ナイロン対POM（アセタール）：エンジニアリングプラスチック比較ガイド

エンジニアリング用途におけるナイロンとPOM（アセタール／デルリン）の直接比較 - 機械的、熱的、化学的、摩耗、加工の違い。.

ナイロン対POM：エンジニアリング・プラスチックの2つの巨人

ナイロン（ポリアミド）とPOM（ポリオキシメチレン、アセタールまたはデルリンとも呼ばれる）は、機械部品に最も使用されている2つのエンジニアリング熱可塑性プラスチックです。どちらも優れた耐摩耗性、低摩擦性、優れた寸法安定性を備えていますが、分子構造が異なるため、精密用途では性能のトレードオフが非常に重要になります。.

ナイロンとPOMのどちらを選ぶかは些細なことではない。POMでは50,000サイクルもつベアリングが、ナイロンでは同じ負荷で8,000サイクルで破損することもある。逆に、自動車用流体にさらされるギヤ・ハウジングは、POMではひび割れますが、PA66では生き残ります。このガイドは、エンジニアが正しい選択をするために必要な、データに基づいた比較を提供します。.

機械的特性の比較

Tensile and Flexural Properties:

Key Insight: Creep Resistance — POM has significantly better creep resistance than nylon. Under sustained loading, POM retains more of its stiffness over time. For components under constant load (spring clips, retaining rings, fastener bushings), POM’s superior creep resistance often makes it the better choice despite similar initial strength.

耐衝撃性 — Nylon has higher unnotched impact resistance. But POM often outperforms nylon in notched impact tests because POM’s ductile failure mode absorbs more energy at the crack tip. For parts with stress concentrations (keyways, holes, threads), POM’s toughness at sharp notches is an advantage.

Fatigue Resistance — Nylon has superior fatigue resistance for repeated loading. In cyclic loading tests, nylon components survive 3-5× more cycles before failure than equivalent POM parts. Critical for components like conveyor belt guides, pump impellers, and hinge mechanisms.

熱性能と環境性能

Thermal Properties:

POM’s thermal weakness — The 175°C melting point of POM is its thermal limitation. At temperatures above 100°C, POM loses mechanical strength rapidly. PA66-GF30 (HDT 250°C) operates at temperatures where POM would melt.

Moisture Absorption Comparison:

POM wins decisively on moisture — At 0.8% maximum moisture absorption, POM is essentially dimensionally stable in humid environments. Nylon’s 8-9% absorption causes measurable swelling and property changes. For underwater or outdoor exposed applications without encapsulation, POM is often the only viable choice.

耐薬品性：各素材の優れた点

Chemical Resistance Comparison:

Critical Decision Points: – Brake fluid or glycol coolants: POM swells and cracks — use PA66 or PA12 – Hot water (>60°C): Nylon hydrolyzes — use POM or PVDF – Plasticizer migration (flexible cables, wire insulation): POM absorbs plasticizers — use PA12 – Automotive under-hood: PA66-GF30 for its heat resistance (180°C+) and fluid resistance – Consumer appliances: POM for its dimensional stability and surface finish

摩耗と摩擦性能

どちらの素材も低摩擦で耐摩耗性に優れているが、重要な違いがある：

The critical difference: wear factor — POM’s wear factor (1-3) is 10-20× lower than nylon’s (10-40). This means POM parts generate less heat and wear more slowly in sliding contact. For high-PV applications (bearings, wear strips, sliding inserts), POM is the superior choice.

Self-lubricating versions: – POM + PTFE: Wear factor drops to 0.5-1.0 — excellent for boundary lubrication – PA6/66 + PTFE or silicone: Significantly reduces friction, but PTFE can migrate to surface and affect bonding – Carbon fiber reinforced: Improves wear resistance in both materials, especially at elevated temperatures

Surface Speed Consideration: At surface speeds above 1 m/s in dry sliding, both materials generate enough heat to cause thermal softening. For high-speed applications, consider internally lubricated grades or oil-impregnated sintered bronze backings.

選び方決断の枠組み

Choose Nylon (PA66-GF30) when: – Operating temperature exceeds 100°C – Repeated impact or cyclic loading is expected – Exposure to brake fluid, coolants, or plasticizers – You need higher fatigue life in dynamic loading – Cost is the primary driver (PA66 is generally less expensive than POM)

Choose POM when: – Dimensional stability in humid environments is critical – Low friction and low wear factor are priorities (sliding/rotating contact) – Parts will be exposed to hot water or steam – Acetone, esters, or plasticizers are present – You need excellent surface finish and tight tolerances

Hybrid Solution — Metal Replacement: For many metal-replacement applications, the choice is not between nylon and POM, but between them and aluminum. Nylon-GF and POM are both excellent metal substitutes for housings, brackets, and structural components, offering 70-85% weight reduction vs. aluminum with adequate strength. For these applications, PA66-GF30 is the default choice due to its superior thermal and fluid resistance.

よくあるご質問

When is Nylon vs. POM (Acetal): Engineering Plastics Comparison Guide a good option?

Nylon vs. POM (Acetal): Engineering Plastics Comparison Guide is a good option when fast iteration, complex geometry, low tooling cost, or low-volume production is more important than molded-part unit cost.

What should be checked before choosing Nylon vs. POM (Acetal): Engineering Plastics Comparison Guide?

部品サイズ、材料特性、表面仕上げ、寸法公差、熱暴露、荷重方向、後処理が必要かどうかを確認する。.

How does Nylon vs. POM (Acetal): Engineering Plastics Comparison Guide compare with CNC machining?

3Dプリンティングは複雑な形状を素早く作ることができるが、CNC機械加工は精密な表面、より厳しい公差、生産グレードの材料に強いことが多い。.

What affects the cost of Nylon vs. POM (Acetal): Engineering Plastics Comparison Guide?

コストは、材料、造形量、印刷時間、レイヤーの高さ、サポート除去、仕上げ、検査、造形物の部品数によって異なる。.