Do you know what various options you have available for injection molded parts surface finish?
Understanding the intention and function of your product and how the end customer will use it may help to determine what resin you should be using for molding. You should be selecting a resin and a surface finish that offers flexibility while meeting the products requirement and visual expectation. The perceived value of the product is what the finished part looks like. Multiple resins can offer a texture and finish that will be durable and visually appealing, and still meet the performance requirements needed to meet requirements. These are some of the initial discussion points you should be having with your mold designer concerning surface finish:
What Type of Surface Finish is Available?
Before you start picking out the final injection molded parts surface finish, you should already have decided what class of mold you need based on production volume and what material the mold will be made from. A steel mold will be harder than an aluminum mold and offer more options for surface finish. Steel has the advantage that it can be polished for a smoother surface finish. That can also be advantageous for painting or another secondary turnkey operation to enhance your product.
Some of the finishes available include:
- Geometric or patterned shapes
- Leathery texture simulating grain
- Prepared for painting or secondary graphics
- Etched with a logo
- Blasted for a rough uniform texture
- Gloss, matte, or satin polish
- Mirror or lens finish
What Surface Finish Can Do
Product surface finish and texture has multiple advantages including being used to make undercuts and hide parting lines. There will be two halves to the mold, and possible multiple slides that move in and out to inject and release the part. All of those adjoining areas form parting lines that may or may not be visually appealing. A strategic texture or finish in those areas can blend or hide the parting lines. Beyond visual appeal, texture can improve grip, offer improved paint adhesion, and can also allow gases to escape the mold during the injection process. The surface finish needs to be decided very early on when choosing your resin to allow for proper design in the mold.
What Surface Finish Can Affect
The surface finish may seem like a small variable to consider during the design phase of the mold, but if left as an after-thought, it can cause headaches later on. One thing that texture can do is affect the flow of resin through the mold. Think of a smooth road vs. a parking lot full of speed bumps. Resin will need to flow across the surface and fill every miniature cavity covered with texture. Be sure to have your mold analyzed through the design process to have certainty that resin will fill the cavity correctly during injection.
Beyond resin flow, surface texture can affect the ability to add embossing, pad printing, or hot stamping with a logo or visual design. You will need to choose a resin and surface texture that will do well with the secondary process and absorb the color you need for your project.
What Can Change Your Surface Finish
The resin material you choose may have an impact on the surface finish options available. There are basic two categories of resins; amorphous and semi-crystalline. Beyond those there are sub-categories and then an even deeper discussion on additives or fillers, fill rate inside the mold, pressure requirements, and temperatures. It’s all connected and can be confusing to know which drives the finish more and what can affect your end product.
When you need a resource to design your mold and select a resin with that meets your needs and expectations, we’re here to help.
For more information on SEA-LECT’s production opportunities, call (425) 339-0288 or email us at email@example.com.