Classification of plastic parts塑料件的分类
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It is very important to understand the material properties of plastic parts during maintenance. Plastic parts can be roughly divided into thermoplastic parts and thermosetting plastic parts according to different materials. Thermoplastics and thermosetting plastics can be either hard plastics or soft plastics.在维修中了解塑料件材料特性十分重要，塑料件根据材料的不同大体可分为热塑性塑料件和热固性塑料件，热塑性塑料和热固性塑料既可以是硬塑料，也可以是软塑料。
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1. Thermoplastic parts:1. 热塑性塑料件：
1 Thermoplastics refer to plastics that can be repeatedly heated, softened, flowed, and cooled to harden within a specific temperature range. This process is reversible and can be repeated, such as polyethylene, polytetrafluoroethylene, etc. Therefore, thermoplastic parts can be heated, melted and solidified repeatedly, so thermoplastic waste can usually be recycled.热塑性塑料是指在特定温度范围内能反复加热软化以至流动，和冷却硬化的塑料，这种过程是可逆的，可以反复进行，如聚乙烯、聚四氟乙烯等。因此，热塑性塑料件可经加热熔融而反复固化成型，所以热塑性塑料的废料通常可回收再利用。
2 Thermoplastic parts are best repaired with a hot iron plastic filler welder, but are usually repaired by replacement.热塑性塑料零件最好用热烙铁塑料材料填充焊机维修，但通常都采用更换方法维修。
3 At present, the materials for interior and exterior surface coverings are mainly modified PP, ABS, PC+ABS, and PVC (artificial leather materials), all of which are thermoplastics and their modified materials thermoplastics; interior and exterior non-surface coverings also use POM, PA, HDPE materials, etc.目前内外饰表面覆盖件的材料主要为改性PP、ABS、PC+ABS、PVC(人造革材料)，都为热塑性塑料及其改性材料热塑性塑料；内外饰非表面覆盖件还有用到POM、PA类、HDPE材料等。
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2. Thermosetting plastic parts:2. 热固性塑料件：
1 Thermosetting plastics refer to plastics that can solidify or have insoluble (melting) properties under heat or other conditions, such as phenolic plastics, epoxy plastics, etc. Thermosetting plastics can soften and flow when heated for the first time. When heated to a certain temperature, a chemical reaction occurs and hardens (solidifies). This change is irreversible. After that, it can no longer soften and flow when heated again. Thermosetting plastic parts are molded and processed based on this characteristic. They use the plasticization flow during the first heating to fill the cavity under pressure, and then solidify into products of a certain shape and size.热固性塑料是指在受热或其他条件下能固化或具有不溶(熔)特性的塑料，如酚醛塑料、环氧塑料等。热固性塑料在第一次加热时可以软化流动，加热到一定温度产生化学反应而变硬(固化)，这种变化是不可逆的，此后，再次加热时已不能再变软流动了。热固性塑料件正是借助这种特性进行成型加工的，利用第一次加热时的塑化流动，在压力下充满型腔，进而固化成为确定形状和尺寸的制品。
2 Thermoset plastic parts are harder and more brittle than thermoplastic parts, and their state is not easy to change when heated. If heating is continued, thermoset plastic parts will be damaged when the temperature exceeds the critical point.热固性塑料件比热塑性塑料件更硬更脆，受热时状态不易变化。如果继续加热，温度超过临界点时会损坏热固性塑料件。
3 Thermosetting plastics are mainly used as structural parts in electronic appliances and safety components for heat insulation, wear resistance, insulation, high voltage resistance, etc. Thermosetting plastics are rarely used in interior and exterior decoration, and only ashtray bodies use phenolic plastics.热固性塑料主要应用在电子电器、安全的部件上做结构件，用于隔热、耐磨、绝缘、耐高压电等。热固性塑料在内外饰用的很少，只有烟灰盒体会采用酚醛塑料。
4 Thermosetting plastics can be repaired with epoxy resin or other harder two-component materials. This chapter only briefly introduces its repair methods.热固性塑料可用环氧树酯或其他更硬的双组份维修材料，本章只简单介绍它的维修方法。
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