J – CAD Inc. has extensive experience in silicone injection molding as silicone is one of the most popular materials used in injection molding. We also work with plastic molding, foam molding and other techniques of mass production if silicone is not the right fit for your project.
Contact us today to have your project quoted by one of our experts.
J – CAD Inc. keeps quality under control by testing parts as they come off the line. We check the parts hardness durometer using the Shore Scale to ensure the proper silicone hardness is achieved. We adhere to international tolerances associated with the Shore Scale so the parts you receive from us are guaranteed 100% high quality and what you ordered!
Silicone rubber is an organosiloxanes polymer. This special feature originates from its unique molecular structure in that it carries both organic and inorganic rubbers. It’s Si-O bond and its inorganic properties make it have more superior qualities compared to ordinary rubber. It exhibits heat resistance, resistance to abrasion, chemical stability, ozone resistance, electrical insulating and weather-ability.
Silicone rubber is classified into two groups based on the curing temperature. It is classified into High Temperature Vulcanization Silicone Rubber (HTV) and Room Temperature Vulcanization Silicone Rubber (RTV). HTV is further divided into two groups based on the degree of polymerization. It is divided into a Mill-able Type and Liquid Type Silicone Rubber.
Liquid Silicone Type Silicone Rubber (LSR) has a different viscosity and curing temperature apart from the Mill-able type and RTV. LSR is well suited for injection molding owing to its excellent liquidity. It’s also very ideal for complex molds since it easily fits in the most complex parts of any mold
RTV silicone is made up of two components mixed in a ratio of 1:1. It exhibits many characteristics including work-ability, heat resistance, flow-ability, non-exothermic, dimensional stability and ease of mold release. It’s used for fire stop material owing to its fire retardant characteristics.
Silicone Sheet exhibits thermal conductivity, very high-temperature resistance and is flame retardant. It is therefore very suitable for use in the thermal management of electronics and heat dissipation. Electronic products are growing smaller and thinner and are becoming richer in features making thermal management essential hence the growing demand for silicone sheet. Its demand is also getting wider into the automotive, medical and shipbuilding industries.
Manufacturing objects, especially ones that require plastic molding, can be done easily using our special 3D printers. However, it’s not just as simple as putting a design into a computer and printing it out.
A few decisions are required before this can happen. For instance, a choice has to be made for the type of material you want to use for your product, like silicone or rubber.
Each material has its own pros and cons which is why it’s important to consider the intricacies of printing a mold and the process of how it’s done.
A liquid silicone injection molding design requires quite a few steps and decisions. These include choosing how large the mold needs to be and the type of surface coating to ensure that the mold stays durable.
The first step to molding liquid silicone (also known as LS) is to design an aluminum casting to pour the hot silicone mixture into. This casting is usually designed with a CNC machine to help prevent any irregularities in it so the mold is formed without deformations.
Once the casting has been designed, a surface coating has to be chosen. The surface coating will help to make removing the mold easy and add a shine or unique coating to the liquid silicone mold.
When it comes time to pour the silicone into a mold, a special pump will measure out the needed silicone before it’s poured into it. After the liquid has been measured out, the pump will move it into a large mixer where it will then be stirred up and packed into a specific mold. The mold will then be heated until the liquid silicone firms up and can be easily removed from it.
An interesting aspect about liquid silicone is that you can mold it to a certain softness or hardness (known as the shore hardness). By using a Shore Scale durometer, at J-CAD Inc. we are able to keep track of how soft or hard a mold should be. The object can be as soft and tender as a gummy bear or hard and heavy-duty like a construction helmet.
There are 3 Shore Scales that are used to help determine this: Shore 00, Shore A, and Shore D. Shore 00 is used to measure soft rubbers and materials, Shore A is used mainly to test flexible rubbers, and Shore D is used to test hard and rigid plastics.
This scale is extremely important when it comes to custom plastic injection moldings because it determines whether or not the product will be properly created.
You have plenty of options when it comes to different silicone mold materials.
A popular choice is a silicone rubber mold. This is made with special components that are a mixture of organic and inorganic materials which helps to make it heat-resistant. This type is commonly used to create electronics and household items.
Liquid silicone rubber (LSR) is also a very popular option because it’s highly heat-resistant. LSR is made with materials like silicone, carbon, and hydrogen which help to make it a very smooth mixture. This liquid can easily fill in all the crevices of a mold to ensure a complete product is made.
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Because it’s so easy to use and strong, it’s used to create almost everything today. You’ll find it in everything from medical devices to wearable technology, like watches.
Another unique type of silicone often used is HTV (High Temperature Vulcanized) silicone rubber. This is a very strong composition of chemicals and typically is used to make silicone sheets and keyboards.
You might hear about it also referred to as RTV (Room Temperature Vulcanization) silicone rubber, but this is a slightly different thing. RTV uses room temperature to cure, hence its name. Because of this different cooling method, RTV tends to be more elastic and is heat-resistant making it perfect for products that you want to use in extremely hot environments.
The last main type of silicone mold that you’ll find is silicone sheets. These long, flexible sheets are made entirely out silicone and are known for being highly fire-resistant. Because of this, you’ll find silicone sheets used in many industries today, especially technological ones.
The temperature for silicone injection molding is vital when it comes to forming objects. As mentioned above, the Shore Scale helps with finding the right temperature when trying to create a certain mold.
How this is determined isn’t necessarily that difficult because it only really depends on the type of silicone you’re using and how much of it. Typically, silicone injection molding temperatures can range anywhere from 340 – 400oF.
When the silicone is first poured into the mold, it starts out as liquid. These high temperatures then work to solidify it slowly. But even with the high temperatures the molding has to go through, it doesn’t burn or melt which shows just how durable and heavy-duty it is.
A common technique that is often used with plastic molding is silicone overmolding. So, what exactly is this?
Silicone overmolding is when a silicone layer is poured over an object, like a wire, to help seal the materials inside and create a composite component. For instance, you’ve probably seen bundles of wires molded together for a computer or TV.
This is basically what silicone overmolding is. It keeps those materials together in one spot. This method is very cost-efficient and easy to create which makes it popular to use.
Now while this process seems rather simple, that isn’t to say it doesn’t come with some problems. Sometimes creating molds can be very difficult, especially if the product is of a certain height, thickness, or material that complicates things.
A common problem that comes with this molding type is that the curing can sometimes not set correctly which can lead to deformed objects and even ones that aren’t able to be removed from their mold.
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To help with this, there are a few things that can be done. One is to make sure that the mixer and pump are often checked to ensure that the liquid inside is being properly measured and stirred. Another way to solve this is by just looking at the durometer. Sometimes the temperature can decrease without you knowing and can cause a problem like this.If the rubber comes into contact with certain ingredients, like sulfur, that can destroy the chemical make of the rubber which can prevent it from forming correctly. Also, if a rubber injection molding is unable to be removed from its specific mold, you can usually increase the temperature to help heat that mold up to loosen the rubber object inside.
If a mold isn’t being completely filled up with materials it’s usually because the pump isn’t measuring things out correctly. This can lead to a bumpy surface on the object and having a lighter weight than it should.
By checking the pump and mixer you can usually help to find the source of this problem. Sometimes the pump might have some solid materials blocking the exit of it which can prevent the even flow of liquid. Because of this, it’s usually a good idea to clean the machine every now and then.
Another common reason why a mold wouldn’t be fully filled would be because the liquid is old. These liquids have a short lifespan and once that time is up they can start to lose their thick viscosity.
Sometimes a product can be created with slight bubbles in it. This is typically a sign of 2 things: either moisture in the silicone or a dirty machine.
To remove moisture a vacuum can be added to the machine to help suck up air. You can also increase the temperature to help absorb the moisture that is causing these bubbles.
However, if you’re just starting out with a molding machine or have put a new liquid batch into it, bubbles are common. They do tend to disappear after a few pumps though so it won’t greatly affect the product.
A strange thing that sometimes happens when machines pump out silicone into a mold is what it called flow lines. These are orange and streaky lines that show up in the object and can ruin the aesthetic appeal of it.
This can be fixed by checking the lifespan of the liquid you’re using, increasing the machine’s temperature and pressure, or by adding a bump. You can also add a layer of chrome to the surface of the mold to help with this.
If you’re looking to have a certain mold created for you, we can help. At J-CAD Inc. we have some of the top-of-the-line machines that can create numerous types of molds for any type of product. Just ask us for a quote, and we’ll do whatever we can to help you create amazing things and make your business grow.
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