In-mold decoration

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By Kenny Pravitz | Jun 12, 2018
Plastic decorating options at GMN

What makes plastic decoration at GMN unique? Along with dedicated engineers to support your projects from concept to creation, state-of-the-art equipment, a robust quality system, and complementary capabilities to plastic injection molding like value-added assembly, GMN provides all the decorating options for plastics under a single roof.

To determine the most appropriate plastic decoration technique for any application, there are multiple factors that go into consideration, including the plastic type, environmental requirements (exposure to fluctuating temperatures, humidity, and moisture), component dimensions, cosmetic requirements, regulatory requirements, and production volume. In this blog, we will be skimming over all the plastic decorating options available at GMN to understand their core advantages and pitfalls.

1) Pad printing - In this printing process, the image is engraved on a plate which is then coated with ink and transferred to the desired surface via a silicone pad.

Advantages:

    • Same set-up for multi-color
    • Can accommodate fine artwork and detailed graphics

Disadvantages:

    • Difficult to print on heavy textures or surface finishes
    • Cannot pad print on swooping or curved surfaces
    • Cannot use metallic inks
    • Size restrictions

 

2) Screen printing - In this method, the artwork is transferred on to the plastic surface using a mesh screen and a squeegee.   

Advantages:

    • Quick set-up time
    • Can accommodate larger artwork
    • Ideal for high-volume production

Disadvantages:

    • Can only be performed on flat surfaces
    • Needs different screens for different colors
    • Longer curing times
    • Challenging to achieve finely detailed graphics

 

3) Hot stamping - This dry printing technique utilizes heat and pressure to transfer colored foil onto the plastic surface.     

Advantages:

    • No ink-mixing or curing of part required
    • Can accommodate metallic colors

Disadvantages:

    • Ribbon can be expensive due to the minimum order of quantity (MOQ)
    • Raised surfaces only
    • Size restrictions

 

4) Laser etching - As the name indicates, this technique employs a laser beam to etch a design on the plastic surface which would have otherwise been difficult to mark mechanically.

Advantages:

    • Details are permanently etched into the surface of the part
    • Ideal for products with barcodes, lot numbers, backlighting, or intricate artwork

Disadvantages:

    • Longer cycle times depending on size and detail of the image
    • Size restrictions

 

5) Spray painting - Often used in conjunction with laser etching, spray painting utilizes either an automated robotic spray or manual hand-spray method to apply the ink on the desired parts. 

Advantages:

    • Can hide flaws on the plastic surface
    • Can utilize the manual method for low-volume to mid-volume production and utilize the automated method for high-volume production
    • Can accommodate multiple colors and materials

Disadvantages:

    • Detailed masking may be required, making the process labor intensive
    • Requires a clean environment
    • Requires longer lead time

 

6) In-mold decoration (IMD) - This advanced technique allows for the printing of highly durable and complex three-dimensional shapes.  

Advantages:

    • Can achieve compound curves and complex 3D forms
    • Well suited for designs incorporating small windows or backlighting  
    • Offers versatile decoration options
    • Ideal for high-wear applications

Disadvantages:

    • Development phase can be long depending on the design
    • Automation can be expensive
By Kenny Pravitz | Jan 30, 2018
IMD allows different graphic overlays to be used in the same molded shape, giving  you customization.

Many industries require the decorative elements of plastic to be highly durable. For example, the aerospace, automotive, and medical industries have many high-wear applications that require strong, durable parts where printed icons won’t scratch off or fade away. Products that are decorated using first-surface decorating processes, where graphics are placed on the outermost layer (such as pad printing, screen printing, or hot stamping), wear out over time and aren’t suitable for these industries. Depending on the materials and processes used, the inks on plastic pieces can fade out over time, making it difficult or impossible to read indicators on those pieces.

In-mold decorating (IMD) is a plastic decorating method that ensures the durability of the graphic overlays and allows for multiple design options for the overlays. In brief, IMD is a process where a graphic overlay is physically fused to injection molded plastic to form one piece. Molten resin is injected either in front or behind the graphic overlay to form a bond between the two. Unlike pad printing, screen printing, or hot stamping – where inks and overlays are exposed to the user that can deteriorate over time – IMD parts have a layer of plastic that encapsulates the ink, protecting it from users and the outside environment.

GMN Plastics, GM Nameplate’s (GMN) plastics division in Beaverton, OR, recently created a video that demonstrates the IMD process. In the video, we see an end-of-arm tool pick up a graphic overlay and place it in the injection mold using a vacuum system, while simultaneously removing a part that was just molded. Both of these functions are completed in one cycle, allowing for faster and more efficient production. Locating pins in both the end-of-arm tool and injection mold itself allow for consistent placement of the overlay in the tool, which is critical for functional parts in regulated industries. If the overlays are not correctly and consistently placed in the mold, some portions of the overlay may not be fully encapsulated by plastic during the molding process.

IMD is ideal for higher volume projects that have stringent durability requirements, as there is more design engineering required up front than with a standard injection molded part. However, one advantage is that once the graphic overlay and molded part is designed, printed graphics on the overlay can be changed at any time to allow for customization and unlimited design options.

To learn more about what the IMD process is, read this blog.

To watch the IMD process, click play on the video below.