Pom (polyoxymethylene), also known as acetal resin, is a top choice for sample models in industries like automotive, électronique, and consumer goods—praised for its excellent résistance mécanique, frottement faible, and superior se résistance à l'usure. Cependant, POM’s unique traits—such as high hardness (comparable à certains métaux) and sensitivity to high temperatures—make it tricky to process; overly aggressive cutting or improper cooling can lead to surface burns, craquage, or dimensional errors. Swiss CNC machines (en particulier Couches de type suisse), avec leur ingénierie de précision and multi-functional capabilities, are perfectly suited to tackle POM’s challenges. They deliver POM sample models with tight tolerances, surfaces lisses, and consistent performance—critical for validating designs before mass production. This guide breaks down the complete Swiss CNC processing process for POM samples, from machine setup to quality control.
1. Swiss CNC Machine Basics: Key Features for POM Processing
Swiss CNC machines’ specialized design sets them apart from conventional equipment, making them ideal for POM. Their focus on stability, précision, and controlled motion addresses POM’s machining pain points—like the need to avoid heat buildup and maintain tight dimensional accuracy.
Core Components of Swiss CNC Machines & POM Processing Benefits
| Composant | Description | Advantage for POM Processing |
| Swiss CNC lathe | Poupée coulissante + Fixe de guidage; compact, cadre rigide | Minimise les vibrations (POM’s hard surface shows vibration marks easily) pour les finitions lisses. |
| Machine structure | Base en fonte robuste; reinforced linear guideways | Absorbe les forces de coupe (POM requires moderate force for material removal) to prevent tool chatter. |
| Axis movement | 4–5 axis linkage; positioning accuracy ±0.001 mm | Handles complex POM sample geometries (Par exemple, bords courbes, multi-sided features) in one setup. |
| Tool turret | 8–12 tourelle de station; Modifications rapides de l'outil (0.3–0.8 seconds) | Permet le traitement «fait en un» (tournant, fraisage, forage) without repositioning POM—reduces heat accumulation from repeated clamping. |
| Vitesse de broche | Adjustable range: 2,000–8,000 rpm; run-out bas (≤0,001 mm) | Controlled rotation prevents POM from melting (high speeds >6,000 rpm cause heat buildup) ou Chipping (Les basses vitesses entraînent des coupes inégales). |
| Machine programming | CNC system (Par exemple, Fanuc, Siemens) with G-code support; CAM software compatibility (Mastercam, Fusion 360) | Ensures repeatable precision (critical for batch POM samples) and optimizes toolpaths to avoid heat-prone areas. |
Analogie: Think of a Swiss CNC machine as a “precision chef” for POM. Just like a chef uses sharp tools and controlled heat to cook delicate ingredients without burning them, a Swiss CNC machine uses optimized paramètres de coupe and stable motion to machine hard, heat-sensitive POM without defects.
2. POM Material Properties: Know Its “Do’s and Don’ts”
POM’s properties directly influence every step of the processing process. Ignoring its unique characteristics—like high dureté and low thermal conductivity—can lead to ruined samples (Par exemple, burned surfaces from excessive heat or dull tools from abrasion).
Critical POM Properties & Implications d'usinage
| Propriété | Spécification | Précaution d'usinage |
| Résistance mécanique | Résistance à la traction: 60–70 MPA; force d'impact: 5–10 kJ/m² (unnotched) | Moderate impact strength means POM can handle standard cutting forces but avoid sudden tool plunges (causes cracking). |
| Dureté | Rockwell M (RM) 80–90; Shore D 78–85 | Abrasive to tools—use wear-resistant cutting materials (Par exemple, carbure) to avoid frequent tool changes. |
| Se résistance à l'usure | Coefficient of friction: 0.15–0,3 (sec); better than most plastics | Low friction means POM chips slide easily—use chip conveyors to prevent buildup (buildup causes surface scratches). |
| Résistance chimique | Résiste aux huiles, solvants, et les acides faibles; attacked by strong alkalis and phenols | Utiliser le liquide de refroidissement soluble dans l'eau (avoid oil-based coolants that leave residues on POM’s surface). |
| Thermal properties | Point de fusion: 165–175°C; conductivité thermique: 0.23–0.3 W/(m · k) (faible) | Heat dissipates slowly—keep cutting temperature <150° C (use high coolant flow) to avoid melting or crystallization. |
| Machinabilité | Bien (low chip adhesion); produces continuous, stringy chips | Use tools with chip breakers to avoid long chip tangles (tangles scratch POM’s surface). |
Question: Why do my POM samples have a burned, brownish surface?
Répondre: Burn marks come from excessive heat (POM’s low thermal conductivity traps heat at the cutting zone). Réparer: 1) Réduisant la vitesse de la broche de 1,000 RPM; 2) Increasing coolant flow rate to 25–30 L/min; 3) Using a tool with a larger rake angle (réduit la friction).
3. Sample Model Design: Optimize for Swiss CNC Processing
A well-designed POM sample model minimizes processing challenges. Focus on simplicity, fabrication, and alignment with Swiss CNC machine capabilities—avoid features that force the machine to make risky cuts (Par exemple, profond, narrow slots that trap heat).
Design Guidelines for POM Samples
| Aspect conception | Recommandations | Pourquoi ça compte |
| Logiciel CAO | Use SolidWorks, Fusion 360, or AutoCAD for 3D Modélisation. Include clear design specifications (Par exemple, diamètre du trou: 6± 0,02 mm). | Enables accurate Programmation machine—the CNC system “knows” exactly what to cut, Réduire les erreurs. |
| Précision dimensionnelle | Set target accuracy based on use: ±0,02–±0,05 mm (functional samples); ±0.01–±0.02 mm (Caractéristiques critiques comme les trous de montage). | Overly tight accuracy (± 0,005 mm) increases processing time by 30%+ without adding value for most POM applications. |
| Tolérances | Suivez ISO 286-1: Use H7/g6 for sliding fits (common in POM gears) and H8/f7 for loose fits (Par exemple, housing components). | Ensures the sample fits with other parts (Par exemple, a POM gear that meshes with a metal shaft) Pendant les tests. |
| Feature complexity | Avoid deep features (profondeur >3x width) or sharp internal corners (rayon <0.5 MM). Utiliser des transitions progressives (rétroviser) Pour les changements d'épaisseur. | Deep features trap heat; sharp corners cause stress concentrations (POM cracks easily at stress points). |
| Model geometry | Pour les pièces cylindriques (Par exemple, POM shafts), keep length-to-diameter ratio <10:1 (prevents deflection). Pour des pièces plates, add ribs (width 0.5x thickness) for rigidity. | POM’s low flexural strength means long, thin parts bend during machining—ribs add support without increasing weight. |
Étude de cas: A client designed a POM valve core with a 2 MM de large, 8 mm deep slot (rapport d'aspect 4:1). Le premier 10 samples had burned surfaces and cracks. By widening the slot to 3 MM (rapport d'aspect 2.7:1) and adding 0.8 mm radii at the corners, all subsequent samples were defect-free—proving how design tweaks solve processing issues.
4. Techniques de traitement: Step-by-Step POM Machining
Swiss CNC processing for POM follows a “precision-first” workflow—prioritizing sharp tools, controlled speeds, and efficient heat management. Ci-dessous le processus étape par étape, with key techniques for each operation to avoid common defects.
Step-by-Step Processing Workflow
- Préparation des matériaux:
- Cut POM bar stock to length (add 5–10% machining allowance: Par exemple, 100 mm final length → 105–110 mm bar).
- Store POM in a dry environment (humidité <60%)—POM absorbs minimal moisture, but dampness causes surface blemishes.
- Configuration de la machine:
- Installer outils de coupe: Carbide turning inserts (Grade K10-K20) pour tourner; TiAlN-coated carbide end mills (2–3 flûte) for milling; forets en carbure (135° Angle de point) pour forage.
- Calibrate axes via Programmation machine: Input tool lengths, rayons, and sample dimensions into the CNC system. Faire un test sec (no cutting) to verify toolpaths.
- Turning Operations:
- Rough turning: Enlever l'excédent de matière (vitesse de broche: 3,000–4,000 rpm; taux d'alimentation: 0.015–0.025 mm/rev; profondeur de coupe: 0.5–1,0 mm). Use high-pressure coolant (25–30 L/min) to dissipate heat.
- Finish turning: Atteindre les dimensions finales (vitesse de broche: 4,000–5,000 rpm; taux d'alimentation: 0.005–0.015 mm/rev; profondeur de coupe: 0.1–0,3 mm). Use a sharp tool with a positive rake angle (10–15 °) pour des surfaces lisses.
- Milling/Drilling (si nécessaire):
- Fraisage: For slots or flats (vitesse de broche: 3,500–4,500 rpm; taux d'alimentation: 0.01–0,02 mm/tour; profondeur de coupe: 0.3–0,6mm). Utiliser la grimpe (tool rotates with the workpiece) Pour réduire les frictions.
- Forage: For holes (vitesse de broche: 2,500–3,500 rpm; taux d'alimentation: 0.01–0.015 mm/rev). Use peck drilling (pause every 1–2 mm) to clear stringy POM chips—prevents jamming.
- Filetage (si nécessaire):
- Use single-point carbide threading tools (60° Angle de filetage). Cut threads in 3–4 passes (depth per pass: 0.1–0.15 mm; vitesse de broche: 2,000–2,500 rpm). Avoid coolant during threading (prevents thread distortion).
- Finition de surface:
- For Ra ≤0.8 μm (functional samples): No post-processing needed if finish turning is done correctly.
- For Ra ≤0.4 μm (aesthetic samples): Polish with 1,000–1,500 grit sandpaper (wet-sanding) or a soft abrasive wheel (1,000 RPM). Avoid high-speed polishing (causes heat damage).
Key Technique Tips
- Contrôle des puces: POM produces long, stringy chips—use tools with chip breakers or adjust feed rate (augmenter de 0.005 MM / REV) to break chips into 2–3 cm pieces.
- Tool wear monitoring: Check tools every 20–30 samples. Outils ternes (Bords arronnés visibles) increase cutting temperature—replace carbide tools after 200–300 POM parts.
- Coolant usage: Use water-soluble coolant with 5–10% concentration. Clean the coolant tank weekly (POM chips degrade coolant over time).
5. Contrôle et inspection de la qualité: Ensure POM Sample Reliability
POM samples often serve critical roles (Par exemple, engrenages, bagues, or medical device components), so strict quality control is essential. Inspect for dimensional accuracy, qualité de surface, and functional performance to ensure the sample meets design goals.
Liste de contrôle d'inspection & Méthodes
| Inspection Aspect | Normes | Outils/Méthodes |
| Chèques dimensionnels | Meet design specifications: Par exemple, outer diameter ±0.02 mm; hole position ±0.03 mm. | Micromètres (précision ± 0,001 mm) pour les petits diamètres; étriers (digital, ± 0,002 mm) for lengths; Coordonner la machine à mesurer (Cmm) pour les géométries complexes. |
| Défauts de surface | No burns, rayures, or chips. Rugosité de surface: RA 0,4 à 1,6 μm (fonctionnel); RA ≤0,4 μm (esthétique). | Mémoire de rugosité de surface; inspection visuelle sous la lumière naturelle (hold sample at 45° angle). |
| Tolerance verification | Adhérer à l'ISO 286-1 tolérances: Par exemple, H7 hole (diamètre 10+0.015/-0 MM) fits g6 shaft (10-0.009/-0.025 MM). | Gages (pin gages for holes; ring gages for shafts); go/no-go gages for quick batch checks. |
| Functional performance | For wear-resistant parts (Par exemple, engrenages): Pass 10,000-cycle wear test (no excessive wear). Pour les parties structurelles: Withstand 1.5x design load (pas de fissuration). | Wear tester; universal testing machine (for tensile/compression tests). |
| Quality standards | Suivez ISO 9001 (qualité générale) and specific industry standards (Par exemple, OIN 10993 for medical POM parts). | Document inspection results (date, inspecteur, mesures) for traceability. |
Pour la pointe: Pour la production par lots (10+ POM samples), use statistical sampling—inspect 20% of the batch for dimensional accuracy and 100% Pour les défauts de surface (fast to check visually). This balances thoroughness and efficiency.
La vue de la technologie Yigu
À la technologie Yigu, we tailor Swiss CNC processing to POM’s unique traits. We use Swiss CNC lathes with high-precision guide bushings (± 0,001 mm) to avoid deflection and TiAlN-coated carbide tools to resist POM’s abrasion. For setup, we optimize toolpaths via CAM software to reduce heat buildup, cutting sample waste by 35%. Our quality control combines CMM for dimensions and wear testing for functional parts. Whether it’s a POM gear or medical component, we deliver samples that meet strict standards—blending precision and efficiency to help clients validate designs fast.
FAQ
- Q: Can Swiss CNC machines process thin-walled POM samples (Par exemple, 0.5 mm thick tubes)?
UN: Oui! Use a guide bushing for support, reduce clamping force to 10–15 N·m, and make shallow cutting passes (0.05–0.1 mm depth). We’ve successfully processed 0.3 mm thick POM tubes with ±0.01 mm dimensional accuracy.
- Q: What’s the best coolant for Swiss CNC processing of POM?
UN: Liquide de refroidissement soluble dans l'eau (5–10% mineral oil + eau) est idéal. It cools effectively (critical for POM’s low thermal conductivity) and doesn’t leave residues that affect POM’s surface or se résistance à l'usure. Avoid oil-based coolants (attract dust) and solvent-based coolants (damage POM).
- Q: Why do my POM samples crack during drilling?
UN: Cracking often comes from excessive feed rate or dull drills. Réparer: 1) Using a sharp carbide drill (135° Angle de point); 2) Reducing feed rate to 0.008–0.01 mm/rev; 3) Using peck drilling (pause chaque 1 MM) to relieve stress—this prevents POM from cracking under pressure.