Choosing the Right Substrate for a Graphic Overlay
Selecting the substrate for the graphic overlay is a key part of the product development process and there are several considerations to review prior to making the decision on which product to use.
The first step is to review the performance/durability requirements for the component:
-will the graphic overlay be exposed to any of the following:
- Extreme heat or cold
- Exposure to any harmful chemicals
- Prolonged exposure to UV
- Impact from user interaction that may be damaging
- Exposure to salt water/residue
The two main types of plastic recommended for graphic overlays are polycarbonate and polyester. There are many specialized versions of these on the market which offer high tech features to the end user; but the basic properties of the two types of plastic are the main consideration for selecting a product.
Polycarbonate is a thermoplastic with a melting point of 155 Degrees Celsius.
The reason polycarbonate is a common material selection for graphic overlays, is the combination of the impact resistance of the surface of the plastic. Polycarbonate is also provides many of the positive features of glass (UV Filter, high gloss clear barrier); at a much lower weight.
Polycarbonate does tend to scratch on the surface easily. So, a frost surface may be recommended to minimize the appearance of the scratch. Chemical resistance of the surface of this plastic is also quite low. Polycarbonate is not recommended for overlays which will be exposed to chemicals in the end use environment.
Thickness: Range from .005″ to .040″ (Note – die cutting of polycarbonate over .030″ thick may result in some quality issues at the end of the part)
Finishes Available: Gloss, Velvet/Matte, Gloss with custom selective texture application
Polyester can be either a thermoplastic or thermoset plastic which can be used in applications with exposure to heat up to 245 Degrees Fahrenheit.
Polyester is a tougher, more durable plastic than polycarbonate. It is harder, and can withstand exposure to almost any commercially available solvent. Polyester films are typically available up to a maximum of .010″ for this application. The thicker polyester films take on a white murky film, which is undesirable in a graphics application.
Graphic overlay components which will be exposed to high/low heat, chemicals, abrasion or general more rough conditions are ideally specified as a polyester substrate. There are many options for hard coat surfaces, and various surface finishes for both polycarbonate and polyester.
If a graphic overlay’s main function will be cosmetic, and the panel will be in a low risk/exposure environment, polycarbonate would be the obvious choice of material. There are more finishes available, it comes in a broad range of thicknesses, and it’s easier to die cut and emboss. Overall, the polycarbonate overlay will be a lower cost than the polyester option.
For more challenging projects, polyester will be a better solution to ensure the part will be durable throughout the life cycle of the component. The higher cost of the part is offset by the assurance that the part will not fail in the end our application.
Our team is dedicated to working clients at the Engineering level to support design/development activities in the early stages of their projects.