Case Study CNC MachiningCustom Parts
2026年5月11日
High-Precision CNC Machining of PVDF Cylinder Plugs (Small Batch Prototyping)
1. Project Overview • Part Name: B-124 Cylinder Plug / Stopper • Application: Precision sealing and fluid connection for pneumatic or chemical handling systems. • Quantity: 12 pieces (Low-volume, high
1. Project Overview
• Part Name:Cylinder Plug / Stopper
• Application: Precision sealing and fluid connection for pneumatic or chemical handling systems.
• Quantity: 12 pieces (Low-volume, high-precision R&D batch).
• Core Challenge: Achieving tight tolerances (±0.05mm)and a superior surface finish (≤0.8mm) on a high-performance polymer in a micro-scale format without the use of injection molding.
2. Technical Specifications
• Material:PVDF (Polyvinylidene Fluoride). Known for excellent chemical resistance and mechanical strength, but challenging to machine due to internal stresses and thermal expansion.
• Critical Dimensions:
◦ Sealing Diameter: 4.65±0.05
◦ Mounting Diameter:6.88±0.05
• Surface Requirement: Roughness≤0.8mm on sealing surfaces (near-mirror finish).
• Geometry: Multi-step flange, tapered barb fitting, and internal grooves within a total length of only 12mm.
3. Manufacturing Strategy: CNC Swiss-Type Turning
Given the small batch size (12 units) and the miniature scale of the part, CNC Swiss-type Machining was selected as the optimal process.
• Why Swiss-type? The sliding headstock and guide bushing provide maximum rigidity for parts under 10mm in diameter, ensuring superior concentricity and preventing deflection during the cutting of theφ2.5mmtapered tip.
4. Technical Challenges & Solutions
Challenge A: Material Deflection and "Spring-back"
• The Issue: PVDF is a semi-crystalline polymer. It is prone to "letting the tool slide" (deflection) due to its elasticity, making it difficult to hold a ±0.05mm tolerance.
• The Solution: We utilized ultra-fine grain carbide tools with extremely sharp cutting edges and high rake angles. This ensures the material is "sheared" rather than "pushed," significantly reducing dimensional variance.
Challenge B: Achieving Ra 0.8umSurface Finish
• The Issue: Machining plastics often results in "tearing" or fuzzy surfaces, which would compromise the airtight seal required for this plug.
• The Solution: A "High-Speed, Low-Feed" strategy was implemented. By optimizing the ratio between the tool nose radius and the feed rate, we achieved a high-gloss finish directly from the machine, eliminating the need for risky manual polishing.
Challenge C: Precision Deburring on Micro-Features
• The Issue: At a total length of 12mm, manual deburring risks rounding off critical edges or scratching the Ra0.8surface.
• The Solution: We programmed in-machine chamfering using specialized micro-tools. This allowed us to remove burrs at the source while maintaining the geometric integrity of the barb and flange.
5. Quality Assurance (QC)
Dimensional Inspection: 100% inspection of critical diameters (ϕ4.65andϕ6.88) using high-precision digital micrometers and an Optical Gaging Product (OGP) system.
Surface Verification: Roughness testers were used to confirm that the sealing zones met the Ra<0.8μm requirement.
Standard Compliance: All non-toleranced dimensions were verified against ISO 2768-1 (Medium).
6. Conclusion
By leveraging advanced Swiss-type CNC technology and a deep understanding of high-performance polymer rheology, we successfully delivered 12 high-precision components that met all aerospace-grade specifications. This case demonstrates our ability to provide rapid, high-quality solutions for complex, small-batch engineering requirements where traditional molding is not cost-effective.