182 扫地机器人与吸尘器件
扫地机的件多且杂
一台扫地机器人有上百个塑料件：主刷罩、边刷卡扣、驱动轮组、万向轮、尘盒、水箱、风机叶轮、齿轮箱、外壳、传感器窗。
每个件的工况都不同，这是扫地机选料的特点——不是选一种料，是选十几种料的组合。
结构件走 PA66-GF30
驱动轮组、齿轮箱壳体、主刷支架这些受力件走 PA66-GF30。
扫地机重量 3-5 kg，跌落高度 0.5-1 m，要抗跌落冲击，所以有些件要增韧。
PA66-GF30 + 增韧剂的组合，强度和韧性平衡，是扫地机结构件的主力。
现场还原：扫地机里的二十个件
2025 年 5 月，苏州一家扫地机器人厂的结构实验室，我们把一台在研机型的 BOM 摊在桌上，塑料件二十多个，一个个过料。
这是他们上一代产品踩过坑之后的动作：上一代的边刷电机支架用通用 PA66，高频振动下八个月出现支架裂纹，售后批次返修；尘盒卡扣用普通 PP，低温运输脆断率千分之五。两个坑加起来，售后成本够把整机的材料升级预算翻三倍。
这一代的选材逻辑就顺了：结构件（主壳、驱动支架）走 PA66-GF30，受力大、要刚性；传动齿轮走 POM（含油），耐磨自润滑；边刷支架走增韧 PA66，抗高频振动疲劳；尘盒和外壳件保持 PP 免成本（不受力部位不必上好料）。
研发负责人的总结很到位：「扫地机的塑料件选材，难点不是选什么料，是承认每类件该走不同的料——一个料打天下的机型，售后会替你纠正。」
扫地机行业卷到极致，BOM 成本压到每一块钱，但那个「二十个件过一遍」的下午，可能是这个品牌性价比最高的一个下午。
齿轮走 POM
扫地机的行走齿轮箱齿轮走 POM（聚甲醛）——POM 的自润滑性和尺寸稳定性在齿轮应用上优于 PA66。
PA66 齿轮的问题是吸湿——吸湿后尺寸涨、齿形变化、噪音上升。
POM 吸湿率只有 0.2%，噪音更小、寿命更长。这是家电齿轮行业的通用选择。
耐磨与自润滑
扫地机在地面长期行走，驱动轮和万向轮是磨损件。轮面走 TPE 或 TPU 包胶（静音 + 防滑），轮芯走 PA66-GF30。
主刷的固定座要耐磨——走 PA66 + MoS₂ 或 PTFE 自润滑，避免长期摩擦产生异响。异响是扫地机退货的头号原因之一。
深一层：齿轮为什么是 POM 的地盘
聊扫地机必然聊齿轮，把 POM 和 PA 在齿轮上的分工讲清楚，是这类产品选材的基本功。
POM 在小模数齿轮上的优势是体系性的：自润滑（含油 POM 摩擦系数低且稳定）、耐磨（磨耗率低）、尺寸稳（吸水率 0.2% 级，齿隙不漂）、成型性好（小模数齿形注塑精度高）。
扫地机的主刷齿轮、边刷齿轮、行走轮减速齿轮，模数小、转速中低、载荷不大、要求噪音低——POM 的特性清单和这些需求几乎逐条对齐。
PA 系在什么位置出场：载荷大、有冲击的传动位。比如行走驱动的大扭矩齿轮，POM 刚性不够会断齿，走玻纤增强 PA66 或增韧 PA。还有高温位（电机端盖附近），POM 的 90℃ 长期使用温度顶不住，PA 顶得住。
组合拳打法是行业主流：减速箱一级大齿轮用 PA66-GF30（抗冲击），末级小齿轮用含油 POM（低噪音耐磨），中间按载荷插值。
齿轮噪音这个隐性指标，一半靠齿形设计，另一半靠材料阻尼——POM 的阻尼特性让末级传动的啸叫明显低一档，这一档在消费电子产品里就是口碑。
一句话：齿轮选料先分位，后选牌。把所有齿轮塞给一种料的方案，要么噪音大、要么断齿早，两种结局选一种。
风机与噪音
吸尘器和扫地机的吸力来自风机，转速 2-5 万 rpm。
叶轮要动平衡好、尺寸稳定、不变形。走 PA66-GF30 或 PC-GF，关键是玻纤分布均匀——分布不均会导致动平衡差。
风机罩要隔音，加隔音棉或双层结构。
电池仓与阻燃
扫地机内置锂电池，电池仓必须阻燃 V-0。走无卤阻燃 PC 或 PA66，并且要通过电池安规。
电池仓的散热也要考虑——充电时电池温度可达 45-55℃，密闭电池仓要留散热通道。这一块的安全事故代价极高，不能降本。
工程实测：4 条强制测试
测试1：齿轮噪音。POM 齿轮噪音 52 dB，PA66 齿轮吸湿后升至 58 dB——齿轮走 POM。
测试2：跌落。1 m 跌落，PA66-GF30 + 增韧不开裂，纯 GF30 在 0.6 m 开裂。
测试3：耐磨。自润滑 PA66 摩擦 10 万次无异响，纯 PA66 在 3 万次出现异响。
测试4：阻燃。电池仓无卤阻燃 PC 达 V-0（1.6 mm），满足安规。
追问三连：采购最常问的三件事
一问：尘盒、水箱这些件要不要上好料。 不受力部位的原则是能省则省：尘盒 PP、透明水箱 SAN 或透明 PP，成本敏感度高的机型这是最大的省料池。但有一条底线：接触边角料位和卡扣位要复核韧性——运输低温脆断是最常见的翻车点，PP 卡扣在冬天北方物流里断过一批的教训，行业里至少传了十年。
二问：风机叶轮的材料讲究什么。 叶轮是转速最高的塑料件（万转级），三条硬要求：动平衡一致性（料密度批间要稳）、抗离心蠕变（长期高速不变形）、还有噪音（叶轮不平衡直接变噪音）。主流 PA66-GF 加低波动牌，动平衡验证按批抽测，这条投入不能省。
三问：阻燃要求卡在哪。 扫地机的阻燃重点位是充电座和电池仓：充电触点附近 V-0 起步，电池仓按电池安规走灼热丝和针焰。行走机构、外壳件一般不强制阻燃——全机阻燃的成本没人兜得住，按「带电位阻燃、非带电位普通」划线，是这个品类的通行做法。### 算一笔材料账：二十个件的 BOM 分层
扫地机的材料账，最有效的工具是 BOM 分层——把二十多个塑料件按受力档分三层，钱花在刀刃上。
第一层，受力件（驱动支架、齿轮、主刷座）：占塑料件成本四成，按高档配（PA66-GF30、含油 POM），不省钱。这一层的失效是售后主力，材料差价的回报率最高。
第二层，功能件（风机叶轮、边刷支架、水管件）：占三成，按中档配，专牌专用——叶轮看动平衡、边刷看疲劳、水管看耐弯折，各配各的。
第三层，外观和静态件（尘盒、面壳、底板）：占三成，通用料压成本，只守住低温韧性和阻燃两条底线。
分层的价值在谈判：供应商按层报价，降本谈第三层，第一层的料档谁也不许动——这是行业里反复验证过的分配原则。反过来的案例（整机统一降档）都在售后数据里还了债。
扫地机行业毛利薄，材料优化是常态，但优化的正确姿势是「结构优化」不是「全线下调」——BOM 分层就是把结构画出来的那张图。一层之差，售后曲线天壤之别。### 边界声明
| 工况 | 推荐材料 |
|---|
| 结构受力件 | PA66-GF30 + 增韧 |
| 齿轮 | POM |
| 驱动轮轮芯 | PA66-GF30 + TPE 包胶 |
| 风机叶轮 | PA66-GF30 或 PC-GF |
| 电池仓 | 无卤阻燃 PC 或 PA66 |
工程备忘
扫地机塑料件量产前必须做跌落 + 齿轮噪音 + 阻燃三项。齿轮走 POM 不走 PA66，吸湿会让噪音上升。
实战案例：常见踩坑与正解
踩坑一：按常温物性表给扫地机件选料，没考虑长期工作温度。家电件长期在 60-90℃ 下工作，常温强度再高也会热老化失效。正解：拿热老化后的数据选料，PA66 在 80℃ 长期工作要选耐热氧老化牌号。踩坑二：为了降本把增强料换成未增强料，或者把 GF30 降到 GF15。扫地机件的玻纤含量是算出来的，不是拍出来的。正解：降玻纤含量必须重算蠕变和强度，不能凭经验。踩坑三：噪音和异响问题最后才查，发现是塑料件摩擦或松动。正解：家电的噪音投诉占比很高，塑料件的配合公差和自润滑要在设计阶段就定。
反向案例：边刷支架的八个月
回头看那家苏州厂上一代的边刷支架裂纹事件，时间线值得完整记一遍。
2023 年 6 月机型上市，销量爬坡顺利。2024 年 2 月起，售后端反馈边刷异响加停转，拆机看是边刷电机支架裂纹——支架用通用 PA66，边刷电机转速高，支架带着边刷高频振动，裂纹从电机固定孔边缘萌生，八个月磨断。
问题不大但很烦：返修批次几千台，换支架要拆底盘，人工比件贵。品质部把裂纹件做了断口分析：疲劳裂纹，源点在固定孔应力集中处，材料的疲劳强度储备不足。
整改三件事：支架换增韧 PA66（疲劳强度高一档）、固定孔加金属衬套（消应力集中）、电机加减振垫。三个动作加起来单机成本多两块钱，售后曲线回到平线。
这个案例在扫地机行业很典型：高频振动是小家电材料的隐形考题——静态强度够用的料，疲劳强度未必够用。振动位的选材，把「疲劳极限」三个字从物性表里找出来，比看拉伸强度有用得多。### 延伸判断：验证顺序不要搞反
扫地机件的验证有固定顺序，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——扫地机件的选型沟通成本，基本都花在这几项反复确认上。
最后一组问答：三个纠结时刻的裁决
纠结一：整机降本压力全压到 BOM，从哪层先动。 从第三层（外观和静态件）动，动到第二层为止，第一层（受力件）设为禁区。分层管理的意义就在降本时刻显形——没有分层的 BOM，降本就是全线下调，售后曲线会替你重新分层。
纠结二：新供应商的料便宜三成，敢不敢切。 看切的层：第三层可以切（验证周期短、失效损失小），第一层切之前要全套疲劳和跌落重验——三成的价差和重验成本加切换风险比，多数时候不划算。层就是风险分级，分级就是采购策略。
纠结三：齿轮噪音投诉，先改齿形还是先换料。 先查磨耗：齿面磨痕分布能区分「设计噪音」（啮合冲击）和「老化噪音」（磨损漂移），前者改齿形，后者换含油牌。两件事反着做，钱花了噪音还在。### 补记：三个现场判断信号
信号一：支架孔位裂纹、断口平整。 高频疲劳，换增韧牌加消应力集中结构，只换料不改结构，裂纹换个位置再来。
信号二：齿轮啮合异响渐大。 磨耗加齿隙漂移，先查齿面磨痕分布，POM 位换含油牌，PA 位查吸湿——PA 齿轮吸湿后齿隙漂移是老问题。
信号三：尘盒卡扣冬天批量断。 低温脆断，PP 卡扣换增韧改性的成本极低，这类坑不用踩第二次。### 验证顺序：三步走完再下单
第一步，分层：BOM 按受力档分三层，各层定各档的验证清单。
第二层，验振动：第一层件全做高频疲劳验证，扫地机的振动工况是这类产品的主考官。
第三步，验低温：运输工况按北方冬季物流做低温脆断验证，PP 卡扣的学费不用再交。三步走完，扫地机的材料体系就能跟住产品的迭代速度。
结语
有些生意我们不做——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。
182 Floor Cleaning Robots and Vacuuming Devices
The sweeping machine has many and various parts
A robotic vacuum cleaner has hundreds of plastic parts: main brush cover, side brush buckle, drive wheel set, caster wheel, dustbin, water tank, fan impeller, gearbox, casing, sensor window.
The working conditions of each piece are different, which is a characteristic of material selection for sweepers—not choosing just one material, but selecting a combination of a dozen or so materials.
Structural parts use PA66-GF30
For load-bearing parts such as the drive wheel set, gearbox housing, and main brush bracket, use PA66-GF30.
The sweeping robot weighs 3-5 kg, with a drop height of 0.5-1 m. It needs to resist drop impact, so some parts need to be toughened.
PA66-GF30 combined with toughening agents balances strength and toughness, making it the main material for the structural parts of sweeping robots.
On-site restoration: the twenty parts inside the floor sweeper
In May 2025, at the structural laboratory of a robotic vacuum cleaner factory in Suzhou, we laid out the BOM of a prototype on the table, with more than twenty plastic parts, going through each one.
This is their response after the previous generation of products encountered problems: the side brush motor bracket of the previous generation used general-purpose PA66, which developed cracks in the bracket after eight months of high-frequency vibration, leading to after-sales batch repairs; the dustbin latch used ordinary PP, with a 0.5% brittleness rate during low-temperature transportation. The combined effect of these two issues caused after-sales costs high enough to triple the material upgrade budget for the entire machine.
The material selection logic for this generation is straightforward: structural components (main shell, drive bracket) use PA66-GF30 for high strength and rigidity; transmission gears use POM (with oil) for wear resistance and self-lubrication; side brush brackets use toughened PA66 to resist high-frequency vibration fatigue; dust box and exterior parts remain PP to save costs (non-load-bearing parts don't need premium materials).
The R&D manager's summary was very precise: 'The difficulty in selecting materials for the plastic parts of a sweeping robot is not about choosing a particular material, but about acknowledging that different parts should use different materials — if you design a model with a single material for everything, after-sales service will correct it for you.'
The robot vacuum industry has been pushed to the extreme, with BOM costs squeezed down to every single yuan, but that afternoon of 'going through twenty parts once' might have been the most cost-effective afternoon for this brand.
Gear runs on POM
The driving gearbox gear of the sweeping robot uses POM (polyoxymethylene) — POM's self-lubricating properties and dimensional stability are superior to PA66 in gear applications.
The problem with PA66 gears is moisture absorption — after absorbing moisture, their dimensions expand, the tooth shape changes, and noise increases.
POM has a moisture absorption rate of only 0.2%, produces less noise, and has a longer lifespan. This is the common choice in the household appliance gear industry.
Wear-resistant and self-lubricating
The floor cleaning robot moves on the ground for long periods, and the drive wheels and caster wheels are wear parts. The wheel surface uses TPE or TPU coating (silent and non-slip), and the wheel core uses PA66-GF30.
The main brush holder needs to be wear-resistant — use PA66 MoS₂ or PTFE self-lubricating materials to avoid long-term friction causing abnormal noise. Abnormal noise is one of the top reasons for vacuum cleaner returns.
A deeper look: Why gears are the domain of POM
When talking about floor-cleaning robots, it is inevitable to talk about gears. Explaining clearly the division of labor between POM and PA in gears is basic knowledge for material selection in this type of product.
The advantages of POM on small modulus gears are systemic: self-lubricating (oil-containing POM has a low and stable friction coefficient), wear-resistant (low wear rate), dimensionally stable (water absorption rate at the 0.2% level, no gear clearance drift), and good moldability (high injection molding accuracy for small modulus gear profiles).
The main brush gear, side brush gear, and driving wheel reduction gear of the floor cleaning machine have small modules, medium to low speeds, not heavy loads, and require low noise — the property list of POM aligns almost item by item with these requirements.
Where PA is used: in positions with heavy loads and impact in the transmission. For example, large torque gears in walking drives—POM lacks sufficient rigidity and can break teeth, so glass fiber reinforced PA66 or toughened PA is used. Also in high-temperature areas (near motor end caps), POM cannot withstand long-term use at 90°C, whereas PA can.
The combination punch approach is the industry mainstream: the first-stage large gear of the gearbox uses PA66-GF30 (impact resistant), the final-stage small gear uses oil-containing POM (low noise and wear-resistant), and the intermediate gears are chosen based on load interpolation.
This hidden indicator of gear noise is half dependent on gear design and half on material damping — the damping characteristics of POM make the whining of the final stage drive noticeably lower by one level, and this one level in consumer electronics equates to reputation.
In short: When selecting materials for gears, first classify by grade, then choose the brand. If you put all gears with one type of material, the outcome is either high noise or early tooth breakage—you have to choose between the two.
Fan and Noise
The suction of vacuum cleaners and floor sweepers comes from the fan, with a rotation speed of 20,000 to 50,000 rpm.
The impeller must have good dynamic balance, stable dimensions, and no deformation. Use PA66-GF30 or PC-GF; the key is uniform glass fiber distribution — uneven distribution will result in poor dynamic balance.
The fan cover needs to be soundproofed, with added soundproofing cotton or a double-layer structure.
Battery compartment and flame retardant
The floor-cleaning robot has a built-in lithium battery, and the battery compartment must be flame-retardant V-0. It should use halogen-free flame-retardant PC or PA66 and must pass battery safety regulations.
Battery compartment heat dissipation also needs to be considered—during charging, the battery temperature can reach 45-55°C, so a closed battery compartment must have heat dissipation channels. Safety accidents in this area are extremely costly, so costs cannot be reduced.
Engineering field measurement: 4 mandatory tests
Test 1: Gear noise. POM gear noise is 52 dB, PA66 gear rises to 58 dB after moisture absorption — gears use POM.
Test 2: Drop. A 1 m drop, PA66-GF30 toughened does not crack, pure GF30 cracks at 0.6 m.
Test 3: Wear resistance. Self-lubricating PA66 showed no abnormal noise after 100,000 frictions, while pure PA66 exhibited abnormal noise after 30,000 frictions.
Test 4: Flame retardant. The battery compartment uses halogen-free flame-retardant PC up to V-0 (1.6 mm), meeting safety regulations.
Three Consecutive Follow-up Questions: The Three Most Common Questions in Procurement
Question: Do dust boxes and water tanks need to use high-grade materials? The principle for non-stressed parts is to save material whenever possible: dust boxes made of PP, transparent water tanks of SAN or transparent PP; for cost-sensitive models, this is the biggest area for material saving. But there is a bottom line: edges in contact with waste material and snap-fit areas must be checked for toughness—brittle fractures during low-temperature transport are the most common failure points. There is a lesson that a batch of PP snaps broke during winter logistics in northern regions, which has been circulated in the industry for at least ten years.
Second Question: What are the requirements for the material of the fan impeller? The impeller is the plastic part with the highest rotational speed (tens of thousands of RPM), with three strict requirements: dynamic balance consistency (material density must be stable between batches), resistance to centrifugal creep (must not deform over long-term high-speed operation), and noise (an unbalanced impeller directly leads to noise). The mainstream material is PA66-GF with low fluctuation grades, and dynamic balance is verified by batch sampling; this investment cannot be skimped on.
Three Questions: Where are the flame-retardant requirements stuck? The key flame-retardant areas of a floor-cleaning robot are the charging dock and the battery compartment: near the charging contacts, start with V-0, and the battery compartment follows battery safety regulations, using glow-wire and needle-flame tests. The walking mechanism and outer casing parts generally do not require mandatory flame retardancy — the cost of making the whole machine flame-retardant is unbearable, so the common practice in this category is to draw the line as 'flame-retardant for live parts, normal for non-live parts.' ### Let's calculate a materials account: layering a BOM of twenty parts.
For the material accounting of the floor cleaning machine, the most effective tool is BOM layering — dividing more than twenty plastic parts into three layers according to their stress levels, spending money where it counts.
The first layer, load-bearing components (drive bracket, gears, main brush holder): accounts for 40% of the cost of plastic parts, using high-end materials (PA66-GF30, oil-containing POM), not cost-saving. Failures at this layer are the main part of after-sales service, and the return on material price difference is the highest.
Second layer, functional parts (fan impeller, side brush bracket, water pipe parts): account for 30%, matched at mid-range, each brand for its own use—look at balance for the impeller, fatigue for the side brush, and bending resistance for the water pipe, each matched to its own.
The third layer, appearance and static components (dustbin, casing, base plate): accounts for 30%, general material compression cost, only maintaining the bottom lines of low-temperature toughness and flame retardancy.
The value of tiered pricing in negotiations: suppliers quote according to tiers, cost reductions are negotiated for the third tier, and no one is allowed to change the material grade of the first tier—this is a distribution principle repeatedly validated in the industry. Cases in reverse (downgrading the entire machine uniformly) have all paid the price in after-sales data.
The floor cleaning machine industry has thin profit margins, and material optimization is a common practice. However, the correct approach to optimization is 'structural optimization,' not 'across-the-board reduction' — BOM layering is the diagram that maps out the structure. A difference of one layer can result in a huge difference in the after-sales curve.### Boundary Statement
| Operating condition | Recommended materials |
|---|
| Structural load-bearing member | PA66-GF30 Toughened |
| Gear | POM |
| Drive wheel hub | PA66-GF30 TPE Coating |
| Fan impeller | PA66-GF30 or PC-GF |
| Battery compartment | Halogen-free flame-retardant PC or PA66 |
Engineering Memo
Before mass production of the floor-sweeping machine's plastic parts, drop tests, gear noise tests, and flame retardancy tests must be conducted. The gears use POM instead of PA66, as moisture absorption will increase the noise.
Practical Case Study: Common Pitfalls and Correct Solutions
Pitfall 1: Choosing materials for robot vacuum parts based on room temperature properties, without considering long-term operating temperatures. Household appliance parts work long-term at 60-90°C, so no matter how high the strength at room temperature is, they will fail due to thermal aging. Correct approach: select materials based on data after thermal aging; for PA66 working long-term at 80°C, choose a grade resistant to heat and oxidative aging.
Pitfall 2: Reducing costs by replacing reinforced materials with unreinforced ones, or reducing GF30 to GF15. The glass fiber content of robot vacuum parts is calculated, not guessed. Correct approach: lowering glass fiber content requires recalculating creep and strength, and cannot rely on experience.
Pitfall 3: Noise and abnormal sounds are checked only at the end, finding that they are caused by plastic part friction or looseness. Correct approach: noise complaints make up a large proportion in household appliances; the tolerance and self-lubrication of plastic parts must be determined during the design stage.
Reverse Case: Eight Months of Brushing the Edge Bracket
Looking back at the previous generation edge brush bracket cracking incident at that Suzhou factory, the timeline is worth recording in full.
The model was launched in June 2023, and sales ramped up smoothly. From February 2024, after-sales feedback indicated abnormal noise from the side brush and stoppage. Upon disassembly, it was found that the side brush motor bracket had cracks — the bracket was made of general-purpose PA66, and the side brush motor rotates at high speed. With the high-frequency vibration of the brush, cracks originated from the edge of the motor mounting hole and propagated to break over eight months.
The problem is not serious but very annoying: there are several thousand units in the repair batch, and changing the bracket requires disassembling the chassis, making the labor cost higher than the parts. The quality department conducted fracture analysis on the cracked parts: fatigue cracks, with the origin at the stress concentration of the mounting hole, and the material's fatigue strength reserve is insufficient.
Three corrective actions: replace the bracket with toughened PA66 (one grade higher in fatigue strength), add a metal bushing to the mounting hole (to relieve stress concentration), and add vibration-damping pads to the motor. These three actions together increase the cost of a single unit by two yuan, and the after-sales curve returns to a flat line.
This case is very typical in the robotic vacuum industry: high-frequency vibration is a hidden challenge for small appliance materials—materials with sufficient static strength may not necessarily have enough fatigue strength. When selecting materials for vibrating parts, finding the words 'fatigue limit' in the material property table is much more useful than looking at tensile strength. ### Extended judgment: Do not reverse the verification order.
The verification of the sweeping machine parts has a fixed order; skipping the earlier steps and directly doing the later ones is equivalent to doing it for nothing.
Step one is to verify the material itself: mechanics, thermology, flame retardancy, and electrical properties, making sure the part number was not chosen incorrectly.
Step 2: Verify the process window: For the same batch of material, parts produced under different mold temperatures and different holding pressures may show performance differences of over 20%, so the process window needs to be determined.
The third step is to perform validation on the complete machine or complete part: install it in actual working conditions to test its lifespan. Many people follow the reverse order—they directly install the machine to test its lifespan. If it fails, they don’t know whether it’s a material problem or a process problem, so they keep changing materials and can’t get results for half a year.
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 parts for the floor-sweeping machine is basically spent on repeatedly confirming these few items.
The final Q&A: Judgments on three moments of dilemma
Dilemma 1: When the pressure to reduce the overall cost of the machine is fully applied to the BOM, which layer should be tackled first? Start from the third layer (appearance and static parts) and move until the second layer; the first layer (load-bearing parts) is set as a forbidden zone. The significance of layered management becomes apparent when cutting costs—without a layered BOM, cost reduction means a blanket reduction across the board, and the after-sales curve will re-layer for you.
Dilemma 2: The materials from the new supplier are 30% cheaper. Do we dare to switch? Consider the layer to switch: the third layer can be switched (short verification cycle, low failure loss), but before switching the first layer, a full set of fatigue and drop retests is required—the 30% price difference compared to the cost of retesting and switching risk is often not worth it. Layers represent risk classification, and classification determines procurement strategy.
Entanglement Three: Gear noise complaints – should we change the tooth profile first or switch materials? First, check for wear: the distribution of wear marks on the tooth surface can distinguish 'design noise' (meshing impact) from 'aging noise' (wear drift); the former requires changing the tooth profile, the latter requires switching to an oil-containing brand. Doing these two things in reverse will spend money but the noise will remain. ### Addendum: Three on-site diagnostic signals
Signal 1: Cracks at the bracket hole positions, fracture surfaces are smooth. High-frequency fatigue; switch to a tougher brand and add stress-relief structures, only change the material without altering the structure, the crack will just occur in another location again.
Signal 2: The abnormal noise of gear meshing is gradually increasing. Wear increases and gear clearance drifts, first check the distribution of wear marks on the gear teeth, for POM position replace with oil-containing grade, for PA position check for moisture absorption—after PA gears absorb moisture, gear clearance drift is an old problem.
Signal Three: Dust box clips break in batches during winter. Brittle at low temperatures, the cost of replacing PP clips with toughened modified ones is very low, so this pit doesn’t need to be stepped into a second time. ### Verification sequence: complete the three steps before placing an order
Step one, layering: The BOM is divided into three layers according to the force levels, and each layer defines the verification checklist for each level.
Second level, vibration testing: all first-level components undergo high-frequency fatigue verification. The vibration conditions of the sweeper are the main examiner for this type of product.
Step three, low-temperature testing: Perform low-temperature brittle fracture verification under northern winter logistics conditions, and there is no need to pay the tuition fee for the PP buckles. After completing the three steps, the material system of the sweeper can keep up with the product iteration speed.
Conclusion
There are some businesses we don't engage in—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.
