用半年转角就裂，胰岛素笔成了一次性。笔外壳开裂别怪摔，转角应力没算进。
结论先摆：胰岛素笔，包胶开裂绑一起
胰岛素笔外壳是“天天揣兜”的件：包胶、耐候、耐摔。材料要包胶牢、耐候好、耐摔——结论先给：胰岛素笔外壳用 SEBS 基 TPE 包胶是主流；要求高的，TPU 复合优先。
胰岛素笔外壳最大的坑：开裂的账，多半埋在选型期。开裂是使用期的问题，根子在选型期——选型期，是开裂的源头。
胰岛素笔外壳是功能件：开裂、脱层都是问题。材料选对，笔才耐用——功能件，别省料钱。
TPE凭啥不裂：包胶可做，耐候可加
胰岛素笔外壳用 TPE 的理由：包胶可做、耐候可做、耐摔可做、效率高——四条合起来，适合笔外壳。
包胶是核心：外壳包胶。剥离强度测试写进验收——脱层，就是问题。
耐候不能省：天天揣兜。耐候测试（按年限）写进验收——开裂，就是问题。
揣一年摔它：体温、冬夏温差、摔碰
揣兜工况：天天揣兜。耐候数据要验——老化，就是问题。
温差工况：冬夏温差。耐温数据要验——开裂，就是问题。
摔碰工况：日常摔碰。耐冲击数据要验——开裂，就是问题。
TPE还是ABS：笔壳上看裂不裂
| 维度 | TPE | ABS |
|---|
| 包胶 | 成熟 | 需处理 |
| 耐候 | 可做 | 一般 |
| 耐摔 | 好 | 脆 |
| 手感 | 软糯 | 硬 |
| 成本 | 中 | 低 |
| 用途 | 包胶层 | 骨架 |
表格读法：ABS 便宜但脆、手感硬；TPE 包胶耐摔——笔外壳，ABS 骨架加 TPE 包胶是主流。
骨架 ABS，包胶 TPE——组合最优。
开裂排查表：转角应力先算
| 时间 | 位置 | 原因 | 对策 |
|---|
| 使用前 | 表面 | 模痕 | 抛光 |
| 3 个月 | 转角 | 应力集中 | 圆角设计 |
| 6 个月 | 包胶界 | 剥离 | 增强粘合 |
| 1 年 | 全件 | 老化 | 换耐候料 |
表格读法：开裂件按时间轴排——装配、使用、老化，根子多半落在选型那天。
选型期，是开裂的源头。
两个坑：开裂怪使用、耐候造假
坑一：开裂怪使用。用半年开裂就怪人不当，其实选型韧性早不够——选型期排查。
坑二：耐候虚标。报告写耐候，实际开裂——耐候按实测验收。
坑三：包胶漏测。脱层——剥离强度测试，必测。
验收三问：装配应力、色差、批次
三问：耐候按多少年、剥离强度多少、包胶配方给不给。一验：实际摔碰实测——三问一验，供应商底细清楚。
选型验证要先行：先把装配应力和低温韧性算进去，再谈价格——选型期，是开裂的源头。
留样要成习惯：每批留样，包胶耐候按批次复测。批次换料先对比再放量——批次稳，客诉少。
胰岛素笔随身携带，跌落测试必做——外壳和包胶层不能开裂脱层。Shore A 70-80 硬弹有支撑，太软摔一下变形。笔外壳选型，跌落和硬度一起验。
笔外壳用半年转角开裂——装配应力集中在转角和卡扣，材料韧性不够。结构设计图给供应商，让材料配合结构优化。
转角开裂的账，选型期就要算进去。
开裂先别怪加工——外壳转角、卡扣、装配应力都是隐患。先查结构设计，再查材料韧性，最后查工艺。开裂根在应力设计，不在调机台。
做装配应力测试，配合结构优化把开裂风险提前消掉。批内色差和尺寸波动多测几个样件，一致性好的批才放行。
装配测试过了，开裂风险才消。
胰岛素笔揣兜里体温加热，冬天出门温差大——按实际温度环境做测试，别拿常温数据应付。接触酒精消毒和汗液，化学兼容性一并验。
按真实使用环境验，数据才有用。
胰岛素笔外壳常见问题与对策表
| 现象 | 原因 | 对策 |
|---|
| 开裂 | 选型期埋根 | 查选型 |
| 脱层 | 粘合不足 | 调参数 |
| 色差 | 色粉漂移 | 小批试产 |
| 老化 | 耐候不足 | 换耐候料 |
| 摔裂 | 耐冲击弱 | 换耐摔料 |
胰岛素笔外壳包胶按 Shore A 60-70 选，反复按压 5000 次不裂。 笔身小批量注塑，包胶厚度 1.5-2.0mm，薄了手感硬、厚了套不进——厚度窗口和硬度一起锁。
胰岛素笔包胶耐汗按汗液浸泡 24h 后不发粘验收。 患者天天揣兜里，手汗渗透后表面发粘就是客诉——耐汗配方和表面耐磨一起验。
科隆客户案例：批次色差被投诉，小批试产7天交付
西安一家医疗器械厂，胰岛素笔外壳批次色差明显，成品频繁被投诉。科隆配合小批试产验证后再放量，色差稳定，交付周期压缩到 7 天内。小批试产，把色差锁死在放量前——批次问题，试产阶段就该暴露。
小结
胰岛素笔外壳的选型，选型期先查，耐候再测，开裂的账多半埋在选型期，别怪使用。
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。
It cracks after half a year of turning, turning the insulin pen into a disposable one. Don't blame drops if the pen casing cracks; the corner stress wasn't taken into account.
Conclusion first: insulin pens, coated with rubber, crack and stick together
The insulin pen casing is an item that is 'carried in the pocket every day': it needs to be coated, weather-resistant, and drop-resistant. The material should have solid coating, good weather resistance, and drop resistance — conclusion first: the mainstream for insulin pen casings is SEBS-based TPE coating; for higher requirements, TPU composites are preferred.
The biggest pitfall of insulin pen casings: the account of cracking is mostly buried in the selection period. Cracking is a problem during the usage period, but its root lies in the selection period—the selection period is the source of cracking.
The insulin pen casing is a functional component: cracking and delamination are problems. Choosing the right material makes the pen durable—it's a functional part, don't skimp on material costs.
Why wouldn't TPE crack: it can be overmolded, and weather resistance can be enhanced
Reasons for using TPE for insulin pen shells: it can be overmolded, weather-resistant, drop-resistant, and efficient—these four combined make it suitable for pen shells.
Encapsulation is key: the casing is encapsulated. Write the peel strength test into the acceptance criteria — delamination is the problem.
Weather resistance cannot be skipped: carry it in your pocket every day. Weather resistance testing (according to the years) should be written into the acceptance—cracking means there is a problem.
Keep it for a year and shake it: body temperature, differences between winter and summer, bumps
Pocket condition: Always carried in the pocket. Weathering data needs to be verified—aging is the problem.
Temperature difference conditions: temperature differences between winter and summer. Temperature resistance data must be tested—cracking is a problem.
Drop and collision conditions: Daily drops and collisions. Impact resistance data must be tested—cracking is a problem.
TPE or ABS: Check the pen casing for cracks
| Dimension | TPE | ABS |
|---|
| Encapsulation | Mature | Needs to be handled |
| weather-resistant | Can do | general |
| Drop-resistant | Good | Crispy |
| hand feel | soft and glutinous | hard |
| Cost | middle | Low |
| Purpose | Coating layer | Skeleton |
Table reading: ABS is cheap but brittle and hard to the touch; TPE coating is impact-resistant — for pen bodies, an ABS framework with TPE coating is mainstream.
Frame ABS, coated with TPE — the optimal combination.
Crack Inspection Checklist: Calculate Corner Stress First
| Time | Position | Reason | Countermeasure |
|---|
| Before use | surface | Mold mark | Polishing |
| 3 months | Corner | Stress concentration | Rounded corner design |
| 6 months | Rubber Coating Industry | Peel off | Enhance adhesion |
| 1 year | All items | Aging | Replace with weather-resistant material |
Table reading: Cracked parts are arranged along a timeline—assembly, use, aging, with the root cause mostly traced back to the day of selection.
The selection period is the source of cracking.
Two pitfalls: use by cracking monsters, weather resistance forgery
Pitfall 1: Using the cracking monster. People blame others for cracks after half a year, but in fact, the toughness was insufficient during the selection phase — check during the selection period.
Pitfall 2: Mislabeling as weather-resistant. The report claims weather resistance, but it actually cracks — weather resistance should be accepted based on actual tests.
Pitfall three: Incomplete testing of coated rubber. Delamination—peel strength testing is necessary.
Three Acceptance Questions: Assembly Stress, Color Difference, Batch
Three questions: How many years is it weather-resistant, what is the peel strength, and will the overmolding formula be provided? One test: Actual drop test measured——with three questions and one test, the supplier's details are clear.
Selection verification must come first: first consider assembly stress and low-temperature toughness, then discuss the price—during the selection phase is the source of cracking.
Making sample retention a habit: retain samples for each batch, and re-test the coated weather-resistant products batch by batch. When changing materials between batches, compare first before increasing production — stable batches result in fewer customer complaints.
Insulin pens are carried around, so drop tests must be done—the casing and coating layer must not crack or delaminate. Shore A 70-80 hardness provides support; if too soft, it deforms when dropped. When selecting the pen casing, both drop impact and hardness should be tested together.
The pen casing cracks at the corners after six months — assembly stress is concentrated at the corners and clips, and the material lacks toughness. Provide the structural design drawings to the supplier so that the material can be optimized according to the structure.
The accounts that crack at the corners should be calculated during the selection period.
Don't blame the processing for cracking first—shell corners, clips, and assembly stress are all hidden risks. First check the structural design, then check the material toughness, and finally check the process. The root of cracking lies in stress design, not in adjusting the machine.
Conduct assembly stress tests and, in conjunction with structural optimization, eliminate cracking risks in advance. Measure several samples when there is significant color difference or dimensional variation within a batch; only batches with good consistency are released.
The assembly test passed, and only then is the risk of cracking eliminated.
Keep the insulin pen in your pocket to warm it with body temperature; winter outings have large temperature differences — test according to the actual temperature environment, don’t just rely on room temperature data. Also check chemical compatibility with alcohol disinfection and sweat exposure.
Data is only useful when tested in real usage environments.
Common Problems and Countermeasures Table for Insulin Pen Casings
| Phenomenon | Reason | Countermeasure |
|---|
| Cracking | Taking root during the selection phase | Check model selection |
| Delamination | Insufficient adhesion | Adjust parameters |
| Color difference | Color powder drift | Small batch trial production |
| Aging | Insufficient weather resistance | Replace with weather-resistant material |
| cracked from a fall | Weak impact resistance | Change to more durable material |
The insulin pen outer shell should be coated with a material selected at Shore A 60-70, able to withstand 5,000 repeated presses without cracking. The pen body is injection-molded in small batches, with a coating thickness of 1.5-2.0 mm; if it's too thin, it feels hard, if too thick, it won't fit—the thickness window and hardness are locked together.
The insulin pen with rubber coating resists sweat and does not become sticky after being soaked in sweat for 24 hours. Patients carry it in their pockets every day, and if the surface becomes sticky after sweat penetration, it counts as a complaint — the sweat-resistant formula and surface wear resistance are tested together.
Cologne Customer Case: Batch Color Difference Complained, Small Batch Trial Production Delivered in 7 Days
A medical device factory in Xi'an had noticeable color differences in batches of insulin pen casings, and the finished products were frequently complained about. After Cologne cooperated with small-batch trial production verification before mass production, the color difference stabilized, and the delivery cycle was shortened to within 7 days. Small-batch trial production locks in the color difference before mass production—the batch problem should be exposed during the trial production phase.
Summary
For the selection of insulin pen casings, check during the selection period first, then test for weather resistance. Most of the cracking issues are buried in the selection period, don’t blame the usage.
Three lines to clarify who we are:
Performance modification—modified thermoplastic elastomers, modified nylon (PA6 / PA66 / PA46 / PA11 / PA12 / PA6T / PA9T and nylon alloys), modified PPO / PPS;
Supply available—nylon resin from major chemical giants, secondary brand materials, large package materials in stock;
Provide judgment—what part, what material to use.
