Pom (polyoxymethylene), also known as acetal resin, is a top choice for sample models in industries like automotive, Elektronik, and consumer goods—praised for its excellent mechanische Stärke, geringe Reibung, and superior Resistenz tragen. Jedoch, POM’s unique traits—such as high hardness (vergleichbar mit einigen Metallen) and sensitivity to high temperatures—make it tricky to process; overly aggressive cutting or improper cooling can lead to surface burns, knacken, or dimensional errors. Swiss CNC machines (besonders Schweizer Drehmaschinen), mit ihren Präzisionstechnik and multi-functional capabilities, are perfectly suited to tackle POM’s challenges. They deliver POM sample models with tight tolerances, glatte Oberflächen, 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, Präzision, 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
| Komponente | Beschreibung | Advantage for POM Processing |
| Swiss CNC lathe | Sliding headstock + fixed guide bushing; compact, rigid frame | Minimizes vibration (POM’s hard surface shows vibration marks easily) for smooth finishes. |
| Machine structure | Heavy-duty cast iron base; reinforced linear guideways | Absorbs cutting forces (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 (Z.B., gekrümmte Kanten, multi-sided features) in one setup. |
| Tool turret | 8–12 station turret; quick tool changes (0.3–0.8 seconds) | Enables “done-in-one” processing (drehen, Mahlen, Bohren) without repositioning POM—reduces heat accumulation from repeated clamping. |
| Spindelgeschwindigkeit | Adjustable range: 2,000–8,000 rpm; low runout (≤ 0,001 mm) | Controlled rotation prevents POM from melting (high speeds >6,000 rpm cause heat buildup) or chipping (low speeds lead to uneven cuts). |
| Machine programming | CNC system (Z.B., 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 Schneidenparameter 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 Härte and low thermal conductivity—can lead to ruined samples (Z.B., burned surfaces from excessive heat or dull tools from abrasion).
Critical POM Properties & Machining Implications
| Eigentum | Spezifikation | Machining Precaution |
| Mechanische Stärke | Zugfestigkeit: 60–70 MPa; Schlagkraft: 5–10 kJ/m² (unnotched) | Moderate impact strength means POM can handle standard cutting forces but avoid sudden tool plunges (causes cracking). |
| Härte | Rockwell M (RM) 80–90; Shore D 78–85 | Abrasive to tools—use wear-resistant cutting materials (Z.B., Carbid) to avoid frequent tool changes. |
| Resistenz tragen | Coefficient of friction: 0.15–0,3 (trocken); better than most plastics | Low friction means POM chips slide easily—use chip conveyors to prevent buildup (buildup causes surface scratches). |
| Chemischer Widerstand | Widersteht den Ölen, Lösungsmittel, and weak acids; attacked by strong alkalis and phenols | Verwenden Sie wasserlösliches Kühlmittel (avoid oil-based coolants that leave residues on POM’s surface). |
| Thermal properties | Schmelzpunkt: 165–175°C; Wärmeleitfähigkeit: 0.23–0.3 W/(m · k) (niedrig) | Heat dissipates slowly—keep cutting temperature <150° C (use high coolant flow) to avoid melting or crystallization. |
| Verarbeitbarkeit | Gut (low chip adhesion); produces continuous, stringy chips | Use tools with chip breakers to avoid long chip tangles (tangles scratch POM’s surface). |
Frage: Why do my POM samples have a burned, brownish surface?
Antwort: Burn marks come from excessive heat (POM’s low thermal conductivity traps heat at the cutting zone). Fix it by: 1) Reducing spindle speed by 1,000 Drehzahl; 2) Increasing coolant flow rate to 25–30 L/min; 3) Using a tool with a larger rake angle (Reduziert die Reibung).
3. Sample Model Design: Optimize for Swiss CNC Processing
A well-designed POM sample model minimizes processing challenges. Focus on simplicity, Hersteller, and alignment with Swiss CNC machine capabilities—avoid features that force the machine to make risky cuts (Z.B., tief, narrow slots that trap heat).
Design Guidelines for POM Samples
| Designaspekt | Empfehlungen | Warum ist es wichtig |
| CAD -Software | Use SolidWorks, Fusion 360, or AutoCAD for 3D Modellierung. Include clear design specifications (Z.B., Lochdurchmesser: 6± 0,02 mm). | Enables accurate Maschinenprogrammierung—the CNC system “knows” exactly what to cut, Fehler reduzieren. |
| Dimensionsgenauigkeit | Set target accuracy based on use: ±0.02–±0.05 mm (functional samples); ±0.01–±0.02 mm (critical features like mounting holes). | Overly tight accuracy (± 0,005 mm) increases processing time by 30%+ without adding value for most POM applications. |
| Toleranzen | Folgen Sie ISO 286-1: Use H7/g6 for sliding fits (common in POM gears) and H8/f7 for loose fits (Z.B., housing components). | Ensures the sample fits with other parts (Z.B., a POM gear that meshes with a metal shaft) Während des Tests. |
| Feature complexity | Avoid deep features (Tiefe >3x width) or sharp internal corners (Radius <0.5 mm). Verwenden Sie allmähliche Übergänge (Verjüngung) für Dickenwechsel. | Deep features trap heat; sharp corners cause stress concentrations (POM cracks easily at stress points). |
| Model geometry | Für zylindrische Teile (Z.B., POM shafts), keep length-to-diameter ratio <10:1 (verhindert eine Durchbiegung). Für flache Teile, 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. |
Fallstudie: A client designed a POM valve core with a 2 mm breit, 8 mm deep slot (Seitenverhältnis 4:1). Der erste 10 samples had burned surfaces and cracks. By widening the slot to 3 mm (Seitenverhältnis 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. Verarbeitungstechniken: Step-by-Step POM Machining
Swiss CNC processing for POM follows a “precision-first” workflow—prioritizing sharp tools, controlled speeds, and efficient heat management. Below is the step-by-step process, with key techniques for each operation to avoid common defects.
Step-by-Step Processing Workflow
- Materialvorbereitung:
- Cut POM bar stock to length (add 5–10% machining allowance: Z.B., 100 mm final length → 105–110 mm bar).
- Store POM in a dry environment (Luftfeuchtigkeit <60%)—POM absorbs minimal moisture, but dampness causes surface blemishes.
- Maschinenaufbau:
- Installieren Schneidwerkzeuge: Carbide turning inserts (grade K10-K20) zum Drehen; TiAlN-coated carbide end mills (2–3 flute) for milling; Carbide Drills (135° point angle) for drilling.
- Calibrate axes via Maschinenprogrammierung: Input tool lengths, Radien, and sample dimensions into the CNC system. Führen Sie einen trockenen Test durch (no cutting) to verify toolpaths.
- Turning Operations:
- Rough turning: Überschüssiges Material entfernen (Spindelgeschwindigkeit: 3,000–4,000 rpm; Futterrate: 0.015–0.025 mm/rev; Tiefe des Schnitts: 0.5–1,0 mm). Use high-pressure coolant (25–30 L/min) to dissipate heat.
- Finish turning: Endgültige Dimensionen erreichen (Spindelgeschwindigkeit: 4,000–5,000 rpm; Futterrate: 0.005–0.015 mm/rev; Tiefe des Schnitts: 0.1–0,3 mm). Use a sharp tool with a positive rake angle (10–15°) für glatte Oberflächen.
- Milling/Drilling (bei Bedarf):
- Mahlen: For slots or flats (Spindelgeschwindigkeit: 3,500–4,500 rpm; Futterrate: 0.01–0.02 mm/rev; Tiefe des Schnitts: 0.3–0.6 mm). Verwenden Sie das Aufstiegsfräsen (tool rotates with the workpiece) Reibung reduzieren.
- Bohren: For holes (Spindelgeschwindigkeit: 2,500–3,500 rpm; Futterrate: 0.01–0.015 mm/rev). Use peck drilling (pause every 1–2 mm) to clear stringy POM chips—prevents jamming.
- Threading (bei Bedarf):
- Use single-point carbide threading tools (60° thread angle). Cut threads in 3–4 passes (Tiefe pro Durchgang: 0.1–0.15 mm; Spindelgeschwindigkeit: 2,000–2,500 rpm). Avoid coolant during threading (prevents thread distortion).
- Oberflächenbeschaffung:
- 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 Drehzahl). Avoid high-speed polishing (causes heat damage).
Key Technique Tips
- Chipkontrolle: POM produces long, stringy chips—use tools with chip breakers or adjust feed rate (increase by 0.005 mm/U) to break chips into 2–3 cm pieces.
- Tool wear monitoring: Check tools every 20–30 samples. Dull tools (visible rounded edges) 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. Qualitätskontrolle und Inspektion: Ensure POM Sample Reliability
POM samples often serve critical roles (Z.B., Getriebe, Buchsen, or medical device components), so strict quality control is essential. Inspect for dimensional accuracy, Oberflächenqualität, and functional performance to ensure the sample meets design goals.
Inspection Checklist & Methoden
| Inspection Aspect | Standards | Werkzeuge/Methoden |
| Dimensionalprüfungen | Meet design specifications: Z.B., outer diameter ±0.02 mm; hole position ±0.03 mm. | Mikrometer (Genauigkeit ±0,001 mm) für kleine Durchmesser; Bremssättel (digital, ± 0,002 mm) for lengths; Koordinatenmessmaschine (CMM) Für komplexe Geometrien. |
| Oberflächenfehler | No burns, Kratzer, or chips. Oberflächenrauheit: RA 0,4-1,6 μm (funktional); Ra ≤ 0,4 μm (ästhetisch). | Surface roughness meter; visual inspection under natural light (hold sample at 45° angle). |
| Tolerance verification | Halten Sie sich an ISO 286-1 Toleranzen: Z.B., H7 hole (Durchmesser 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 (Z.B., Getriebe): Pass 10,000-cycle wear test (no excessive wear). Für strukturelle Teile: Withstand 1.5x design load (Kein Knacken). | Wear tester; universal testing machine (for tensile/compression tests). |
| Quality standards | Folgen Sie ISO 9001 (Allgemeine Qualität) and specific industry standards (Z.B., ISO 10993 for medical POM parts). | Document inspection results (Datum, inspector, Messungen) for traceability. |
Für die Spitze: Für die Serienproduktion (10+ POM samples), use statistical sampling—inspect 20% of the batch for dimensional accuracy and 100% für Oberflächenfehler (fast to check visually). This balances thoroughness and efficiency.
Yigu Technology’s View
Bei Yigu Technology, 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.
FAQs
- Q: Can Swiss CNC machines process thin-walled POM samples (Z.B., 0.5 mm thick tubes)?
A: Ja! 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?
A: Wasserlösliches Kühlmittel (5–10% mineral oil + Wasser) ist ideal. It cools effectively (critical for POM’s low thermal conductivity) and doesn’t leave residues that affect POM’s surface or Resistenz tragen. Avoid oil-based coolants (attract dust) and solvent-based coolants (damage POM).
- Q: Why do my POM samples crack during drilling?
A: Cracking often comes from excessive feed rate or dull drills. Fix it by: 1) Using a sharp carbide drill (135° point angle); 2) Reducing feed rate to 0.008–0.01 mm/rev; 3) Using peck drilling (pause every 1 mm) to relieve stress—this prevents POM from cracking under pressure.