上季度，一家做机器人本体的客户发来一张爆炸图，圈了三个位置：底座、导轨滑块、限位块。他问得很直接："这三个件，能不能都换成改性尼龙？"
我看了图，回他：这三个件，答案不是"能"或"不能"，是三个不同的答案。
底座的主体，大概率要留在金属上；导轨滑块的耐磨衬件可以做；限位块和减振垫，反而是最适合上塑料的。
很多人把一组件打包问一次料，这本身就是选材容易走偏的起点。这篇就把这三类件分开讲。
一、先分清：底座是"承力主体"，不是"结构件"
底座在机器人里的角色是承力基准——它要把整机重量和动态反力传到地面，还要提供一个不变的安装平面。
这个角色决定了它对材料的要求是：高模量、抗蠕变、长期平面度稳定。
而热塑性材料在这三项上，恰恰都不是强项。
所以底座的主体（底板、立柱、安装面）几乎都是铸铁、钢或铝合金。这不是保守，是物理层面的分工：金属的模量比塑料高一到两个数量级，长时载荷下的蠕变也小得多。
那底座上有没有塑料件的位置？有，但是配角件：
- 减振垫 / 隔振块：金属垫片传导振动，用弹性体或增韧尼龙做隔振，反而更好；
- 线缆固定块、防护罩、盖板：不承力，做塑料完全是合理选择；
- 限位块：承受撞击但不承受持续静载，也是塑料的合适位置。
一句话：底座这件事，要问的不是"底座能不能用塑料"，是"底座上哪些件不用塑料"。
二、导轨滑块：耐磨与刚性，是两笔不同的账
导轨滑块（直线导轨的滑块）里的塑料件，通常是滑块衬、保持架、端盖、防尘件。
这些件的工况有几条特点：
往复次数极高。 一趟行程一次往复，一天上万次，一年就是几百万次。这类件是典型的高周低应力疲劳件。
表面要耐磨。 滑块衬与导轨直接接触，磨耗决定精度保持。
要有一定刚性。 滑块衬如果太软，在侧向力下会变形，影响导向精度。
但注意一点：滑块承受的主载荷，仍由导轨与滚珠承担。塑料衬件的作用是导引、减磨、防尘、降噪，不是承担主承载路径。把滑块衬当成承力件来设计，是把角色搞错了。
这里有一个容易被忽略的点：滑块衬的磨耗，取决于"塑料对钢"的摩擦副，不是塑料对塑料。选材要看的是这对摩擦副的配合，而不是单看塑料的硬度。
还有一条：滑块衬的结构比材料更容易出问题。
壁厚不均、卡口过薄，都会在侧向力下先变形。
衬件的账，一半在摩擦副，一半在截面设计上。
尺寸这一项在滑块衬上也别忽略。
衬件吸湿后会涨，涨了就是预压变大，滑动阻力跟着上来。
预压的余量要按湿态留，不能按干态留。
三、限位块与减振件：这才是塑料的主场
限位块、缓冲块、减振垫这一类件，是最适合上塑料的。
原因很简单：它们承受的是冲击和振动，不是持续静载。
冲击载荷的特点是时间短、峰值高。这时材料需要的是韧性和阻尼，而金属的阻尼很差、韧性也未必高。尼龙和热塑性弹性体在这里反而有优势——吸能、降低噪音、不损伤对偶件。
这也是我们在一线观察到的现象：客户拿着底座来问塑化，十有八九方向就错了；但拿着限位块、缓冲垫来问，方向往往是对的。因为这两类件的失效模式不同——一个是蠕变，一个是冲击。
四、选型判据表（这是本篇最该收藏的一页）
门限值是方向性建议，不是验收标准——实际数值必须由你的载荷、行程和寿命实测确定。
| 指标 | 方向性门限 | 验证方法 / 标准 | 常见失效 | 通行解法 | 对应助剂体系 |
|---|
| 长期蠕变（持续载荷下） | 设计寿命内变形可控 | ISO 899 或长期加载实测 | 缓慢下沉、平面度超差 | 提高刚性/结晶度，或改回金属 | 成核剂（提高结晶度） |
| 弯曲模量 | 按结构刚性要求定 | ISO 178 | 受力挠曲、导向失准 | 玻纤 / 矿物填充 | 偶联剂（界面） |
| 磨耗（对钢导轨） | 按往复次数定寿命目标 | 自建往复台架 | 衬件磨薄、精度下降 | 耐磨体系 + 对偶面配合 | 耐磨填料 / 润滑剂 |
| 缺口冲击（限位/缓冲件） | 覆盖最大冲击载荷 | GB/T 1043 | 撞击开裂、崩块 | 增韧体系 | 增韧剂 |
| 平面度 / 尺寸稳定 | 调湿后满足装配要求 | 三坐标 / ISO 294 | 装配应力、导向偏差 | 低吸水基材 + 调湿 | — |
| 长期热氧保留率 | 按实际温度考核 | ISO 527 | 变脆、发白 | 稳定化体系 | 抗氧剂 |
| 阻尼 / 减振（缓冲件） | 按振动测试效果定 | 振动台对比 | 振动传导大、噪音高 | 选高阻尼体系 | — |
| 滑动阻力（衬件） | 按预压与吸湿余量定 | 装导轨实测推力 | 吸湿后变紧、卡滞 | 湿态留预压余量 | 润滑剂（内外平衡） |
| 嵌件拉脱 | 按装配与维修工况定 | 拉脱力实测 | 嵌件松、维修损坏 | 嵌件结构与预热 | — |
怎么用这张表：先看第一行"长期蠕变"。这是结构件选材的第一道关。如果这个件要长期承受静载荷，蠕变过不去，其他指标都不用看——因为它的失效是缓慢而不可逆的。
五、四种常见失效，和它们真正的根因
失效一：件装上去半年，平面度超差、定位偏移。
根因是长期蠕变。持续静载下材料缓慢变形，件"塌"了一点点。这一条在塑料件上比磨耗更常见，也更容易被误判为"装配问题"。
失效二：滑块衬磨薄，导向精度下降。
根因是磨耗。要查两件事：对偶导轨的表面粗糙度与硬度；润滑状态。塑料对钢的摩擦副，磨损常发生在塑料侧，诱因却在钢材侧。
失效三：限位块被撞裂。
根因通常是低温缺口冲击不足或结构圆角不够。低温环境与低温工况要单独考核——常温做出来的数据，冬天会不一样。
失效四：同一批件尺寸散、装配困难。
这多半是吸湿或分散不均。玻纤填充件尤其要注意玻璃纤维的分散与长度保留。看到这个现象，先查混料和干燥，再谈换料。
失效五：衬件装上去就发紧，跑一会儿才顺。
根因常是吸湿后的预压变大，或有毛边卡在配合面上。
先查湿态尺寸和飞边，别急着换更软的料。
装上去就紧的件，数据上往往早有预警，只是按干态出的报告把它盖住了。
这里有一条要直说的：结构件的失效排查，先分清这个件承受的是"持续载荷"还是"冲击载荷"，再谈材料。 两类件的解法方向相反——持续载荷要刚，冲击载荷要韧。
六、加工与验证：几件必须提前定的事
干燥。 尼龙必烘，含水率超标会在熔融时水解降解，玻纤填充件尤其明显。干燥窗口按实测含水率定。
玻纤的取向与熔接线。 玻纤件是各向异性的。熔接线是弱区，玻纤含量越高越明显。 限位块这类受冲击的件，熔接线绝不能落在受冲击方向。
纤维长度保留。 玻纤在加工中会断裂，件上的实际纤维长度比料里短。样条数据不等于件上性能，这一点在薄壁件上尤其明显。
验证顺序。 建议这样排，顺序不要换：
1. 材料级：蠕变、模量、冲击、磨耗
2. 件级：平面度、装配间隙、嵌件拉脱
3. 结构台架：按实际载荷做静载与振动
4. 整机：装到本体上跑典型动作
5. 环境叠加：温度 + 湿度 + 长时载荷
七、边界：什么时候这事不该谈
以下四种情况，这些件走改性尼龙不建议推进：
其一，承担主承载路径且要求长期精度稳定。 这就是底座主体的角色——留在金属上。塑料的模量和蠕变特性决定了它不适合当高精度承力基准。
其二，长期静载且温度较高的位置。 温度会显著加快蠕变。高温 + 持续载荷，是塑料结构件最危险的组合。
其三，要求亚微米级平面度的安装基准面。 这类精度需要金属或特种材料，塑料靠调湿稳定不到这个量级。
其四，年用量小到摊不平模具。 这类件通常要开专用模，用量太小从经济上不成立。
其五，要求长期尺寸零漂移的定位件。 尼龙吸湿后的尺寸变化是客观存在的。
定位件的公差如果小于吸湿变化的量级，靠材料和调湿都压不住，要回到金属。
把这五条写在前面，不是劝退，是省时间。 把不该塑化的件塑化了，最后往往退回来——回退的成本，比一开始就不做高得多。
八、三个件分开算：一张对照表
把三类件摆在一起看，差异一目了然。
| 件 | 在整机里的角色 | 主要载荷 | 能不能塑化 | 关键指标 |
|---|
| 底座主体 | 承力基准 | 持续静载 + 动态反力 | 不建议 | 模量、抗蠕变、平面度 |
| 导轨滑块衬件 | 导引与减磨 | 高周低应力 + 摩擦 | 可以 | 磨耗、刚性、湿态预压 |
| 限位块 / 减振垫 | 撞击与隔振 | 短时冲击 + 振动 | 首选塑料 | 韧性、阻尼、低温冲击 |
这张表最该带走的不是"能"和"不能"，是那句"为什么不建议"。
底座主体不是不能用塑料，是它承担的精度责任，塑料接不住。
限位块不是"凑合能用"，是它要的韧性正好是塑料的长处。
选型最容易犯的错，是把三类件放在一句话里问。
一句话问出来的答案，必然是按最难的那类件给的，另外两类就白挨了。
分件问，反而省时间。
换料风险清单（从金属换到改性尼龙，要动的东西）
| 环节 | 要动什么 | 容易漏的点 |
|---|
| 模具 | 收缩补偿按件做，玻纤件有方向性 | 沿用金属件尺寸直接开模 |
| 干燥 | 玻纤填充尼龙按实际含水率定窗口 | 回用料掺入带入的水分 |
| 料温 / 模温 | 玻纤件模温影响浮纤与表面 | 只按牌号推荐值给 |
| 保压与脱模 | 厚壁件收缩大，保压曲线要重定 | 脱模太早导致变形 |
| 嵌件 | 嵌件周围熔接线要避让受力区 | 嵌件预热与包胶温度 |
| 调湿 | 需调湿的件要定条件与复测 | 忽略吸湿带来的尺寸变化 |
| 验证顺序 | 材料 → 件级 → 结构台架 → 整机 → 环境 | 只做短时测试，不做蠕变 |
一页纸汇报表（给要向上汇报的人）
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项目：机器人底座周边结构件 · 材料路线评估
结论方向：分件决策——滑块衬与限位块可塑化，底座主体建议留金属
一、必须守住的三条
1. 先分清"持续载荷件"与"冲击载荷件"，两类分开选
2. 持续载荷件必须做蠕变数据，不能只看短时强度
3. 冲击件必须按最低温做缺口冲击
二、前置条件（任一不满足则建议暂缓）
· 该件不承担主承载路径
· 长时载荷下的变形量在设计允许内
· 有蠕变或长期加载验证手段
· 年用量足以摊薄专用模具
三、下一步动作
1. 把爆炸图上的件按"承力 / 非承力"分类
2. 对候选件做长时加载变形测试
3. 冲击件补做最低温缺口冲击
风险提示：本类件的主要不确定性在长期蠕变，不在初始强度。
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读者常问的两句
问：机器人底座整体换成玻纤增强尼龙，能减重不少吧？
减重是能减，但底座要的是不变形，玻纤尼龙的模量和蠕变达不到这个量级。减重应该从非承力件上找，不该从基准件上找。 把基准件换成塑料，省下的重量会在精度上还回去。
问：滑块衬和限位块能不能用同一种料？
不推荐。滑块衬要耐磨、要刚性；限位块要韧性、要吸能。两者一个怕磨、一个怕撞，是同一种基材的两个相反方向。 分开选，各用各的体系。
结语
机器人底座周边件的选材，说到底是一道分件题，不是一次性选料题。
判断链只有三条：
先分承力与非承力 → 再看载荷是持续还是冲击 → 最后才选体系。
三条都定完，"能不能用塑料"这个问题自然就有答案了。
如果你手上正有一组结构件要定料，把三样东西发过来就能给方向：件在整机里的受力角色、长时载荷量级、有没有冲击。
最后补一句：结构件塑化最容易省下的，是重量；
最容易还回去的，是精度和维修次数。这两笔要一起算。
关于我们，四句话。
做改性尼龙粒子：PA6、PA66、PA46、PA11、PA12、PA6T、PA9T 及尼龙合金，也做改性 PPO、PPS 与热塑性弹性体。
做原料：各大化工巨头的尼龙树脂、副牌料与大包料现货。
做回收：长期收尼龙原料、水口回料与各类尼龙废料，有正规处置渠道。
做陪跑：把一个件从选料聊到试模，把不该上塑料的地方先讲清楚。
Last quarter, a client who makes robot bodies sent over an exploded diagram, circling three positions: the base, the guide rail slider, and the limit block. He asked very directly: 'Can all three of these parts be replaced with modified nylon?'
I looked at the picture and replied to him: For these three items, the answer is not 'can' or 'cannot,' it is three different answers.
The main body of the base will most likely need to remain metal; the wear-resistant lining of the guide rail slider can be made; the limit block and vibration damping pad, on the other hand, are most suitable for plastic.
Many people package a component and ask about the material all at once, which itself is a starting point where material selection can easily go astray. This article separates these three types of parts for discussion.
1. First distinguish: the base is the 'load-bearing main body,' not a 'structural component'
The role of the base in a robot is to serve as the reference for bearing force — it has to transfer the entire machine's weight and dynamic reaction forces to the ground, and also provide a fixed mounting surface.
This role determines that its requirements for the material are: high modulus, creep resistance, and long-term flatness stability.
And thermoplastic materials, in these three aspects, are precisely not strong.
So the main body of the base (base plate, columns, mounting surface) is almost all made of cast iron, steel, or aluminum alloy. This is not conservatism; it's a division on the physical level: the modulus of metals is one to two orders of magnitude higher than that of plastics, and their creep under long-term loads is also much smaller.
Is there a place for plastic parts on the base? Yes, but it's for secondary parts:
- Vibration damping pad / isolation block: Metal washers transmit vibration, using elastomers or toughened nylon for isolation works even better;
- Cable fixing blocks, protective covers, and panels: they do not bear load, so making them out of plastic is completely reasonable;
- Limit block: bears impact but not continuous static load, also an appropriate location for plastic.
In a word: regarding the base, the question is not 'Can the base be made of plastic?' but 'Which parts of the base should not be made of plastic?'.
2. Guide Rail Slider: Wear Resistance and Rigidity Are Two Separate Issues
The plastic parts in the guide rail slider (linear guide slider) are usually the slider liner, retainer, end cap, and dustproof parts.
The working conditions of these parts have several characteristics:
The number of reciprocations is extremely high. One trip counts as one reciprocation, which occurs tens of thousands of times a day, amounting to several million times a year. These kinds of parts are typical high-cycle, low-stress fatigue parts.
The surface must be wear-resistant. The slide block liner is in direct contact with the guide rail, and wear determines the maintenance of accuracy.
It needs to have a certain rigidity. If the slider bushing is too soft, it will deform under lateral force, affecting the guiding accuracy.
But note one point: the main load borne by the slider is still supported by the guide rails and balls. The role of the plastic liner is to guide, reduce friction, prevent dust, and reduce noise, not to bear the main load path. Designing the slider liner as a load-bearing component is mistaking its role.
Here is a point that is easily overlooked: the wear of the slider lining depends on the 'plastic against steel' friction pair, not plastic against plastic. When selecting materials, one should consider the compatibility of this friction pair, rather than just the hardness of the plastic.
There is one more thing: the structure of the slider lining is more prone to problems than the material.
Uneven wall thickness and overly thin joints will deform first under lateral forces.
The accounting for the liner is half in the friction pair and half in the cross-section design.
Don't ignore the size aspect on the slider lining either.
After the lining absorbs moisture, it will swell. When it swells, the preloading increases, and the sliding resistance rises accordingly.
The precompression allowance should be left according to the wet state, not the dry state.
3. Limit Blocks and Vibration Dampers: This Is the True Realm of Plastics
Limit blocks, buffer blocks, and vibration-damping pads are the most suitable parts for being made of plastic.
The reason is simple: they bear impact and vibration, not continuous static load.
The characteristics of impact loads are short duration and high peak. At this time, what the material needs is toughness and damping, but metals have poor damping and not necessarily high toughness. Nylon and thermoplastic elastomers actually have an advantage here—they absorb energy, reduce noise, and do not damage mating parts.
This is also a phenomenon we have observed on the front line: when customers bring the base to ask about plasticization, nine times out of ten the direction is wrong; but when they bring the limit block or buffer pad to ask, the direction is often correct. This is because the failure modes of these two types of parts are different—one is creep, the other is impact.
4. Selection Criteria Table (This is the page you should collect the most in this article)
Threshold values are directional recommendations, not acceptance criteria—the actual numbers must be determined by your load, stroke, and service life measurements.
| Indicator | Directional Threshold | Verification Method / Standard | Common Failures | Common solution | Corresponding auxiliary agent system |
|---|
| Long-term creep (under sustained load) | Deformation controllable within the design life | ISO 899 or long-term load testing | Slow sinking, extremely poor flatness | Increase rigidity/crystallinity, or revert to metal | Nucleating agent (increases crystallinity) |
| Bending modulus | Determined according to structural rigidity requirements | ISO 178 | Deflection under force, misalignment in guidance | Fiberglass / Mineral Filled | Coupling agent (interface) |
| Wear (on steel guide rails) | Set lifespan target based on the number of reciprocations | Self-built reciprocating test bench | Liner thinning and precision decline | Wear-resistant system Paired surfaces | Wear-resistant filler / Lubricant |
| Notch Impact (Limit/Buffer Component) | Cover the maximum impact load | GB/T 1043 | Impact cracking, spalling | Toughening system | Toughening agent |
| Flatness / Dimensional Stability | Meets assembly requirements after humidity adjustment | Coordinate Measuring Machine / ISO 294 | Assembly stress, guiding deviation | Low water absorption substrate Humidity adjustment | — |
| Long-term thermal-oxygen retention rate | Assess based on actual temperature | ISO 527 | become brittle and turn white | Stabilization system | Antioxidant |
| Damping / Vibration Reduction (Cushioning Components) | Determine according to the vibration test results | Vibration Table Comparison | High vibration transmission and loud noise | Choose a high damping system | — |
| Sliding Resistance (Liner) | Determined by pre-pressing and moisture absorption margin | Measured thrust with installed guide rail | Becomes tight and stuck after absorbing moisture | Wet-state reserved preloading margin | Lubricant (Internal and External Balance) |
| Insert pull-out | Determined according to assembly and maintenance conditions | Pull-out Test | Loose insert, damaged during maintenance | Insert structure and preheating | — |
How to use this table: first look at the first row 'long-term creep'. This is the first critical step in selecting materials for structural components. If the component has to endure a static load for a long time and it fails the creep criteria, there is no need to look at other indicators — because its failure is slow and irreversible.
Five, four common failures and their real root causes
Failure 1: After being installed for six months, the flatness is extremely poor and the positioning is off.
The root cause is long-term creep. Under continuous static load, the material slowly deforms, and the part 'sags' a little bit. This is more common in plastic parts than wear and is also more easily misjudged as an 'assembly problem'.
Failure 2: The slider lining is worn thin, and the guiding accuracy decreases.
The root cause is wear. Two things need to be checked: the surface roughness and hardness of the paired guide rails; the lubrication condition. For a plastic-to-steel friction pair, wear often occurs on the plastic side, but the trigger is on the steel side.
Failure 3: The limit block is cracked.
The root cause is usually insufficient impact from low-temperature gaps or inadequate structural fillets. Low-temperature environments and low-temperature conditions need to be evaluated separately—data obtained at normal temperature will be different in winter.
Failure 4: The dimensions of the same batch of parts are inconsistent, making assembly difficult.
This is mostly due to moisture absorption or uneven dispersion. Special attention should be paid to the dispersion and length retention of glass fibers in glass fiber-filled parts. When you see this phenomenon, first check the mixing and drying, then talk about changing the material.
Failure 5: The liner feels tight when installed and only becomes smooth after running for a while.
The root cause is often the increase in pre-pressure after moisture absorption, or burrs getting stuck on the mating surface.
First check the wet dimensions and flash, don't rush to switch to softer material.
Parts that become tight once installed often had early warnings in the data, but they were covered up according to the dry-state report.
There's something that needs to be said directly: When investigating the failure of a structural part, first distinguish whether the part is bearing a 'static load' or an 'impact load' before discussing the material. The approaches for the two types of parts are opposite — static loads require stiffness, while impact loads require toughness.
6. Processing and Verification: Several Things That Must Be Decided in Advance
Drying. Nylon must be baked; if the moisture content exceeds the standard, it will hydrolytically degrade during melting, which is especially obvious for glass fiber-filled parts. The drying window is determined according to the measured moisture content.
Orientation of glass fibers and weld lines. Glass fiber parts are anisotropic. Weld lines are weak areas, and the higher the glass fiber content, the more pronounced they are. For parts like limit blocks that are subjected to impact, weld lines must never be located in the direction of impact.
Fiber length is retained. Glass fibers break during processing, so the actual fiber length in the part is shorter than in the material. Spline data does not equal part performance, which is especially evident in thin-walled parts.
Verification order. It is recommended to arrange it like this, do not change the order:
1. Material level: creep, modulus, impact, wear
2. Component level: flatness, assembly clearance, insert pull-out
3. Structural test bench: perform static load and vibration according to actual load
4. Whole machine: attach to the main body and perform typical actions
5. Environmental superposition: temperature humidity long-term load
7. Boundaries: When This Matter Should Not Be Discussed
In the following four situations, it is not recommended to proceed with modified nylon for these parts:
First, it bears the main load path and requires long-term precision stability. This is the role of the base body—to remain on the metal. The modulus and creep properties of plastic determine that it is not suitable as a high-precision load-bearing reference.
Secondly, locations with long-term static loads and relatively high temperatures. High temperatures significantly accelerate creep. The combination of high temperature and sustained load is the most dangerous for plastic structural components.
Thirdly, it requires a mounting reference surface with sub-micron level flatness. This level of precision requires metal or special materials; plastic cannot achieve this scale of stability even with humidity adjustment.
Fourth, the annual usage is too small to justify the mold. Such parts usually require a specialized mold, and if the usage is too low, it is not economically feasible.
Fifth, positioning parts that require long-term dimensional stability. The dimensional changes of nylon after moisture absorption are an objective reality.
If the tolerance of the positioning part is smaller than the magnitude of moisture absorption changes, neither material choice nor humidity adjustment can control it; it has to go back to metal.
Writing these five points at the beginning is not to discourage, but to save time. Items that shouldn't be plasticized but are plasticized often end up being returned — the cost of return is much higher than not doing it in the first place.
8. Count the three items separately: one comparison table
Placing the three types of components together, the differences are immediately clear.
| piece | The role in the whole machine | Main payload | Can it be plasticized? | Key indicators |
|---|
| Base body | Load-bearing reference | Continuous static load Dynamic reaction | Not recommended | Modulus, creep resistance, flatness |
| Guide Rail Slider Bushing | Guiding and Reducing Friction | High frequency, low stress Friction | Okay | Wear, rigidity, wet-state precompression |
| Limit block / Vibration damping pad | Impact and Vibration Isolation | Short-term impact vibration | Preferred plastic | Toughness, damping, low-temperature impact |
The thing that should be taken away from this table the most is not 'can' and 'cannot,' but the sentence 'why it is not recommended.'
The base body is not incapable of using plastic; it's that it bears precision responsibility, which plastic cannot handle.
The limit block is not 'just good enough to use'; the toughness it requires happens to be the strength of plastic.
The easiest mistake in selection is to put three types of components in one sentence when asking.
The answer given to a question asked in one sentence is bound to be based on the most difficult type; the other two types will be ignored.
Asking in parts actually saves time.
Material Change Risk List (from metal to modified nylon, things that need to be changed)
| link; segment; part | What needs to be moved? | Points that are easy to overlook |
|---|
| Molds | Shrinkage compensation is done per piece, and fiberglass parts have directionality. | Directly make the mold using the existing metal part dimensions |
| Dry | Glass fiber reinforced nylon sets the window according to the actual moisture content | Recycled materials mixed with the water content brought in |
| Material Temperature / Mold Temperature | The effect of mold temperature of fiberglass parts on floating fibers and surface | Give only according to the recommended value by grade |
| Pressure Holding and Demolding | Thick-walled parts have large shrinkage, and the holding pressure curve needs to be redefined. | Removing from the mold too early causes deformation |
| Insert | The weld line around the insert should avoid the stress area | Insert Preheating and Encapsulation Temperature |
| Humidity control | Parts that require humidity adjustment need to set conditions and re-measure | Ignore dimensional changes caused by moisture absorption |
| Verification order | Material → Part level → Structural test rig → Complete machine → Environment | Only perform short-term tests, do not perform creep tests |
One-page report sheet (for people who need to report upwards)
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Project: Peripheral Structural Components of Robot Base · Material Route Evaluation
Conclusion direction: Part decision — the slider lining and limit block can be plasticized, the base body is recommended to remain metallic
1. Three Rules That Must Be Followed
1. First, distinguish between 'continuous load parts' and 'impact load parts', and select them separately.
2. Components subject to sustained loads must undergo creep testing; short-term strength alone is not sufficient.
3. The impact test piece must be notched and impacted at the lowest temperature.
2. Precondition (It is recommended to postpone if any are not met)
· This part does not bear the main load path
· The deformation under long-term load is within the design allowance
· Means to verify creep or long-term loading
· Annual usage is enough to amortize the dedicated mold
3. Next Steps
1. Classify the parts on the exploded view as 'load-bearing / non-load-bearing'
2. Perform long-term load deformation test on the candidate part
3. Re-manufacture impact test specimen for minimum temperature notch impact
Risk warning: The main uncertainty of this type of material lies in long-term creep, not in initial strength.
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Two questions readers often ask
Q: If the robot base is entirely replaced with glass fiber reinforced nylon, it should reduce the weight quite a bit, right?
Weight reduction is possible, but the base needs to remain undeformed, and the modulus and creep of glass fiber nylon do not reach this level. Weight reduction should be sought from non-load-bearing components, not from reference components. Replacing the reference component with plastic will save weight, but that weight will be paid back in terms of precision.
Question: Can the slider bushing and the limit block be made from the same material?
Not recommended. Slider liners need to be wear-resistant and rigid; limit blocks need to be tough and energy-absorbing. One is afraid of wear, the other is afraid of impact—they are two opposite directions of the same base material. Select them separately and use each within its own system.
Conclusion
The selection of materials for the peripheral parts of the robot base is ultimately a component-by-component question, not a one-time material selection question.
There are only three judgment chains:
First distinguish between load-bearing and non-load-bearing → then see whether the load is continuous or impact → finally choose the system.
Once all three are set, the question of 'whether you can use plastic' naturally has an answer.
If you currently have a set of structural components to determine the materials, sending over three things can give direction: the role of the part in the overall machine's load-bearing, the magnitude of long-term loads, and whether there are impacts.
Finally, one last point: the easiest thing to save when plasticizing structural parts is weight;
The easiest to return are precision and the number of repairs. These two should be calculated together.
About us, four sentences.
Manufacture modified nylon pellets: PA6, PA66, PA46, PA11, PA12, PA6T, PA9T, and nylon alloys, also produce modified PPO, PPS, and thermoplastic elastomers.
Raw materials: Nylon resins from major chemical giants, secondary-grade materials, and bulk material stock.
Engage in recycling: long-term collection of nylon raw materials, sprue regrind, and various nylon wastes, with proper disposal channels.
Act as a running companion: discuss an item from material selection to mold testing, and clarify the areas that shouldn't be made of plastic in advance.
