硬度计一压一个数，同一件两个人测出三个值。TPE硬度读不准，选型从根上就歪了。
TPE硬度怎么读？先分清两个刻度
TPE 的硬度，是所有选型的起点，也是最容易被误读的一个数。
先分清刻度：TPE 主力刻度是 Shore A，0 到 100；超软料用 Shore 00，硬料用 Shore D。三个刻度对应三种手感区间，用错刻度，读数毫无意义。
| 刻度 | 手感区间 | 典型物 |
|---|
| Shore 00 | 豆腐→橡皮 | 凝胶垫、仿生皮肤、减震内衬 |
| Shore A | 橡皮→硬塑料 | 玩具、护套、密封条、鞋底 |
| Shore D | 硬塑料 | 波纹管、齿轮、脚轮 |
Shore A 是 TPE 的基本语言：0 是接近液态的果冻，100 是接近硬塑料。每 10 度一档，手感完全不同：
| Shore A | 实物锚点 | 常见件 |
|---|
| 0-10 | 果冻、软糖 | 凝胶垫、仿生皮肤 |
| 20-30 | 橡皮筋、鼠标垫 | 玩具、表带内衬 |
| 40-50 | 手机壳、轮胎胎面 | 护套、握把 |
| 60-70 | 牙刷柄、鞋底 | 工具手柄、密封件 |
| 70-80 | 轮胎、雨刮条 | 鞋底、脚轮 |
| 80-95 | 实心轮胎、擀面杖 | 脚轮、耐磨件 |
Shore A 70 手感约等于牙刷柄——这是行业里公认的“手感标尺”，采购和工程师都拿它当锚点。
你捏过牙刷柄，就知道 70A 是什么手感；你说要“比橡皮筋硬一点”，对应的就是 30-40A。
技术金句：硬度数字会骗人，手感锚点不会——把 Shore 值翻译成摸过的东西，选型才不走样。
硬度表不是随便印的：正规物性表会标注测试标准（ASTM D2240 / ISO 868 / GB/T 531.1 一类）和测试条件，没有标注的硬度值，参考价值要打个问号。
看表先看脚注，这是老采购的习惯——脚注里藏着测试条件，测试条件决定数字含义。
为什么硬度会读不准？温度、厚度、仪器三头骗人
硬度读数不对，六成不是料的问题，是测法的问题。四个最常见的干扰：
一是温度。 TPE 的硬度对温度极其敏感：同样一批料，25℃ 测是 70A，40℃ 测可能只有 65A，冬天 10℃ 测又变成 75A。温度每差 10℃，读数能差 3-5 度。
所以“夏天软的料冬天变硬”，很多时候不是批次变了，是环境变了。
二是厚度。 硬度计的压针会压穿试样，试样太薄，读数偏硬。标准要求试样厚度至少 6mm（或三片叠加），很多人拿 2mm 的片材直接测，读数凭空高 5-10 度。
三是仪器。 不同厂家、不同状态的硬度计，读数可能差 5 度。A 型和 D 型混用、压针磨损、弹簧老化，都会让数字漂移。
同体系对比，必须用同一台仪器、同一个环境。
四是读数时间。 压针压下去，读数会随时间漂移：1 秒读和 15 秒读，能差 2-5 度。标准里 A 型 1 秒读数、D 型 15 秒读数，混着读，数字就乱了。
批次漂移是另一类原因：配方里油分、填料比例微调，硬度就会变；发泡不均、气泡残留，表面硬度虚低；干燥不充分，
注塑件表面和内部硬度不一致。
温度、厚度、仪器、时间——四个干扰项记住，硬度读数就靠谱了一半。测法对、批次稳，硬度才是可信的——先把测法查清楚，再谈批次。
排查步骤：硬度计这样用才对
遇到“硬度不对”的投诉，按这个顺序排查，多数问题三分钟定位：
1. 先查测试条件：温度是不是 23±2℃？试样厚度够不够 6mm？用的什么刻度、什么仪器？条件不对，读数作废，先别怪料。
- 2. 再查测试手法：压针垂直吗？读数时间对吗？取了几点平均？单点读数波动大，先重测。
3. 三查同批一致性：同一批料，不同位置、不同模穴测 3-5 点，如果波动超过 ±3A，查配方和发泡；如果稳定，查是不是环境温差。
4. 四查批次对比：把“这批”和“上批留样”放同一环境、同一仪器上测，对比才有意义。不同时间、不同环境测的两个数，不能直接比。
给采购和质检一个动作建议：把测试条件写进验收标准——温度、厚度、仪器、读数时间、取样位置，五样固定，硬度才有验收价值。
只写“硬度 70A”不写条件，等于没验收。
硬度怎么报？给供应商的三句话
把硬度要求说清楚，是有套路的。同样一句“我要软一点的料”，专业和业余，沟通效率差出好几倍：
业余问法：“给我来个软的 TPE，别太硬也别太软。”——供应商只能猜，猜错了两边都浪费。
专业问法：“硬度 Shore A 55±3，23℃ 测，厚度 6mm 以上，手感参考鼠标垫。”——硬度值、测试条件、实物锚点三样齐全，供应商直接对牌号。
给供应商报硬度，三句话就够了：
- 1. 硬度值加公差：“55A±3”比“55A”专业——没有公差，双方验收各说各话；
- 2. 测试条件：温度、厚度、刻度，一次写全——条件不同，数字没有可比性；
- 3. 实物锚点：“手感像鼠标垫”“像牙刷柄”——数字之外，再给一个供应商能摸到的参照。
**三句话齐了，供应商报回来的牌号，命中率能高一大截。
** 很多硬度不对的纠纷，根源不是料不对，是需求没说清——需求说清了，一半问题自动消失。
读数偏差从哪来：料、模具、工艺三处找
硬度不达标，按三方向排查，别一上来就换料：
料的方向：同一体系内，硬度靠油分和填料调——油多则软，填料多则硬。
要求硬度上浮或下调 5 度以内，让供应商微调配方就能解决，不必换体系。
但跨体系调硬度要谨慎：SEBS 基做到 90A 和 TPU 做到 90A，手感、回弹、耐温完全不同，体系变了，一切重来。
模具的方向：模具温度影响表面硬度读数——模温高，表面固化慢，硬度略低；模温低，表面硬化快，读数偏高。
同一副模具，不同模温，读数能差 3-5 度。先固定工艺，再谈硬度。
工艺的方向：注塑压力、保压时间、冷却时间都影响内部密度和残余应力，进而影响硬度。
发泡料尤其敏感：发泡倍率差一点，硬度差一截。工艺稳定了，硬度自然稳定。
谁先谁后？ 先查测法（多半是它），再查工艺，最后才动配方和体系——这个顺序能避免大量冤枉的换料。
问答：60A 和 65A，手感差多少？ 五个 Shore 度，普通人不一定能摸出来；十个度，绝大多数人能明显感觉“软硬不同”。
所以采购沟通时，公差 ±3A 是行业常见做法——标 60A，收到 57-63A 都算正常波动。要求 ±1A 的，不是不能做，是要挑料、加钱、锁批次，先问自己值不值。
问答：透明 TPE 的硬度为什么更难报？ 透明料为了透光，配方里填料加得少，硬度往往比同体系不透明料软 5-10A。
“透明的 70A”和“不透明的 70A”不是一回事——报需求时，透明度和硬度要一起说，别让供应商猜。
硬度与性能怎么联动？看懂物性表
硬度是索引，不是全部。同样 70A 的 TPE，物性表可能差出两套故事。看懂四个联动关系，物性表就不白看：
硬度 × 拉伸强度：同一个体系里，硬度越高，拉伸强度通常越高——分子链堆得更紧，拉扯更难拆开。想换硬料，先问拉伸强度跟不跟得上。
硬度 × 伸长率：硬度越低，伸长率越高——软料能拉得更长不断。密封件、卡扣这类靠形变工作的件，伸长率比硬度更要紧。
硬度 × 回弹：硬度适中（40-70A）回弹表现更好；太软回弹慢，太硬接近塑料、失去弹性体意义。回弹是弹性体的灵魂，硬度只是外壳。
硬度 × 压缩永久变形：这个指标最容易被忽略——压久了还能不能弹回来。高温下的压缩永久变形，直接决定密封件寿命。
硬度一样的两个料，压缩永久变形可能差一倍。
| 联动项 | 硬度升高的趋势 | 选型提醒 |
|---|
| 拉伸强度 | 升高 | 换硬料先确认强度够 |
| 伸长率 | 下降 | 靠形变的件要留余量 |
| 回弹 | 先升后降 | 40-70A 是舒适区 |
| 压缩永久变形 | 改善 | 密封件必看这一项 |
下次看物性表，别只盯硬度一格——把拉伸强度、伸长率、压缩永久变形三行一起看，才能判断这个 70A 是不是你想要的 70A。
科隆客户案例：批次色差，小批试产先验证再放量
常州一家母婴用品厂，连续两批成品出现明显色差，投诉电话不断。科隆排查后发现：问题出在放量节奏上——样品色板过了就直接上量产，没做批次验证，配方微调带来的色差没被拦住。
科隆配合的做法是：先小批试产，色板、硬度、物性三方数据一起验证，确认没问题再放量，交付周期压缩到 7 天内。批次色差和硬度漂移，多半是同一个根：跳过验证直接放量——小批试产这一步，省不得。
预防措施：批次留样加验收标准
硬度问题的预防，落成两条动作：
先做批次留样。 每一批到货，留 500g 原样，标好批号和日期。
以后任何“这批不对”的争议，把留样和现批放同一环境对比，五分钟见分晓。留样不花钱，却是所有质量争议里最硬气的凭证。
第二，验收标准写全。 采购单上别只写“硬度 70A”，要写：
```
硬度：Shore A 70±3（23±2℃，试样厚度≥6mm，ASTM D2240 类方法）
读数时间：1 秒；取样：每批 3 点平均；留样：500g/批
```
条件写全，供应商想糊弄都糊弄不了；条件不写，验收就变成了“双方各说各话”。
再补一条：同体系比硬度，一定要和物性表联动看。硬度 70A 的 SEBS 基和硬度 70A 的 TPV，拉伸强度、压缩永久变形差一大截——硬度只是索引，物性表才是全貌。
第三条：硬度计定期校准。 工厂里的硬度计，压针磨损、弹簧疲劳是常态。半年不校，读数漂 5 度自己都不知道。
每季度用标准硬度块校验一次，比换十次料都管用——仪器不准，验收就是“拿不准的尺子量东西”。
第四条：把“手感”存档。 样品确认时，留一对手感标准件（一软一硬），盖上章封存。
以后任何“和样品不一样”的争议，拿出来一摸，胜负立判。
手感标准件是采购手里最便宜的仲裁员——不用化验，不用扯皮，一摸就懂。
再往深说一层：硬度还和温度挂钩。夏天软冬天硬，不是批次问题，是 TPE 的本性——玻璃化转变温度决定了它对温度的敏感度。
要求“全年手感一致”的件（如手柄、握把），选料时优先问供应商低温硬度曲线，而不是只看 23℃ 的单一读数。
多问一句，冬天少一堆投诉。
还有一个隐藏考点：硬度与温度的关系，要看玻璃化转变温度（Tg）。Tg 在 -60℃ 附近的 SEBS 基，冬天依然柔软；Tg 偏高一点的体系，冬天就发硬。
**户外、冷库用的件，选料时问一句“零下多少度还软”，比问“硬度多少”更接近答案。
** 这些细节问得越多，供应商就越知道你是行家，报过来的方案也越靠谱。
**再补一个实操细节：测硬度前，试样要在 23℃ 环境放置至少 16 小时（行业内习惯做法）。
** 刚从注塑机出来的件，余温还在，立刻测硬度，读数会比稳定后高 2-4A。
“打出来就测”和“放一晚再测”，是两个硬度——验收对比时，两边用同一个“冷却流程”，数字才有意义。
**还有一道容易忽略的工序：硬度受模具表面状态影响。
** 模腔抛光亮、脱模顺畅，表面层致密，硬度读数略高；模腔磨损、脱模不顺，表面发花发白，读数偏低。
模具保养状态，也写在硬度读数里。
给 QA 一句提点：硬度读数要记“测试条件页”。 每张硬度记录表，附一行条件（温度、仪器、试样厚度、读数时间），将来复盘才有依据。
没有条件的硬度数据，三年后就是一张废纸。
硬度入门就到这——把刻度、条件、测法、联动四件事装进脑子，你就是半个行家。
小结
把上面的判据过一遍，TPE的选型方向基本就清楚了，也欢迎转给需要的同事。
硬度三个刻度认全、四种干扰记牢、五步排查走完、批次留样落地——TPE 硬度这条线，就再也骗不了你。
我们站在树脂厂和注塑厂之间。
A durometer gives one reading per press, and the same item measured by two people gives three values. TPE hardness cannot be read accurately, and the selection is fundamentally wrong.
How to read TPE hardness? First, distinguish between the two scales
The hardness of TPE is the starting point for all selections, and it is also the number that is most easily misread.
First, distinguish the scales: the main scale for TPE is Shore A, 0 to 100; for ultra-soft materials, use Shore 00, and for hard materials, use Shore D. The three scales correspond to three different tactile ranges, and using the wrong scale makes the readings meaningless.
| Scale | Tactile Range | typical object |
|---|
| Shore 00 | Tofu → Eraser | Gel pads, bionic skin, shock-absorbing liners |
| Shore A | Rubber → Hard plastic | Toys, covers, seals, shoe soles |
| Shore D | hard plastic | Bellows, gears, casters |
Shore A is the basic scale for TPE: 0 is jelly-like, close to liquid, and 100 is hard, like plastic. Each 10-degree increment feels completely different:
| Shore A | Physical anchor | Common parts |
|---|
| 0-10 | Jelly, gummy candy | Gel pads, bionic skin |
| 20-30 | Rubber bands, mouse pad | Toys, watch strap lining |
| 40-50 | Phone case, tire tread | Sheath, handle |
| 60-70 | Toothbrush handle, shoe sole | Tool handle, seals |
| 70-80 | Tires, wiper blades | Soles, Casters |
| 80-95 | Solid tires, rolling pin | Casters, wear parts |
Shore A 70 feels roughly like a toothbrush handle — this is recognized in the industry as the 'feel standard,' and both purchasers and engineers use it as a reference point.
If you've pinched a toothbrush handle, you know what the feel of 70A is; if you say you want it 'a bit harder than a rubber band,' that corresponds to 30-40A.
Technical saying: Hardness numbers can be deceiving, but tactile reference points won't—translate the Shore value into something you've physically touched, and your selection won't go wrong.
Hardness tables are not printed casually: a proper physical property table will indicate the testing standards (such as ASTM D2240 / ISO 868 / GB/T 531.1) and testing conditions. Hardness values without such annotations should be questioned in terms of their reference value.
When looking at a chart, first look at the footnotes. This is the habit of experienced buyers—test conditions are hidden in the footnotes, and the test conditions determine the meaning of the numbers.
Why is the hardness reading inaccurate? Temperature, thickness, and instruments can all be misleading.
The hardness reading is incorrect; 60% of the time, it’s not a material problem, it’s a measurement issue. The four most common interferences are:
First is temperature. The hardness of TPE is extremely sensitive to temperature: for the same batch of material, measuring at 25°C gives 70A, at 40°C it may only be 65A, and in winter at 10°C it becomes 75A. For every 10°C difference in temperature, the reading can vary by 3-5 degrees.
So 'soft in summer, hard in winter' is often not because the batch changed, but because the environment changed.
Second is thickness. The hardness tester's indenter will press through the sample; if the sample is too thin, the reading will be harder. The standard requires the sample thickness to be at least 6mm (or three layers stacked). Many people directly test 2mm sheets, resulting in readings that are artificially 5-10 degrees higher.
Third is the instrument. Hardness testers from different manufacturers or in different conditions may have readings that differ by 5 degrees. Mixing type A and type D, needle wear, and spring aging can all cause the numbers to drift.
For comparisons within the same system, the same instrument and the same environment must be used.
Fourth is the reading time. When the probe is pressed down, the reading will drift over time: a 1-second reading and a 15-second reading can differ by 2-5 degrees. In the standards, Type A readings are taken at 1 second, Type D readings at 15 seconds, and mixing them will mess up the numbers.
Batch drift is another type of cause: slight adjustments in the oil and filler ratios in the formula can change the hardness; uneven foaming or residual bubbles can make the surface hardness appear lower; insufficient drying,
The surface and internal hardness of the injection-molded part are inconsistent.
Temperature, thickness, instrument, time—remember these four interfering factors, and the hardness reading will be half reliable. Only when the measurement method is correct and the batch is stable is the hardness trustworthy—first clarify the measurement method, then discuss the batch.
Troubleshooting Steps: This is the Correct Way to Use a Hardness Tester
When encountering complaints about 'incorrect hardness,' check in this order, most problems can be located in three minutes:
1. First check the test conditions: Is the temperature 23±2℃? Is the sample thickness sufficient at 6mm? What scale and instrument are being used? If the conditions are not correct, the readings are invalid, so don’t blame the material yet.
- 2. Check the testing method again: Is the needle pressed vertically? Is the reading taken at the correct time? How many points were averaged? If the reading at a single point fluctuates significantly, retest first.
3. Three checks for batch consistency: For the same batch of material, measure 3-5 points at different positions and different mold cavities. If the fluctuation exceeds ±3A, check the formula and foaming; if it is stable, check whether it is due to environmental temperature differences.
4. Batch Comparison Check: Placing 'this batch' and 'the previous batch sample' in the same environment and on the same instrument is meaningful for comparison. Two numbers measured at different times or in different environments cannot be directly compared.
A suggested action for procurement and quality inspection: include test conditions in the acceptance criteria—temperature, thickness, instruments, reading time, sampling location. Only with these five fixed items does hardness have acceptance value.
Just writing 'hardness 70A' without specifying the conditions is equivalent to not performing the acceptance inspection.
How to report hardness? Three sentences for the supplier
Be clear about hardness requirements; there’s a method to it. The same sentence, 'I want a softer material,' can result in communication efficiency several times different between professionals and amateurs:
Amateur question: 'Give me a soft TPE, not too hard and not too soft.' — The supplier can only guess, and if they guess wrong, both sides waste resources.
Professional wording: 'Hardness Shore A 55±3, tested at 23℃, thickness above 6mm, touch feel similar to a mouse pad.' — With the hardness value, test conditions, and physical reference all provided, the supplier can directly match the grade.
Report the hardness to the supplier; three sentences are enough:
- 1. Hardness value with tolerance: '55A±3' is more professional than '55A' — without tolerance, each party may interpret it differently during acceptance.
- 2. Test conditions: temperature, thickness, scale, all written at once — under different conditions, the numbers are not comparable;
- 3. Physical anchor points: 'Feels like a mouse pad,' 'like a toothbrush handle' — beyond numbers, give the supplier a reference they can actually touch.
**With three sentences in place, the brand reported back by the supplier can have a much higher hit rate.
** Many disputes over incorrect hardness don't stem from the wrong material, but from unclear specifications—once the requirements are clarified, half of the problems disappear automatically.
Where does reading deviation come from: Look for material, mold, and process .
If hardness does not meet standards, check from three directions and don't switch materials immediately:
Direction of material: Within the same system, hardness depends on oil content and filler adjustment—more oil means softer, more filler means harder.
requires hardness to be raised or lowered by 5 degrees, and the supplier can fine-tune the formula to solve it, no need to change systems.
But cross-system hardness adjustments must be cautious: SEBS base requires 90A and TPU 90A, with completely different hand feel, rebound, and temperature resistance. The system changes, everything starts over.
Mold direction: Mold temperature affects surface hardness reading—higher mold temperature means slower surface curing and slightly lower hardness; Low mold temperature means faster surface hardening and higher reading.
Same mold, different mold temperatures, readings can differ by 3-5 degrees. Fix the process first, then discuss hardness.
Process direction: Injection pressure, holding time, and cooling time all affect internal density and residual stress, which in turn affect hardness.
Foam material is especially sensitive: slightly lower foaming ratio means much lower hardness. When the process stabilizes, hardness naturally stabilizes.
Who comes first, who comes later? Check the testing method first (usually it), then the process, and finally the formula and system—this sequence helps avoid a lot of unnecessary material changes.
Q&A: How much difference does the feel between 60A and 65A differ? Five shore degrees—ordinary people might not be able to tell the difference; Ten degrees is something most people can clearly feel as "different in hardness."
So when discussing procurement, tolerances of ±3A are common industry practices—if you bid 60A, receiving 57-63A is considered normal fluctuation. If you require ±1A, it's not that you can't do it—you have to choose materials, pay more, lock in batches, and ask yourself if it's worth it.
Q&A: Why is it harder to report the hardness of transparent TPE? For transparent materials, to transmit light, less filler is added in the formula, and their hardness is often 5-10A softer than opaque materials of the same system.
"Transparent 70A" and "opaque 70A" are not the same thing—when submitting requirements, transparency and hardness should be mentioned together, so suppliers don't have to guess.
How do hardness and performance work together? Understanding the physical property table
Hardness is an index, not everything. For TPE with the same 70A, the physical property table may have two different stories. Once you understand the four interconnections, the physical property table is worth reading:
Hardness × Tensile strength: Within the same system, the higher the hardness, the higher the tensile strength—the tighter the molecular chains, the harder it is to pull apart. If you want to switch to a hard material, first ask if tensile strength keeps up.
Hardness × Elongation: The lower the hardness, the higher the elongation—soft materials can stretch longer without breaking. For seals and clips, which rely on deformation, elongation is more important than hardness.
Hardness × Rebound: Moderate hardness (40-70A) performs better with rebound; If too soft, rebound is slow; if too hard, it's close to plastic and loses the meaning of elastomer. Rebound is the soul of the elastomer; hardness is just the outer shell.
Hardness × Compression Permanent Deformation: This indicator is most easily overlooked—whether it can bounce back after prolonged compression. Compression permanent deformation at high temperatures directly determines the seal's lifespan.
Two materials with the same hardness may have twice as much compression permanent deformation.
| Linkage Item | Trend of Hardness Increase | Selection Reminder |
|---|
| Tensile Strength | Increase | Change Hard Material First Confirm Sufficient Strength |
| Elongation Rate | Decrease | Leave Extra Space for Deformation Parts |
| Rebound | Rise Then Decrease | 40-70A is the comfort zone |
| Compression permanent deformation | Improve | Seals must see this item |
Next time check the physical property chart, don't just focus on hardness—look at tensile strength, elongation, and compression permanent deformation together to judge if this 70A is the 70A you want.
Cologne customer case: Batch color differences, small-batch trial production first validated before ramping up.
A mother and baby products factory in Changzhou showed obvious color differences in two batches of finished products, causing constant complaint calls. After investigation, Cologne found: the problem was in the ramp-up pace—after sample color swatches passed, they went straight to mass production without batch validation, so color differences caused by formula fine-tuning were not stopped.
Cologne's cooperating approach was: first, small-batch trial production, verifying color swatch, hardness, and physical property data together, confirming everything is fine before ramping up, and the delivery cycle was compressed to within 7 days. Batch color difference and hardness drift mostly share the same root: skipping verification and ramping up directly—small-batch trial production is a step that can't be skipped.
Preventive measures: batch retained samples plus acceptance standards
Hardness issues prevented, completed in two steps:
first conduct batch sample retention. For each batch upon arrival, keep 500g of original samples, labeled with batch number and date.
For any future disputes about "this batch is wrong," compare the retained samples with the current batch in the same environment, and the result will be clear in five minutes. Sample retention costs nothing, yet it is the strongest proof of all quality disputes.
Second, fully state acceptance standards. Don't just write "Hardness 70A" on the purchase form; instead, write:
'
Hardness: Shore A 70±3 (23±2°C, sample thickness ≥6mm, ASTM D2240 method)
Reading time: 1 second; Sampling: average of 3 points per batch; Sample retention: 500g/batch
'
Conditions fully stated, suppliers can't fool them even if they want to; If conditions are not written, acceptance becomes "both sides speaking their own way."
One more thing: When comparing hardness within the same system, you must check it in conjunction with the physical property table. SEBS base with 70A hardness and TPV with 70A have a big difference in tensile strength and compression permanent deformation—hardness is just an index, the physical property table is the whole picture.
Third: Regular calibration of hardness testers. In factories, pin wear and spring fatigue are the norm for hardness testers. If you don't calibrate for half a year, you won't even notice a reading of 5 degrees.
Checking with standard hardness blocks every quarter is more effective than changing materials ten times—if the instrument isn't accurate, acceptance is like "measuring things with a ruler you can't get it right."
Fourth: Save the "tactile feel." When confirming the sample, keep a pair of tactile standard parts (one soft, one hard), stamp and seal them.
Any future disputes about "different from samples" can be decided by touching and winning.
Tactile standard parts are the cheapest arbitrators in the buyer's hands—no testing, no need for disputes, just a touch and you'll understand.
To dig deeper: hardness is also linked to temperature. Soft in summer and hard in winter isn't a matter of batch, it's the nature of TPE—the temperature transition during glass transformation determines its sensitivity to temperature.
For pieces that require "consistent feel all year round" (such as handles and grips), prioritize asking the supplier about the low-temperature hardness curve when selecting materials, rather than just looking at a single reading of 23°C.
One more question means fewer complaints in winter.
Another hidden point: the relationship between hardness and temperature depends on the glass transition temperature (Tg). Tg at SEBS bases near -60°C remains soft in winter; Systems with slightly higher Tg become hard in winter.
**For outdoor or cold storage parts, asking "At what temperature below zero is it still soft?" is closer to the answer than asking "How much hardness is it?"
** The more details you ask, the more the supplier knows you're an expert, and the more reliable the proposal they provide
**An additional practical detail: before testing hardness, the sample should be placed in an environment of 23℃ for at least 16 hours (common industry practice).
**For parts just out of the injection molding machine, if measured immediately while still warm, the reading will be 2-4A higher than after stabilization.
“Measure immediately after molding” and “measure after cooling overnight” are two different hardnesses—when doing acceptance comparisons, both sides should use the same "cooling process" for the numbers to be meaningful.
**Another easily overlooked step: hardness is affected by the condition of the mold surface.
**A polished, smooth cavity that releases parts well has a dense surface layer, resulting in slightly higher hardness readings; a worn cavity with poor release, surface mottled or cloudy, results in lower readings.
The maintenance status of the mold is also reflected in the hardness reading.
A tip for QA: hardness readings should record the "test conditions sheet." Each hardness record sheet should include a line of conditions (temperature, instrument, sample thickness, reading time) so that future reviews have a basis.
Hardness data without conditions is just a piece of scrap paper three years later.
That's all for hardness basics—remember the four things: scale, conditions, method, and linkage, and you'll be halfway to becoming an expert.
Summary
Go through the above criteria, and the direction for selecting TPE will basically be clear, and feel free to share with colleagues who need it.
Know all three hardness scales, remember the four interference factors, complete the five-step troubleshooting, and keep batch samples—this TPE hardness line can no longer deceive you.
We stand between the resin factory and the injection molding factory.
