224 改性尼龙与PEI和PEEK怎么选
从一炉高压灭菌讲起
去年，苏州一家医疗器械厂为手术器械托盘伤透了脑筋：托盘要反复进高压蒸汽灭菌器，一百三十四度、水汽饱和，一次灭菌四十分钟。原来用的 PA 料，半年不到就开始发黄、脆裂，边缘一磕就掉渣——灭菌次数远没到品牌方承诺的循环次数，就成批报废。
换成 PEI 之后，同一个托盘用了两年、三百多个灭菌循环，颜色和强度都还稳。采购感叹料价是 PA 的十倍，但报废周期拉长四倍、灭菌失效的临床风险归零，科室的账算下来反而省了。
更高工况的地方还有 PEEK：植入物、航空结构件、半导体晶圆载具，那些场合不是 PEI 能碰的。这一篇讲的就是这条升级链——PA、PEI、PEEK 各自守着哪一段工况，钱花在哪一级才不冤。
特种工程塑料的定位
工程塑料的性能金字塔：通用塑料（PP、PE）< 通用工程塑料（PA、PC、POM、PBT）< 特种工程塑料（PPS、PEI、PSU、PEEK）< 超高温材料（PI）。PA 在第二层，PEI 和 PEEK 在第三层。
从 PA 升级到这一层，价格涨 10-30 倍。所以必须确认 PA 真的不行。
PEI 的特点
PEI（聚醚酰亚胺）长期使用温度 170℃，HDT 200℃。优点：耐温高、阻燃天然 V-0、透明（琥珀色）、尺寸稳定、耐水解、可蒸汽消毒。缺点：价格高（是 PA66 的 8-15 倍）、不耐某些溶剂（如丙酮）、加工温度高（340-400℃）、韧性一般。典型应用：医疗消毒器械、航空内饰、高温电气件。
PEEK 的特点
PEEK（聚醚醚酮）长期使用温度 250℃，HDT 315℃，是量产塑料里耐温最高的品种之一。优点：耐温极高、耐化学性优异（几乎耐所有化学品）、耐磨、耐水解、阻燃、耐辐射。
缺点：价格极高（是 PA66 的 20-30 倍）、加工温度高（380-420℃）、加工设备要求高。典型应用：石油井下、半导体、医疗植入、航空。
性能与价格的性价比曲线
从 PA66 到 PPS 到 PEI 到 PEEK，价格呈指数上升：PA66 约 25-35 元/公斤；PPS 约 60-90 元；PEI 约 250-400 元；PEEK 约 600-1000 元。
性能提升是线性的，价格提升是指数的。所以选材的原则是：选刚好够用的那一档，不要过度设计。很多人一上来就问 PEEK，其实 PPS 就够了。
升级的判断顺序
从 PA 往上升级的正确顺序：第一步：先确认是不是 PA 的牌号没选对——换高温尼龙（PA46、PA6T、PA9T）能解决大部分耐热问题，价格只涨 2-4 倍。
第二步：再考虑 PPS——耐温 200℃、耐化学极好，价格涨 2-3 倍。第三步：才是 PEI 和 PEEK——只在极端工况（250℃ 以上、强腐蚀、植入人体）才需要。
替代金属时的考虑
PEEK 经常用来替代金属——在石油、半导体、航空领域，PEEK 替代不锈钢和钛合金的案例很多。逻辑是：虽然 PEEK 单公斤贵，但省掉了机加工成本、减轻了重量、耐腐蚀性更好。算整件成本，PEEK 有时反而更便宜。这种账要算清楚再下结论。
加工 PEEK 的门槛
PEEK 的加工不是普通注塑机能做的：料筒温度 380-420℃，普通注塑机的加热圈和热电偶到不了这个温度；模具温度 160-200℃；螺杆要用耐高温耐腐蚀的特殊材质；
干燥要求严格（150℃ 3 h 以上）。没有相应设备的工厂，接不了 PEEK 的单子。这也是 PEEK 加工费高的原因。
工程实测：4 条强制测试
测试1：耐温。PA66 长期 120℃，PPS 200℃，PEI 170℃，PEEK 250℃——按需选档。
测试2：价格。PA66 30 元/公斤，PPS 80 元，PEI 300 元，PEEK 800 元——指数上升。
测试3：耐化学。PEEK 几乎耐所有化学品，PA66 不耐强酸碱——极端工况才上 PEEK。
测试4：加工。PEEK 料筒 380-420℃，普通注塑机达不到——设备门槛。
边界声明
| 工况 | 推荐材料 |
|---|
| 耐温 150-200℃ | 高温尼龙或 PPS |
| 耐温 200℃ 以上 | PEI 或 PEEK |
| 强腐蚀 + 高温 | PEEK |
| 医疗消毒件 | PEI 或 PPSU |
| 替代金属 | 算整件成本再决定 |
工程备忘
升级顺序：高温尼龙 → PPS → PEI → PEEK。价格指数上升，选刚好够用的那一档，不要过度设计。
实战案例：常见踩坑与正解
踩坑一：尼龙与PEEK只比强度就下结论。选材对比要看短板——PA 的短板是吸水和耐酸，PBT 的短板是耐热和冲击，金属的短板是重量和成本。正解：列一张短板对照表，看哪家的短板在这个工况下不致命。
踩坑二：以塑代金属时直接按金属件的形状做塑料件。正解：塑料和金属的设计逻辑不同，塑料靠加强筋和壁厚分布，金属靠截面惯性矩，必须重新设计。踩坑三：换了材料不重算成本。
材料便宜了但壁厚要加厚，或者后处理工序增加，总成本可能反而更高。正解：算整件成本，不算单公斤价格。
延伸判断：选型前要先确认的三件事
尼龙与PEEK在选料之前，有三件事要先问清楚，顺序错了后面全部返工。
第一：长期使用温度是多少。短时峰值温度和长期工作温度是两回事，物性表上的热变形温度是短时指标，长期工作温度一般要打七折看。
第二：接触什么介质。油、水、清洗剂、汗液、电解液，每一种都会改变料号选择，介质清单比温度表更重要。
第三：有没有认证要求。阻燃、CTI、食品接触、涉水卫生、安规认证，有认证要求的件，换料号就要重新验证，代价远高于材料差价的几十块钱。这三件事问清楚，选料就完成了一半。
把这三件事写成一张表发给供应商，比打十通电话有用——尼龙与PEEK的选型沟通成本，基本都花在这几项反复确认上。
性能地图：三段工况三把钥匙
把三种材料放进同一张工况地图里，边界就清楚了。
PA 的领地是 150℃ 以下的结构受力件——齿轮、支架、外壳，性价比之王。一旦工况越过蒸汽灭菌、反复热循环、长期湿热的门槛，PA 的水解和老化就开始计息。
PEI 的领地是 200℃ 级的反复热环境。它的分子链里嵌着苯环，刚性大、玻璃化温度高，高温下不软化、尺寸不走样；水解稳定性好，蒸汽灭菌几百个循环面不改色；本色透明、阻燃低烟，医疗和航空内饰都认它。它的软肋是缺口敏感和耐化学一般——强碱和部分溶剂会侵蚀它。
PEEK 的领地是 260℃ 级的极限工况加苛刻介质。耐化学近乎全谱（除了浓硫酸这类狠角色），耐磨自润滑，生物相容性做到植入级——脊柱笼、关节置换件用的就是它。半导体的晶圆载具看中它的低析出，航空件看中的是阻燃低烟低毒全套认证。
钱要花在工况的门槛上：工况在 150℃ 以内，PEI 和 PEEK 是杀鸡用牛刀；工况过了 PEI 的门槛，高温尼龙也是缓不济急。买 PEI 和 PEEK 的理由，一半是性能，另一半是认证——医疗、航空、半导体这三个行业的准入证，本身就是材料价格的一部分。
PEI 与 PEEK 的高频问答
问：PEI 除了蒸汽灭菌，干热环境行不行？ 行。长期干热一百七十度上下是它的舒适区，电子行业的反射镜支架、飞机内饰件、汽车车灯内的反光支架都在这个区间。要注意的是它的缺口敏感性——厚薄突变处加大圆角，成本为零，效果立竿见影。
问：PEEK 做小批量件，注塑和机加工怎么选？ 几十件以内的批量，棒料板料机加工划算，免掉几十万的模具费；量过千件，注塑摊薄模具之后反超。半导体制程里的治具多数是机加工 PEEK，量产品才走注塑。
问：高温尼龙 PA6T、PA9T 能顶到哪一级？ 干态环境一百八十度以内、没有湿热循环的工况，高温尼龙是 PEI 的平替，价格只有三分之一。一旦工况进了蒸汽灭菌、反复湿热循环，酰胺键的水解就顶不住了——这道门槛，是 PEI 的护城河。
问：换成特种料的认证周期要留多久？ 医疗器械换材料涉及注册变更，国内走流程半年起步；航空件要做适航材料清单报批，周期以年计。认证周期要排进项目计划的最前面——它比模具费更容易卡死上市时间。
升级前的工况盘点五问
掏钱买 PEI 或 PEEK 之前，先把五个问题问自己，答案能省下不少冤枉钱。
一问温度上限。连续使用温度和峰值温度各多少？两百五十度的连续工况，PEI 也顶不住，直接看 PEEK；一百五十度以内，高温尼龙可能就够了。
二问介质谱。接触什么化学品、什么浓度、什么温度？PEEK 的耐化学近乎全谱，PEI 要查表核对，强碱环境两者都要慎。
三问湿热循环。有没有蒸汽、反复高低温交变？有，酰胺系（包括高温尼龙）的分子结构就先输一半。
四问认证门槛。行业要不要医疗、航空、食品级认证？认证成本是特种料价格的一部分，没有认证要求的行业，为它多付的钱是白付。
五问寿命次数。反复使用的次数是几百次还是百万次？疲劳和磨损数据要向供应商要到实测曲线，别只看物性表的单点值。
五问过完，该升哪一级、能不能不升，答案就在纸面上——特种料的每一块钱，都应该花在问出来的工况上。
问：PEI 的透明性有什么实际用处？ 用处不小——本色透明可以直接做观察窗、液位标、指示灯罩，一体成型省掉二次装配；染色之后颜色也匀，医疗设备外壳用它一套料解决结构件和外观件。注塑参数要稳，温度波动带来的银纹在透明件上藏不住。
问：PEEK 加碳纤的版本值得多花钱吗？ 看用途。轴承、密封环、齿轮这些要耐磨导热的件，碳纤版刚性和耐磨全面上台阶，钱花在刀刃上；但碳纤带来更强的各向异性，设计时要把取向和翘曲纳入考量，图纸不改就换料，尺寸会教育人。
三级跳：一家设备厂的升级路径
华东一家半导体设备厂的做法，值得想升级的厂抄作业。
他们的晶圆传输臂，第一代用 PPS，二百度的干热工况勉强够用，但析出物控制过不了客户端的洁净度审计。第二代换 PEI，析出和刚性都过了，耐化学窗口在新的制程化学品面前又矮了一截。
第三代，接触化学品的臂体部分换 PEEK，结构件保留 PEI——分级用料，整机成本只涨了四成，性能短板全部清零。
这中间的验证成本没有想象中大：每一级都在上一级的测试框架里加项验证，PPS 时代的测试治具改改继续用，三轮验证共用了一套设备。
厂里的采购总监总结：升级不是一步登天，是每一步都踩在上一级的验证积累上。 直接跳 PEEK 的厂，花的钱更多，交的学费更重。
别忘了中间还有 PPS
聊升级链的时候，有一站经常被跳过——PPS。
它站在 PA 和 PEI 的正中间：长期两百度的干热工况扛得住，耐化学覆盖大半张溶剂表，价格只有 PEI 的一半。晶圆载具之外的很多"该上特种料"的场合——水泵叶轮、引擎周边传感器件、化工泵组件——其实是 PPS 的活，不需要直接跳到 PEI 和 PEEK。
它也有明显的边界：脆，缺口冲击是短板；韧性要求高的件要加增韧配方，刚性受力件倒是正好。纤维增强之后，它的强度和尺寸稳定性在两百度段位里相当能打。
所以升级链的完整版应该是四级：PA、PPS、PEI、PEEK——每一级之间隔着几倍的价差和一段明确的工况。把 PPS 插回地图里，很多升级项目的预算能省下三分之一，这可能是这一篇最值钱的一句话。
问：特种料的库存怎么管？ PEEK 棒料、板料是通用规格，机加工用的常备一些周转快；注塑牌号按订单采购，呆滞一年的牌号料费没人敢认。折中做法是常备两成的安全库存，大单锁价、散单即采——特种料的资金占用量大，库存策略本身就是成本项。
结语
料是同一个料，工艺是两套工艺——选料这件事，越早问越省事。
这类件的选料与试模，可以一起聊。
224 How to choose between modified nylon, PEI, and PEEK
Starting with a high-pressure sterilizer
Last year, a medical device factory in Suzhou had a hard time with surgical instrument trays: the trays had to go repeatedly into a high-pressure steam sterilizer at 134 degrees, with saturated steam, for forty minutes each time. The PA material originally used began to yellow and become brittle in less than six months, and the edges would chip easily—before reaching the number of sterilization cycles promised by the brand, entire batches were scrapped.
After switching to PEI, the same tray has been used for two years and over three hundred sterilization cycles, with both color and strength remaining stable. The procurement department remarked that the material price is ten times that of PA, but with the scrap cycle extended fourfold and the clinical risk of sterilization failure reduced to zero, the department's accounts actually show savings.
PEEK is used in areas with higher operating conditions: implants, aerospace structural components, semiconductor wafer carriers—situations where PEI cannot be used. This article discusses this upgrade chain—PA, PEI, PEEK, each covering a certain range of operating conditions, and where spending money is justified.
Positioning of engineering plastics
Performance pyramid of engineering plastics: General plastics (PP, PE) < General engineering plastics (PA, PC, POM, PBT) < Special engineering plastics (PPS, PEI, PSU, PEEK) < Ultra-high temperature materials (PI). PA is in the second layer, PEI and PEEK are in the third layer.
Upgrading from PA to this level increases the price by 10-30 times. So you must make sure that PA really doesn't work.
Characteristics of PEI
PEI (Polyetherimide) long-term use temperature is 170°C, HDT 200°C. Advantages: high temperature resistance, naturally flame retardant V-0, transparent (amber), dimensionally stable, hydrolysis resistant, can be steam sterilized. Disadvantages: high price (8-15 times that of PA66), not resistant to certain solvents (such as acetone), high processing temperature (340-400°C), average toughness. Typical applications: medical sterilization instruments, aerospace interior components, high-temperature electrical parts.
Characteristics of PEEK
PEEK (polyether ether ketone) has a long-term use temperature of 250℃ and an HDT of 315℃, making it one of the high-temperature resistant varieties among mass-produced plastics. Advantages: extremely high temperature resistance, excellent chemical resistance (resistant to almost all chemicals), wear resistance, hydrolysis resistance, flame retardancy, and radiation resistance.
Disadvantages: Extremely high price (20-30 times that of PA66), high processing temperature (380-420°C), high equipment requirements. Typical applications: oil wells, semiconductors, medical implants, aviation.
Performance-to-price ratio curve
From PA66 to PPS to PEI to PEEK, prices increase exponentially: PA66 is about 25-35 yuan/kg; PPS is about 60-90 yuan; PEI is about 250-400 yuan; PEEK is about 600-1000 yuan.
Performance improvement is linear, while price increase is exponential. Therefore, the principle of material selection is: choose the grade that is just sufficient, without overdesigning. Many people immediately ask for PEEK, but actually PPS is enough.
Upgrade judgment sequence
The correct order for upgrading from PA: Step 1: First, confirm whether the grade of PA selected is incorrect — switching to high-temperature nylons (PA46, PA6T, PA9T) can solve most heat resistance issues, with the price increasing only 2-4 times.
Step two: Then consider PPS — resistant to heat up to 200℃, excellent chemical resistance, price increases 2-3 times. Step three: Only then are PEI and PEEK — only needed in extreme conditions (above 250℃, strong corrosion, implantation in the human body).
Considerations When Replacing Metals
PEEK is often used to replace metals—in the petroleum, semiconductor, and aerospace fields, there are many cases where PEEK replaces stainless steel and titanium alloys. The logic is: although PEEK is expensive per kilogram, it saves on machining costs, reduces weight, and has better corrosion resistance. When calculating the total cost of the whole part, PEEK can sometimes actually be cheaper. This calculation needs to be clear before drawing a conclusion.
The threshold for processing PEEK
Processing PEEK cannot be done with an ordinary injection molding machine: the barrel temperature is 380-420℃, the heating rings and thermocouples of ordinary injection molding machines cannot reach this temperature; the mold temperature is 160-200℃; the screw needs to be made of special material that is high-temperature and corrosion-resistant;
Drying requirements are strict (150°C for more than 3 hours). Factories without the appropriate equipment cannot take orders for PEEK. This is also the reason why PEEK processing costs are high.
Engineering field measurement: 4 mandatory tests
Test 1: Temperature resistance. PA66 long-term 120℃, PPS 200℃, PEI 170℃, PEEK 250℃—select grade as needed.
Test 2: Prices. PA66 30 yuan/kg, PPS 80 yuan, PEI 300 yuan, PEEK 800 yuan — prices rise.
Test 3: Chemical Resistance. PEEK is resistant to almost all chemicals, while PA66 cannot withstand strong acids and bases—PEEK is only used in extreme conditions.
Test 4: Processing. PEEK barrel 380-420°C, ordinary injection molding machines cannot reach it — equipment threshold.
Boundary Declaration
| Operating condition | Recommended materials |
|---|
| Temperature resistant 150-200℃ | High-temperature nylon or PPS |
| Temperature resistant above 200℃ | PEI or PEEK |
| Strong corrosion High temperature | PEEK |
| Medical disinfection items | PEI or PPSU |
| Alternative metal | Calculate the total cost first and then decide |
Engineering Memo
Upgrade sequence: High-temperature nylon → PPS → PEI → PEEK. As price indices rise, choose just enough for your needs and avoid overdesigning.
Practical Case Study: Common Pitfalls and Correct Solutions
Pitfall 1: Concluding based on the strength comparison between Nylon and PEEK alone. Material selection should focus on weaknesses—PA's weaknesses are water absorption and acid resistance, PBT's weaknesses are heat resistance and impact resistance, and metals' weaknesses are weight and cost. Correct approach: Make a table of weaknesses to see which ones are not critical under this working condition.
Pitfall 2: When replacing metal with plastic, directly making the plastic part in the shape of the metal part. Correct approach: The design logic for plastic and metal is different; plastic relies on ribs and wall thickness distribution, while metal relies on section moment of inertia, so a redesign is necessary. Pitfall 3: Changing materials without recalculating costs.
The material is cheaper, but the wall thickness needs to be increased, or additional post-processing steps are added, so the total cost may actually be higher. Correct approach: calculate the cost of the whole piece, not the price per kilogram.
Extended Judgment: Three Things to Confirm Before Choosing a Model
Before choosing between nylon and PEEK, there are three things that must be clarified first; if the order is wrong, everything afterward will need to be redone.
First: What is the long-term use temperature. Short-term peak temperature and long-term operating temperature are two different things. The heat distortion temperature on the material property table is a short-term indicator, and the long-term operating temperature is generally considered to be 70% of that.
Second: What kind of medium is it in contact with. Oil, water, cleaning agents, sweat, electrolyte—each will change the choice of material number. The list of media is more important than the temperature chart.
Third: Are there certification requirements? Flame retardancy, CTI, food contact, water hygiene, safety certification—parts with certification requirements must be re-verified for replacement numbers, costing much more than the material price difference. Clarify these three matters, and the material selection is half done.
Write these three things into a form and send it to suppliers, which is more effective than ten phone calls—the costs of nylon and PEEK selection communication are basically spent on repeated confirmation of these items.
Performance map: Three key work cycles
put three materials into the same working condition map, and the boundaries are clear.
PA's territory is structural load-bearing parts below 150°C—gears, brackets, housings, the king of cost performance. Once the operating conditions cross the thresholds of steam sterilization, repeated thermal cycling, and prolonged humid heat, the hydrolysis and aging of PA begin to take hold.
PEI's domain is a 200°C repeatedly heated environment. Its molecular chains are embedded with benzene rings, giving it high rigidity and high vitrification temperature, so it does not soften or deform in size at high temperatures; It has good hydrolysis stability, with hundreds of steam sterilization cycles without changing color; It is naturally transparent, flame-retardant, and low smoke, recognized by medical and aerospace interiors. Its weak points are notch sensitivity and average chemical resistance—strong alkalis and some solvents can erode it.
PEEK territory is extreme conditions at 260°C combined with harsh media. Chemical resistance is nearly full spectrum (except for tough players like concentrated sulfuric acid), wear-resistant and self-lubricating, and biocompatibility up to implant-grade — this is what spine cages and joint replacement parts use. Semiconductor wafer carriers value their low precipitation, while aerospace parts value full certifications for flame retardancy, low smoke, and low toxicity.
Spend money on the operating condition threshold: operating conditions below 150°C, PEI and PEEK are like a tool used to crack a nut; Beyond the PEI threshold, high-temperature nylon is also a slow solution. The reasons for buying PEI and PEEK are half performance, half certification — the entry passes for medical, aerospace, and semiconductor industries themselves are part of material prices.
PEI High-Frequency Q&A with PEEK
Q: Besides steam sterilization, is PEI suitable in dry and hot environments? Yes. Long-term dry heat around 170 degrees is its comfort zone. Mirror brackets in the electronics industry, aircraft interior parts, and automotive headlight reflector brackets all fall within this range. Note its notch sensitivity—increasing rounded corners at sudden thickness changes costs zero and delivers immediate results.
Q: For small batch PEEK parts, how should injection molding and machining be chosen? For batches of several dozen pieces, machine processing of bar and sheet materials is cost-effective, saving hundreds of thousands in mold fees; For batches over a thousand pieces, after thinning molds by injection molding, they surpass others. Most fixtures in semiconductor processing are machined PEEK, and only mass products go through injection molding.
Q: What grade can high-temperature nylon PA6T and PA9T achieve? In dry environments below 180 degrees Celsius and without damp-heat cycling, high-temperature nylon is an alternative to PEI, costing only one-third. Once the conditions enter steam sterilization and repeated damp-heat cycling, hydrolysis of amide bonds becomes unbearable—this threshold is PEI's moat.
Q: How long does the certification cycle for switching to specialty materials last? Medical device material changes involve registration changes, and domestically, the process starts at six months; For aviation parts, a list of airworthy materials must be submitted for approval, with the cycle calculated by years. The certification cycle should be at the very top of the project plan—it is more likely to delay market launch than mold fees.
Review of pre-upgrade operating conditions: Five questions
Before buying PEI or PEEK, ask yourself these five questions first; the answers can save you a lot of unnecessary money.
First, ask about the upper temperature limit. What are the continuous operating temperature and peak temperature? At 250 degrees continuous operation, PEI can't handle it, just look at PEEK; Within 150 degrees, high-temperature nylon might be sufficient.
Second, ask about medium spectrometry. What chemicals are you exposed to, what concentration, and what temperature? PEEK's chemical resistance is almost complete; PEI must be checked on the meter, and both must be carefully checked in strong alkaline environments.
Third question: Moist-heat cycle. Is there steam or repeated alternating high and low temperatures? Yes, for amide-based (including high-temperature nylon) molecular structures, half of the requirements are lost first.
Four questions: Certification threshold. Does the industry need medical, aviation, or food-grade certification? Certification costs are part of the price of specialty materials. For industries without certification requirements, the extra money paid for them is wasted.
Five questions about lifespan. Is the number of repeated uses hundreds or millions? Fatigue and wear data should be obtained from suppliers up to measured curves; don't just look at single points in the physical property table.
After five questions, the answer is on paper for which level to upgrade and whether not to upgrade .
Ask: What practical use is PEI's transparency? Its usefulness is significant—natural transparent can be used directly as observation windows, liquid level markers, and indicator lampshades, forming as one piece without reassembling the material; After dyeing, the color is uniform, and medical equipment casings are used with this material to solve structural and appearance parts. Injection molding parameters must be stable; silver patterns caused by temperature fluctuations cannot be hidden on transparent parts.
Question: Is the PEEK plus carbon fiber version worth spending extra money? It depends on the intended use. Bearings, sealing rings, gears, and other wear-resistant parts that require wear resistance and heat conduction, the carbon fiber version's rigidity and wear resistance have all been upgraded, so money is spent wisely; But carbon fiber provides stronger anisotropy, so orientation and warpage must be considered in design. If the drawings are not changed, the material should be changed, and the dimensions will teach people.
Three-level jump: The upgrade path of an equipment factory
A semiconductor equipment factory in East China's approach—a factory-copying project worth considering for upgrades.
Their wafer transfer arm, first generation uses PPS, barely sufficient for 200-degree dry heat conditions, but precipitate control cannot pass client-side cleanliness audits. Second generation switches to PEI, with precipitation and rigidity both passed, and the chemical resistance window is even lower compared to new process chemicals.
Third generation: the arm body that contacts chemicals is replaced with PEEK, structural parts retain PEI—graded materials, total machine cost only increased by 40%, and all performance shortcomings are eliminated.
The verification costs in between aren't as high as imagined: each level adds validation within the previous testing framework, the PPS era testing fixtures are kept in use, and three rounds of validation use the same equipment.
The factory's procurement director summarizes: upgrading isn't about achieving success in one step; it's about stepping on the accumulation of validation at the previous level. Factories that jump directly to PEEK cost more and pay heavier tuition.
Don't forget there's also PPS in the middle .
When talking about the upgrade chain, there's one stop often skipped—PPS.
It stands right between PA and PEI: it can withstand long-term dry heat conditions of 200°C, chemically covers most of the solvent table, and costs only half as much as PEI. Many other "special materials" outside wafer carriers—pump impellers, engine peripheral sensor components, chemical pump assemblies—are actually PPS's work, without needing to jump directly to PEI and PEEK.
It also has clear boundaries: brittleness and notch impact are weaknesses; parts requiring high toughness require toughness formulations, while rigid load-bearing parts are just right. After fiber reinforcement, its strength and dimensional stability are quite strong in the 200-degree range.
So the full upgrade chain should be four levels: PA, PPS, PEI, PEEK—with several times the price difference and a clear operating condition between each level. Putting PPS back on the map, many upgrade projects can save a third of their budget, which might be the most valuable sentence in this article.
asks: How do you manage specialty material inventory? PEEK bar and sheet materials are general specifications; some are kept on hand for machining for faster turnover; Injection molding grades are purchased by order, and no one dares to accept the fees for grades that are stagnant for a year. A compromise is to keep 20% of safety stock, lock prices for large orders, and buy for individual orders—special materials require a lot of capital, and inventory strategy itself is a cost item.
Conclusion
Material is the same material, but the process is two sets — the earlier you ask about material selection, the easier it is to ask.
For these types of parts, material selection and mold trial can be discussed together
