Silicone compression molding is a versatile and guaranteed process of manufacturing high-precision silicone products. Over the years silicone manufacturers have prioritized this process for manufacturing their silicone parts. However, have you considered what made this process special and most preferred in the industry? Well, let’s discover it together.
What Is Silicone Compression Molding
Silicone compression molding is a process in which silicone material is used to get a shape using various compression techniques.
This process is done by placing silicone in a mold and then applying heat as a treatment to form your desired shape. When this is done, the heated silicone material will take the shape of the mold cavity.
To further explain this, heat is the primary agent used to cure silicone material. To cure silicone material means to transform raw or in-vulcanized silicone material from its current state to a useful product.
Nevertheless, apart from using heat to cure silicone material, you can also use other means of curing like room temperature vulcanizing (RTV), platinum curing, and so on.
Types Of Mold Steels For Silicone Compression Molding
Silicone compression molding will be impacted based on the type of mold utilized in the process of compression. However, listed below are the main types of mold steel materials commonly used:
- 45# Steel: This type of mold steel is mostly used for industrial molding, and can be particularly used for silicone compression molding. It’s a product of medium non-alloy and has excellent tensile properties, as well as medium-strength carbon steel with good machinability.
- P20 Steel: You can also utilize this mold steel for silicone compression molding. The mold is versatile and has low alloy tool steel that comes with good though at a moderate strength level. P20 steel is a popular tool for silicone compression molding.
- S136 Steel: This is another type of mold steel utilized in silicone compression molding. It has excellent corrosion resistance, high hardness, and polishability, it ensures durability and precision. Its resistance to wear and ability to maintain surface finishes make it ideal for producing intricate, high-quality silicone components.
Step-By-Step Process Of Silicone Compression Molding
If you have asked how is silicone molded through the compression molding technique, the paragraphs below show the step-by-step guide in which silicone compression molding is done:
Getting Ready
Preparing Raw Material: The first thing you need to do before you start processing silicone compression molding is to know the type, characteristics, quantity, and quality of the silicone material you want to use. The reason for this is to make sure there are no impurities and deterioration.
Note: Make sure the quantity of the silicone will be enough for your required production.
Mold Preparation: Secondly, make sure you thoroughly clean the mold and be sure there are no oil stains or foreign objects. Next, verify to make sure the integrity and the accuracy of the mold closing are intact (Repair and readjust it if there is a need). The next thing is to install the mold.
Note: Be sure you install the mold firmly and make sure you position it accurately.
Silicone Mixing
At this stage, weigh the silicone and curing agent. You need to be more cautious here as the curing agent and the silicone need to be proportional. That’s the grams need to be enough for themselves with very little differences that can be controlled if need be.
Now is the right time to use your special mixing tools to evenly distribute the silicone material with the curing agent. Remember, the time you’ll spend on mixing is usually determined by the process required and the characteristics of the materials.
Note: Do not incorporate air to prevent bubbles. However, you can utilize vacuum defoaming or other methods to eradicate bubbles if there are.
Compression Molding
This is the stage where you process the compression molding itself. Next, put the actual amount of your mixed silicone in the mold cavity.
Note: Make sure the silicone material is evenly distributed to avoid excessiveness in some parts while it will be insufficient in some areas.
Now, based on the mold size, silicone characteristics, and product requirements, set the right pressure and control the mold closing pressure. Next, you need to stabilize the pressure for the silicone to fill the cavity and for it to solidify under the same pressure.
Note: How much time it takes for the silicone to fill the cavity and solidify is based on the product thickness.
Silicone vulcanization characteristics or other curing methods you use are what ensure the full curing of the product as well as its stable performance.
Post-Demolding Treatment
At this stage, take out your silicone products after opening the mold, and familiarize yourself with the demolishing method so that you don’t damage the products. Next, do the trimming, grinding, and other treatments on the demolded products. The purpose of this is to remove burrs and other defects for a smooth surface of the product. Plus, for the size to be up to requirements.
The next thing is to carry out processes such as surface printing, painting, secondary, vulcanization, etc depending on the product requirements. The purpose of this process is to improve the performance of the product and the appearance quality.
Lastly, make sure you carry out a thorough inspection of the product. You can do this quality inspection by checking the appearance, size, performance, and so on. When you have ascertained the products are up to standard, package and store them in the warehouse. Meanwhile, deal with unqualified products according to the rules and regulations of your company.
Types Of Silicones Utilized In Silicone Compression Molding
Silicone elastomer manifestations are in various forms. The molecular structure of silicone as well as the external conditions are great determinants of the forms. However, it’s important to know that the actual method by which you want to manufacture silicone will determine the type of silicone you want to use. Now, let’s take a look:
High Consistency Rubber Silicone (HCR)
HCR silicone is in the form of clay in its uncured state. You can cure them with platinum or peroxide curing methods for you to achieve durometer and other properties. Additionally, you can also cure them with a heat-curing method. You can use HCR silicone to produce various medical products due to their biocompatibility.
Medical-Grade Silicone
Using silicone for medical purposes means you must look out for silicone that will meet such requirements. With that said, medical-grade silicone is the best option for medical purposes. This type of silicone biocompatibility has been approved, meaning you can use it for internal and external body use. Some examples of the medical products you can use it for are implants, prosthetics, and so on.
Fluorosilicone
The polymer chain of this type of silicone has trifluoro-propyl and methyl groups. Due to these molecular groups, the silicone has advanced chemical resistance. Fluorosilicone is costly due to its outstanding characteristics, thus leading to durability in its final output.
Electrically Conductive Silicone
Electrically conductive silicone comes with electrically charged properties. With this, the silicone can be used for products that necessitate continuous dissipation. The molecular composition features electrodes that make this very possible. Although this property is uncommon, you can always use it to cater to specific situations.
Reasons For Silicone Compression Molding
Silicone compression molding is the most suitable process of molding silicone when compared to its pairs. But what made this molding technique the best? Well, let’s look deep into it:
- With Compression Molding, Silicone Maintains Its Mechanical And Chemical Properties: Because the material is not rigorously impacted during compression molding, the silicone can have similar properties as when the silicone material has not been compressed.
- Compression Molding Is Practical For Some Products: This silicone molding technique cannot be used for all types of silicone products. For example, transfer molding is perfect for manufacturing silicone products with inserts. The above approach is used due to its reliability, effectiveness, and accuracy.
- Suitable For Particular Specifications: With compression molding, it’s possible for you to manufacture products with an actual dimension and properties. That is, without silicone compression molding, there are certain shapes that you cannot achieve.
Normally, the required temperature used in compression molding of silicone is between 160°C and 232°C because it’s the only alternative applicable to specific situations. Additionally, compression molding of silicone is indisputable based on its versatility, characteristics, and benefits.
Advantages Of Silicone Compression Molding
There are a variety of advantages attached to manufacturing your silicone through silicone compression molding. Here are some:
- Cost-Effective: As you know cost is a major factor in business. Therefore, silicone compression molding techniques have low production cost and high production quantity.
- Applicable In Various Industries: Since the silicone compression molding process is versatile, you can use it to mold various products for diverse industries.
- Straightforward Process: The process of compression molding is not complicated, making it a go-to for various product dealers.
- Perfect For Large-Size Products: The product size manufactured with compression molding is adjustable due to varying mold sizes such as large and small.
The benefits of the silicone rubber compression molding process are not limited to the list above. Other advantages are more specific to your industry.
Disadvantages Of Silicone Compression Molding
Despite the numerous advantages of silicone rubber compression molding, it has some drawbacks just like every other method. Here are they:
- Not Perfect For Complex Designs: Silicone compression molding machines can achieve up to some extent complex designs. However, molding is generally limited in constructing a more detailed configuration.
- Long Post-Production: There’s a delay in post-production that makes the overall process hectic and costly because products pass through visual inspection and de-flashing for them to be refined after curing.
- Some Compression Techniques Are Slow: regularly, it takes more time for compression molding to cure the mold. Therefore, the production process is automatically lengthened and makes the output slow.
Overall, some manufacturers did not prefer silicone compression molding due to some of the disadvantages outlined in this paragraph. Nevertheless, one good thing about this molding technique is it’s the most perfect for specific applications that there are high expectations of these disadvantages, but can however be tolerated.
Applications Of Silicone Compression Molding
The silicone compression molding process is used in producing various parts in diverse industries based on its versatility. The subsequent paragraphs explain it:
For Automotive Parts Production
Automotive parts like LEDs and headlamps, sealants, head gaskets, potting components, and thermal transfer materials are produced through the silicone rubber compression molding process due to their ability to resist various conditions such as heat, friction, and other higher conditions.
Fabricating Medical Equipments
Silicone is used to manufacture medical equipment like digit covers, menstrual cups, radio plaque materials, nursing pads, and medial gaskets due to its biocompatible properties.
Personal Care Products
Various personal care products like make-up, beauty tools, cosmetics accessories, and hairdressing tools are produced using silicone due to their revolving properties.
For Houseware Production
Silicone has thermal resistance properties that make it possible for it to be used in the production of various houseware products like oven mitts, bowls, spatulas, straws, spoons, and so on.
Conclusion
Transforming silicone material from its uncured state into a useful product is a process that must be done willingly. As discussed in this article, silicone compression molding is one simple process of molding silicone to get your desired shape without compromising the properties of the silicone.
More Resources:
Ultimate Guide to Silicone Die Cutting – Source: TOGOHK
In-Depth Guide To Understanding Silicone Extrusion Process – Source: TOGOHK
Silicone Foam Molding: All You Need To Know – Source: TOGOHK
A Complete Guide to Silicone Mixing – Source: TOGOHK
Step By Step Guide To Silicone Transfer Molding Techniques – Source: TOGOHK