Time to read: 5 min
后处理可改善塑料注射模制零件的特性，从而准备好最终使用。它包括纠正措施，以消除表面缺陷和用于装饰或功能目的的次要过程。例如，柱成型操作可以去除多余的材料（称为闪光灯）或应用零件号。
顾名思义，后处理总是在injection moldingis complete. It adds costs, but these costs may be less than what you would pay by using more expensive tooling or materials. For example, painting parts after molding may cost less than using an expensive colored plastic.
通过注射成型，有六种常见的类型后处理活动。
- 门修剪
- Painting
- Laser Marking
- Pad Printing
- Heat Staking
- 超声波焊接
Within each process, there may be variations. For example, there is more than one way to paint injection molded parts. By understanding all of your options, you can choose the right post-processing for your next project.
门修剪
Flash mars the finish of molded parts and can interfere with sealing, sealing, and assembly. Typically, this surface defect occurs when excess plastic is forced from a mold cavity at the parting line or ejector pin locations. Quality tooling limits the amount of flash that is created, but gate trimming may still be needed as a secondary operation.
门是使熔融塑料进入霉菌腔的开口。尽管大多数这种塑料在腔体内固化以形成零件，但某些物质在大门和突出处固化。栅极修剪或脱水，可以在注射造型机内或部分弹出后去除这些突起。
Painting
Painting is a form of post-processing for plastic injection molding that adds colored coatings to molded parts. Injection molders can use colored plastic instead, but pigmented polymers tend to be more expensive. In-mold painting is another option but may not be as cost-effective as painting after the fact. Coatings that provide shielding against electromagnetic interference (EMI) are also considered to be post-process painting.
但是，通常，塑料注射模压零件被涂上用于装饰或隐藏表面缺陷。在绘画之前，可能需要清洁或打磨，以使油漆更容易粘附。具有低表面能的塑料（例如聚乙烯和聚丙烯）需要血浆处理。该过程增加了表面能，因此油漆和塑料之间的分子吸引力更强。血浆治疗是成本效益, especially in comparison to deep cleaning.
有三种零件绘制方法。
- 喷漆是最简单的过程，可以使用空气干燥的自固化油漆。还可以使用两部分用紫外线（UV）光治疗的油漆。
- Powder coating施加粉末状塑料，并需要紫外线固化以确保表面粘附并帮助避免碎裂和剥落。
- Silk screeningis used when parts need two different colors. For each color, a screen is used to mask, or hide, the area that should remain unpainted.
With each of these processes, it’s possible to achieve virtually any color in a gloss or satin finish.
Laser Marking
激光标记是一个快速，无工具的过程，可以消除表面制备的需求，同时将高分辨率效应赋予塑料注射的模制零件。像绘画一样，它为内部绘画和模具图形提供了替代方案，在注射成型过程中它们都应用了装饰效果。
During laser marking, injection molded plastics undergo visible surface changes made by a solid-state pulsed laser. For crisp, clear markings, the light from the laser needs to have a wavelength that the molded plastic will absorb. Often, laser marking is used to produce logos or apply unique identifiers to parts that require traceability. Examples include medical devices and aerospace parts.
Because the term “laser marking” is sometimes used to describe several different laser technologies, it’s important to discuss your requirements with your service provider. Traditionally, laser marking refers to the process of producing surface discoloration in black or gray to create letters, numbers, or logos. Laser marking provides an alternative to conventional printing but is not suitable for plastics that resist color changes.
Pad Printing
PAD打印是一个常规的标记过程，将二维（2D）图像转移到三维（3D）对象上。首先，将传输垫压在装有所需图像的墨水板上。然后将墨垫放在注射模制的零件上，然后按在零件的表面上以传递墨水并涂上图像。
Pad printing can be used on irregular shapes or surfaces. It’s ideal for transferring detailed images and provides good print quality. Quick-drying inks speed processing times and help to avoid problems with dripping, running, or smearing that can occur when ink is applied. Transfer pads and inks are subject to airborne contaminants, however, so quality assurance is a critical part of the process.
As a form of offset printing, pad printing can be used to add single-color or multi-color graphics and lettering to a wide range of塑料斜纹布ls。Applications include toys, sporting goods, and housings for electronics and appliances. Although pad printing equipment varies, most machines have an ink cup, shuttle, and transfer pad. Process automation supports higher volumes.
Heat Staking
热量堆积将金属插入件安装到塑料老板和外壳中。通常，这些插入物是threadedto support the use of screws during product assembly. With thermoplastic staking, as this process is sometimes known, heat is applied to the metal insert so that the plastic softens as it is pushed into the part. Like the injection molding process itself, heat staking melts the plastic at a specific temperature and pressure to achieve optimal fill.
Applications for heat staking include joining molded plastic housings to printed circuit boards (PCBs). This assembly technique is also used with the plastic bosses in automotive door panels. In addition, there are applications for heat staking with consumer appliances such as coffee makers. For almost any type of plastic, thermoplastic staking can produce strong joints. Its low insertion force also supports the use of metal inserts with thin plastics that could split or shatter.
超声波焊接
Ultrasonic welding is a joining process that uses high-frequency ultrasonic acoustic vibrations to create a solid-state weld between two pieces of plastic. An ultrasonic horn vibrates between 20,000 and 40,000 times per second while maintaining slight contact with the plastic. This vibration produces friction and, in turn, enough heat to melt the plastic. To ensure that parts don’t move as they cool, a clamping force is applied for a specific hold time.
Like heat staking, ultrasonic welding provides an alternative to insert molding, the process of molding a plastic around a non-plastic part. Whether vibrations or heat are used to melt the plastic, the softened resin flows into voids and then hardens to form a firm bond with the insert itself. Often, ultrasonic welds are used in medical devices because they eliminate the need for chemical solvents and adhesives that may raise biocompatibility concerns.
准备后处理
Post-processing for plastic injection molding is the last part of the production process. However, that doesn’t mean you have to wait until the end of your design process to consider flash removal, painting, laser marking, pad printing, or whether to handle threaded inserts with heat staking or ultrasonic welding. In fact, thinking about post-processing sooner rather than later could save you time and money in the end. Fictiv wants to help you with your next molding project, and our experts can help figure out which type of post-processing is right for you!Contact Fictiv for a quotetoday.
