Silicone Compression Molding

Inox Silicone Compression Molding

Inox casting is a high-professional silicone compression molding provider and manufacturer. We are proud to offer our services nationwide. Inox Casting has countless experience in the molding industry. You can expect the best services from Inox Casting.

The inox Casting silicone compression molding is capable of having superior quality, surface finish, parting line locations, and flash tolerances. It makes your products withstand stress and exhibits less wear than other substances.

Due to its simplicity, the Inox silicone compression molding is very cost-effective when compared to other techniques. The Inox Casting silicone compression molding is ideal for manufacturing large, fairly intricate parts. The other benefits of this methods are the following:

• High production rates and shorter production cycles
• Allows for close tolerances in small intricate parts
• Requires little post-production work
• Full automation is possible

Whether you need silicone compression molding services, Inox Casting is the right choice for you. We are the trusted one that can meet your special requirements. Inox Casting always provides outstanding, reliable, and quality work.

Due to our experience, aside from silicone compression molding, we also provide a wide range of services like die casting, mold tooling, and many more. Inox Casting is your one-stop silicone compression molding solution.

You can reach us if you ever have any clarification regarding our silicone compression molding!

Silicone Compression Molding: The Ultimate Guide

Probably, you would like to learn more about silicone compression molding.

A reason this guide explores all the vital aspects of silicone compression molding – keep reading to learn more.

1.  What Is Silicone Compression Molding?

Silicone compression molding is a manufacturing method where you fashion silicone material into the desired shape using a heated mold pairing.

You place the silicone inside the cavity of the mold halves before subjecting to a compression and heating press.

silicone compression molding

This process results in the vulcanization of the silicone material creating a part.

Silicone compression molding allows you to quickly produce prototypes with low cost tooling.

2.  Steps In Silicone Compression Molding Process

The silicone compression molding process takes the following steps:

Mold Creation

You can produce tooling of the silicone compression molding process using various techniques including as die casting, machining, and 3D printing.

The mold typically consists of a core and cavity which you position inside a press.

Machine Set Up

Setting up may include processes such as mold cleaning and heating up.

You may also have other procedures based on the equipment or device you’re using.

Charge Preparation

Charge refers to the material you intend to use in your compression molding process, in this case silicone.

You should determine the appropriate amount since using excess material will cause seepage forming flash that you need to cut.

Charge Insertion

You position the charge at the bottom mold’s center upon mounting and heating. The charge’s weight, size and orientation will impact on the finished part’s performance.

You can pre-form or pre-heat the charge before insertion.

Part Compression

Compress the piece by closing the press and applying pressure causing the material to fill up the mold cavity.

Heating during the process allows you to soften the material thus increasing the production speed.

Part Release

You release the pressure to remove the part from the tool upon curing. It’s possible that you may need to cut off a little quantity of material flash.

Part Cleaning

During cleaning, you cut off resin flash usually at the edges before undertaking routine cleaning prior to final assembly.

You avoid flaws and warping by ensuring stricter temperature management.

You can prevent pre-cure defects to the material when left long in the hot mold by ensuring rapid cycle times.

silicone compression molding process

3.  Application Of Silicone Compression Molding

You find silicone compression molding results in parts with high strength-to-weight ratio, allowing for the manufacture of precise, strong, and light parts.

As a result, you find use of these products in a wide range of applications such as:

• Automotive and Aerospace components: Silicone compression molding finds use in making panels and parts for cars and even aircrafts.

Many interior and engine plastic pieces in vehicles are formations of silicone compression molding.

• Computers and Gaming: Silicone compression molding finds use in creation of parts of video game controllers such as keypads and other components.
• Electrical Components: You find silicone compression molding employed in the formation of switches, metering devices and faceplates.
• Medical Parts: Silicone parts have found use in the medical world in forming equipment such as respirator masks and syringe stoppers.

4.  Types Of Silicone Compression Molding Machines

Silicone compression molding machines come in a variety of sizes, from huge industrial machines to little home projects.

Some of these machines include:

Cold Silicone Compression Molding Machines

You can carry out silicone compression molding with or without heat.

However, you have to heat the silicone prior to inserting them in the mold.

cold silicone compression molding machine

 By injecting heat at certain periods, you can control product curing and reduce production cycles.

Hydraulic Silicone Compression Molding Machines

This machine is ideal for creating huge commercial parts.

Hydraulic lift systems allow for achievement of high pressure manufacturing and generating huge, consistent pieces.

hydraulic silicone compression molding machine

Tabletop Presses

These silicone compression machines serve the production of tiny to medium-sized parts and products. While they take up significantly less area than massive industrial compression machines, they can still handle large runs.

table top press

Wet Silicone Compression Molding Machines

In these machines, you combine silicone material with solid fabrics, epoxies, resins and other liquid chemicals.

wet silicone compression molding machine

Wet compression is especially popular in producing long-lasting automobile parts and components.

5.  Silicone Compressions Molding Parameters

You identify the following important parameters when using silicone compression molding:

Clamp Close Speed

Usually between 500 – 1900 inches per minute. Since the press must squeeze the material such that it prevents pre-cooling, speeds are higher compared with thermosets.

Preheating and premeasuring helps to prevent precure while also reducing extra flash.

Clamp Tonnage

Usually between 1000–2500 psi on the part’s molded surface area.

By eliminating part faults and machine breakdowns, ensuring proper clamp tonnage would boost output and thus saving money.

It’s critical to choose a machine that can handle your materials and procedures.

Pressing Speed

Usually between 0–35 inches per minute. It can vary with the charge size, cooling and curing time, making the cycle run between a few minutes and an hour.

Some pressing cycles can achieve speeds over 190 inches per minute, ensuring optimal manufacturing output.

This also prevents residual stress buildup in the parts that result in cracking, fatigue, and warping.

Temperatures

Typically range between 290 to 400°F. Unlike silicone, other thermoplastic components do not crosslink allowing melting and reuse without affecting the material’s chemical composition.

You work on them in the molten state while cooling determines its internal structure.

6.  Types Of Silicone To Use In Compression Molding

You find the following silicone types useful in silicone compression molding:

Solid Silicone Rubber (High-Temperature Vulcanized)

This silicone type consists polymers with long chains and high molecular weight.

You obtain them in an uncured state and thus have to process them using typical processes for rubber processing.

solid silicone rubber

Liquid Silicone Rubber

This is a thermoset elastomer with a high purity and low viscosity that maintains mechanical qualities across a wide temperature range.

liquid silicone rubber

It is especially useful where you need good optical clarity and long-term endurance in a tough environment.

Room Temperature Vulcanized (RTV)

You derive this type of silicone rubber from RTV-1 (one-part) or RTV-2 (two-component) systems with a mild to medium hardness range.

You can employ them in potting, as sealants, encapsulating, among other things.

Fluorosilicone Rubber (FSR)

Fluorosilicone rubber is a stable elastomer with long life.

This silicone type finds use in gaskets, components of aerospace fuel systems, seals, diaphragms, O-rings and hose lining.

7.  Properties Of Silicone Making Useful For Compression Molding

Some of the properties that make silicone useful for compression molding include:

• Excellent resistance to oxygen, ozone, and UV radiation.
• Exceptional thermal and thermoxidative resistance across a wide temperature range.
• High electromagnetic and particle radiation resistance.
• Its non-stick and non-adhesive qualities are excellent.
• Outstanding mechanical properties especially high tear strength and elongation.
• Silicone is thermally stable between -80 to 250 degrees Celsius.
• Silicone material has excellent optical transparency with low chemical reactivity.
• Silicone material has low temperature of glass transition making it flexible at low temperatures.
• The insulating properties and biocompatibility of silicone are excellent.
• Toxic-free biocompatibility making it suitable for use in food and medicinal applications.

8.  Additives AND Fillers To Use In Silicone Compression Molding

You can combine silicone material with other additives and fillers to achieve high-performance material for a desired purpose. These include:

• Colors and Pigments: The transparency of silicone rubbers is higher allowing easier tinting with pigments according to application needs.
• Crosslinking: Peroxide crosslinkers such as benzoyl peroxide and dicumyl peroxide find use in curing of silicone rubbers. This results in mechanically stable cured product.
• Fillers: The most often used reinforcing and non-reinforcing fillers are pyrogenic silica and quartz. Fillers allow you to make modified silicone rubber with increased conductivity or tear strength.
• Flame retardants: These make silicone rubbers more fire resistant and include platinum compounds, aluminum trihydrate, carbon black, ceric compounds or zinc.
• Stabilizers: These find use mostly in improving the heat resistance of silicone rubber.

9.  Advantages Of Silicone Compression Molding

You find the following advantages of silicone compression molding:

Design Flexibility

As silicone compression molding is low-cost, it is perfect for prototyping.

You can build simple silicone compression molds using CAD software or 3D printing to form a variety of materials.

Ideal for Larger and Thicker Components

Silicone compression molding involves directly feeding the material into the mold cavity.

Consequently, there are no part weight restrictions other than those imposed by part design and equipment.

Thus, you can work on larger quantities of material to produce larger products.

Less Complicated

When compared to other molding techniques, silicone compression molding is comparatively simple and forthright.

This makes it easier for operators to accomplish some part designs, resulting in cheaper total production costs.

Produces High-Quality Parts

Silicone compression molding results in solid pieces with no flow or knit lines.

Silicone compression molded items have a high structural stability.

You can also employ silicone compression molding in making parts out of composite materials, allowing production of long-lasting, corrosion-resistant products.

There are No Gates, Sprues, or Runners.

Gates, sprues, and runners, are tooling elements that materials pass through in other production approaches before inflowing into the mould cavity.

These find no use on silicone compression molding. They consume additional material, increasing expense, and detracting from a part’s cosmetic needs.

Tooling is Less Expensive.

The tooling has less infrastructural requirements than other molding technologies because the process does not entail an injection or transfer cycle.

You only need specific features of the cavity that will generate the molded pieces, as per the product design.

10.  Choosing Mold For Silicone Compression Molding

You have numerous mold-making alternatives when carrying out silicone compression molding.

Most important is your molds endure the process, such as withstanding rapid temperature changes when utilizing heat.

Some common mold choices for silicone compression molding are:

Die Casting

Die casting is a commonly applied methods for making molds for silicone compression molding.

It produces long-lasting parts at a lower cost than other technologies with CNC machining used to create dies.

CNC Machining

For highly detailed silicone compression molds, CNC machining is the best option. The digital component of this method allows engineers more design freedom.

However, tooling creation can be costly requiring combination with other techniques such as die casting to be cost-effective.

Three-Dimensional Printing

You can employ 3D printing to create silicone compression molding tooling especially when prototyping small parts.

Here, it is cost-effective and time-efficient and find common use for heatless applications.

11.  Design Considerations For Silicone Compression Molding

Some of the design considerations for silicone compression molding are:

• As the method usually employs a single plane mold, you have limitations with the geometric complexity of the part.
• Parts must be between 3 mm² and 1.5 m² in size.
• Section thickness has to fall between 0.8 mm to 13 mm.
• You can add features like ribs, threads, holes, bosses and writing,

12.  Types Of Molds To Use In Silicone Compression Molding

You find the following mold types applicable in silicone compression molding:

i. Flash Mold: This mold type is popular due to its construction simplicity and keeping part density and thickness within tight limits.

The surplus material forms a thin fin as it escapes over the land during mold closure.

ii. Positive Type: These molds have a deep chamber and a plunger that compacts the silicon at the mold base.

You observe very little material escape requiring close control of charge during weighing.

iii. Landed Positive Type: It is identical to a positive mold, but with lands for stopping the plunger from moving past a certain point.

The density varies with the charge while you afford greater loading room thus allowing processing of bulkier goods.

iv. Semi-Positive Mould: This is a hybrid of the flash and landed molds consisting of flash ridges with limitation of plunger movement.

While the land absorbs some of the strain, the molded component is kept under pressure.

13.  Common Defects In Silicone Compression Molding

Some of the defects you encounter in silicone compression molding are:

i. Blistering: A blistering flaw is typically caused by a silicone rubber compound that is uncured.

ii. Chips: Chips are damages to the component’s surface, commonly around the edge.

They can result due to rough handling, a mold fault, or a tooling issue.

iii. Contamination: Foreign material in the raw silicone results in a contaminated finished product.

iv. Flow Lines: These show during prototype construction.

They result from molten material changing direction at different speeds while passing between the mold’s turns and ridges.

v. Porosity: An inadequate material charge can cause the material to flow too freely, or the flash line becoming too tight.

Also when the mold temperature rises too quickly.

vi. Short Moldings: Defects can result from lack of material charge, low pressure, improper material distribution, or a slow press closure speed.

14.  Factors Affecting Silicone Compression Molding Cost

There are six crucial considerations you should keep in mind when silicone compression molding:

• Choosing an adequate heating method.
• Choosing the right amount of material.
• Curing Time: Calculating the shortest time to heat the material.
• Mold Shape: Creating a mold that allows the material to cool quickly upon squeezing.
• Predicting the required force to guarantee that the shot takes on the right shape.
• Temperature: Calculating the least amount of energy required to heat the material.

15.  Silicone Compression Molding Vs Injection Molding

In silicone compression molding, you heat the material and deposit it in the mold cavity.

You then plug the mold cavity’s top to pressurize and seal the mold as curing occurs via heat and pressure application.

silicone compression molding

Silicone injection molding entails injecting hot material into a closed chamber and vulcanizing it.

This results in a properly cured rubber with dimensional stability that doesn’t require any maintenance.

Injection molding is great for mass-producing products such as cones, automobile parts and components, balls, gaskets, and other rubber items in large quantities.

injection molding

Main Distinctions

i. Final Product Shape: Silicone compression molded goods are blocky and straightforward. Injection molding allows for the creation of more complex pieces.

ii. Product Size: Silicone compression molding enables creation of larger items, whereas injection molding is best for smaller items with strict tolerances.

iii. Production Time: Silicone compression molding takes substantially longer than injection molding.

iv. Quality: Injection molding improves part quality by increasing part strength.

v. Quantity: Injection molding is better for high-volume series, while silicone compression molding is better for low and medium-volume series of large objects.

More Resources:

Compression Molding

Silicone Parts

Injection Molding Process

For any questions or inquiry on silicone compression molding, contact us now.