218 改性尼龙PA66聚合工艺与牌号体系
从一次价差两成的报价说起
去年年中，江苏一家做发动机周边件的厂要上一个新的护套件，采购收了两份 PA66 报价，一吨差了两成。图省钱的方案先上了线，做出来的件外观看不出毛病，装车之后经过发动机舱高温环境，三个月不到表面就开始发黄变脆。
把问题料和正常料一起送检，DSC 曲线一拉就露了馅：正常 PA66 熔点在 260℃ 上下，问题料的熔融峰又矮又宽，中间还夹着 220℃ 的峰——里面掺了 PA6 或者回料。价差两成的谜底，就藏在这条曲线上。
这个案例里最可惜的不是那批料，而是三个月的验证时间。PA66 的价差不是玄学，它藏在聚合工艺和原料纯度里。这一篇就把 PA66 从尼龙盐到切片的过程讲清楚，再看牌号怎么选。
PA66 的聚合原理
PA66 由己二胺和己二酸先成盐、再缩聚脱水而成。与 PA6 的水解开环不同，PA66 是典型的缩聚反应——需要脱出水分才能提高分子量。反应后期要在高温高真空下进行固相增粘（SSP）才能达到高粘度。这个工艺特点决定了 PA66 的生产门槛和成本高于 PA6。
尼龙盐是关键中间体
己二胺和己二酸先中和成尼龙盐（AH 盐），精确的 1:1 摩尔比是分子量的前提。配比偏差会导致分子量上不去。所以尼龙盐的纯度和配比控制是 PA66 生产的核心技术之一。
这也是为什么 PA66 的分子量分布一般比 PA6 窄、性能一致性更好。
PA66 的粘度分级
PA66 同样按相对粘度分级，但粘度数值体系与 PA6 不同（一般用 RV 2.4-3.2 或特性粘度 IV）。低粘度：薄壁件、单丝。中粘度（RV 2.7 左右）：通用注塑，是用量最大的等级。
高粘度：挤出、吹塑、高强度工程件。中粘度牌号占 PA66 用量的六成以上。
PA66 相比 PA6 的优势
熔点高 40℃（260℃ vs 220℃），刚性更高、抗蠕变更好、耐磨更优、吸湿率略低。这些优势让 PA66 在汽车发动机周边、电子连接器、工业结构件这些要求高的场合成为首选。简单说：要求高用 PA66，成本敏感用 PA6。
PA66 的劣势
三点：一是价格高（一般比 PA6 贵 15-30%）；二是供应波动大（己二腈集中度高）；三是加工温度高（280-300℃，接近分解温度，加工窗口比 PA6 窄）。
尤其是第三点——PA66 的热稳定性比 PA6 差，加工时必须加抗氧剂，并严格控制停留时间。
PA66 的加工注意
四个要点：干燥——含水率 < 0.2%，80℃ 4-6 h；温度——料筒 280-300℃，不要超过 310℃；停留时间——控制在 10 min 以内，避免热降解；
模温——80-120℃，提高结晶度。这四条做到，PA66 的加工基本不会出问题。
牌号选择的实用建议
给采购和工程师的建议：常规注塑件选中粘度通用牌号——供应充足、价格合理；薄壁件选低粘度或高流动牌号；受力结构件选高粘度或增强牌号；同一牌号保持两家供应商——PA66 的供应风险需要用双源来对冲。
另外要关注国产 PA66 的质量提升——近年国产料的性价比已经明显改善。
工程实测：4 条强制测试
测试1：熔点。PA66 260℃，加工温度 280-300℃——窗口比 PA6 窄。
测试2：抗蠕变。PA66 蠕变比 PA6 低 40%——长期受力件选 PA66。
测试3：干燥。含水率 < 0.2%，80℃ 4-6 h——必做。
测试4：价格。PA66 比 PA6 贵 15-30%——成本差要权衡。
边界声明
| 工况 | 推荐材料 |
|---|
| 要求高的受力件 | PA66 中高粘度 |
| 成本敏感件 | PA6 |
| 薄壁件 | 低粘度或高流动 PA66 |
| 长期受力件 | PA66（抗蠕变优 40%） |
| 供应风险 | 保持两家供应商 |
工程备忘
PA66 的特点：性能优于 PA6 但价格高、供应波动大、加工窗口窄。加工必须控温和控停留时间。
实战案例：常见踩坑与正解
踩坑一：PA66牌号只按牌号选，不看分子结构。不同基材的性能上限是分子结构决定的，改性只能在结构框架内优化，改不出结构没有的性能。正解：先看碳链长度和酰胺基密度，判断吸水、耐温、耐化学的大方向，再谈改性。
踩坑二：为了省成本把高温尼龙降成 PA66，结果热老化不过。正解：温度是硬约束，超过基材上限必须换基材，不能靠改性硬撑。踩坑三：换了基材不重跑工艺。不同基材的熔点、结晶速度、收缩率都不同。正解：换基材等于重新开发，工艺窗口必须重跑。
延伸判断：验证顺序不要搞反
PA66牌号的验证有固定顺序，跳过前面的直接做后面的，等于白做。
第一步验证材料本身：力学、热学、阻燃、电气这几项，确认料号没选错。
第二步验证工艺窗口：同一批料在不同模温、不同保压下打出来的件，性能差异可能超过 20%，工艺窗口要跑出来。
第三步才做整机或整件验证：装到实际工况里跑寿命。很多人的顺序是反的——直接装机跑寿命，不合格了不知道是料的问题还是工艺的问题，于是反复换料，半年出不了结果。
把这三件事写成一张表发给供应商，比打十通电话有用——PA66牌号的选型沟通成本，基本都花在这几项反复确认上。
从尼龙盐到切片：聚合线上的五个关口
PA66 的聚合线比 PA6 更讲究，五个关口走下来，牌号的底细就摸清了。
成盐是起点。己二胺和己二酸在水里等摩尔中和，生成尼龙 66 盐。配比偏了，分子量封顶就矮一截——端基失衡的切片做出来强度不够，这不是下游改性能补的。所以正规树脂厂对盐溶液的浓度和酸碱度都有在线控制。
浓缩脱水。盐溶液从百分之五十左右的浓度继续蒸发浓缩，同时要把溶解氧赶干净——氧留在体系里，高温一碰就是黄变的引子，切片发黄、端胺基损耗都跟这一步有关。
带压预聚是 PA66 的特征关口。常压下水分蒸发会把缩聚反应往回拽，所以要在 1.7 MPa 上下带压升温，让分子链在液相里长起来。这条高压线的装置投入大、安全等级高，全球能做这条线的厂商屈指可数，这也是 PA66 产能长期集中的原因。
闪蒸与终缩聚。预聚物降压闪蒸，快速脱掉水分，再进终聚釜把分子量推到位。闪蒸的速度和温度曲线控制不好，分子量分布就宽，后面注塑时批间差异就藏不住了。
切粒增粘收尾。出料切粒、干燥包装，高粘度挤出级再走一道固相增粘。出厂前的批间混匀仓是很多大厂的秘密武器——几个批次的切片混匀再发，把 0.05 以内的波动再抹平一层。
采购验供应商，按这五关问过去：盐液控制、脱氧方式、预聚压力、终聚粘度、混匀工序。能答清楚这五问的，切片品质基本可以放心。
供应格局变化给出的采购窗口
PA66 这两年的供应格局，跟五年前完全是两个故事。
卡脖子的环节是己二腈——它是己二胺的原料，全球产能几十年握在少数几家外资手里，国内 PA66 切片长期依赖进口切片和进口原料，价格贵、供货周期长，一有风吹草动就涨价。
这几年国内己二腈技术突破之后，聚合产能陆续释放，供应宽松了，价格中枢也下来了。
对采购来说，这个窗口期有几件事值得做。长协和现货搭配：用量稳的部分谈年度长协锁基价，波动部分走现货，两头兼顾。借价格回落期做认证切换：从贵的天花板料切换到性价比更好的国产料，验证费在新价格下更容易摊平——但切换要一次做透，认证本身就是成本，不要一年换三个牌号。
也要留一个心眼：新产能有品控爬坡期。前年一家客户赶上扩产潮换了新供应商的首批料，粘度合格但端胺基偏高，做成阻燃件之后热老化数据不达标。新线首批料做加严验证——全套力学加热老化一起做，多花两周，避开后面的隐形坑。
供应格局的每一次变化，都是采购重新议价和优化供应链的机会。抓住窗口、验足首批、锁好长协，这三步走完，PA66 的采购成本和稳定性都能上一个台阶。
价格条款也要跟上行情。 己二酸的原料端跟着原油走，切片报价一年里波动几个来回是常态。长协里建议写进季度复盘或限价条款，现货采购分两到三批下，比一把押一个大单稳当——前几年 PA66 行情大起大落，一次性押注的厂不是压了库存，就是高价追过单，两头都交过学费。
PA66 牌号的高频问答
问：PA66 为什么比 PA6 贵？ 两头都在花钱。原料端，己二胺的合成路线比己内酰胺长，成本摆在那里；工艺端，PA66 预聚要在 1.7 MPa 上下带压进行，装置投入和能耗都比 PA6 高一截。这两条决定了它的价格地板，行情再宽松也压不到 PA6 的水平。
问：PA66 改性加工和 PA6 有什么差别？ 温度整体抬高 20 到 30℃，螺杆组合和模温都要相应调。更要紧的是它更怕氧化——高温下暴露时间长，黄变和分子量下降都来得快，抗氧体系要配足，干燥也得更严格，含水率控在 0.15% 以下比较稳。
问：怎么分辨 PA66 里掺了 PA6？ 最直接的是 DSC：PA66 熔点约 260℃，PA6 约 220℃，掺混料会出现两个峰或一个被拉宽的峰。没有检测条件的话，做一块样条放烤箱里 150℃ 烘几天，掺 PA6 的样条黄变和强度衰减会明显得多。
问：改性之后熔点会不会变？ 会。跟 PPO、无规共聚成分共混之后，熔融峰会往低走，幅度取决于配比。判断耐温等级要看改性料的 DSC 曲线和热变形温度，不能拿纯树脂的指标套用——这一点在签技术协议时要写明白。
问：同一牌号不同批次的颜色对不齐，正常吗？ 纯树脂切片本身允许有轻微色差，但肉眼明显可见的批间色差要警惕——背后可能是聚合温度波动、抗氧体系不足，也可能混了回料。
做本色件和浅色件的厂，验收标准要加一条色差指标，按留样比对，超出范围整批挂起。深色件和后续要染色的件可以放宽，但放宽的幅度要写进进料标准，不能凭感觉。
换牌号必跑的四道验证
PA66 的牌号切换成本高，切换前把四道验证跑全，比切换之后返工省心得多。
第一道，熔融曲线。拿新牌号和现用牌号各打一份 DSC，熔融峰的位置和宽度对上，热历史才算对齐——峰形异常的料，后面三道验证都不用做了，直接退。
第二道，工艺窗口。用现有模具试打二十模，从常规参数向两端各探一档，记录缺料、浮纤、翘曲出现的边界。窗口比现用料窄一档以上，量产风险就高了。
第三道，力学全项。样条做拉伸、弯曲、冲击，加一件热老化后的对比——干态数据好看不算数，热老化之后的保持率才是 PA66 的真功夫。
第四道，装车验证。发动机周边件在实车环境里跑一段再拆检，台架和实车的温差、震动工况都补上，这一步不能省，省了就是给售后埋雷。
四道验证走完一般两到四周，换来的是切换之后不再反复。PA66 的件多数在发动机舱里待着，出问题就是售后大事——验证的成本，永远低于召回的零头。
结语
结语
只是一颗粒子——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。
218 Modified Nylon PA66 Polymerization Process and Grade System
Starting from a 20% Price Difference
In mid-last year, a factory in Jiangsu specializing in engine peripheral parts wanted to launch a new protective kit, and purchased two PA66 quotes, with a 20% difference per ton. The money-saving solution was launched first. The finished parts looked flawless, but after being installed and exposed to the engine compartment's high temperature, the surface started to yellow and become brittle in less than three months.
Submitted the problematic material and normal material for inspection, and the DSC curve was immediately exposed: normal PA66 has a melting point around 260°C, but the melt peak of the problematic material is low and wide, with a 220°C peak sandwiched in between—PA6 or recycled material mixed in. The answer to the 20% price difference lies in this curve.
The biggest pity in this case isn't the batch of material, but the three-month validation period. The price difference of PA66 isn't mystical; it's hidden in the polymerization process and raw material purity. This article will explain the process from nylon salt to slicing of PA66, then let's look at how to choose the grade.
PA66 polymerization principle
PA66 is formed by first forming salt from hexamethylenediamine and adipic acid, then condensing and dehydrating. Unlike the hydrolytic ring opening of PA6, PA66 is a typical polycondensation reaction—it requires water removal to increase molecular weight. In the later stages of the reaction, solid-phase tasting (SSP) is performed under high temperature and vacuum to achieve high viscosity. This process feature determines that the production threshold and cost of PA66 are higher than those of PA6.
Nylon salt is the key intermediate
hexadipiamine and adipic acid are first neutralized into nylon salt (AH salt), and a precise 1:1 molar ratio is the prerequisite for molecular weight. Proportion deviation leads to stagnation in molecular weight. Therefore, controlling the purity and ratio of nylon salts is one of the core technologies in PA66 production.
This is also why PA66's molecular weight distribution is generally narrower and its performance is more consistent than that of PA6.
PA66 viscosity grading
PA66 is also graded by relative viscosity, but the viscosity numerical system differs from PA6 (generally using RV 2.4-3.2 or intrinsic viscosity IV). Low viscosity: thin-walled parts, monofilaments. Medium viscosity (around RV 2.7): general injection molding, the most widely used grade.
High viscosity: extrusion, blow molding, high-strength engineering parts. Medium viscosity grades account for more than 60% of PA66 usage.
PA66 Advantages over PA6
have a melting point 40°C higher (260°C vs 220°C), higher rigidity, better creep resistance, better wear resistance, and slightly lower moisture absorption. These advantages make PA66 the preferred choice for automotive engine peripherals, electronic connectors, and industrial structural parts with high requirements. Simply put: use PA66 for high requirements, use PA6 for cost sensitivity.
PA66 disadvantages of
three points: First, high price (generally 15-30% more expensive than PA6); Second, large supply fluctuations (high concentration of adiponitrile); Third, the processing temperature is high (280-300°C, close to decomposition temperature, with a narrower processing window than PA6).
Especially the third point — PA66 has poorer thermal stability than PA6, so antioxidants must be added during processing and residence time strictly controlled.
PA66 Four key points for processing
: Drying—moisture content <0.2%, 80°C for 4-6 hours; Temperature — barrel 280-300°C, do not exceed 310°C; Residence time — controlled within 10 minutes to avoid thermal degradation;
mold temperature — 80-120°C to improve crystallinity. By following these four points, PA66 processing will basically be problem-free.
Practical Advice on Grade Selection
Advice for Procurement and Engineers: For conventional injection-molded parts, choose general grades with viscosity—sufficient supply and reasonable prices; For thin-walled parts, choose grades with low viscosity or high flow; For load-bearing structural parts, choose grades with high viscosity or reinforcement; Maintain the same grade with two suppliers—PA66 supply risk should be hedged through dual sources.
Additionally, pay attention to quality improvement of domestic PA66—the cost-effectiveness of domestic materials has significantly improved in recent years.
Engineering Testing: 4 mandatory tests
Test 1: Melting point. PA66 at 260°C, processing temperature 280-300°C—window is narrower than PA6.
Test 2: Creep resistance. PA66 creep is 40% lower than PA6—choose PA66 for long-term load-bearing parts.
Test 3: Drying. Moisture content < 0.2%, 80°C for 4-6 hours—mandatory.
Test 4: Price. PA66 is 15-30% more expensive than PA6—cost difference must be weighed.
boundary declaration
| operating condition | recommended material |
|---|
| high-demand load-bearing parts | PA66 medium-high viscosity |
| cost-sensitive parts | PA6 |
| thin-walled parts | low viscosity or high flow PA66 |
| Long-term load-bearing parts | PA66 (creep resistance superior by 40%) |
| Supply risk , | Maintain two suppliers , |
Engineering memo
PA66 Features of performance superior to PA6 but higher price, large supply fluctuations, and narrow processing window. Processing requires controlling temperature and residence time.
Practical Case: Common pitfalls and correct answers
Pitfall 1: PA66 grade is chosen only by grade, not molecular structure. The upper performance limits of different substrates are determined by molecular structure; modification can only be optimized within the structural framework and cannot achieve properties the structure lacks. Correct answer: first check carbon chain length and amide density, judge the general direction of water absorption, temperature resistance, and chemical resistance, then discuss modification.
Pitfall 2: To save costs, lowering high-temperature nylon to PA66 results in poor thermal aging. Correct answer: Temperature is a hard constraint; if the substrate limit is exceeded, the substrate must be changed, not forced by modification. Pitfall 3: Changing the substrate means no repeating the process. Different substrates have different melting points, crystallization speeds, and shrinkage rates. Correct answer: Changing the substrate is equivalent to redevelopment; the process window must be restarted.
Extended judgment: Do not reverse the verification order
PA66 Grade verification has a fixed order; skipping the earlier and doing the later ones is essentially wasted.
Step 1: Verify the material itself: mechanical, thermal, flame retardancy, electrical components, and confirm the correct part number selection.
Step 2: Verify the process window: For parts produced by the same batch under different mold temperatures and holding pressures, performance differences may exceed 20%, so the process window must be validated.
Step 3: Only complete machine or whole piece verification: install under actual working conditions to test lifespan. Many people do the opposite — just install the machine and run the lifespan. If it doesn't meet standards, it's unclear whether it's due to the material or the process, so they keep changing the material, and after half a year, no results come out.
Writing these three things into a sheet and sending it to suppliers is more effective than making ten phone calls—the cost of selecting PA66 grades is basically spent on repeated confirmations.
From nylon salt to slicing: the five checkpoints on the polymerization line
PA66 The polymer line is more particular than PA6. After passing through these five checkpoints, the details of the grade become clear.
Forming salt is the starting point. Hexadipiamine and adipic acid are neutralized in water by molar to form nylon 66 salt. If the proportions are off, the molecular weight cap drops significantly—chips with imbalanced end bases lack sufficient strength, which is not something downstream modification can fix. Therefore, formal resin factories have online control over the concentration and pH of the salt solution
Concentration and dehydration. Continue evaporating and concentrating the salt solution from about 50% concentration, while also driving out dissolved oxygen—oxygen remains in the system. High temperature contact triggers yellowing, and slicing and terminal amine group loss are related to this step.
Pressurized prepolymerization is a characteristic threshold for PA66. At atmospheric pressure, water evaporation pulls the polycondensation reaction back, so it must be pressurized and heated around 1.7 MPa to allow molecular chains to grow in the liquid phase. This high-voltage line requires large investment and high safety levels. Few manufacturers worldwide can operate this line, which is why PA66 production capacity has been concentrated for a long time.
Flash and final polycondensation. Prepolymer pressure reduction flash quickly removes moisture, then fed into the final polymer kettle to push molecular weight into place. If the speed and temperature curve of flash distillation are poorly controlled, the molecular weight distribution becomes wide, and later injection molding differences between batches cannot be hidden.
pelletizing and tackling finish. Discharge pelletizing, dry packaging, then a high-viscosity extrusion stage followed by a solid-phase tack enhancement. The inter-batch mixing silo before leaving the factory is a secret weapon of many big manufacturers—several batches of slices are mixed and then released, smoothing out fluctuations within 0.05 by another layer.
Suppliers and Suppliers Ask Questions According to These Five Steps: Salt Control, Deoxidation Method, Pre-polymerization Pressure, Final Polypolymerization Viscosity, Mixing Process. If you can answer these five questions clearly, you can basically trust the quality of the slices.
Procurement Window Given by Changes in Supply Structure
PA66 The supply pattern over the past two years is a completely different story from five years ago.
The bottleneck is adiponitrile—the raw material for adiponitrile. Global capacity has been controlled by a handful of foreign companies for decades. Domestic PA66 chips have long relied on imported chips and raw materials, with high prices and long supply cycles, and prices rise at the slightest sign of trouble.
After recent breakthroughs in domestic adiponitrile technology, polymerization capacity has been gradually released, supply has become more relaxed, and the price center has dropped.
For procurement, there are several things worth doing during this window period. Long-term contracts and spot price combinations: For stable usage, negotiate annual long-term contracts to lock in base prices; for fluctuating parts, go for spot goods—balancing both ends. Switching certification during price pullbacks: switching from expensive ceiling materials to better domestic materials, with verification fees easier to spread out at new prices—but the switch must be done all at once; certification itself is a cost, don't change grades three times a year.
Also need to be cautious: new capacity has a quality control ramp-up period. Two years ago, a customer caught the wave of expansion and switched to a new supplier's first batch of materials. The viscosity was qualified but the terminal amino groups were high, and after being made into flame-retardant parts, thermal aging data did not meet standards. The first batch of new production line materials was tightened for validation—the full set of mechanical heating and aging was done together, spending two extra weeks to avoid hidden pitfalls later. Every change in
's supply structure is an opportunity for procurement to renegotiate and optimize the supply chain. Seizing the window, verifying the first batch, and securing long-term contracts—these three steps can raise PA66's procurement cost and stability to a new level.
Price clauses also need to keep up with market trends. The raw material side of adipic acid follows crude oil, and it's normal for sliced prices to fluctuate several times a year. Long-term contracts suggest including quarterly reviews or price cap clauses, and for spot purchases in two to three batches, it's safer than betting on a single big order—a few years ago, PA66 prices fluctuated wildly, and manufacturers either put up inventory or chased orders at high prices, paying tuition fees on both sides.
PA66 High-frequency Q&A about grades
Q: Why is PA66 more expensive than PA6? Both sides are spending money. On the raw material side, the synthesis route for hexadipiamine is longer than caprolactam, so the cost is there; On the process side, PA66 prepolymerization must be done at around 1.7 MPa under pressure, which means higher equipment investment and energy consumption than PA6. These two factors determine its price floor; no matter how loose the market, it cannot beat PA6's level.
Question: What is the difference between modified PA66 processing and PA6? The overall temperature is raised by 20 to 30°C, and the screw assembly and mold temperature must be adjusted accordingly. More importantly, it is more vulnerable to oxidation—longer exposure at high temperatures causes faster yellowing and molecular weight loss, so the antioxidant system must be properly equipped, drying must be stricter, and moisture content controlled below 0.15% is more stable.
Question: How can you tell if PA66 is mixed in? The most direct is DSC: PA66 has a melting point of about 260°C, PA6 about 220°C, and the blended material will show two peaks or one widened peak. If you don't have testing conditions, make a spline and bake it in the oven at 150°C for a few days. If you bake a spline with PA6 for a few days, the yellowing and strength loss of the PA6-doped spline will be much more noticeable.
Question: Will the melting point change after modification? Yes. After blending with PPO or random copolymer components, the melt peak will decrease, depending on the mixing ratio. To determine the temperature resistance grade, look at the DSC curve and heat distortion temperature of the modified material. You can't use pure resin indicators for this point—this should be clearly stated when signing the technical agreement.
Question: Is it normal for colors from different batches of the same grade to be misaligned? Pure resin chips themselves allow slight color differences, but be wary of obvious inter-batch color differences visible to the naked eye—it may be due to polymerization temperature fluctuations, insufficient antioxidant systems, or mixed materials.
For factories handling both natural and light-colored parts, the acceptance criteria must add a color difference indicator, compare according to retained samples, and hang up the entire batch outside the range. Dark-colored parts and parts to be dyed later can be relaxed, but the extent of the relaxation should be written into the feeding standard, not based on intuition. The four verification steps
must do when changing grades
PA66 have high grade switching costs; running all four verification steps before switching is much less hassle than redoing after switching.
First stage: melt curve. Use a DSC for both the new grade and the current grade; only when the melt peak positions and widths align will thermal history be considered aligned—for materials with abnormal peak shapes, the last three verification steps are skipped, just withdrawn.
Second stage, process window. Test twenty molds with existing molds, probing one stop at each end from conventional parameters, recording the boundaries of material shortage, loose fibers, and warping. The window is more than one level narrower than the current material, increasing the risk of mass production.
Third stage, full mechanics. Spline is stretched, bended, and impacted, plus a thermal aging comparison—dry state data looks good but doesn't count; retention rate after thermal aging is the real skill of PA66.
Fourth stage: vehicle installation verification. Engine peripheral parts run in the actual vehicle environment for a while, then disassemble and inspect. The temperature difference and vibration conditions between the frame and the real vehicle are all compensated. This step can't be skipped; skipping it would be a landmine for after-sales service.
Four stages of verification usually take two to four weeks, but after switching, there is no repetition. Most PA66 parts stay in the engine bay; if something goes wrong, it's a major after-sales issue—the cost of verification is always less than a fraction of the recall.
Conclusion
Conclusion
It's just a small detail—the earlier you ask about material selection, the easier it is.
For material selection and mold testing of these parts, you can talk about it together
