Understanding the entire making process of silicone hoses can help you avoid decision-making errors during procurement, thereby improving the quality of the silicone hoses purchased and reducing production costs. We will clearly explain each step of the silicone hose making process for you, hoping it will be helpful for your business.
Raw Material Preparation for Silicone Hoses
Silicone Raw Materials
You can choose between fumed and precipitated silicone, depending on your application requirements. If you are in the medical or food industry, the fumed silicone has fewer impurities and is more suitable for you. Moreover, it has high transparency, high purity, and outstanding mechanical properties.
When you are in the general industrial applications, we recommend using the precipitated silicone. Although its performance is slightly inferior to that of fumed silicone, precipitated silicone is cheaper in cost, has a similar tensile strength difference. So it can meet the basic performance requirements, thus being able to meet your daily usage needs.
Reinforcement Layer Materials
You can choose different reinforcement layer materials according to the working conditions.
If your silicone hose is to be used in a vacuum environment and for heavy-duty operations, steel wire helix can withstand negative pressure and prevent kinking, making it more suitable for you. Aramid yarn has outstanding strength and is resistant to cutting, and is suitable for high-pressure and extreme working conditions.
If you don’t have any specific application requirements and just want to enhance the pressure resistance of the silicone hose, we recommend polyester yarn. Through its open mesh weaving structure, this material can effectively improve the pressure resistance of the hose.
Additives
According to the required performance of the silicone hose, various additives are added to the silicone. You can use carbon black fillers to enhance the UV resistance of the silicone hose; while plasticizers can increase the flexibility of the silicone.
If you want to improve the success rate of the vulcanization process for the silicone hose, you should also add a curing agent.
Core Production Process Selection for Silicone Hoses
Extrusion Molding Process
If you want standard straight silicone hoses, extrusion molding is the most commonly used manufacturing process. Usually, the production follows the sequence of mixing, feeding, screw extrusion, vulcanization, cooling, and fixed-length cutting.
This process is relatively easy to control the mold accuracy, and can precisely control the inner and outer diameter tolerance of the silicone hose within ±0.1mm. The key point of this process is to match the extrusion speed with the curing rhythm, ensuring that the silicone fully cures.
We recommend that you equip yourself with a laser diameter measuring instrument. It can monitor the dimensions in real time online and ensure the stability of product specifications and quality.
Compression Molding Process
The compression molding process is suitable for manufacturing special-shaped silicone hoses and corrugated silicone hoses.
You can refer to the following steps: First, prepare the different formulations of the inner and outer layers of the silicone compound. Some of the silicone compounds are pre-sulfurized in advance. Then, the multi-layer silicone sheets are wound around the core mold to form a cylindrical silicone hose.
Second, place the silicone hose on the corrugated core mold and tightly adhere it by vacuuming. Finally, complete the vulcanization process under high temperature and high pressure, and after cooling, the mold can be removed, resulting in a complete and regular-shaped corrugated hose silicone product with the specified specifications.
Capsule Molding Process
This capsule molding process can effectively address the problem of difficult demolding in the traditional hard core method.
The process steps are as follows: First, form the silicone hose blank directly on the surface of the capsule. Second, insert it into the mold cavity. After closing the mold, inject pressure into the capsule interior. Once the vulcanization is complete, release the pressure and the capsule can be easily removed.
This process not only has the advantage of easy demolding, but also has the advantage of a smooth inner wall without burrs in the manufactured silicone hose. If your supplier uses this process, they will provide you with more stable product quality because it can prevent the silicone hose from breaking due to compression.
Post-treatment and Finishing for Silicone Hoses
Fixed-length Cutting
Inconsistent lengths of silicone hoses can lead to prolonged assembly times on your production line, poor product sealing, and an increase in the scrap rate. Therefore, when purchasing a large quantity of silicone hoses, you can ask the supplier whether they are cut using automated precision cutting equipment instead of being trimmed manually.
You can make the judgment based on the following points:
- Length tolerance: The standard length is ±1.0 millimeters.
- Square cutting: Perpendicular to the axis of the silicone hose to form the largest sealing surface.
- Smooth edges: Enhanced fibers without wear and loose silicone particles.
Post Curing
The initially vulcanized silicone hose will retain peroxide by-products and trace volatile substances. If the silicone hose you purchase is not treated, it will cause an unpleasant odor, release substances, and increase the permanent compression deformation of the silicone hose. Especially in food and medical sealed applications, this is not allowed.
High-quality silicone hoses require a post curing process at a constant temperature of 200℃ for at least 4 hours to completely remove residual volatile substances. This also helps to optimize compression set, enhance elastic recovery and stabilize surface performance.
Flaring and Punching
The ordinary straight-cut silicone hoses you purchase usually cannot be directly installed. Many working conditions require port processing, such as flaring, beveling, and drilling. If the supplier you are working with does not have the capability for fine processing, you will need to do it yourself. This will increase labor, equipment costs and quality risks.
Quality Control for Silicone Hoses
The final step is to conduct quality control tests to ensure that your silicone hoses complies with industry standards.
Physical Performance Testing
In order to prevent the silicone hose from cracking or deforming during use by your customers, it is necessary to require the supplier to provide physical performance tests. This can precisely control the quality of the raw materials and finished products of the silicone hose. The specific tests can be referred to in the following table:
| Test Item | Standard Method | Typical Specification |
| Hardness | ASTM D2240 | Shore A 50-80 |
| Tensile Strength | ASTM D412 | ≥5 MPa, typical 1320 psi |
| Elongation at Break | ASTM D412 | Typical 200-300% |
| Tear Strength | ASTM D624 | Typical 320 ppi |
| Compression Set | ASTM D395B | Typical 20% |
Functional Performance Testing
Testing the functional and performance of the silicone hose can provide a multi-dimensional verification of the actual reliability of the product in use. It is crucial to check whether the hose can withstand high temperatures, especially when it is to be used in automotive and industrial applications. The following table lists the specific test items and methods:
| Test Item | Method |
| Burst Pressure Test | Pressurize until rupture |
| Temperature Resistance | Cyclic test from -50°C to 204°C |
| Dimensional Accuracy | Laser diameter gauge |
| Surface Finish | Roughness tester |
| Vacuum Resistance | ISO 8033 |
Chemical and Biocompatibility Testing
If you are involved in the food and medical industries, and require suppliers to conduct chemical and biocompatibility tests for silicone hoses, you can ensure the quality of your products from three aspects: safety, compliance, and compatibility. The test items and certification standards can be referred to in the following table:
| Test Item | Certification Standard | Application |
| Cytotoxicity | ISO 10993-5 / USP 87 | Medical grade |
| Bacterial Endotoxin | USP 85 | Pharmaceutical applications |
| Extractables and Leachables | USP 665 | Biopharmaceuticals |
| Heavy Metal Residue | RoHS | Environmental compliance |
| Odor Residue | Sensory evaluation | Food-grade requirements |
FAQ
What Are the Differences Between Platinum-Cured and Peroxide-Cured Silicone Hoses?
The main applications are different. The peroxide-cured silicone hose has a lower cost and requires secondary removal of volatile substances. It is suitable for applications such as industrial and ordinary automobiles.
The platinum-cured silicone hose has very little residue and low leaching substances. It is easy to comply with regulations and is mostly used in industries such as medicine, pharmaceuticals, and food. However, its cost is higher.
Is the Reinforcement Layer of Silicone Hoses Necessary?
It is not absolutely necessary. For example, in applications without system pressure such as transportation and discharge, a silicone hose without a reinforcement layer is sufficient. However, if the application experiences significant system pressure, the silicone hose without a reinforcement layer is at risk of rupture, expansion or even explosion.
How Long Can Silicone Hoses Last Under Continuous High-Temperature Conditions?
Ordinary silicone hoses can be used for 2000-5000 hours at a continuous working temperature of 200°C, while high-quality heat-resistant silicone hoses may last for more than 5000 hours. If you use the silicone hose in an environment of 150°C, its service life may be significantly extended.
What Causes Longitudinal Cracking of Silicone Hoses?
Silicone hoses that are over-cured will become brittle, resulting in longitudinal cracks in the silicone hoses. The partially uncovered reinforcement layer may create stress concentration points and lead to tearing.
If you use silicone hoses manufactured by the mandrel method, insufficient internal connection will cause them to rupture under pressure or when bent.
Why Are Some Silicone Hoses Translucent While Others Are Opaque?
This is because the type and amount of the filler are different. The silicone hose without any filler or filled with fumed silica is semi-transparent or even transparent. While the silicone hose filled with precipitated silica or with added pigments is opaque. Transparency is not a criterion for measuring the quality of the silicone.
Final Thoughts
Legensilico is a silicone manufacturer with over 20 years of experience. No matter which industry you are in, we can provide you with a variety of different types of high-quality silicone hoses. If you are interested in our silicone hoses, please feel free to contact us at any time.
