87 电热水器外壳与内胆用什么改性尼龙
电热水器工况分层
电热水器分外壳和内胆两件，工况完全不同。外壳长期接触 70-80℃ 热水 + 蒸汽 + 反复启停温度冲击；内胆长期接触 90℃ 热水 + 水垢 + 镁棒反应。
外壳要耐热老化，内胆要耐水垢 + 长期热水水解。这两件的料不能混用——外壳料不能用作内胆，内胆料成本太高不能用外壳。
现场还原
前年七月，一家厂的售后把三十张返修单摆在我们面前，全是外壳发黄开裂，集中在华南沿海城市。拆了三台样机，外壳内侧有盐雾留下的白痕，裂纹从挂耳根部开始。售后的原话是，同一批料装在内陆的机器没事，装到海边的机器就出问题。
后来外罩料换成耐候等级更高的改性体系，挂耳根部加了一道圆角。两年过去，这条售后线再没冒出来。这件事我们每年都讲给新客户听，材料问题从来不是实验室里打出来的，是装在谁家里、装在哪面墙上决定的。
外壳选料的三个关键
第一：耐热氧老化。80℃ 长期 + 氧气，外壳 PA66 不加耐热剂 2 年就脆。必须加抗氧剂 + 热稳定剂双件套。第二：阻燃 V-0。
外壳是家电外壳，必须 UL94 V-0 阻燃。PA66-GF20 + 阻燃剂是主流。第三：尺寸稳定。80℃ 下尺寸变化要小于 0.3%，否则与内胆密封失效。
三个要求同时成立的料号要仔细选——市场上能同时通过的 PA66-GF20 不超过 5 个牌号。
内胆选料的特殊性
电热水器内胆工况比外壳更严苛：长期 90℃ 热水 + 水垢 + 镁棒反应。PA66 在这里撑不过 3 年——镁棒析出的金属离子 + 90℃ 热水会加速水解。
主流内胆走 PPS 或搪瓷——PPS 是塑料方案，搪瓷是金属方案。塑料方案的优势是不结垢——这是 PPS 内胆 10 年寿命的根本原因。
外壳和内胆的连接
外壳和内胆之间有保温层 + 加热管 + 温控器。加热管穿过外壳的孔最容易漏——必须用 PA66-GF30 + 阻燃 + 耐热，不能省玻纤含量。
温控器座接触高温蒸汽，PA6 在这里两年就脆，必须 PA66-GF20。保温层和外壳的间隙 5-10 mm 是设计余量，不能少——少了温度积聚到外壳表面会烫伤人。
商用与家用的差别
商用热水器（30-100 L 大容积、24h 连续工作）工况比家用严得多。商用内胆必须 PPS，家用 50 L 以下可走搪瓷 + 镁棒方案。
商用外壳必须 PA66-GF30 + 阻燃——玻纤含量比家用高 50%。商用热水器的寿命预期 8-10 年，家用 6-8 年——这个差异决定了料号玻纤含量的差异。
延伸判断：内胆的隐性变量
内胆有三件容易漏掉的隐性变量。一是镁棒的位置——镁棒必须离内胆壁 5 mm 以上，否则局部腐蚀加速——这是内胆漏水最常见的隐性原因。
二是加热管的接地——加热管的接地必须通过金属嵌件，不能通过塑料——塑料电阻太大不安全。
三是泄压阀的设定压力——0.8 MPa 泄压阀是国际通用值，国产有些降到 0.6 MPa——这会让内胆长期过压，缩短寿命 30%。
深一层：几个数字的来历
温度分层是这门生意的底图。内胆表面70度，保温层外侧45度，外壳背后还有墙面的辐射热，同一个外壳件的不同位置温差接近30度。选料按最高点算，不按平均算，长期耐热至少要按85度的数据看。
镁棒半年一换，换棒时泄压阀一开，热水带着水垢冲进管路。端盖和管接件要耐碱性的垢液，垢液的酸碱度能到9以上，普通料泡久了表面失光。失光本身不影响功能，但用户会拍照片发评价，图比字杀伤力大。
干烧的边界要单算。温控失灵时内胆表面能冲到105度以上，贴近内胆的端盖件要按瞬时105度验证。这项测试很多厂在出厂验证里省掉了，省掉的后果是干烧事故里外壳变形，引出二次投诉。
泄压阀的开启压力0.75兆帕，阀体要同时耐温和耐疲劳。弹簧腔里的塑料件一年动作几十次，蠕变会让开启压力漂移，漂移超过0.1兆帕就该换件。所以阀体料的抗蠕变数据比强度数据重要，选料时把这两张报告分开看。
内胆两端的封盖是塑料的，位置常年泡在热水里，这个件的耐水解等级是整机里最高的。按常规热水数据选料会低估，要按加速老化换算到十年的账来算，算完再定牌号。
商用热水器全天保温，塑料件的热龄是家用的三到五倍。同一张料单在商用机上要整体上浮一档耐热等级，这是两个市场之间最常见的照搬错误，错一次就是一条售后线。
工程实测：四条强制测试
测试1：耐热氧老化 1000 h。80℃ 烘箱 1000 h 后，PA66-GF20 + 抗氧双件套拉伸保持 88%，未加的降至 60%——外壳必须加抗氧双件套。
测试2：热水水解加速。90℃ 水 1000 h 后，PPS 拉伸保持 95%，PA66 降至 40%——内胆必须 PPS，不能图省事用 PA66。
测试3：阻燃 UL94 V-0。PA66-GF20 + 阻燃剂可达 V-0（1.6 mm），PA6-GF20 仅 V-2——外壳必须 PA66，不能用 PA6 顶替。
测试4：水垢附着测试。PPS 内胆 1000 h 结垢 0.02 mg/cm²，搪瓷内胆 0.15 mg/cm²——塑料方案不结垢是优势。
边界声明
| 工况 | 推荐材料 |
|---|
| 家用外壳 50L 以下 | PA66-GF20 + 阻燃 + 耐热 |
| 商用外壳 30-100L | PA66-GF30 + 阻燃 |
| 家用内胆 | PPS 或搪瓷 |
| 商用内胆 | PPS（必须） |
| 加热管穿孔 | PA66-GF30 + 阻燃 + 耐热 |
工程备忘
电热水器外壳和内胆工况完全不同——外壳走 PA66-GF20 + 阻燃耐热，内胆走 PPS。
混用一定会出问题。镁棒位置和泄压阀压力是两个最容易漏掉的隐性变量——内胆漏水的隐性原因。
追问三连
问一：外壳能不能直接用普通ABS？ABS便宜，但85度就软化，贴着保温层的位置会慢慢变形。外壳件至少要用耐温改性体系，成本差得不多，变形的售后差得多，这笔账不用犹豫。
问二：挂耳为什么老裂？挂耳承受整机几十公斤的悬挂载荷加墙面震动，注塑的熔接线如果正好落在挂耳根部，强度直接打七折。模具设计时要把熔接线赶离受力位，这是模具上的事，不是换料能解决的。
问三：耐候怎么验证？氙灯两千小时加 盐雾五百小时，两个都过才算沿海可用。只过氙灯的料在沿海照样粉化，粉化从挂耳和螺丝孔这些积水位开始，巡检时先看这几个点。
反向案例与收尾判断
有家厂把内胆封盖的料降了一档，加速老化测出来差三个月，决策者觉得整机设计寿命八年，差三个月可以接受。结果实际水质比实验室用水硬，寿命差距被放大到两年，第五年开始批量渗漏。
材料衰减从来不是线性的，实验室用水和真实水质的差距，会在寿命曲线的后半段突然放大。选料时给关键件留的余量，不是给测试留的，是给真实世界里那些没写进工况表的变量留的。
实战案例：常见踩坑与正解
踩坑一：按家用件物性表直接套到商用场景，结果商用电热水器2 年内集中漏水 / 变形 / 失效。
正解：商用和家用是两条产品线，料号玻纤含量、抗水解剂、阻燃等级全部要重新选——这是 80% 售后投诉的根因。
踩坑二：为了省成本用同一种料做整件，结果铰链 / 卡扣 / 阀座这些关键件先坏，整件报废。正解：结构件、连接件、外观件分别选料，不要图省事用同一种料。
踩坑三：耐候件没加 UV 三件套，结果户外安装半年就黄变脆裂。正解：任何户外或窗边安装必须加 UV 吸收剂 + HALS + 抗氧剂三件套，这是 5 年寿命的基本盘。
这三个坑都是量产前必须自查的清单，少一项量产后集中爆，修一颗螺丝的成本是新件的三倍。
补记：能效、回南天与拆机检验
能效等级倒逼的不只是保温层。一级能效的机器保温层更厚，外壳和内胆之间的温度梯度更平缓，塑料件的热龄反而更轻。但保温层加厚之后，外壳的挂耳间距变了，安装孔位的应力重新分布，老模具改腔体的机器，挂耳开裂的位置会转移。
能效升级的项目里，塑料件要跟着重新验证一轮，这条写在项目清单里，能省掉一批莫名其妙的售后。
回南天是华南特有的工况。连续一周墙体返潮，外壳背后是湿墙，前面是暖气，塑料件在两面不同的湿度里反复吸放湿气，尺寸漂移比恒温恒湿实验室里测出来的大一倍。
带卡扣配合的外壳件，间隙要按回南天工况放大，卡死了打不开的维修单，师傅上门一趟的成本够重开一套模具的零头。
拆机检验是售后体系里最被低估的环节。返修的机器换完件就发回去，旧件直接报废，等于把最真实的老化样本扔掉了。有家厂让售后每台返修机拍三张照片存档，塑料件的老化位置、颜色变化、裂纹走向，季度汇总一次。
两年下来他们能对着照片库直接判断哪一批料的老化模式不对，来料争议的时候，照片库就是证据。数据的积累没有捷径，一台一台攒出来的东西，竞争对手抄不走。
补记二：安装环节与说明书里的材料学
热水器这类产品，材料问题有一半是在安装环节埋下的。挂耳的膨胀栓打偏，墙面不平整硬拧，整机挂在斜的受力点上，塑料挂耳长期受侧向力，开裂位置从根部挪到了侧面，售后看照片判成料脆，其实是安装的锅。
后来那家厂给安装师傅做了一页纸的图示，膨胀栓的水平和垂直公差画成照片，装歪的返工率掉了一半。材料工程师写的说明书没有一句废话，难的是让安装环节真的看。
说明书里还有一条值得写，镁棒更换周期的提醒。镁棒不换，内胆结垢加速，端盖和管接件接触的垢液浓度跟着涨，材料的老化速度是连锁反应的一环。
把镁棒提醒从纸质卡片改成机器提醒，端盖的售后记录同步往下走，这两件事的关联，在工况表上找不到，在售后数据的相关性里看得清清楚楚。做材料的人要习惯把视野往外推一级，你选的料，使用寿命的另一半握在用户的使用习惯手里。
延伸：三个来自售后的细节
细节之一，安装卡子丢失。师傅上门装机器，卡子掉进保温层缝里，临时用扎带替代，半年后扎带在热水环境里松弛，外壳开始晃。给安装包里多放两颗卡子的成本几乎为零，省下的是整趟上门。
细节之二，外壳接缝的蜘蛛网。注塑排气不畅会在接缝处留细丝，用户擦机器的时候挂抹布，投诉的是做工不是材料。模具排气槽清一清就能解决的事，别让它变成品质会议的议题。
细节之三，冬天通电的爆裂声。北方干冷，外壳和内胆的热胀系数差在急升温时发出脆响，用户以为机器坏了。选料时把两种材料的收缩率匹配写进验证项，比在客服话术里解释一百遍都管用。
结语
料有人卖，判断不一定有人给——这是我们做的每一份选料建议的验收线。
家用 / 卫浴 / 智能家居整套生活件的选料与试模，可以一起聊。
87 What type of modified nylon is used for the outer shell and inner tank of an electric water heater
Electric Water Heater Operating Condition Stratification
The electric water heater consists of two parts: the outer shell and the inner tank, with completely different operating conditions. The outer shell is in long-term contact with 70-80°C hot water and steam, and undergoes repeated start-stop thermal shocks; the inner tank is in long-term contact with 90°C hot water, scale, and magnesium rod reactions.
The outer shell must be heat-aging resistant, and the inner liner must be scale-resistant for long-term hot water hydrolysis. The materials for these two parts cannot be mixed—the outer shell material cannot be used for the inner liner, and the inner liner material is too expensive to be used for the outer shell.
On-site restoration
In July the year before last, the after-sales team of a factory laid thirty repair orders in front of us, all for yellowed and cracked cases, concentrated in coastal cities of South China. We disassembled three prototype machines, and there were white marks from salt spray on the inside of the cases, with cracks starting from the base of the mounting ears. The exact words from the after-sales team were, 'Machines with the same batch of material are fine inland, but have problems when installed by the sea.'
Later, the outer casing material was changed to a modified system with a higher weather resistance rating, and a fillet was added to the root of the hanging ear. Two years passed, and this after-sales issue never appeared again. We tell this story to new clients every year; material problems are never determined in the laboratory—they are decided by whose home it's installed in and on which wall it's mounted.
Three Key Points in Selecting Shell Materials
First: Heat and oxygen aging. At 80°C for a long time in oxygen, the PA66 casing without heat-resistant additives becomes brittle in 2 years. It is necessary to add a combination of antioxidant and heat stabilizer. Second: Flame retardant V-0.
The casing is an appliance casing and must meet UL94 V-0 flame retardant standards. PA66-GF20 flame retardant is mainstream. Third: dimensional stability. The dimensional change at 80°C must be less than 0.3%, otherwise the seal with the inner liner will fail.
Part numbers that meet all three requirements must be carefully selected — there are no more than 5 grades of PA66-GF20 on the market that can meet all of them simultaneously.
The specificity of lining material selection
The working conditions inside the electric water heater tank are harsher than those of the outer shell: long-term 90°C hot water, scale, and anode rod reaction. PA66 cannot last more than 3 years here — the metal ions released from the anode rod and 90°C hot water accelerate hydrolysis.
Mainstream inner liners use PPS or enamel—PPS is a plastic solution, and enamel is a metal solution. The advantage of the plastic solution is that it does not scale—that is the fundamental reason why PPS liners have a 10-year lifespan.
Connection between the outer shell and the inner liner
There is an insulation layer between the shell and the inner liner, along with a heating tube and a thermostat. The heating tube passing through the hole in the shell is the most prone to leakage — it must use PA66-GF30, which is flame-retardant and heat-resistant, and the glass fiber content cannot be reduced.
The thermostat base comes into contact with high-temperature steam, and PA6 will become brittle here in two years, so PA66-GF20 is required. The gap between the insulation layer and the outer shell of 5-10 mm is the design allowance and cannot be less — if it is less, heat will accumulate on the shell surface and can burn people.
The difference between commercial and household use
Commercial water heaters (30-100 L large capacity, 24h continuous operation) operate under much harsher conditions than household ones. The inner tank of a commercial water heater must be PPS, while household models under 50 L can use the enamel and magnesium rod solution.
Commercial cases must be PA66-GF30 flame-retardant — the glass fiber content is 50% higher than that of household cases. The expected lifespan of a commercial water heater is 8-10 years, while for a household one it is 6-8 years — this difference determines the difference in the glass fiber content of the material.
Extended Judgment: The Hidden Variable of the Inner Liner
There are three hidden variables inside the liner that are easily overlooked. The first is the position of the magnesium rod — the magnesium rod must be more than 5 mm away from the liner wall, otherwise localized corrosion will accelerate — this is the most common hidden cause of liner leakage.
Second is the grounding of the heating tube—the heating tube must be grounded through a metal insert, not through plastic—plastic has too high a resistance and is unsafe.
Third is the set pressure of the pressure relief valve—0.8 MPa. The pressure relief valve is an international standard value, but some domestic ones have reduced it to 0.6 MPa—which will cause the inner tank to be over-pressurized for a long time, shortening its lifespan by 30%.
A Deeper Look: The Origin of Several Numbers
Temperature stratification is the underlying map of this business. The inner liner surface is 70 degrees, the outside of the insulation layer is 45 degrees, and there is also radiated heat from the wall behind the outer shell. The temperature difference between different positions of the same outer shell component is nearly 30 degrees. Material selection is based on the highest point, not the average, and long-term heat resistance should be considered based on data of at least 85 degrees.
The magnesium rod should be replaced every six months. When replacing the rod, opening the pressure relief valve will cause hot water mixed with scale to rush into the pipeline. The end caps and pipe fittings need to withstand alkaline scale liquid, as the pH of the scale liquid can exceed 9. Ordinary materials will lose their surface luster if soaked for a long time. The loss of luster itself does not affect functionality, but users may take photos and post reviews, and pictures are more impactful than words.
The boundary of dry burning must be calculated separately. When the temperature control fails, the inner liner surface can reach over 105 degrees, and the end cap parts close to the inner liner should be tested to withstand an instantaneous 105 degrees. Many manufacturers skip this test during factory validation, and the consequence of skipping it is that in dry burning accidents, the outer casing deforms, leading to secondary complaints.
The opening pressure of the pressure relief valve is 0.75 MPa, and the valve body must withstand both temperature and fatigue. The plastic parts in the spring chamber operate dozens of times a year, and creep can cause the opening pressure to drift. If the drift exceeds 0.1 MPa, the parts should be replaced. Therefore, the creep resistance data of the valve body material is more important than the strength data, and when selecting materials, these two reports should be considered separately.
The end caps of the inner liner are made of plastic, and their position is immersed in hot water all year round. The hydrolysis resistance grade of this part is the highest in the whole machine. Choosing materials based on conventional hot water data will underestimate it; it should be calculated by converting accelerated aging to a ten-year estimate, and then the grade should be determined.
Commercial water heaters maintain heat all day, and the thermal aging of plastic parts is three to five times that of household ones. Using the same material specification for a commercial machine requires an overall increase of one heat resistance grade; this is the most common copy-paste mistake between the two markets, and making this mistake once results in a line of after-sales issues.
Engineering field measurement: four mandatory tests
Test 1: Heat and oxygen aging 1000 h. After 1000 h in an 80°C oven, the tensile retention of PA66-GF20 with antioxidant two-piece set is 88%, while without it it drops to 60%—the casing must include the antioxidant two-piece set.
Test 2: Hydrolysis acceleration in hot water. After 1000 hours in 90℃ water, PPS retains 95% of its tensile strength, while PA66 drops to 40% — the inner liner must be PPS; using PA66 for convenience is not acceptable.
Test 3: Flame retardant UL94 V-0. PA66-GF20 flame retardant can reach V-0 (1.6 mm), while PA6-GF20 is only V-2 — the casing must be PA66 and cannot be replaced with PA6.
Test 4: Scale adhesion test. PPS liner 1000 h scaling 0.02 mg/cm², enamel liner 0.15 mg/cm² — the fact that the plastic solution does not scale is an advantage.
Boundary Declaration
| Operating condition | Recommended materials |
|---|
| Household casing under 50L | PA66-GF20 Flame Retardant Heat Resistant |
| Commercial Housing 30-100L | PA66-GF30 Flame Retardant |
| Household inner liner | PPS or enamel |
| Commercial inner liner | PPS (Mandatory) |
| Heater tube perforation | PA66-GF30 Flame Retardant Heat Resistant |
Engineering Memo
The operating conditions of the outer shell and the inner tank of the electric water heater are completely different—the outer shell uses PA66-GF20 for flame retardancy and heat resistance, while the inner tank uses PPS.
Mixing will definitely cause problems. The position of the magnesium rod and the pressure relief valve pressure are the two most easily leaked hidden variables—the hidden cause of inner tank water leakage.
Follow-up question three times
Question 1: Can the casing be directly used with regular ABS? ABS is cheap, but it softens at 85 degrees, and the area where it is attached to the insulation layer will gradually deform. At least the casing parts must use a temperature-resistant modification system, which is cost-effective and much less after-sales service for deformation. No need to hesitate about this.
Question 2: Why do the hanging ears crack? The hanging ears bear tens of kilograms of hanging load and wall vibrations. If the injection-molded weld line falls exactly at the base of the hanging ear, the strength is reduced by seventy. During mold design, the fusion line must be removed from the load-bearing position. This is a mold-related issue, not something that can be solved by changing the material.
Question 3: How to verify weather resistance? Xenon lamp 2,000 hours plus salt spray for 500 hours—both must pass to be considered coastal use. Materials that only pass xenon lamps will still crumble along the coast, starting from water levels like hanging ears and screw holes. During inspection, check these points first.
Reverse Case and Final Judgment
A factory lowered the material for the inner tank cap by one level, accelerating aging and measuring a difference of three months. The decision-maker thought the design lifespan of the whole machine was eight years, so a three-month difference was acceptable. As a result, the actual water quality was harder than laboratory water, and the lifespan gap was magnified to two years. Batch leaks began in the fifth year.
Material degradation is never linear; the gap between laboratory water and real water quality suddenly widens in the latter half of the life curve. The margin left for key components when selecting materials is not reserved for testing, but for variables in the real world that aren't recorded in the operating chart.
Practical Case: Common pitfalls and correct answers
Pitfall 1: Applying the household component property table directly to commercial scenarios, resulting in concentrated water leakage, deformation, or failure within 2 years of commercial electric water heaters.
Correct answer: Commercial and household use are two product lines; the part number, glass fiber content, anti-hydrolysis agent, and flame retardant rating all have to be reselected—this is the root cause of 80% of after-sales complaints.
Pitfall 2: To save costs, use the same material for the whole piece, but key parts like hinges, latches, and valve seats fail first, and the whole thing is scrapped. Correct answer: Choose materials for structural parts, connectors, and appearance parts separately; don't save effort by using the same material.
Pitfall 3: Weather-resistant parts don't include the UV three-piece set, so after half a year of outdoor installation, they turn yellow and crack. Correct answer: Any outdoor or window-side installation must include a UV absorber + HALS + antioxidant three-piece set—this is the basic five-year lifespan.
These three pitfalls are all checklists you must check before mass production. If one is missing, it will all break down in bulk, and repairing one screw costs three times more than new parts.
Supplement: Energy efficiency, Hui Nantian, and disassembly inspection
Energy efficiency ratings are not just about insulation layers. Machines with first-level energy efficiency have thicker insulation layers, a gentler temperature gradient between the casing and inner tank, and the plastic parts actually have lighter heat age. But after thickening the insulation layer, the spacing between the casing hanging lugs changes, stress at the mounting holes is redistributed, and machines with old molds rerouting cavities will shift where the hanging ears crack.
In energy efficiency upgrade projects, plastic parts need to be re-verified along with this. Writing this in the project list can save a batch of inexplicable after-sales expenses.
Hui Nantian is a unique working condition in South China. For a week of continuous wall moisture, the back of the shell is a wet wall, the front is the heater, and the plastic parts repeatedly absorb and release moisture at different humidity levels on both sides, with dimensional drift twice as large as measured in the constant temperature and humidity lab.
For housing parts with latch fittings, the gap must be enlarged according to the return of Nantian conditions. If the repair order gets stuck and can't be opened, the technician's visit cost is just a fraction of the cost of reissuing a whole set of molds.
Disassembly inspection is the most underestimated part of the after-sales system. After refurbishing the machine, it is sent back after replacement, and the old parts are discarded directly, essentially discarding the most authentic aging samples. One factory has after-sales staff take three photos of each rework machine for archiving, summarizing the aging location, color changes, and crack directions of plastic parts quarterly.
After two years, they can directly judge which batch of material has the wrong aging pattern by looking at the photo library. When there is a dispute over incoming materials, the photo library serves as evidence. There are no shortcuts to data accumulation; what is built up one unit after another cannot be copied by competitors.
Supplementary Note 2: Materials Science in the Installation Process and the Manual
For products like water heaters, half of the material issues are buried during the installation stage. The expansion plug of the hanging ears is misaligned, the wall surface is uneven and hard twisted, and the whole machine hangs at an angled stress point. The plastic ears have long been subjected to lateral force, causing cracks to shift from the root to the side. After-sales judges the material is brittle from photos, but it's actually the installation fault.
Later, that factory made a sheet of diagrams for the installer, drawing the horizontal and vertical tolerances of the expansion plugs in photos, and the rework rate for crooked installations was cut in half. The materials engineer's manual never wastes a word; the challenge is to make sure the installation process is actually read.
The manual also has a noteworthy reminder about the magnesium rod replacement cycle. If the magnesium rod is not replaced, scaling in the inner tank accelerates, and the concentration of scale liquid in contact between the end cap and pipe fittings rises, making material aging a chain reaction.
changed the magnesium rod reminder from a paper card to a machine reminder, and the after-sales records of the end cap were synchronized downward. The connection between these two things couldn't be found in the working schedule, but the correlation in after-sales data was clear. Material makers should get used to pushing their perspective outward; the material you choose holds half of its lifespan in the hands of the user's habits.
Extension: Three details from after-sales
Detail one, the installation clip is lost. When a technician came to install the machine, the clip fell into the insulation layer crack, so cable ties were used as a temporary substitute. After half a year, the cable ties loosened in the hot water environment and the casing started to wobble. Adding two extra clips to the installation package cost almost zero, saving the entire visit.
Detail two: Spider webs at the shell seams. Poor injection exhaust leaves fine threads at the seams; users hang cloths when cleaning the machine, complaining about workmanship rather than materials. Cleaning the mold exhaust groove can solve the problem; don't let it become a topic in quality meetings.
Detail Three: The cracking sound when powered on in winter. In the north, it's dry and cold, and the difference in thermal expansion coefficients between the shell and inner tank causes a crisp sound when the temperature rises, making users think the machine is broken. When selecting materials, writing the shrinkage rate matching of the two materials in the verification criteria is more effective than explaining it a hundred times in customer service scripts.
Conclusion
Material sells, but judgment doesn't necessarily mean someone will give it—this is the acceptance line for every material selection recommendation we make.
For the selection and mold testing of the entire set of household / bathroom / smart home lifestyle items, you can chat together
