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Two-Shot Molding | A Competitive Advantage for Your Products

10.22.2021 Posted in: Blog
HOME/Latest News/Blog/Two-Shot Molding | A Competitive Advantage for Your Products

Using Two-Shot Molding as a Competitive Advantage for Your Products

Rogan 2 Shot Infographic

If you’ve ever held a power drill with an ergonomic handle or used a plastic toothbrush with a colorful rubber grip, then you’ve likely come in contact with a product manufactured through the two-shot injection molding process.

Rogan Corporation has been utilizing two-shot molding since 1982, beginning with a unique line of instrument knobs, and over time added two-shot clamping knobs, adjustable clamping levers and handles. Since that time, many companies have adopted this process in a multitude of products due to the many advantages provided by the two-shot process.

So, what is two-shot molding? This process uses a single plastic molding machine, specially made to inject two materials sequentially, or one on top of the other. It is like having two molds together side-by-side in one machine. Parts are molded in one half of the mold (the first shot) before the mold rotates, lining up the molded parts with a second mold and injection unit. The second material (second shot) is then molded over or around the first shot. In the case of our products, the materials form a molecular bond with each other. If the materials being used do not bond, then mechanical joining features can be designed in to make the part more structurally sound. The plastics can be different colors, made of hard or soft material (measured by durometer) or have different properties altogether.

When the part comes out of the machine, it is complete and ready to use. There are many benefits that designers obtain by creating a part using the two-shot process. These include:

  • Molding a hard plastic first shot with a soft rubber second shot to provide a soft touch grip. This process was a game changer for knobs.
  • Molding multiple colors for a more creative design and added functional features.
  • Molding in features such as markings or logos. This eliminates the need and cost of secondary operations and also shortens the lead time to produce the part. Logos can be molded in for improved product differentiation.
  • Molding with different materials to eliminate assembly operations.
  • Adding features such as a living hinge, where the plastic itself forms the hinge.

Advantages obtained by using the two-shot process include reduced part cost, reduced production and assembly times, and the ability to produce more complex and creative designs.

Overmolding is another process used to obtain many of the benefits of two-shot molding. Overmolding is where a part is molded in one machine and then inserted into another machine where the additional shot is molded over it. This process is generally not as fast as two-shot molding and may not produce the same bond between the materials. This process, however, may be used until the volume is sufficient to justify the higher cost of a two-shot machine.

Shown below are a few examples of the benefits and advantages of the two-shot process. Rogan is known for our plastic knobs, handles and levers, but these advantages can and have been used in thousands of different products and industries.

Control Knobs

This two-shot control knob series is what started it all for Rogan. We combined the advantages of a soft rubber material over a different color hard plastic.

 

 

Clamping Knobs

We then designed clamping knobs, which utilize a softer, more comfortable grip.

 

Markings

Adding in a marking or indicator line. This eliminates a secondary operation such as pad printing, hot stamping or paint filling.

 

Two-shot molding

Molding two different materials to eliminate an assembly operation

 

Customized Graphics

Adding features such as a company name or a logo.

 

Custom Colors

Molding the red and black together eliminated the need to pad print both the red and white.

 

Glow-in-the-dark knobs

Adding glow-in-the-dark material is another option

 

Clamping Levers & Pull Handles

Two-shot molding increased the usefulness and comfort of other products such as clamping levers and pull handles.

 

Flexible Materials

Two flexible materials can be two-shot molded together, as was done with these phone cases.

 

 

Maintaining Our High Standard of Quality

Before two-shot molding was created, most knobs were made of a phenolic material, ABS, or even machined metal. Having the ability to mold a soft thermoplastic elastomer (TPE) material onto a hard plastic base allowed Rogan to improve on standard knobs and handles and make them usable for a wider range of applications.

Rogan sells to a diverse set of industries, all of which need specific types, sizes, and specifications for their knobs and hand hardware. Our knobs can be used for the following industry applications:

  • Audio
  • Music
  • Consumer electronics
  • Medical/dental equipment
  • Furniture
  • Kitchen and cooking equipment
  • Laboratory equipment
  • Marine components
  • Power equipment
  • Automotive applications

Rogan’s injection molds are maintained in our toolroom with a rigorous preventative maintenance program, ensuring your product is made to the highest possible standard. Two-shot molding tends to be a delicate operation, and Rogan’s team of injection molding professionals are well-equipped to handle all two-shot injection molding challenges thanks to years of industry experience. We have consistently been at the forefront of injection molding technology, finding new ways to deliver innovative solutions for all our customers.

What Types of Materials are Used in Two-shot Injection Molding?

When it comes to Rogan’s two-shot injection molded knobs, most often there are two variations of resin material used: a stronger base material as the knob or handle, and a softer, more flexible rubber molded onto it. Most often we use a standard grade polypropylene or a glass-filled polypropylene for the base material – the standard grade polypropylene is used in control knobs, while the glass filled grades are often used in clamping knobs.

Typically, TPE rubber is used for molding on the base material to enhance the grip. The TPE Rogan uses is a bondable grade to polypropylene, meaning that the rubber material chemically bonds with the plastic without the need of mechanical bonding. The chemical bonding is so strong that it cannot be separated from the base material.

How Two-Shot Injection Molding at Rogan Got Started

In 1979, Rogan was the first knob company to mold a knob with two different resin materials – a specialized process known today as two-shot injection molding. Throughout the 1980s, our company continued to be a pioneer in two-shot and multi-shot injection molding, which then paved the way for the introduction of our PureTouch® Series of control knobs. These knobs feature a rubber TPE molded onto polypropylene, which helps add texture, create a better feel, and enhance the appearance. To this day, Rogan continues to maintain the industry standard with high-quality soft touch knobs manufactured to customers’ exact specifications.

The Rogan Difference

For many years, we have developed a vast array of unique and different styles of knobs to cover a wide range of industries. This innovation has led to Rogan providing extensive customization with our knobs, which is a key advantage over our competition.

Rogan Corporation is driven by our mission to deliver the highest level of quality with every knob and hand hardware we manufacture. As an ISO 9001:2015 certified supplier, Rogan understands safety, quality and an efficient work environment are key to creating the best possible products.

Contact us today to learn more about two-shot injection molding.

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