新能源汽车的塑料件里，三电系统是增量最大、也最容易选错的一块。
原因不复杂："三电"听起来是一个系统，其实是四个材料世界。
电池包结构件、电机电控壳体、高压电气件、热管理件——四类件的核心指标几乎没有交集。
用一个牌号去打四类件，结果一定是每类都差一口气。
开篇先讲个现场
去年参加一个新势力车企的三电件定点会，一上午听了六个零件的材料方案汇报。有意思的是提问环节：主机厂的材料工程师问得最多的一句话，不是多少钱，而是——这个件的 CTI 是多少、在什么厚度下？六个方案里有两个当时答不上来，会后被要求补测。
那场会让我确认了一个判断：新能源汽车对尼龙的要求，和传统车已经不是一张考卷。传统车问的是耐热和强度，三电问的是电压、温升和寿命。同样的 PA66，在三电件上要同时扛电、扛热、扛冷却液，还要扛十五年不坏。
这篇按三电的物理结构重新分类，把“三电”拆成四类件分别讲：电池包结构件轻量化的账怎么算、电机电控壳体过温升那道关、高压电气件被 CTI 卡住的分水岭、热管理件只看一件事的简单粗暴。
再给五个坑和一条边界。给三电供应链上的读者提个醒：报价前先把这一篇读完，特别是第四节，CTI 那道分水岭每年都让一批供应商在定点会上翻车。
一、先把"三电"拆成四类件
| 件类 | 代表件 | 核心矛盾 | 第一指标 |
|---|
| 电池包结构件 | 端板、侧板、箱体上盖、托盘 | 轻量 + 抗蠕变 + 阻燃 | 弯曲模量 / 阻燃 |
| 电机电控壳体 | 控制器壳体、OBC 外壳、端盖 | 耐温 + 绝缘 + 刚性 | 长期耐温 |
| 高压电气件 | 高压连接器外壳、汇流排支架 | 绝缘 + 耐电痕 | CTI / 阻燃 |
| 热管理件 | 冷却管路、快接头、水泵壳体 | 耐水解 + 低吸水 | 水解后强度保持 |
这张表建议先存下来。 后面所有选料动作，都是在这四行里各自往下走。
还有一条通用原则值得先记住：三电件的选料，先看"这个件会不会进整车法规清单"。
进了法规清单的件（碰撞相关、防火相关、高压安全相关），材料选型要按法规要求倒推，而不是按成本倒推。这一步判断错了，后面所有优化都是白做。
二、电池包结构件：轻量化的主战场
电池包是整车"以塑代钢"最集中的地方。因为电池包本身重，任何减重都能直接换成续航。
主要塑化位置：
电池模组端板：原本是铝板，现在 PA66-GF50 方向做得很成熟- 电池侧板 / 隔板：板状结构件，PA66-GF30 起步- 箱体上盖：大尺寸件，常走阻燃 + 低翘曲方向- 汇流排支架：电气功能件，阻燃 + 绝缘要求高- 电池包托盘：尺寸大、承载高，塑化需谨慎
端板为什么能做到 GF50？
端板是典型的"高刚性 + 抗蠕变"件——它要长期压住模组，不能慢慢变形。GF50 的弯曲模量能到 GF30 的 1.3 倍以上，抗蠕变明显更好。
但 GF50 有三个代价，必须一起认：
冲击韧性掉得厉害，跌落工况要单独验证- 各向异性更明显，长件翘曲难控- 浮纤严重，外观件不合适
所以正确姿势是：端板用 GF50，侧板用 GF30，盖板用低翘曲体系。三类件三个方向，不是全包一样的料。
两个常被忽略的小件
模组压紧件和隔热垫片，不承主结构，但长期处在压力 + 温度循环里。
它们的失效模式很特别：不裂、不断，是慢慢失去预紧力。 所以选料要看的是压缩永久变形和长期蠕变，不是拉伸强度。
很多电池包后期出现异响和松动，源头就是这几个不起眼的件。 它们不出现在碰撞安全清单里，却直接影响整包的一致性。
一句话：电池包减重不是把料换掉，是把每个件的受力搞清楚，然后分别配。
阻燃：电池包的硬门槛
电池包件的阻燃不是"可选项"。要求通常是：
UL94 V0 起步- 无卤体系优先（整车厂的合规趋势）- 长期耐温 105-125℃ 以上
注意一个容易忽略的点：阻燃剂会显著影响力学性能和加工流动性。做高玻纤 + 无卤阻燃的复合体系，是三个需求互相打架的组合——刚性要玻纤，阻燃要加量大，流动性要降低。这类配方才是真正考验改性能力的。
三、电机与电控壳体：耐温是第一道关
电机控制器、OBC、DCDC 这些件的共同特点：靠近热源，还要绝缘。
| 件 | 长期温度区间 | 材料方向 |
|---|
| 电机控制器壳体 | 120-150℃ | PA66-GF + 热氧稳定 / PA6T |
| OBC / DCDC 外壳 | 105-135℃ | PA66-GF30 + 阻燃 |
| 电机端盖 | 120-150℃ | PA66-GF / PA46 |
| 定子包胶 / 绝缘件 | 150℃+ | PA6T / PPA 方向 |
这里的分界线是 150℃。
120-140℃：PA66-GF + 热氧稳定体系可以覆盖- 150℃ 以上长期：要上 PA46、PA6T 这些高温尼龙- 180℃ 以上：往 PPA 家族走
不要用"耐热改性 PA66 硬撑 150℃"。 耐热体系能抬高短期峰值，但长期连续温度的上限是由树脂本身的热稳定性决定的，不是靠助剂堆出来的。
这一条我们在别的文章里反复说过，在三电件上尤其适用：温度是硬边界，改不动。
四、高压电气件：CTI 才是分水岭
这是三电里最容易翻车、也最容易被低估的一类。
高压连接器外壳、汇流排支架、高压线束件——它们在选料时，很多人第一眼看的是 UL94。
看错了。
UL94 考的是"能不能自熄"，CTI 考的是"会不会漏电起痕"。
新能源汽车是高压平台（400V / 800V），长期处在电压 + 污渍 + 湿气的组合环境里。漏电起痕才是真正让安规过不了的那一项。
| 指标 | 考什么 | 典型要求 |
|---|
| UL94 | 自熄性 | V0 |
| GWIT | 灼热丝起燃 | 750-960℃ 视安规 |
| CTI | 漏电起痕 | 高压件常要求 600V 档 |
| 相对温度指数 RTI | 长期耐温 | 视整车要求 |
做到高 CTI + V0 + 高耐温的组合，是高压件最难的地方。 因为阻燃剂和耐电痕助剂之间往往互相抑制——加了这个，那个掉。
这就是为什么高压件经常要往 PA6T、PA9T 甚至 PPA 走。 半芳香族树脂本身 CTI 基线高、吸水率低，比 PA66 更容易把三个指标同时做上去。
代价是价格。但在 800V 平台上，这笔溢价换的是认证能不能过——这钱省不了。
五、热管理件：这里只看一件事
热管理件（冷却管路、快接头、电子水泵壳体）的逻辑和前面三类完全不同。
它的核心只有一条：耐水解 + 低吸水。
这一块内容量大，我们单独写了一篇（第 19 篇）专门讲电池液冷管路，这里只留一句判断：
长期接触冷却液（尤其乙二醇基）的件，不要用 PA6 和 PA66。 换长碳链尼龙，PA612 / PA12 / PA1010 方向。
另外两个位置也值得单独提：
电子水泵壳体和叶轮。 壳体要耐水解 + 耐温，叶轮要耐磨 + 耐水解。这两个件经常被合起来选料，其实要求不一样——壳体看尺寸稳定，叶轮看耐水解和动平衡。
冷却液快接头。 和管路不同，快接头要看密封面和插拔寿命，长碳链 + 增强是主流方向。
CTI 分水岭上的一票否决
三电件定点会上翻车的供应商，一大半栽在 CTI 这道分水岭上。这里把判据说死，方便直接抄用：四百伏以上系统的高压电气件，PTI 四百起步，爬电距离按污染等级重新核算；八百伏平台，主流方案往半芳香族走，CTI 六百档是入场券。
两个高频错误顺手提出来：一是拿干态 CTI 冒充湿热后数值，湿热处理掉一到两档是常态，招标文件里要写明按处理后判定；二是拿外壳料的 CTI 顶骨架件的用，同一个连接器里，带电件和不带电件对 CTI 的要求差一个档位，混用省下的钱不够一次售后。
CTI 这条线的本质是安全，安全项上没有性价比可言，达标就是达标，不达标就是出局。
六、三电用尼龙的五个坑
坑 1：四类件用同一个牌号。 全文都在说这件事。结构件、电气件、热管理件三者的指标互相冲突，一个牌号打不下来。
坑 2：高压件只看 UL94。 CTI 才是高压平台的分水岭。UL94 过了不代表安规过了。
坑 3：拿耐热改性顶长期高温。 150℃ 是分界线，跨过去要换树脂，不是加助剂。
坑 4：忽略长期蠕变。 电池端板、模组压紧件是长期受力件，看的是 1000 小时蠕变数据，不是单次强度。
坑 5：把改性料当原厂料用。 同一树脂，不同厂商的改性和批次管理差别很大。三电件一旦进整车验证，换料成本极高——选供应商时要考虑三年后的稳定性，不是只看第一批。
七、边界：这些件别急着塑化
| 件 | 结论 | 原因 |
|---|
| 电池包主承力托盘（大尺寸） | 需谨慎 | 刚度与碰撞法规要求高 |
| 高压母排本体 | 不适合 | 导电体，不是结构件角色 |
| 电机转轴 / 转子 | 不适合 | 动平衡、磁路、扭矩 |
| 长期 >180℃ 件 | 不适合 | 超出尼龙体系 |
| 防火要求 ECE R100 相关件 | 见法规 | 需按整车法规单独验证 |
行业里的一条实感
三电件的询盘里，我们反复见到一种情况：
客户说"我们要用塑料替代这个铝件"，但图纸还是铝件的图纸。
厚度照抄、加强筋照抄、装配孔位照抄。然后打样出来一测，刚性差 40%，装配时孔位对不上。
这不是材料的问题，是设计没跟着换。
金属件换成塑料件，本质是重新做一次结构设计：壁厚要加、加强筋要重排、螺栓连接要改成自攻或卡扣、公差链要重算。
我们接这类询盘，会先问三句话：这个件原来什么材料？结构改过没有？有没有有限元算过？
三句里但凡有一句是"没改"，那这个项目现在的瓶颈不在料上，在图纸上。
料换得再对，结构不跟着改，也只是把金属的答案抄到塑料的卷子上。
读者追问两则
追问一：三电件的验证周期怎么压？ 三电验证里最耗时间的是寿命类项目，压周期有两个合规路径：一是加速模型，按时间温度等效原理提高温度做加速老化，再用换算系数折回实际寿命，前提是换算系数有依据；
二是借用同体系的历史验证，同基材同改性体系、工况覆盖的历史数据可以引用，只补增量项。把这两条写进 DV 计划，周期往往能从一年半压到十个月内，还不牺牲证据链完整性。
追问二：冷却液和防冻液对三电塑料件的攻击一样吗？ 不一样，这是容易合并处理的误区。传统防冻液是乙二醇加缓蚀剂，攻击路径偏水解；三电专用冷却液的配方更温和，但某些新型号的添加剂对尼龙有未知影响，别拿传统车的经验直接平移。稳妥做法是拿你们量产用的那桶液做浸泡验证，供应商的通用耐受表只做初筛。
再补一个不少团队踩过的组织坑：三电项目里，材料验证往往卡在谁的预算谁签字上。电池结构件的验证算电池部门的，高压连接件的算电气部门的，同一个供应商的同类材料被两个部门各验证一遍，钱花了两遍，结论还互相打架。
建议在项目启动时就把材料验证的归属划清：按件不按部门，一个件一个验证责任人，跨件共用的基材数据建共享库。组织上的这一小步，比任何检测技巧都省时间。
定点会材料答辩卡
参加三电定点会，把答辩卡提前备好，五个问题必有答案。第一问工况：温度场、电压等级、介质接触、寿命要求，四项数字背熟。第二问选型依据：为什么是这个基材、这个改性体系、这个玻纤含量，三层理由各一句话。
第三问关键数据：干湿态两套性能、CTI 及其测试状态、热变形温度、长期老化数据，页码都标好。第四问验证计划：DV 到 PV 的项目清单和周期，加速模型的换算依据。第五问风险坦白：这个方案里最弱的环节是什么、监控手段是什么——主动交底比被问出来体面得多，也真实得多。
答辩卡的底色是诚实，主机厂的材料工程师见过的套路比你多，卡上每个数字经得起追问，定点自然水到渠成。
还有一个容易被忽视的角落要提醒：维修和售后场景的材料一致性。量产件的选型评审做得再严，售后更换件往往绕过评审直接下单，仓库里有什么用什么，结果原厂件和售后件的牌号体系不一致，客户拿到的同一台车换了两种料。
建议把售后备件纳入选型管理：每个量产件的备件料号与量产锁定，供应商变更走同样的验证流程。三电件的售后周期长达十几年，这道闸门不设，前期所有的验证严谨都会在某个维修日被稀释掉。
结语
三电系统用尼龙，记住四个世界：
电池包结构件看刚性和抗蠕变，电机电控壳体看长期耐温，高压电气件看 CTI，热管理件看耐水解。
四条线，四个方向。分清了，选料就是查表；分不清，选料就是猜。
再补一句实战经验：三电项目通常是"材料跟着结构走"，不是"结构跟着材料走"。所以材料方越早介入，越能避免后期返工——等到结构冻结、模具开完再来选料，能选的已经不多了。
Among the plastic parts of new energy vehicles, the three-electric system is the one with the largest increase and is also the easiest to choose incorrectly.
The reason is not complicated: 'Three electrics' sounds like a system, but it is actually the world of four materials.
Battery pack structural components, motor and electronic control housings, high-voltage electrical components, thermal management components—the core indicators of these four types of components almost do not overlap.
Using one grade to handle four types of parts will inevitably result in each type performing just a little below standard.
Let's start with a scene.
Last year, I attended a parts sourcing meeting for an emerging car company, focusing on the three electric components. In one morning, I listened to material solution reports for six parts. What was interesting was the Q&A session: the question that the automaker's materials engineers asked most often was not about the cost, but—what is the CTI of this part, and at what thickness? Among the six solutions, two couldn't answer at the time and were required to perform additional testing after the meeting.
That meeting confirmed a judgment for me: the requirements for nylon in new energy vehicles are no longer the same as for traditional cars. Traditional cars focus on heat resistance and strength, while electric components concern voltage, temperature rise, and lifespan. The same PA66, when used in electric components, has to withstand electricity, heat, and coolant, and also last fifteen years without breaking.
This article reclassifies according to the physical structure of the 'three electrics', breaking the 'three electrics' into four categories and discussing them separately: how to calculate the lightweighting of battery pack structural components, the temperature rise barrier for motor and electronic control housings, the watershed where high-voltage electrical components are blocked by CTI, and the simple and crude approach of only focusing on one thing for thermal management components.
Give five more pitfalls and one boundary. A reminder to readers in the power supply chain: read this article before quoting, especially Section Four—CTI's watershed causes a batch of suppliers to crash at the annual fixed-point meeting every year.
1. First, disassemble the 'three electrics' into four categories of parts
| item type | Representative item | core contradiction | First Indicator |
|---|
| Battery pack structural components | End plate, side panel, box cover, pallet | Lightweight Creep-resistant Flame-retardant | Bending Modulus / Flame Retardant |
| Motor and electrical control housing | Controller housing, OBC casing, end cover | Temperature resistance Insulation Rigidity | Long-term heat resistance |
| High-voltage electrical components | High-voltage connector housing, busbar bracket | Insulation Tracking resistance | CTI / Flame Retardant |
| Thermal management components | Cooling pipeline, quick connector, pump housing | Hydrolysis resistant Low water absorption | Strength retention after hydrolysis |
It is recommended to save this table first. All subsequent material selection actions will proceed downward within these four rows respectively.
There is also a general principle worth remembering first: when selecting materials for the three electrical components, first check whether this component will be included in the vehicle regulation list.
For items included in the regulatory list (related to collisions, fire safety, high-voltage safety), material selection must be back-calculated according to regulatory requirements, rather than based on cost. If this step is judged incorrectly, all subsequent optimizations will be in vain.
2. Battery Pack Structural Components: The Main Battlefield of Lightweighting
The battery pack is the area of the whole vehicle where 'plastic instead of steel' is most concentrated. Because the battery pack itself is heavy, any weight reduction can directly translate into extended range.
Main plastification position:
Battery module end plate: originally was aluminum, now PA66-GF50 is very mature in this direction - Battery side plate / partition: plate-like structural component, starting with PA66-GF30 - Battery case top cover: large-sized part, often in the flame-retardant, low-warping direction - Busbar bracket: electrical functional component, flame-retardant with high insulation requirements - Battery pack tray: large size, high load-bearing, plasticization needs to be cautious
Why can the end plate achieve GF50?
The end plate is a typical 'high-rigidity, creep-resistant' component—it needs to press down on the module for a long time without slowly deforming. The bending modulus of GF50 can reach more than 1.3 times that of GF30, and its creep resistance is significantly better.
But the GF50 comes with three costs that must be acknowledged together:
Impact toughness has dropped significantly, and drop performance needs to be verified separately - Anisotropy is more pronounced, warping of long parts is difficult to control - Severe floating fibers, not suitable for visible parts
So the correct approach is: use GF50 for the end plates, GF30 for the side plates, and a low-warpage system for the cover plates. Three types of components in three directions, not the same material for everything.
Two often overlooked small items
Module fasteners and insulating gaskets do not bear the main structure, but are subjected to long-term pressure and temperature cycles.
Their failure mode is very particular: they don't crack or break, but slowly lose their preload. Therefore, material selection should focus on compressive permanent deformation and long-term creep, not tensile strength.
Many battery packs later develop abnormal noises and looseness, and the source is these few inconspicuous components. They do not appear on the collision safety checklist, yet they directly affect the consistency of the entire pack.
In a word: reducing the weight of a battery pack is not about replacing the materials, but about understanding the stress on each part and then matching them accordingly.
Flame Retardant: The Hard Barrier of Battery Packs
Flame retardancy of the battery pack is not an 'optional feature.' The typical requirements are:
UL94 V0 as the starting point - Halogen-free system preferred (compliance trend of vehicle manufacturers) - Long-term temperature resistance above 105-125℃
Pay attention to a commonly overlooked point: flame retardants can significantly affect mechanical properties and processing fluidity. Creating a high glass fiber, halogen-free flame-retardant composite system is a combination of three conflicting requirements — rigidity requires glass fiber, flame retardancy requires a large amount of additive, and fluidity needs to be reduced. Such formulations truly test modification capabilities.
3. Motor and electrical control housing: Temperature resistance is the first hurdle
The common characteristics of motor controllers, OBC, and DCDC: they are close to heat sources and also need insulation.
| item | Long-term temperature range | Material direction |
|---|
| Motor controller housing | 120-150℃ | PA66-GF Thermal and oxidative stability / PA6T |
| OBC / DCDC Enclosure | 105-135℃ | PA66-GF30 Flame Retardant |
| Motor end cover | 120-150℃ | PA66-GF / PA46 |
| Stator Overmold / Insulating Parts | 150℃ | PA6T / PPA Direction |
The dividing line here is 150℃.
120-140℃: PA66-GF. The thermo-oxidative stabilizing system can cover long-term temperatures above 150℃. For temperatures above 180℃: need to move toward the PPA family.
Do not rely on 'heat-resistant modified PA66 to withstand 150°C'. The heat-resistant system can raise the short-term peak, but the long-term continuous temperature limit is determined by the thermal stability of the resin itself, not by stacking additives.
We have repeatedly mentioned this in other articles, and it is especially applicable to the three electrical components: temperature is a hard boundary and cannot be changed.
4. High-voltage electrical components: CTI is the watershed
This is the category in the three electrics that is easiest to crash and also easiest to underestimate.
High-voltage connector housings, busbar brackets, high-voltage wiring harness components — when selecting materials for them, many people first look at UL94.
Misread it.
UL94 tests whether it can self-extinguish, while CTI tests whether it is prone to tracking due to leakage.
New energy vehicles have high-voltage platforms (400V / 800V) and are long-term exposed to an environment combining voltage, dirt, and moisture. Leakage tracking is what truly causes failure in safety regulations.
| Indicator | What exam | Typical requirements |
|---|
| UL94 | Self-extinguishing | V0 |
| GWIT | The hot wire ignites | 750-960℃ Depending on safety standards |
| CTI | Tracking due to leakage current | High-voltage components often require a 600V rating |
| Relative Temperature Index (RTI) | Long-term heat resistance | According to the requirements of the whole vehicle |
Achieving a combination of high CTI, V0, and high heat resistance is the most difficult part for high-voltage components. This is because flame retardants and tracking-resistant additives often inhibit each other—adding one causes the other to decrease.
This is why high-voltage components are often made with PA6T, PA9T, or even PPA. Semi-aromatic resins themselves have a high CTI baseline and low water absorption, making it easier than PA66 to improve all three indicators at the same time.
The cost is the price. But on the 800V platform, this premium buys whether the certification can pass — this money cannot be saved.
5. Thermal management components: Here we only look at one thing
The logic of thermal management components (cooling pipelines, quick connectors, electronic water pump housings) is completely different from the previous three types.
It has only one core principle: hydrolysis resistance and low water absorption.
This section is quite large, so we wrote a separate article (Article 19) specifically about battery liquid cooling pipelines. Here, we will only leave one judgment:
For parts that are in long-term contact with coolant (especially ethylene glycol-based), do not use PA6 and PA66. Switch to long-chain nylon, such as PA612 / PA12 / PA1010.
The other two positions are also worth mentioning individually:
Electronic water pump housing and impeller. The housing needs to be hydrolysis-resistant and temperature-resistant, while the impeller needs to be wear-resistant and hydrolysis-resistant. These two parts are often selected together, but their requirements are actually different—the housing focuses on dimensional stability, and the impeller focuses on hydrolysis resistance and dynamic balance.
Coolant quick connector. Unlike the piping, quick connectors need to consider the sealing surface and the insertion/removal lifespan, and long carbon chain reinforcement is the mainstream direction.
A veto on the watershed of CTI
Most of the suppliers who fail at the fixed-point meetings for the three-electrical components stumble at the CTI watershed. Here the criteria are set strictly for easy reference: for high-voltage electrical components of systems above 400V, PTI starts from 400, and creepage distances are recalculated according to pollution levels; for 800V platforms, the mainstream solutions tend towards semi-aromatic compounds, and CTI in the 600 range is the entry ticket.
Two common mistakes to point out: first, using the dry-state CTI to pretend it represents the values after damp-heat treatment; it's normal for damp-heat to reduce the rating by one to two levels, so the tender documents should clearly state that the judgment is based on the treated value. Second, using the CTI of the housing material for the skeleton parts; in the same connector, the CTI requirements for live and non-live parts differ by one level, and saving money by mixing them won't cover even one after-sales service.
The essence of the CTI line is security. When it comes to security, there is no question of cost-effectiveness; meeting the standard means meeting the standard, and failing to meet it means being out.
6. Five Pitfalls of Nylon for Three Electronics
Pitfall 1: Four types of parts use the same grade. The whole text is talking about this issue. The specifications of structural parts, electrical parts, and thermal management parts conflict with each other, and one grade cannot meet all the requirements.
Pitfall 2: High-voltage components are only judged by UL94. CTI is the real dividing line for high-voltage platforms. Passing UL94 does not mean passing safety regulations.
Pitfall 3: Using heat-resistant modifications to withstand long-term high temperatures. 150°C is the dividing line; if you go beyond it, you need to change the resin, not just add additives.
Pitfall 4: Ignoring long-term creep. Battery end plates and module clamps are components under long-term stress, and what matters is the 1,000-hour creep data, not single-instance strength.
Pitfall 5: Using modified material as if it were original factory material. Even with the same resin, different manufacturers have significant differences in modification and batch management. Once the three electrical components go through whole-vehicle validation, the cost of changing materials is extremely high—when choosing suppliers, you need to consider stability three years down the line, not just the first batch.
7. Borders: Don't rush to plasticize these parts
| piece | Conclusion | Reason |
|---|
| Battery Pack Main Load-Bearing Tray (Large Size) | Need to be cautious | High stiffness and crash regulation requirements |
| High-voltage busbar body | Not suitable | Conductor, not a structural component |
| Motor shaft / Rotor | Not suitable | Dynamic balance, magnetic circuit, torque |
| Long-term >180℃ parts | Not suitable | Beyond the nylon system |
| Fire protection requirements related to ECE R100 components | See regulations | Needs to be separately verified according to whole vehicle regulations |
A real feeling in the industry
In inquiries about the three electrical components, we repeatedly see a certain situation:
The customer said, 'We want to use plastic to replace this aluminum part,' but the drawing is still for the aluminum part.
Copy the thickness, copy the ribs, copy the assembly hole positions. Then make a sample for testing, the rigidity is 40% worse, and the hole positions don't align during assembly.
This is not a problem with the material; it's that the design wasn't changed accordingly.
Replacing metal parts with plastic parts essentially means redoing the structural design: wall thicknesses need to be increased, ribs need to be rearranged, bolt connections need to be changed to self-tapping screws or clips, and the tolerance chain needs to be recalculated.
When we receive this type of inquiry, we first ask three questions: What material was this part originally made of? Has the structure been modified? Has it been analyzed using finite element analysis?
If any one of the three sentences is 'not changed,' then the current bottleneck of this project is not in the materials, but in the drawings.
Even if the material is replaced correctly, if the structure is not changed accordingly, it's just copying the answer for metal onto the paper for plastic.
Two Reader Inquiries
Follow-up Question 1: How to shorten the verification cycle of the three electrical components? The most time-consuming part of the three electrical verifications is the life-related projects. There are two compliant ways to shorten the cycle: one is the accelerated model, which increases the temperature according to the time-temperature equivalence principle to perform accelerated aging, and then uses a conversion factor to translate back to the actual lifespan, provided that the conversion factor has a basis;
Second, leverage historical validation within the same system. Historical data from the same substrate and the same modified system under similar operating conditions can be referenced, only supplementing the incremental items. Including these two points in the DV plan can often reduce the cycle from a year and a half to within ten months, without sacrificing the completeness of the evidence chain.
Follow-up question two: Do coolant and antifreeze attack plastic parts of the three electric components the same way? No, this is a misconception that easily leads to combination. Traditional antifreeze uses ethylene glycol and corrosion inhibitors, which attack more hydrolyzed; The formula for the three-electric coolant is gentler, but some new additives have unknown effects on nylon, so don't just apply traditional car experience. The safer approach is to use the container you use for mass production for soaking verification, and the supplier's general tolerance test only does preliminary screening.
Add another organizational pitfall many teams have fallen into: in three-electric projects, material verification often depends on whose budget is who signs. Verification of battery structural parts falls under the battery department, high-voltage connectors on the electrical department; similar materials from the same supplier are each tested by two departments, spending money twice, and conclusions even clash.
It is recommended to clarify the attribution of material verification at the start of the project: by item, not by department, with each item assigned a verification responsible person, and a shared database of substrate data shared across parts. This small organizational step saves more time than any testing technique.
Designated Meeting Material Defense Card
Attend the Three Electrical Designated Meeting and prepare the defense card in advance; there will definitely be answers to these five questions. First question: working conditions: temperature field, voltage level, medium contact, and lifespan requirements—memorize these four numbers. Second question: Basis for selection: why this substrate, this modified system, and this glass fiber content—each of the three reasons is one sentence.
Third Key Data: Both wet and dry state performances, CTI and its test state, thermal distortion temperature, long-term aging data, all labeled with page numbers. Question 4: Verification plan: Project list and cycle from DV to PV, basis for model conversion acceleration. Question 5: Risk honesty: What is the weakest link in this plan? What is the monitoring method? — Proactive disclosure is much more dignified and realistic than being asked.
The defense card is honesty. The material engineers at OEMs have seen more tricks than you; every number on the card can withstand questioning, and the fixed location naturally follows.
Another easily overlooked corner to remind us of: material consistency in maintenance and after-sales scenarios. No matter how strict the selection and evaluation of mass-produced parts is, after-sales replacement parts often bypass the review and place orders directly. What's in the warehouse is used, resulting in inconsistent grading systems between original parts and after-sales parts, and the customer receiving the same car gets two different parts.
Suggests including after-sales spare parts in selection management: for each mass-produced part, the part number is locked in mass production, and supplier changes follow the same verification process. The after-sales cycle for the three electrical components lasts more than ten years. Without this gate, all the initial verification rigors will be diluted on a certain maintenance day.
Conclusion
Nylon for the three electrical systems, remember the four worlds:
Battery pack structural parts look at rigidity and creep resistance; motor control housings look at long-term temperature resistance; high-voltage electrical parts look at CTI; thermal management parts look at hydrolysis resistance.
Four lines, four directions. If you distinguish clearly, selecting materials means checking the table; If not, selecting materials means guessing.
adds another practical experience: For three-electric projects, "materials follow the structure," not "structure follows the material." So the earlier the materials side gets involved, the more they can avoid later rework—wait until the structure freezes and the mold is finished to select materials, and there's not much left to choose from
