Liquid Silicone Rubber Molding

Silicone Co-injection molding

Silicone compression molding

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Silicone Compression Molding


Compression molding has been used to mold rubber parts since the beginning of the rubber manufacturing industry. It is one of the oldest methods still used to mold rubber parts. The process parameters include molding time, temperature, and pressure. Usually, a 300-400 ton clamp pressure is used.

Z.S.R International Group(HONG KONG)CO., LIMITED is a silicone products molding company that has utilized compression molding since the year 2007. Silicone compression molding offers ZSR‘s customers an effective and efficient way to manufacture their liquid silicone rubber prototypes and low-volume silicone production parts. ZSR Group has the ability to produce silicone consumer products to scale by silicone compression molding.

Characteristics Of Solid Silicone

The hardness range of Solid Silicone is 10-80A, with heat resistance, translucent, good processability, easy demolding and good tear strength, etc. Products are generally used to make the protective sleeve as well food contact applications, automotive parts, roller, household appliance parts and other products. There is two kinds of making process for solid silicone rubber.

There are two kinds of making processes for solid silicone rubber.

Precipitated silicone rubber

Fumed silicone rubber

And Precipitated silicone rubber can pass FDA, Fumed Silicone Rubber can pass the LFGB. The FDA (Food and Drug Administration) is standard in America(US FDA is internationally applied) 

LFGB is standard mainly for Europe, Silicone products that pass either one of these tests are safe for human use. In terms of pricing,  products in LFGB standard will be more expensive than FDA standard,  so FDA is more widely used.

The difference between LFGB and FDA lies in the different way of testing methods, and LFGB is more comprehensive and more strict.

Silicone products Design And Materials

Silicone molded products must not only perform as intended but must also be designed from the beginning to be manufacturable. When you design silicone products. You need to consider:

Material Specifications, Grades and Durometer, Part Size, Shot Size, Dimensional Accuracy, Shrinkage, Drafts and Undercuts, Parting Lines, Gates.

By making the right material, color, durometer, dimension, and tolerance choices OEMs can develop molded products that can be reliably manufactured in large volumes — while minimizing scrap rates and their losses. So, there are a few things to consider when deciding on silicone to use for manufacturing. These include the type of silicone (liquid silicone rubber or high consistency rubber), durometer (hardness), and even color. Each of these can have an impact on manufacturability. Z.S.R group we have the experienced Engineer, we will offer our professional selection and suggestion from the material form that fits with the silicone products being made

Solid Silicone Tooling & Solid Silicone Compression Molding

Silicone Compression Tooling:

In Z.S.R Group, we own our in-house silicone tooling workshop allows us to react quickly to customers changing requirements. Customized CNC tooling and EDM machine can fasten the production process.

Silicone compression molding:

Silicone rubber compression molding is the process of placing un-vulcanized silicone material into the cavity of one or both halves of the mold. The mold is then assembled, placed into a heated compression molding press and cycled.

Silicone is vulcanized through this process and a part is formed. While this molding process itself is somewhat slower than injection molding, it does yield quick turns on prototype or R&D parts. It also has less costly tooling upfront.

The most cost-effective production method is to create high multiple cavity tooling.

The Process of silicone compression molding

Silicone compression molding includes the following 10 steps:

Most of the silicone mass production compression mold was made by steel. Before you make the silicone compression mold, you should design the molds according to the products requirements. Z.S.R expert engineer can design the mold for you.

Creating a steel mold involves several precise steps.

CNC milling machines carve out the mold’s cavities and cores from steel or aluminum, following the 3D CAD model.

For finer details, Electrical Discharge Machining (EDM) is used. Once the machining is done, the cavities are polished to achieve a smooth finish.

The necessary textures or surface are added through etching, laser engraving or polishing.

In Z.S.R Group, we own our in-house silicone tooling workshop allows us to react quickly to customers changing requirements. Customized CNC tooling and EDM machine can fasten the production process.

The silicone raw materials are in block form, usually milky white. These raw materials cannot be directly hot pressed and need to be added with vulcanizers (ripening agents). During the preparation process, the ingredients must be accurately weighed according to the formula.

Silicone Rubber mixing: Put the raw materials together with the vulcanizer and other required additives according to product requirements. Mix them through a rubber mixer, and the general mixing time is about 30 minutes to ensure that the raw rubber and the compounding agent are evenly mixed.

Cutting: Cut the refined silicone raw materials into the required size. The cut raw materials need to be placed on the wake-up rack for a period of time, usually about 8 hours, to ensure the cleanliness and stability of the raw materials.

Heat the silicone compression mold,Set the silicone production compression mold up the machine and heat it to certain temperature according to this silicone products mass production needed.

After mixing and mold heated, our workers clean the compression mold cavity and cut materials into slices of different lengths and widths according to the weight of the product. Then feeding the material on the compression mold.

After all the material is in the compression mold, The silicone compression mold is closed. This motion is vertically compressing. The pressure is applied to compress the silicone. This pressure causes the silicone to flow and fill the mold cavity completely, taking the shape of the mold. Curing: Heat is applied to the mold, causing the silicone to cure (vulcanize) and solidify into its final shape. Compression molding machines keep the temperature and pressure to cure the material into the shape wanted.

After the silicone product is cured, it is cooled and removed from the mold.

Inspect the formed products to check for stains, missing edges, unripeness, cracks and other defects, and select the defective products.

Remove the burrs of qualified products and remove excess scraps. Ways for deflashing include:

  • Manual tearing
  • Tumbling
  • Precision Grinding
  • Cryogenic processing
  • Demolding
  • Trimming
  • Flashing

Depending on product requirements, surface spraying, printing, laser engraving and other processing may be required.

Perform the final inspection of the product to ensure quality, and then package it.

The silicone compression over molding

A: Silicone Over Silicone – First a silicone substrate is molded. Then another silicone is molded onto or around the substrate. The silicone could differ in color and/or hardness.

B: Silicone Over Plastic – First a rigid plastic substrate is molded. Then a soft Silicone is molded onto or around the substrate. This is often used to give a soft grip area to a rigid part.

C: Silicone Over Metal – First a metal substrate is machined, cast or formed. Then, the substrate is inserted into a liquid silicone molding tool and the silicone is molded onto or around the metal. This is often used to capture metal components in a silicone part.

Solid Silicone Rubber Products Production

More than 10 years, Z.S.R Group offer Our Solid Silicone rubber compression molding to the Brands/Wholesalers/Retailers for consumer goods. As we own 20sets of the compression molding machine. we’ve been manufacturing a wide range of silicone products, mainly focused on customized silicone consumer products. Our one-stop silicone products manufacturing factory operates at a high capacity and is focused on producing your personalized silicone products to meet your scalability requirements

Benefits Of Solid Silicone Compression Molding

  • Wall Thickness: This technique allows diversity in wall thickness. Generally, the design can vary between 1.3 mm to 2.54CM.
  • Seamless: A uniform part is created without any flow lines or knitting. Gaskets are a great example of how Silicone compression molding allows for a cohesive part. The part is ejected with a good surface finish immediately.
  • Lower Costs: As a low-pressure mold, the production of multiple cavities is done at a lower cost.

Good for High Volume Manufacturing: Although this technique has a longer cycle time, it is a low-pressure mold, which means it’s inexpensive to produce a variety of cavities without high tooling costs.

Industries And Applications

It is widely used in medical and sanitary products except for Industrial, daily necessities (such as silicone housewares, kitchenware, silicone gifts, etc.), baby products and other fields that require high levels of safety and environmental protection. They are in :

  1. Home & housewares & Appliances ( Kitchen & dinning&table & Drink ware &household.etc.)
  2. Baby & Toys ( Baby care & Baby Feeding & Baby Toy & kids learning toy etc)
  3. Health & Beauty & Personal Care (Oral care & Beauty tools/Accessories & hair care ,etc.)
  4. Stationery & Office Products(Arts & Crafts& School products & Office products etc. )
  5. Sports & Outdoor & Garden ( Sports and fitness & Travelling & Outdoor portable etc. )
  6. Pets Supplies
  7. Electronic & Cell Phones Accessories ( Protective cover& Case, holder etc.)
  8. Automotive & Aerospace & Military
  9. Smoking products
  10. Promotional products (Licensed products & Mascot & Gifts & Blind box products)

Solid Silicone products Quality Standards

image 5 - Silicone Compression Molding - ZSR

Material Standard: FDA and LFGB
Size and Tolerances:+/- 0.15 mm Tolerances or according to the 2D drawing request
Surface and Color: Check the surface to see if there is any damage, lack of glue, deformation, different color… and other UN-quality, etc

Custom Solid Silicone Compression Molding Solutions For Your Business

In Z.S.R Group, we work with your timeline and budgets. Our cost-effective prototypes can be populated in small production runs that align with your schedule. We work closely for achieving high-quality custom silicone products for your company. Get in touch to learn more and order your custom silicone rubber products.