Plastic parts, once manufactured, can be left bare after they come out of the plastic injection molds. However, modern industries and consumer markets like to add more character to their plastic parts.
While leaving the parts as it is can be more cost-effective, modern markets are now getting over the budget considerations and thinking in terms of plastic part decoration as a valuable addition.
Various methods like painting, adhesives like films, laser marking, metallic plating, etc are regularly used by manufacturers for plastic part decoration. Other modern techniques like in-mold decoration and overmolding are also gaining huge popularity amongst plastic part manufacturers.
The sections below present some of the most common options used for decorating/enhancing a plastic part.
1. Painting techniques
Painting a part is the most conventional methods used to liven up a plastic part. Depending on the need, different techniques for painting a part are employed by manufacturers.
This is the easiest technique of painting used for plastic parts. As the name suggests, the technique involves adding color to a part using liquid spray. Robotics is often used to handle and control the spray equipment to maintain uniformity of color and shades.
Once a layer of paint has been added, the plastic parts are then left for self-curing/drying. The use of UV radiation in curing is also considered to enhance durability.
Powdercoating is a more modern approach to plastic part decoration. While the process has been traditionally used for coating metals, modern technical additions have made it possible to use it on plastics.
The process involves the spraying of powdered plastic on the bare parts and baking them in place. While powdered components easily adhere to plastics (with the given temperature conditions), it is a difficult task to get them electrostatically bonded to the plastic parts. Modern methods of UV curing are hence used.
Silkscreening techniques are used for painting plastic parts need designs or patterns printed on them. So, when you need to apply design to a small area of a plastic part, silkscreening should be your method of choice.
The process utilizes a thin plastic sheet placed on the part. The sheet has a mesh which is cut in the desired design pattern. The silk screen is placed over the plastic part and paint is sprayed on the mesh. The screen is then removed showing a thin layer of patterned paint on plastic.
The process is very useful when intricate designs, logos, etc with multiple colors are needed to be displayed on plastic parts.
Pad printing is very similar to stamping. The process is popular for being quick, accurate as well as cost-effective. The technique involves a large rubber stamp, also known as the pad that picks up the ink and presses it on the plastic surface. Needless to say, the ink impression picked up on the pad is a mirror reflection of the one that is required to be printed on the plastic part.
2. Application of films
Film processes have gained huge popularity in the last few decades. The technique involves the application of thin adhesive/film on the plastic surface.
Film processes have multiple advantages as compared to other plastic part decoration techniques. Simple working technique along with the ease of applying it in the assembly house of the customer makes it a very time saving and cost-efficient method.
Films, just like stickers can be cut to any shapes and sizes and are available in a wide range of materials and textures.
Various other film processes like Hydrographics are also being used by manufacturers for plastic part decoration. The process is definitely more expensive than basic film process but offers high durability.
The technique of hydrographics, also known as immersion painting involves placing a thin layer of paint on water. Ink being low in density floats on water. After the plastic part is ready, it is dipped in the tank and submerged in the tank and acquires a coating of ink. Ink adheres to the plastic part and envelops it completely. A clear paint cost is applied to make the painted surface more durable.
Out of mold decoration (OMD) involves texturing a thin piece of plastic with a design pattern. The sheet is then adhered to the main part and trimmed.
3. Metal plating
Metal plating technique for plastic part decoration is highly popular in sectors where plastic parts need to resemble metals in their look and feel but need to have the lightweight advantage of plastics.
Electroplating and PVD (Physical vapor deposition) techniques are commonly used for the purpose. Various metals like copper, tin, nickel, and gold are used for electroplating purposes.
Metal plating has various advantages to offer. It increases the durability of the plastic part while enhancing its physical appearance. Additionally, it is a beneficial technique in the electronics industry where certain plastic parts need to be covered by metal layers to avoid interference of electromagnetic waves.
Lasers are the latest technology being used for plastic part decoration or marking. Lasers offer multiple advantages compared to conventional plastic part labeling techniques.
They are popular amongst manufacturers and plastic part designers for their efficiency, accuracy and high production speed. Additionally, they are considered to be a completely eco-friendly process when it comes to plastic part decoration.
Various laser technologies like laser marking, laser engraving, laser etching, foaming are used for marking plastic parts.
5. Digital printing
Digital printing on injection molded parts is a very commonly used plastic part decoration technique. Digital printing is very similar to OMD where thin plastic films are printed with custom design and later adhered to the plastic part.
In this technique, a thin layer of paint/dye is printed on the transfer paper which is then placed on the plastic part. Using a heat press, the color and pattern is transferred and bonded to the plastic resin.
Final Words: Plastic part decoration is now an integral part of the plastic injection molding industry. More and more consumer sectors are now looking for parts with a unique character, rather than the conventional bare parts in original resin colors.
The idea is not just to make the part aesthetically appealing. Decoration options increase the functionality and durability of parts. With in-mold decorating options, consumer industries have now found a good balance of cost-effectiveness and the desired finish/textures. Simple color options also save the costs that are otherwise required for post-mold processes to give separate appearances to the parts.
As mentioned above, multiple decoration options are now available for plastic part designers. From multiple paint processes to films, metal plating, digital printing and lasers, there is a big choice available for designers in the plastic industry.