V.A.V. Group is known for excellent sealing solutions and superb Finnish quality products, but you may not be aware of the process that leads to the well-known end product. Especially our silicone extrusion process and the newly implemented vertical extrusion line are much requested topics, so we invited our production experts to tell you more about our silicone extrusion process, and how the new vertical extrusion line enhances it.
Step one: Mixing the silicone compound
When we receive the blueprints of the requested profile from our client, we calculate the amount of raw materials depending on the length, wall thickness, and shape of the silicone profile. The raw material is stored as silicone bricks, which are cut and weighed to match the need of the requested total length of the profile. Hard and soft silicone compounds are mixed together with the dying agent to match the selected hardness and colour of the end product. This is done by feeding the silicone through a steel mill over and over again, until the “dough” is homogenous from texture and colour.Silicone rubber is a very versatile material and it can be produced in all RAL colours, but it can also contain additional agents and chemicals to enhance its properties, such as fire-retardant chemicals. Even without any additives, silicone rubber is highly resistant to high temperatures, pressure, chemicals, and oils, which is why it is often used in various operating environments.
Step two: Extrusion
Once the silicone rubber has been prepared for extrusion, the custom tool that forces the silicone into a recognisable shape of the requested profile is installed. The extruder feeds the softened silicone rubber mass through the tool or die, shaping the silicone into the desired profile and thus resulting in a seal or profile that matches the client’s requests. Before producing large quantities of the profile, we have ensured that the blueprints and the end product are a perfect match by sending our client a prototype to ensure the dimensions are just right.
Step three: Furnace
The extruder then feeds the profile into the furnace. The heat of the furnace vulcanises the profile, stabilising it. Our traditional furnace uses coils that surround the conveyor belt on which the profile travels through the furnace, but our revolutionary vertical furnace drives the profile upwards through the air with no contact with a conveyor belt. The infrared heaters are a lot faster to heat up than the traditional heater’s coils, which means a smaller carbon footprint for the end product. A further advantage of the vertical furnace is that since the profile is not in contact with a conveyor belt, we are able to manufacture more complex designs of seals and profiles with it.To read more about our vertical extrusion line, click here.
Step four: Cooling and curing
From the furnace, the profile is transferred into a pool of water mixed with talcum, where it cools down efficiently. The talcum ensures that the surface of the profile does not become sticky, making it easier to handle and install. After this phase the silicone profile is in its final shape and has reached the desired consistency.
Step five: Drying and quality control
Finally, the profile will be dried after its water bath with compressed air. Before packing the product into boxes or reels and shipping them to our clients, we run the final quality control on our product by cutting a 100 cm piece of the profile, weighing it, and comparing the results with the original references.Our quality control process also utilises several other optical and mechanical measuring tools to ensure that the client will get exactly what they need. Not only will this result in happy clients, but it is also beneficial for us as the manufacturer, because we are able to pinpoint any possible faults or hiccups in any part of the manufacturing process if the measurements were off even by a margin.
Further processing and profile assembly
Since V.A.V. Group specialises in custom seals and profiles, some further assembly or processing is often (but not always) the last step of the silicon extrusion process. Laser engravings and mounting tapes are the most common additional features, but we have vast experience in joining the profiles into frames of all shapes, making pneumatic profiles, and attaching all sorts of valves and metal connectors to our custom made seals and profiles, so that the client will receive a product that is 100% ready for installation.
To read more about our wide range of processing and assembly services, click here.
Conclusion
The silicone extrusion process is relatively simple and there are only a handful of steps in our highly automated process. The difference between superior and inferior products is in the human touch: We put great effort into prototyping, process management and quality control, which reduces wastage and reclamations. From the initial weighing of the silicone blocks to a finalised product (excluding further processing or assembly services), producing 120 kg of silicone profile takes merely an hour.The traditional and vertical furnaces complement each other and neither would be sufficient on its own. The more complex or delicate structures demand a vertical extrusion line to achieve the perfect result, but the efficiency of our trusted furnace cannot be underestimated during the most hectic times at our factory. The horizontal extrusion line is ideal for producing large quantities of a certain profile in one go since it is very precise once calibrated. Then again, the vertical furnace’s infrared heaters respond rapidly and producing smaller batches in one shift is more efficient.There is one more factor that underlines the need for both extrusion lines at our growing production facility: The colour of the profile. The lighter colours react differently to the infrared heaters of the vertical furnace, which means the darker colours heat up faster than the lighter. The traditional furnace’s coils work like an oven, so the profile reaches the optimal temperature despite its colour.Thanks to the two different types of extrusion lines, we have broadened our range of available products significantly. If this woke interest in our services, we advise you to read more about our services or simply contact us to hear about possible solutions for your individual needs!
