material Adaptability and Environmental Friendliness

Compatible with ABS, PC, POM, etc., the process is chemical-free. Inert gas-protected sandblasting ensures dust emission ≤5mg/m³, complying with ISO 14001 standards.

4. Process Flexibility and Automation

The equipment supports one-click parameter switching for different plastics. Combined with local finishing by the small sand blasting machine, it adapts to complex structures, enabling fully automated production.

Conclusion

From cryogenic embrittlement to sandblasting finishing, the deflashing system composed of Liquid nitrogen flash machine, Sand blasting machine, and small sand blasting machine achieves three-stage processing of "precise embrittlement-kinetic energy removal-fine polishing", significantly improving surface quality while ensuring dimensional accuracy. This technology breaks through the efficiency bottleneck of traditional manual deflashing and provides standardized solutions for plastic part processing in automotive, electronics, medical, and other fields, driving industry upgrading to intelligent manufacturing.