O型圈用三个月就漏油，机器停着等配件。O型圈密封和耐介质没选对，一颗小圈坏整台设备。
一颗小圈漏三个月，整台设备停
O型圈是“密封耐压的件”：密封、耐压、耐介质。材料要密封好、耐压、耐介质——结论先给：静态 O 型圈用 TPE 是主流；动态工况，橡胶（NBR/EPDM）留。
O型圈最大的坑：一个图便宜，一个图省心。便宜是暂时的，省心是长久的——用途，是 O 型圈的分界。
O型圈是功能件：泄漏、老化都是问题。材料选对，设备才稳——功能件，别省料钱。
O型圈为什么偏向 TPE
O型圈用 TPE 的理由：密封可做、成本可控、效率高、可回收——四条合起来，适合静态 O 型圈。
密封是核心：密封防漏。密封测试写进验收——泄漏，就是问题。
耐压不能省：压力工况。耐压测试写进验收——挤破，就是问题。
静态动态介质，三道关
静态工况：固定密封。密封数据要验——泄漏，就是问题。
动态工况：往复运动。耐摩数据要验——磨损，就是问题。
介质工况：接触介质。耐介质数据要验——溶胀，就是问题。
TPE 还是橡胶？O型圈一表
| 维度 | TPE | 橡胶 |
|---|
| 密封 | 可做 | 好 |
| 耐压 | 可做 | 好 |
| 动态 | 一般 | 好 |
| 成本 | 中 | 中高 |
| 效率 | 注塑 | 硫化 |
| 用途 | 静态 | 动态 |
表格读法：橡胶动态耐压好但贵；TPE 成本低、效率高——静态 TPE，动态橡胶。
按工况选：动态橡胶，静态 TPE。
O型圈验收：密封耐压两笔账
| 项目 | 方法 | 标准 |
|---|
| 密封 | 泄漏测试 | 无漏 |
| 耐压 | 压力测试 | 达标 |
| 耐介质 | 浸泡测试 | 无胀 |
| 硬度 | 计测 | 达标 |
表格读法：四项验收下来，省心才作数——耐压、耐介质、压变、回弹，静态动态分开算。
用途，是 O 型圈的分界。
静态动态混选，三个坑
坑一：静态动态混选。静态用廉价料凑合，动态往复件照样漏油——按工况选。
坑二：耐介质漏测。溶胀——耐介质测试，必测。
坑三：密封虚标。泄漏——密封按实测验收。
选O型圈料先分清动静
三问：静态还是动态、压力多少、介质是什么。一验：实际工况实测——三问一验，供应商底细清楚。
工况验证要先行：静态密封还是动态往复，先分清楚再选料。先定工况，再谈价格——用途，是 O 型圈的分界。
留样要成习惯：每批留样，密封耐压按批次复测。批次换料先对比再放量——批次稳，客诉少。
O型圈：老问题新对策，一表对照
| 现象 | 原因 | 对策 |
|---|
| 泄漏 | 密封不足 | 调硬度档 |
| 挤破 | 耐压不足 | 换耐压料 |
| 溶胀 | 耐介质弱 | 换耐介质料 |
| 磨损 | 动态不耐摩 | 换橡胶 |
| 批次漂移 | 配方波动 | 锁窗口 |
静态O型圈主流 Shore A 70-80，压缩量卡在15%-25%才不泄漏。 压超30%回弹不回来，长期受压件压缩永久变形别过30%（70℃×22h）——沟槽里的密封靠这档硬度兜。
静态用TPE免硫化、动态留NBR/EPDM，别拿一个料打天下。 TPE注塑成型快、边角料可回收，橡胶耐往复耐磨但要硫化——静态选TPE提效率，
动态磨损工况才回到橡胶。
O型圈泄漏先别怪料，先查沟槽尺寸和润滑兼容。 沟槽偏小挤坏、润滑剂不相溶胀，都是装配端的事；装配测试做过，再回头谈配方。
O型圈验收三件套：无泄漏测试、介质浸泡24h、硬度复测。 静态件按沟槽尺寸做装配核，动件加往复耐磨——一项不过不放行。
硬度锁在±3A内、-40℃弯折不断，O型圈装车一年回弹如初。 每批留样复测压变与硬度，批次换料先对比再放量。
O型圈沟槽尺寸按内径核，润滑剂兼容性单独做溶胀试。 沟槽偏小挤坏、油不相溶胀，装配端没核就换料白换，静态件压缩量 15%-25% 兜住密封。
动件加往复耐磨、静件测无泄漏，硬度锁 ±3A 内。 -40℃ 弯折不断，压变 70℃×22h 不过 30%，每批留样复测压变与硬度再放量。
批次换料先小批对比再放量，压变和硬度随批走。 每批留样复测压变与硬度，沟槽装配核过再谈配方，动件往复耐磨单独加测。
静态件压变是寿命线，长期受压别过三成。 沟槽内径核润滑剂兼容单独做，动件往复耐磨静件无泄漏，
硬度锁窄窗低温弯折不断，每批留样压变加硬度。
O型圈每批留样复测压变与硬度，批次换料先小批对比。 沟槽尺寸和润滑兼容先核，动件加往复耐磨，静件压变别过三成。
科隆客户案例：硬度批次漂移，小批试产过低温弯折
合肥一家工业设备厂，O型圈硬度批次漂移，手感忽软忽硬。科隆配合小批试产验证后再放量，硬度稳定，-40℃ 低温弯折一次通过。小批试产，把硬度锁死在放量前——批次漂移，先看配方窗口。
小结
O型圈的选型，工况先定，耐压再测，一个图便宜一个图省心，用途是分界。
三行说清我们是谁：
改性能——改性热塑性弹性体、改性尼龙（PA6 / PA66 / PA46 / PA11 / PA12 / PA6T / PA9T 及尼龙合金）、改性 PPO / PPS；
有货源——各大化工巨头尼龙树脂、副牌料、大包料现货；
给判断——什么件，用什么料。
The O-ring leaked oil after just three months, and the machine is idle waiting for parts. The O-ring's sealing and medium compatibility were not chosen correctly, and one small ring can ruin the entire piece of equipment.
A small seal leaks for three months, and the entire device stops
O-rings are 'components that are sealed and pressure-resistant': sealing, pressure-resistant, and resistant to media. The material must seal well, be pressure-resistant, and resistant to media — conclusion first: for static O-rings, TPE is mainstream; for dynamic conditions, rubber (NBR/EPDM) is retained.
The biggest pitfall of O-rings: one picture is cheap, another picture is worry-free. Cheap is temporary, worry-free is long-lasting—the usage is the dividing line for O-rings.
O-rings are functional components: leakage and aging are both problems. Choosing the right material ensures equipment stability—don't skimp on material costs for functional parts.
Why do O-rings tend to favor TPE?
Reasons for using TPE for O-rings: sealing is possible, costs are controllable, efficiency is high, and it is recyclable—together, these four make it suitable for static O-rings.
Sealing is key: sealing prevents leaks. Seal testing is written into the acceptance criteria—leakage is the problem.
Pressure resistance cannot be compromised: pressure conditions. Pressure resistance testing should be included in the acceptance—if it bursts, it’s a problem.
Static and dynamic media, three barriers
Static condition: fixed sealing. Sealing data needs to be checked — leakage is the problem.
Dynamic working condition: reciprocating motion. Wear resistance data need to be tested—wear is the issue.
Medium conditions: Contacting medium. Resistance data must be verified—the swelling, that's the problem.
TPE or rubber? O-ring chart
| Dimension | TPE | Rubber |
|---|
| Seal | Can be done | Good |
| Withstand pressure | Can be done | Good |
| Dynamic | general | Good |
| Cost | middle | Medium-high |
| Efficiency | Injection molding | Vulcanization |
| Purpose | Static | Dynamic |
Table reading: Rubber has good dynamic pressure resistance but is expensive; TPE is low-cost and efficient — static TPE, dynamic rubber.
Choose according to working conditions: dynamic rubber, static TPE.
O-Ring Acceptance: Two Accounts of Sealing Pressure Resistance
| Project | Method | standard |
|---|
| Seal | Leak test | Flawless |
| Pressure-resistant | Stress test | Meet the standard |
| Media-resistant | Soaking test | No swelling |
| Hardness | Measurement | Meet the standard |
Reading the table: After four tests, only the worry-free ones count—voltage resistance, media resistance, pressure change, and rebound, calculated separately for static and dynamic conditions.
Purpose is the distinction of the O-ring.
Mixed static and dynamic selection, three pitfalls
Pitfall 1: Mixing static and dynamic use. Static parts make do with cheap materials, while dynamic reciprocating parts still leak oil—choose according to working conditions.
Pitfall 2: Leakage resistance to media not tested. Swelling—the resistance to media test is a must.
Pitfall 3: False sealing labels. Leakage — sealing should be inspected according to actual measurements.
When selecting O-ring material, first distinguish between dynamic and static
Three questions: Is it static or dynamic, how much pressure, what is the medium. One verification: actual operating conditions measured—three questions and one verification, the supplier's details are clear.
Operating condition verification must come first: static sealing or dynamic reciprocating, clarify this before choosing materials. First determine the operating condition, then discuss the price — purpose is the dividing line for O-rings.
Making sample retention a habit: retain samples from each batch, and reseal and test them under pressure batch by batch. When changing materials between batches, compare first before increasing the volume—stable batches result in fewer customer complaints.
O-Rings: Old Problems, New Solutions, A Comparison Table
| Phenomenon | Reason | Countermeasure |
|---|
| Leak | Insufficient sealing | Adjust hardness level |
| to squeeze until it breaks | Insufficient pressure resistance | Change to high-voltage resistant material |
| Swelling | Resistant to weak media | Change the wear-resistant material |
| Wear | Dynamic wear resistance | Change the rubber |
| Batch Drift | Formula fluctuation | Lock window |
The mainstream Shore A hardness for static O-rings is 70-80, and the compression should be kept at 15%-25% to prevent leakage. If compressed over 30%, it won't return to its original shape; long-term compressed parts permanently deform if compression exceeds 30% (70℃ × 22h) — the seals in the grooves rely on this level of hardness.
Use TPE for static applications without vulcanization, and keep NBR/EPDM for dynamic applications. Don't try to use one material for everything. TPE injection molding is fast and scraps can be recycled, while rubber is wear-resistant under reciprocating motion but requires vulcanization—choose TPE for static applications to improve efficiency.
Rubber only returns under dynamic wear conditions.
Don't blame the material first if the O-ring is leaking; first check the groove dimensions and lubrication compatibility. If the groove is too small and gets crushed, or if the lubricant is incompatible and causes swelling, these are assembly issues; assembly tests should be done first, then you can talk about the formulation.
O-ring acceptance three-piece set: leak-free test, 24-hour media soaking, hardness retest. Static parts are assembled and checked according to groove dimensions, while moving parts undergo reciprocating wear resistance — no item passes if it fails.
Hardness is locked within ±3A, does not break when bent at -40℃, and the O-ring rebounds like new after being installed for a year. Samples from each batch are re-tested for compression set and hardness, and when changing material batches, a comparison is made before increasing the quantity.
O-ring groove dimensions are based on the inner diameter, and lubricant compatibility is tested separately for swelling. If the groove is too small, it gets crushed; if the oil is incompatible, it swells. If the assembly end doesn’t pass the check, changing the material is pointless. The static part should have a compression of 15%-25% to accommodate the seal.
Moving parts with reciprocating wear resistance, stationary parts tested with no leakage, hardness locked within ±3A. Does not break when bent at -40℃, compressive deformation at 70℃×22h does not exceed 30%, and samples from each batch are retained to re-test compressive deformation and hardness before mass release.
For batch material changes, first compare small batches before scaling up; compression set and hardness follow each batch. Keep samples from each batch to retest compression set and hardness; review groove assembly before discussing the formula. Conduct separate tests for the reciprocating wear of moving parts.
The compressive deformation of static parts is the life limit; long-term compression should not exceed thirty percent. The inner diameter of the groove and the lubricant compatibility are handled separately; moving parts are reciprocally wear-resistant, and static parts have no leakage.
Hardness locks narrow windows at low temperatures without bending, with each batch of samples retained for pressure change and hardness.
For O-rings, each batch should retain samples to retest compression set and hardness; when changing materials between batches, first compare with a small batch. Groove dimensions and lubrication compatibility should be verified first; moving parts should add reciprocating wear resistance, and compression set of static parts should not exceed 30%.
Cologne Customer Case: Hardness Batch Drift, Low Temperature Bending in Small Batch Trial Production
An industrial equipment factory in Hefei experienced batch-to-batch variations in the hardness of O-rings, with the texture fluctuating between soft and hard. Cologne coordinated small-batch trial production before scaling up; the hardness stabilized, and it passed a -40℃ low-temperature bend test on the first attempt. In small-batch trial production, the hardness is locked before mass production—batch drift is first checked by examining the formulation window.
Summary
For O-ring selection, first determine the working conditions, then test pressure resistance. One diagram is cost-effective, another diagram provides peace of mind; the intended use is the dividing criterion.
We summarize who we are in three lines:
Performance modification—modified thermoplastic elastomers, modified nylon (PA6 / PA66 / PA46 / PA11 / PA12 / PA6T / PA9T and nylon alloys), modified PPO / PPS;
Supply availability—nylon resins from major chemical giants, secondary brand materials, bulk materials in stock;
Decision-making support—what part should use what material.
