169 导电尼龙与电磁屏蔽件
导电尼龙不是一种料，是一类
导电尼龙按用途分三档：抗静电级（表面电阻 10⁹-10¹² Ω）——防止静电吸附灰尘，用于电子包装和洁净室。
静电消散级（10⁶-10⁹ Ω）——防止静电放电损坏元件，用于电子装配夹具。
导电电磁屏蔽级（10²-10⁶ Ω）——屏蔽电磁干扰，用于电子设备外壳。先定电阻档位，再选填料。
四种填料的分工
碳黑：最便宜，抗静电级够用，但导电性差（10⁴ Ω 已是极限），且只能做黑色。碳纤维：导电性好（可到 10² Ω）、同时增强，是屏蔽级主流。金属纤维（不锈钢纤维）：导电最优、可做浅色，但价格是碳纤维的 3 倍。镍包石墨：导电好、可做灰色，但密度大、对螺杆磨损大。
现场还原：喷漆线上的静电之痛
2025 年 5 月，苏州一家电子结构件厂的喷涂车间主任来电话，说静电喷漆的工装板换了一批新的，挂上去粉末吸得乱七八糟，喷出来的涂层厚薄不均，不良率从 2% 窜到 15%。
到现场看：新工装板是外购的「导电尼龙板」，测表面电阻，有的 10 的 6 次方量级，有的 10 的 9 次方，同一块板上不同位置能差两个数量级。
静电喷漆要求表面电阻稳定在 10 的 4 到 6 次方这个窗口，超出窗口，粉末要么吸附不住、要么吸得太死不好清理。
那批板子的根因：碳黑分散不均，小厂挤出工艺压不住分散度。
我们供的是碳纤维导电 PA66 粒子，客户自己压板。碳纤维的好处在这就显出来了：纤维搭接形成导电网络，阈值附近分散均匀性比碳黑好控，表面电阻稳定在 10 的 5 次方量级，批次间波动小于半个数量级。换板之后不良率回到 2% 以下。
喷涂线上，工装板是耗材，导电是命——这个命不在「标称导电」，在「每一块都导电、每一批都一样」。
导电性与力学性能的取舍
填料加得越多导电越好，但冲击强度下降越快。碳纤维加到 20% 时，缺口冲击强度从 60 kJ/m² 掉到 8 kJ/m²。
屏蔽件一般不加玻纤——碳纤维本身就有增强作用，再加玻纤会更脆。这是导电料配方和结构料配方最大的区别。
导电尼龙能做静电喷漆
汽车和家电的塑料件要喷漆，传统工艺要先喷导电底漆。导电尼龙可以直接静电喷漆——表面电阻低到 10⁶ Ω 以下就能吸附涂料。
省掉底漆工序，单件成本下降明显。这是导电尼龙在汽车外饰件上增长最快的应用。
深一层：渗流阈值——导电尼龙的全部秘密都在这
聊导电塑料，绕不开一个概念：渗流阈值。理解了它，导电尼龙的一半问题就通了。
导电填料加到塑料里，并不是加一点就导电一点。填料浓度低时，粒子彼此孤立，材料还是绝缘的；浓度爬到某个临界点，粒子之间突然搭成连续通路，电阻率垂直下落——可以掉十个数量级——这个临界点就是渗流阈值。
过了阈值再往上加，电阻率缓慢下降，力学性能却一路恶化。
不同填料的阈值不一样：导电碳黑要 15-20 份，碳纤维 8-12 份就够（纤维是搭接成网，效率高），碳纳米管 3-5 份（最贵）。
配方设计的核心功力就是在阈值附近走钢丝：填料少一点不导电，多一点韧性报废，加工剪切一强，网络结构还可能被剪断。
所以导电料选型要看三个数，缺一个都别下单：体积电阻率（指标定到应用对应的档位）、表面电阻率（喷涂和静电耗散场景用这个）、以及两个指标的批次波动范围。
还有一句丑话：导电和力学天生打架，填料加到阈值，冲击韧性通常掉三成起步——结构强度要求高的件，要么局部导电件加结构件分体设计，要么接受性能折让，把折让算进安全系数。
屏蔽效能的现实边界
导电尼龙的屏蔽效能一般在 30-60 dB，金属外壳可以到 80 dB 以上。
导电尼龙能解决大部分民用电子的屏蔽需求，但军工和医疗设备的高屏蔽要求还是要靠金属外壳或金属化涂层。
不要为了减重把高屏蔽场景做成导电塑料。
加工与成本的隐性变量
导电填料对螺杆和模具磨损严重，必须用到耐腐蚀螺杆和加硬模具钢。
碳纤维导电料流动性差，薄壁件难填充。另外导电料的单价是普通 PA66 的 2-4 倍，要核算综合成本：省掉屏蔽涂层和底漆工序后，总成本未必更高。
工程实测：4 条强制测试
测试1：表面电阻。碳黑 10⁴ Ω，碳纤维 20% 达 10² Ω，不锈钢纤维达 10¹ Ω——按需求选填料。
测试2：屏蔽效能。碳纤维 20% 屏蔽 45 dB，不锈钢纤维 60 dB，铝壳 85 dB——高屏蔽仍需金属。
测试3：冲击强度。碳纤维 20% 缺口冲击 8 kJ/m²，未填充 60 kJ/m²——导电料必然变脆。
测试4：静电喷漆。表面电阻 < 10⁶ Ω 可直接静电喷漆，上漆率从 65% 升到 90%。
追问三连：采购最常问的三件事
一问：导电尼龙的电阻率能不能指定到某个精确值。 不能精确指定，只能定档。渗流阈值附近的配方对加工剪切敏感，同一配方不同设备做出 10 的 4 到 7 次方都正常。合理做法是按应用定档（静电耗散、电磁屏蔽、喷涂工装各有一档），收货按档验收。
二问：加了导电填料，力学还剩多少。 参考区间：碳系导电 PA66 对比同基材未填充料，拉伸略升，冲击降三到五成，韧性折让是刚性的。结构部位要提前算安全系数，或者分体设计。
三问：电阻率会不会随时间漂。 会，两个来源：吸湿改变表面电阻（表面电阻对湿度敏感是物理本性），还有高温下填料网络微动（体积电阻缓慢上漂）。要求稳的场景，验收数据要包含湿热后电阻率，只看出厂干态数据等于没验。### 算一笔材料账：导电料的档位经济学
导电尼龙的价格跨度极大，从每公斤三十元到三百元都有，价差背后的分档逻辑值得讲透。
第一档是碳黑体系：电阻率做到静电耗散档（10 的 6 到 9 次方），单价最低，适合周转托盘、工装板这类量大档位要求稳的场景。
第二档是碳纤维体系：电阻率低两到三个数量级，兼有增强作用，适合电磁屏蔽和结构性导电件，单价是第一档的三到五倍。
第三档是特种体系（镀银、镍系、碳纳米管）：屏蔽效能和电阻稳定性最高，军用和高端电子用，按克论价。
选错档位的代价两个方向都存在：拿第一档去干第二档的活，屏蔽不达标，EMC 整改的钱十倍奉还；拿第三档去干第一档的活，成本翻十倍，采购年度考评直接垫底。
我们的建议是把「电阻率档位」当采购参数写进询价单，和单价并列。档位定准了，报价的可比性立刻出现——导电料行业的报价混乱，一半源于买卖双方没把档位这个锚定住。锚一落定，这门生意就变得清爽。### 边界声明
| 工况 | 推荐材料 |
|---|
| 抗静电包装 | 碳黑抗静电 PA |
| 电子夹具 | 碳纤维静电消散 PA |
| 屏蔽外壳 | 碳纤维导电 PA |
| 浅色屏蔽 | 不锈钢纤维 PA |
| 静电喷漆件 | 碳纤维 PA 表面电阻 < 10⁶ Ω |
工程备忘
导电尼龙量产前必须测表面电阻 + 屏蔽效能 + 冲击强度三项。导电性和韧性是取舍关系，不能两头都要。
实战案例：常见踩坑与正解
踩坑一：只看阻燃等级不看 CTI。导电尼龙装在带电回路附近，阻燃 V-0 但 CTI 只有 250 V，长期爬电后表面碳化短路。正解：带电件必须 CTI ≥ 400 V（相比漏电起痕指数），V-0 只解决起火，不解决爬电——这是电气件最常被漏掉的一条。踩坑二：用回收料或副牌料做绝缘件，介电强度批次波动大，耐压测试 5% 击穿。正解：绝缘件一律走正牌新料，批次附耐压报告。踩坑三：端子件装完一段时间扭矩衰减，以为是螺丝松了，实际是尼龙蠕变。正解：导电尼龙承载螺纹连接时必须玻纤增强到 GF25 以上，并在装配 24 h 后复拧一次。
反向案例：十个数量级的批次落差
2024 年 3 月，华东一家做芯片周转托盘的工厂吃过一次大亏。ESD 托盘走静电耗散档，要求表面电阻 10 的 6 到 9 次方。
他们换了家便宜的导电料供应商，首批到货抽检合格，上量产线一个月后，客户反馈晶圆批次异常，追到托盘上：近期到货的托盘表面电阻冲到 10 的 12 次方——和普通绝缘料没区别。
复盘发现那批料换了碳黑批次，填充量在阈值下方，导电网络没搭起来。一百多万只托盘在客户端返检，运费加赔付加订单信任，损失七位数。
那家厂现在的验收规程是行业里比较狠的一份：每批测表面电阻，加湿热后复测，抽样从 AQL 换成了按 GB 档要求的加严抽样，同时和备用供应商保持双源。
采购总监在复盘会上说的原话：「ESD 件的失效不发生在失效现场，发生在客户的客户那里——你根本来不及知道。
」
导电料这个行业，报价单上的数字人人会写，渗流阈值两边的那点分寸，才是真正值钱的部分。### 延伸判断：最容易被漏掉的隐性变量
导电尼龙的量产事故里，有一半不是料选错了，是隐性变量没控住。
第一个变量是含水率。PA 系材料出厂含水率、干燥条件、注塑前的存放时间，三者共同决定实际含水率，含水率不对，强度和外观都会变。
第二个变量是模具温度。模温低 20℃，表面浮纤和熔接痕强度可能差一倍。
第三个变量是装配后的时间。装完 24 h 和装完 30 天的扭矩、尺寸、密封压缩量都不一样。
这三个变量都不写在物性表上，但都写在失效报告里。
把这三件事写成一张表发给供应商，比打十通电话有用——导电尼龙的选型沟通成本，基本都花在这几项反复确认上。
补记：三个现场判断信号
信号一：同批件电阻率散布超过一个数量级。 分散工艺出问题了，整批判退，抽检合格也别侥幸——散布大意味着阈值附近，漂移随时发生。
信号二：涂层忽厚忽薄、清理难易不均。 喷涂场景的典型导电失稳，先测工装件表面电阻分布，再调喷房参数。
信号三：冬天合格夏天漂移。 湿度对表面电阻的影响是季节性的，验收标准里要有湿热后数据，否则每年夏天都要重新交一遍学费。### 验证顺序：三步走完再下单
第一步，定档：按应用（耗散、屏蔽、喷涂工装）定电阻率档位，写入询价和验收标准。
第二步，验波动：每批测表面和体积电阻率分布，加湿热后复测——散布比均值更能预测现场风险。
第三步，验力学：导电档位下的冲击韧性折让要进安全系数，结构位分体设计提前做。三步走完，导电料的采购就从玄学变成了工程。
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。
169 Conductive nylon and electromagnetic shielding components
Conductive nylon is not the same material; it is a type of
conductive nylon divided into three levels by application: anti-static grade (surface resistance 10⁹-10¹² Ω) — prevents static electricity from adsorbing dust, used in electronic packaging and cleanrooms.
static dissipation stage (10⁶-10⁹ Ω) — prevents electrostatic discharge from damaging components, used for electronic assembly fixtures.
conductive electromagnetic shielding stage (10²-10⁶ Ω) — shields electromagnetic interference, used for electronic device housings. Adjust the resistance level first, then select the packing material.
Division of Four Fillers
Carbon Black: The cheapest, sufficient antistatic grade, but poor conductivity (10⁴ Ω is the limit), and can only be made black. Carbon Fiber: Good conductivity (up to 10² Ω), reinforced simultaneously, mainstream shielding grade. Metal Fiber (Stainless Steel Fiber): Optimal conductivity, can be made in light colors, but costs three times more than carbon fiber. Nickel-Clad Graphite: Good conductivity, can be made into gray, but high density and wears heavily on the screw.
On-site Replication: The Pain of Static Electricity on the Paint Line
In May 2025, the director of the spraying workshop at an electronic structural parts factory in Suzhou called to say that the tooling boards for electrostatic spray painting had been replaced with new ones. When hung, the powder was mixed up, the coating thickness was uneven, and the defect rate jumped from 2% to 15%.
On-site Inspection: The new tooling boards are externally purchased "conductive nylon sheets." When measuring surface resistance, some are on the sixth power of 10, others on the 9th power of 10. Different positions on the same board can differ by two orders of magnitude.
Electrostatic spray painting requires surface resistance to be stable at the 4th to the 6th power of 10. Beyond that, powder either can't be adsorbed or absorbed too hard to clean.
The root cause of that batch of boards: uneven dispersion of carbon black, small factories can't control the dispersion in extrusion processes.
We supply carbon fiber conductive PA66 pellets, customers press the boards themselves. This is where the benefits of carbon fiber become apparent: fiber overlap forms a conductive network, dispersion uniformity near the threshold is better controlled than carbon black, surface resistance stabilizes at the power of 10 to the power of 5, and batch-to-batch fluctuations are less than half an order of magnitude. After board replacement, the defect rate returns to below 2%.
On the spraying line, tooling boards are consumables, conductivity is life—this lifeblood isn't about 'nominal conductivity,' but about 'every piece conducts electricity, and every batch is the same.'
The trade-off between conductivity and mechanical properties
The more filler added, the better the conductivity, but the impact strength drops faster. When carbon fiber is added to 20%, the notch impact strength drops from 60 kJ/m² to 8 kJ/m².
Shielding components generally don't use glass fiber—carbon fiber itself has a reinforcing effect, and adding more fiberglass makes it even more brittle. This is the biggest difference between conductive material formulations and structural material formulas.
Conductive nylon can be used for electrostatic spray painting
Plastic parts of automobiles and home appliances need to be painted, while traditional processes require a conductive primer first. Conductive nylon can be directly sprayed electrostatically—surface resistance as low as 10⁶Ω can absorb the coating.
Eliminates the primer process, significantly lowering the cost per piece. This is the fastest-growing application of conductive nylon in automotive exterior parts.
Deeper layer: Seepage threshold—all the secrets of conductive nylon are here .
Talking about conductive plastics, you can't avoid one concept: leakage threshold. Once you understand it, half of the problem with conductive nylon is solved.
Adding conductive fillers to plastic doesn't mean just a little more conductivity. When the packing concentration is low, particles are isolated from each other, and the material remains insulating; When concentration reaches a certain threshold, particles suddenly form a continuous path, and resistivity drops vertically—by ten orders of magnitude—this critical point is the seepage threshold.
After crossing the threshold and further up, resistivity slowly decreases, but mechanical properties deteriorate all the way.
Different fillers have different thresholds: conductive carbon black requires 15-20 parts, carbon fiber requires 8-12 parts (fibers are layered into a web for high efficiency), and carbon nanotubes require 3-5 parts (the most expensive).
The core skill of formula design is walking a tightrope near the threshold: less packing is non-conductive, more toughness is scrapped, and the stronger the processing and shearing, the network structure may even be sheared.
So when selecting conductive materials, consider three numbers. If you miss any one, don't place an order: volumetric resistivity (set to the appropriate application level), surface resistivity (used for spraying and static dissipation scenarios), and the batch fluctuation range of these two indicators.
There's another harsh saying: conductivity and mechanics are inherently competing. When packing is added to a threshold, impact toughness usually drops by at least 30%—for parts with high structural strength requirements, either local conductive parts are designed separately, or performance discounts are accepted, and discounts are included in the safety margin.
Realistic Limits of Shielding Efficiency
Conductive nylon generally has shielding efficiency of 30-60 dB, while metal shells can exceed 80 dB.
Conductive nylon can meet most consumer electronics shielding needs, but high shielding requirements for military and medical equipment still rely on metal casings or metallized coatings.
Don't make conductive plastics for high-shielding scenarios just to reduce weight.
Hidden Variables in Processing and Cost
Conductive fillers cause severe wear to screws and molds, requiring corrosion-resistant screws and hardened mold steel.
Carbon fiber conductive materials have poor flowability, making thin-walled parts difficult to fill. Additionally, the unit price of conductive materials is 2-4 times that of ordinary PA66, so the overall cost must be calculated: after omitting shielding coatings and primer processes, the total cost may not be higher.
Engineering Testing: 4 mandatory tests
Test 1: Surface resistance. Carbon black 10⁴ Ω, carbon fiber 20% up to 10² Ω, stainless steel fiber up to 10¹ Ω—choose filler as needed.
Test 2: Shielding efficiency. Carbon fiber 20% shields 45 dB, stainless steel fiber 60 dB, aluminum shell 85 dB — high shielding still requires metal.
Test 3: Impact strength. Carbon fiber with a 20% notch impact of 8 kJ/m², unfilled at 60 kJ/m²—conductive material inevitably becomes brittle.
Test 4: Electrostatic spray painting. Surface resistance < 10⁶ Ω can be directly electrostatic sprayed, increasing paint application rate from 65% to 90%.
Follow-up triple question: The three most frequently asked questions in procurement
One question: Can the resistivity of conductive nylon be specified to a certain precise value? If it can't be specified precisely, only set the grade. Formulas near the seepage threshold are sensitive to machining and shear; using the same formula and different equipment can be done with 4 to 7 powers of 10. A reasonable approach is to set the grade according to application (one each for static dissipation, electromagnetic shielding, and spray tooling), and inspect the goods according to the tier upon receipt.
Second question: After adding conductive filler, how much mechanics remain? Reference range: Carbon-based conductive PA66 compared to the same substrate without filling, tensile stretching slightly increases, impact reduction by 30-50%, and toughness is rigid. Safety factors should be calculated in advance for structural parts, or separate designs should be used.
Third question: Will resistivity drift over time? Yes, two sources: moisture absorption changes surface resistance (surface resistance is physically sensitive to humidity), and micro-movement of the packing network at high temperatures (volume resistance slowly floats up). For scenarios requiring stability, acceptance data must include resistivity after wet heating; only looking at factory dry state data means no testing has been done. ### Doing the Math: Conductive Material Grade Economics
Conductive nylon prices range widely, from 30 to 300 yuan per kilogram, and the price difference logic is worth explaining.
The first tier is the carbon black system: resistivity reaches the electrostatic dissipation level (10 to the power of 6 to 9), with the lowest unit price, suitable for high-volume scenarios like turnover pallets and tooling boards where stability is required
The second category is the carbon fiber system: it has a resistivity two to three orders of magnitude lower, also provides reinforcement, is suitable for electromagnetic shielding and structural conductive components, and its unit price is three to five times that of the first category.
The third tier is the special system (silver-plated, nickel-based, carbon nanotubes): it has the highest shielding efficiency and resistance stability, used for military and high-end electronics, priced by weight.
The cost of choosing the wrong gear exists in both directions: using the first gear to do the work of the second gear results in inadequate shielding, and the money for EMC rectification is returned tenfold; using the third gear to do the work of the first gear results in costs increasing tenfold, and the annual procurement evaluation directly ranks at the bottom.
Our suggestion is to include 'resistivity grade' as a purchasing parameter in the inquiry form, listed alongside the unit price. Once the grade is set accurately, the comparability of quotations appears immediately—the chaos in the conductive materials industry’s quotations is half due to the failure of buyers and sellers to anchor this grade. Once the anchor is set, this business becomes straightforward. ### Boundary Statement
| Operating condition | Recommended materials |
|---|
| Anti-static packaging | Carbon Black Antistatic PA |
| Electronic fixture | Carbon Fiber Electrostatic Dissipation PA |
| shielding enclosure | Carbon Fiber Conductive PA |
| Light-colored shielding | Stainless Steel Fiber PA |
| Electrostatic spray-painted parts | Carbon fiber PA surface resistance < 10⁶ Ω |
Engineering Memo
Before mass production of conductive nylon, three items must be tested: surface resistance, shielding effectiveness, and impact strength. Conductivity and toughness are trade-offs; you can't have both.
Practical Case Study: Common Pitfalls and Correct Solutions
Pitfall 1: Only looking at the flame retardant rating and not the CTI. Conductive nylon installed near live circuits may be V-0 flame retardant but with a CTI of only 250 V, leading to surface carbonization and short circuits after long-term tracking. Correct approach: Live components must have CTI ≥ 400 V (compared to tracking index); V-0 only addresses fire, not tracking — this is the most commonly overlooked point in electrical components. Pitfall 2: Using recycled or sub-brand materials for insulation parts, resulting in large batch-to-batch fluctuations in dielectric strength, with 5% failing the pressure test. Correct approach: All insulation parts must use authentic new materials, with dielectric test reports for each batch. Pitfall 3: Torque of terminal parts decreases after a period of installation; it's often thought that the screw is loose, but the real reason is nylon creep. Correct approach: Conductive nylon used for threaded connections must be reinforced with glass fiber to GF25 or above, and retightened 24 hours after assembly.
Reverse case: a batch discrepancy of ten orders of magnitude
In March 2024, a factory in East China that makes chip handling trays suffered a major loss. ESD trays operate in the electrostatic dissipation range, requiring a surface resistance of 10^6 to 10^9 ohms.
They switched to a cheaper conductive material supplier. The first batch passed random inspection, but a month after mass production started, the customer reported wafer batch anomalies. Tracing it back to the pallets: the surface resistance of the recently delivered pallets shot up to 10 to the 12th power—no different from ordinary insulating material.
Reviewing the situation, we found that the batch of materials had a different carbon black batch, the filler amount was below the threshold, and the conductive network was not established. Over a million pallets were returned for inspection by the client, with shipping costs plus compensation and order trust, resulting in a seven-figure loss.
The current acceptance procedure at that factory is one of the stricter ones in the industry: each batch is tested for surface resistance, re-tested after humidity and heat treatment, the sampling has been changed from AQL to stricter sampling according to GB standards, and they maintain dual sourcing with backup suppliers.
The procurement director said at the review meeting: 'ESD failures do not occur at the failure site; they occur at the customer's customer — you simply don't have time to find out.'
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In the conductive materials industry, everyone can write the numbers on the quotation sheet, but the subtle margin on either side of the percolation threshold is the part that really holds value.### Extended judgment: the hidden variables most easily overlooked
In mass production accidents of conductive nylon, half are not due to selecting the wrong material, but because the hidden variables were not controlled.
The first variable is moisture content. The factory moisture content of PA series materials, drying conditions, and storage time before injection molding together determine the actual moisture content. If the moisture content is incorrect, both strength and appearance will be affected.
The second variable is the mold temperature. If the mold temperature is 20°C lower, the surface fiber floating and weld line strength may differ by a factor of two.
The third variable is the time after assembly. The torque, dimensions, and seal compression amount are all different after 24 hours and 30 days of assembly.
These three variables are not listed on the material properties table, but they are all included in the failure report.
Write these three things into a table and send it to the supplier; it's more useful than making ten phone calls—the communication cost of selecting conductive nylon is basically spent on repeatedly confirming these items.
Supplementary Note: Three On-Site Judgment Signals
Signal 1: The resistivity distribution of the same batch of components exceeds one order of magnitude. There is a problem with the dispersion process; the entire batch should be rejected. Even if the sample inspection passes, don’t take chances—the large distribution means that near the threshold, drift can occur at any time.
Signal 2: The coating is uneven in thickness, sometimes thick and sometimes thin, and cleaning difficulty varies. A typical conductive instability in spraying scenarios is to first measure the surface resistance distribution of the workpiece and then adjust the spray booth parameters.
Signal Three: Pass in winter, drift in summer. The effect of humidity on surface resistance is seasonal, and the acceptance criteria should include data after damp heat; otherwise, every summer you would have to pay the tuition again. ### Verification sequence: complete three steps before placing the order.
Step one, set the range: Determine the resistivity range according to the application (dissipation, shielding, spraying tooling), and write it into the inquiry and acceptance standards.
Step two, check for fluctuations: Measure the surface and volume resistivity distribution for each batch, then re-measure after humidification and heating — the scatter ratio predicts field risk better than the mean value.
Step three, mechanical testing: Under the conductive gear position, the impact toughness discount needs to include a safety factor, and the structural position should be designed as a separate unit in advance. After completing these three steps, the procurement of conductive materials changes from mysticism to engineering.
Conclusion
It's just a particle—when it comes to choosing materials, the earlier you ask, the less trouble it is.
The material selection and mold trial for this type of part can be discussed together.
