The existing methods of deburring mainly include physical deburring, mechanical deburring, frozen deburring, chemical deburring and reducing the generation of deburring from the perspective of mold design.
This article will conduct an in-depth analysis of various methods from the aspects of cost, efficiency, and impact on product performance to help select the optimal deburring solution.
Formation mechanism and hazards of rubber flash
The flash of rubber seals is an inevitable byproduct of the vulcanization molding process. Its formation is mainly due to the following factors:
1. Rubber overflow caused by mold gap (0.01-0.03mm).
2. The matching degree of rubber fluidity (Mooney viscosity and shear thinning characteristics) and vulcanization rate.
3. Glue overflow caused by insufficient mold clamping pressure (usually 20-50MPa).
4. Excessive filling of preformed rubber blanks (exceeding the mold cavity volume by 5-10%).
The presence of flash not only affects the dimensional accuracy of the product (may cause dimensional deviation of 0.05-0.2mm), but also:
- destroys the continuity of the sealing surface (leakage risk increases by 30-50%).
- reduces the fatigue life of dynamic seals (shortened by 20-40%).
- increases the failure rate of subsequent assembly processes (rework costs increase by 15-25%).
Analysis of mainstream deflashing technology system
(一)Physical and mechanical method
1. Manual Trimming
- Technical principle: manual cutting with a scalpel/rotating blade.
- Cost composition: 0.5-1.2 yuan/piece (85% of labor).
- Efficiency index: 50-100 pieces/person/hour.
- Applicable scenarios: small batches, special-shaped parts (such as O-ring special-shaped sections).
- Performance impact: There is a risk of surface damage of 0.02-0.1mm.
2. Mechanical Automated Trimming
- Technical upgrade: CNC five-axis linkage + visual positioning system.
- Equipment investment: 800,000-3 million yuan (ROI cycle 2-3 years).
- Processing accuracy: ±0.03mm (repeat positioning accuracy).
- Efficiency improvement: up to 2,000 pieces/hour (automotive oil seal case).
- Limitations: There are dead corners in complex surface processing (about 5-8% residual rate).
(二)Low temperature embrittlement method
1. Liquid nitrogen freezing trimming
- Process parameters: -196℃/5-15 minutes (embrittlement below Tg).
- Medium selection: liquid nitrogen (0.8-1.2 yuan/L) vs CO2 (0.3-0.5 yuan/L).
- Equipment configuration: drum type (400,000-800,000 yuan) vs shot peening type (1.2-2.5 million yuan).
- Efficiency comparison: drum type 500kg/h vs shot peening type 200kg/h.
- Advantages: can handle micro-flash below 0.02mm (medical grade seals).
2. Dry ice blasting technology
- Innovation: 3mm dry ice particles + 6-8bar compressed air.
- Environmental benefits: no secondary pollution (VOC emissions reduced by 100%).
- Cost analysis: equipment depreciation 0.05 yuan/piece + consumables 0.12 yuan/piece.
- Application case: Surface treatment of aerospace seals.
(三)Mold optimization method
1. Precision mold technology
- Parting surface processing: Ra≤0.4μm (mirror EDM).
- Gap control: 0.005-0.015mm (high-precision wire cutting).
- Mold flow analysis: Moldflow software optimizes the flow path of the rubber.
- Benefit comparison: flash thickness is reduced by 80% (from 0.2mm→0.04mm).
2. Self-trimming mold design
- Shear blade structure: 30-45° blade angle + HRC58-62 hardness.
- Dynamic mold closing: secondary pressure mechanism (pressure increase 15-20%).
- Application limitations: only applicable to medium and high hardness rubbers such as EPDM.
Comparative Analysis of Multidimensional Evaluation Systems
| Indicator Dimensions | Manual Trimming | Mechanical Trimming | Frozen Trimming | Mold Optimization |
| Unit cost (yuan) | 0.8-1.5 | 0.3-0.6 | 0.5-0.8 | 0.05-0.1 |
| Processing accuracy (mm) | ±0.1 | ±0.03 | ±0.01 | ±0.005 |
| Efficiency | Low | High | Very High | N/A |
| Product damage rate | 3-5% | 0.5-1% | 0.1-0.3% | 0 |
| Equipment investment | Low | High | Very High | Medium |
| Applicable rubber type | All | Hard rubber | All | Specific rubber types |
Comprehensive evaluation of technical and economic feasibility
1. Small batch and multi-variety scenarios (<100,000 pieces/year)
- Optimal solution: manual trimming + formula optimization.
- Cost control: 40-60% reduction in overall cost.
- Typical case: customized seal trial production.
2. Medium and large batch production (500,000-5 million pieces/year)
- Best combination: precision mold + frozen trimming.
- Efficiency improvement: 30 times increase in per capita output.
- Successful case: automotive transmission oil seal production line.
3. Ultra-high precision requirements (medical/aerospace)
- Technical route: self-trimming mold + dry ice blasting.
- Quality assurance: Achieve ISO 3601-3 Class A standard.
- Application example: Heart valve sealing ring manufacturing.
Conclusions
1. For conventional products: the combination of "precision mold (gap ≤ 0.01mm) + frozen trimming (-150℃×10min)" can achieve a comprehensive cost of 0.3-0.5 yuan per piece, meeting the automotive industry's ≤ 0.05mm flash standard.
2. High-end application areas: The "self-trimming mold (HRC60) + laser trimming (100W pulse laser)" technical route is recommended. Although the initial investment increases by 800,000-1.2 million yuan, the product qualification rate can be increased from 92% to 99.5%.
3. Long-term strategic direction: A technical system of "prevention first, removal as a supplement" should be established, and the flash thickness should be controlled below 0.02mm from the source through mold flow simulation (Moldex3D software) + intelligent vulcanization control (PID temperature control ±0.5℃).
