Some plastic injection molding suppliers offer “automated” DFM analysis, which is necessarily limited to only the most basic part designs on tools with no cooling circuits. This severely limits your design freedom. At Star Rapid, every project receives a personalized DFM review tailored to your exact needs.

We make tools and dies from S136H, 2316H, H13 hardened, 2316H, P20, 8407, and NAK80 semi-hardened steels. We offer standard SPI finishes, EDM texturing, and several different types of etched textures. We also have thousands of thermoforming plastics available – contact us for details.

We offer more than just tool making and molding services. Our complete package includes every manufacturing process you need for a total product development solution.

Different materials get processed in 2 shot injection molding processes. In a different product other than in the image above the materials could vary. For example, silicone rubber is replaced by thermoplastic. This should be one with a lower melting point than the substrate. The substrate could be injection-molded material other than plastic. For example metal or glass. To determine what goes in the first or second shot, the thermal properties are important. If a material with a lower softening temperature as the substrate poses a problem. If the second shot has a higher melt temperature this softens the substrate. This leads to a distortion of the structure of the substrate. It could also cause the mixing of the two materials since they are both now soft. So at the very least, the melt temperature of the substrate should be much higher than that of the second shot.

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The process where two shots inject into the same mold during a cycle requires modifying. Two shots fill at the same time into two separate cavities of the same mold. So the 2 shot injection molding requires more machinery. These are a second injection unit and a rotating mold mechanism. This does not mean having to buy a second injection molding machine. Two injection units integrate into the same machine. This way two separate feed hoppers channel to respective injection units. This feeding of the substrate and the overmold materials through different paths. The filling is manual or automated depending on the scale and type of process.  It is possible to use the same ancillary systems to operate the two injection units. For example, connecting the injection units to the same temperature control units. This depends on the required setting for the types of materials used. For example the melting points and melt viscosity of the materials.

Want to learn more about plastic injection molding and why it may be the right choice for your product? Contact our production team here at Star Rapid® for a free project review.

A reputable manufacturer will positively identify all incoming raw materials, and will carefully control every stage of production to ensure process repeatability. Full ISO certification is a good demonstration of their commitment to excellence.

The figure below gives an example process illustration. In the illustration, the first shot is an injection of thermoplastic. The second shot is liquid silicone rubber. The thermoplastic will melt to the softening point of the plastic. When injected into the mold, it hardens through cooling only. The silicone rubber can harden either at room temperature or at elevated temperature. Elevating the temperature could increase the rate of hardening of the silicone rubber. How the silicone hardens depends a lot on the chemistry of the specific silicone. The silicone rubber overmold also takes some heat from the hardened thermoplastic. This is if injected at a lower temperature. The thermoplastic could have hardened but still is hot.

In this Serious Engineering video, Star Rapid CEO Gordon Styles offers some helpful strategies for dealing with weld lines and witness marks on plastic injection molded parts.

A product developer should be looking to save money on the cost of a mold tool. In most cases, a less expensive tool is going to be of poorer quality, less durable, with looser tolerances and a bad surface finish. These are not cost-savings. Instead, they’re expensive mistakes. Rather, savings can be made long-term through production efficiency, fast cycle times, and process stability. As volumes increase, the relative cost of the tool goes down until it’s almost free.

The process has some similarities with other overmolding processes like insert injection molding. The difference here is that an insert is not placed in the mold. The substrate is molded in the same mold. Also, the 2 shot system uses two injection units feeding different materials. This is unlike conventional systems where one injection unit feeds the same material. This process requires an initial shot, followed by a second shot. Hence the name 2 shot injection molding. This process uses two injection units.

Star Rapid is a world-class provider of advanced plastic injection molding services. We offer a complete manufacturing solution that covers every aspect of raw material verification, tool making, part fabrication, finishing, and final inspection. Our international team of manufacturing experts is committed to providing you with the highest level of professional support for plastic injection molding services of any size or complexity.

We support your development goals by having no minimum order volumes or value for our injection molding production. In addition, we have a proprietary AI quoting algorithm that provides fast, accurate, and transparent pricing on every project, every time.

The 2 shot injection molding is a variation of injection molding. It allows for the production of more complex designs in a single cycle. With this type of injection molding, extra processes to join parts are not needed. Application of 2 shot injection molding cuts across several industries.

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The mold rotation mechanism is in such a way that it happens after the first shot. It then rotates for the second shot to fill the mold while a first shot fills into the empty molds. So each mold gets two shots. The timing of the rotation allows time for solidification or hardening of the first shot. This requires the engineer to have a good knowledge of the properties of the material. Factors such as crystallization temperature and shrinkage are important. For example in determining the point at which the second shot fills. This aids in the proper timing of the mold rotation. The usual design is a two-plate mold system where the mold opens in half after cooling. The base half of the mold then rotates. The half closer to the injection unit remains stationary. This is because of the simplest design. This half of the mold attaches to the injection unit. Opening the mold is quicker than detaching the two injection units from the molds. This saves cycle time. Since the mold rotates after opening and closing, the fit is important. The rotated half must match the other half with precision. If when rotated the mold is not identical, it either doesn’t close well or leaks.

The more components introduced, the more complex the product. This means more cost of the material. For products such as thermoplastics, this makes recycling difficult. A 2 shot recycling process makes separation easier. A part of the material that can easily separate from the other part. For example, one part can dissolve away in a type of solvent which the other is insoluble. Separation could also be by melting point and density. One part of the product melts at a lower temperature this way the higher melting part can float or filter off. Such processes are more mass reproducible. This is compared to recyclers fiddling with glued parts by hand.

After receiving your drawings, our engineers will analyze your custom plastic injection molding parts right away. We actively work with you to clarify all details before providing a quote that is both economical and accurate.

One crucial factor here is timing. The timing of the screw rotation must synchronize with one another. The rotation of the screws and the firing of shots must also synchronize with the mold rotation. The shot sizes for the different injection units are often different. This depends on the design need of a specific product. The difference in shot sizes makes it more challenging to synchronize the processes. The 2 shot injection molding system means that there are more processes in one cycle. The success of the process depends on how seamless the repeated sequence of steps is.

At Star Rapid we specialize in producing high-quality plastic injection molded parts and mold tools. We offer machining and finishing services to make tools from various materials and can produce 50 to 100,000+ finished parts in a wide variety of plastics. Our international team of engineers and technicians is dedicated to making your custom parts using the most advanced equipment and techniques including Plastic Injection Moulding, CNC Machining, 3D Printing and Vacuum Casting. We’re here to make your product ideas a reality!

A comprehensive design for manufacturing review comes with every tool and product design project. You’ll receive superior results while saving time and money.

The finest production mold tools start with quality raw materials, strict process control, and expert toolmakers. Only a supplier with years of experience supporting Fortune 500 companies can ensure repeatable results for your production tooling needs. Here are some of the advantages that Star Rapid offers for high-volume production tool making and injection molding services.

Depending on the complexity of the design and possible heat treatment, a plastic injection mold tool can be made in five days to two weeks.

Plastic injection molding is the process of filling a mold tool with liquid plastic resin under great pressure. The tool may comprise a single cavity or hundreds of cavities in order to make indefinite numbers of parts. Once the mold tools have been carefully designed and manufactured, the molding process consists of the following basic steps:

This has the advantage of giving better aesthetics. In some cases, it also contributes to the better functioning of the product. For example, joining by welding or gluing introduces vulnerable points in a product. The 2 shoot process creates a more uniform appearance and better joining.

Plastic is very useful in the medical field. Resins are lightweight, non-toxic, inexpensive and can be reused or recycled. Applications include syringes, catheters, dispensers, tubing, and other appliances. For more information about plastic injection molding in the medical field, read our blog post.

Plastic products used in agriculture must be strong and durable, able to resist UV light and chemicals. Engineered plastic parts are used in conveyor belts, drive trains, feeders, water sprinklers, fencing, tools, and much more. Learn why plastic injection is a great solution for the agriculture industry.

You might find 2 shot injection molding also called other names. It is also called twin shot injection molding. Other names are, overmolding, multi-component molding, or assembly injection molding. In a sense, it is a variation of the overmolding injection molding. Although you will find both terms used in some publications. Understanding what distinguishes one from the other is important. 2 shot injection molding requires the same main components as the conventional type. An injection unit, a clamp unit comprising the runner, the sprue, gate, and mold are the main components. The process begins in the same way as conventional injection molding. The starting feed for the material passes into the hopper. For thermoplastic, this is the pellets of plastics. These then mix and melt in the heated barrel as the screw applies shearing force. The screw pushes the melt forward into the melt chamber. The melt reaches the set shot size when the reciprocating screw reaches the limit switch. This triggers the screw to move forward at high velocity powered by a hydraulic cylinder. This action forces the melt into the mold(s). This is the first shot. As the mold cools, the machine begins the second phase of the cycle.

The 2 shot injection molding process is a step up to the conventional injection molding. Of course, there are products produced fine without 2 shot injection molding. When deciding if 2 shot molding is the right process, the following are factors to consider. This article presents them as sort of boxes to tick when deciding.

Get 7-day standard lead times on simple parts between 0.5 in. x 0.5 in. and 4 in. x 3 in. Upload your part to see if it’s eligible.

There are many advantages to plastic injection molding. These include the ability to make large volumes of parts quickly, high surface quality, many resins to choose from, color flexibility, and durable tooling that can last for years.

A more demanding quality management system for products and services related to medical devices. Setting the bar just a little higher!

Plastic resins expand and contract because of temperature, mechanical stress and moisture. Our manufacturing tolerance guide gives you general information on the shrinkage characteristics of most common resin types to help guide your design decisions.

Once a tool is made, plastic injection molding is the fastest and most cost-effective way of manufacturing hundreds of thousands of finished plastic parts. Molded parts have excellent surface finishes with reliable and repeatable dimensional tolerances. And there are resins available to suit most common applications.

Thousands of companies of every size from around the globe have chosen to work with Star Rapid to help them develop new injection mold tools and finished parts. Your success is the foundation of our reputation.

In the 2 shot injection molding, a two-part product gets made in a single cycle. This is compared to when a cycle is only making half of the part. This means more done in one cycle. Even where this makes one cycle longer. It is faster than the time it takes to run two separate cycles. At the very least the cooling of the parts occurs at the same time. The few seconds saved per cycle adds up. When for instance where over a thousand cycles run in a day.

Your regulatory compliance and your peace of mind are assured with our industry-leading positive material identification department. People trust Star Rapid when the job absolutely must be right.

The following are some of the advantages of using 2 shot injection molding. Note that these are as well as the general advantage of injection molding.

All orders are carefully reviewed by our tooling engineers to provide design for manufacturing optimization. We also work closely with outside design consultancies who can offer expert advice on the process of moving a product from the concept stage to production-ready.

This depends on the complexity of the tool design and the type of material the tool is made from. Generally speaking, a very basic square shape made from relatively soft steel such as P20 can be made in less than one week. Very hard steels take longer to cut and to heat treat, while complex shapes or advanced surface textures can require three or more weeks to prepare.

The second shot is next. The screw begins to rotate and move back again as more material mixes and melts in the barrel. In this time it takes to refill the melt chamber, the first shot in the mold(s) cools, the mold also rotates. This is in such a way that the filled mold cavity moves to another point replaced by an empty cavity. Once the melt chamber fills, the screw reciprocates in the same manner as before and fills the empty mold. At the same time, a separate injection unit then fires a second shot. Usually with a different material, over the first shot of the filled mold. This second shot fills over the first shot which by now has hardened. The first shot serves as the substrate while the second shot serves as the overmold. An example of substrate material is for example a thermoplastic. The overmold can then be a thermoplastic or thermoset elastomer.

Raw plastic pellets are first dried and, if necessary, mixed with coloring agents. Inside the machine the pellets are heated and mixed until the resin is semi-liquid. This liquid is then injected under high pressure through a nozzle and into the gate and runner system of the mold. Resin fills the cavity, forming the shape of the part. It’s then cooled, the part ejected, and the process begins again.

Compared to single-shot injection molding. The use of two shots can make more complex designs possible. Some designs may not be possible by injection of the melt into the mold in a single shot. These are possible by using two shots. For example, achieving double layers with different colors.

The cost of a plastic injection mold tool can be a significant percentage of the total order for small volumes. However, this cost can be amortized over larger volumes so that it doesn’t become an issue. Rather, plastic resin and cycle times become the main cost drivers for larger volumes.

2 shot injection molding is one of such advances in conventional injection molding. It is adaptable to the production of complex designs using a wide range of materials. 2 shot injection molding achieves high quality of products. It is a well-established technology in the manufacturing industry.

Our quality-control system includes several steps to ensure safe, high-performing products for our clients. As with all of our services, we conduct comprehensive material verification and testing before molding begins. This includes the metal used in our molds and the plastics used in production. During production, we carefully control all processing conditions — including temperature and humidity — to maintain repeatable results. Many molding companies neglect to do this, which can lead to flaws in the finished parts. We also 3D scan complex shapes to ensure accuracy.

The injection units could be a combination of horizontal and vertical injection molding. In such a process, the first shot is from the horizontal injection unit. The second is from the vertical. This way the process takes advantage of the vertical injection process. In this combination of orientation, the injection of the overmold is easier. The image below is an illustration.

At the tip of the barrel, a nozzle injects the liquid resin into the cavity of the mold. Once the plastic is then cooled and solidified, the mold opens and the finished part is ejected.

The conventional injection molding process manufactures products that meet diverse industry needs. But some products need some modifications to the conventional injection molding process. This could be to achieve a more complex design or to make the production process more efficient. Such advancement could result in significant cost reduction and time-saving.

Unless otherwise specified, we comply with the DIN 16742 standard tolerances for injection moldings. Ensuring the highest quality is an important part of our production process. Be sure to read about the visual quality standards guide that we apply to injection molded parts.

In Episode 11 of Serious Engineering, Star Rapid CEO Gordon Styles takes us through a closer look at four of the most common resins used for plastic injection molded parts.

We use plastic every day for work and play. Plastic compounds with different chemical properties are found in computer keyboards and mice, game controllers, headphones, toys, home appliances and kitchen gadgets – anywhere you look.  Learn more about plastic used for consumer products.

Star Rapid operates a world-class manufacturing facility. Talk to our experts who will help you to make your design ideas a reality.

As part of our design analysis, we’ll indicate any areas that might produce thermal stress, shrinkage, warping, or other avoidable defects in your injection molded parts. For more information, consult our manufacturing design guide on common defects and how to avoid them.

Injection mold tools can be textured to provide a variety of functional and cosmetic features to molded parts. Learn how we do it in this Serious Engineering video.

Our molding service is strengthened by our extensive expertise and a wide range of production capabilities. Our industry-leading facilities allow us to handle projects ranging from micromolding (10 tons) to large projects over 500 tons. This means we’re capable of producing parts ranging from millimeters to cubic meters in size. Our production of such a wide variety of parts enables us to best meet your needs. Further, we have unique access to tooling experts with decades of experience. They are available for video conferencing and customer support. We’re united in our efforts to help you have a satisfactory injection molding experience!

The fact that two parts get processed at once reduces the time required. It also reduces the need for more stages or equipment for joining. The joining 2 shot injection molding machine achieves might otherwise need complex machinery. Processes like micro-welding or laser welding add cost and time to the process.

Components like circuit boards, switches, wires, batteries, and sensors must be placed in strong, lightweight, non-corrosive, and non-conductive housings to protect them while also safeguarding the user. Learn why plastic injection molding is an ideal solution to support the electronics industry.