In the previous article, we analyzed the reasons cause bubble during vulcanizing. This time let’s learn how to solve such problem.
Methods for material
1. Take drying measure after cutting rubber. Strictly control the moisture and volatile matter. Besides, reduce the moisture content in raw rubber.
2. Take anti-moisture measures when store chemicals and additives, especially in rainy days. Take care and avoid the moisture during transport, storage and process.
3. Open the wrapper of steel wire and cord 1 hour before use. Keep the humidity in a proper scope to avoid moisture.
4. Heat and dry fibre cord before calender. The moisture regain of fibre cord should be less than 1% before calender.
Methods for semi-finished product
1. Replace the present additive with dispersive one. Increase the use of dispersing agent and homogenizing agent to improve the dispersing performance.
2. The mixed rubber is produced by a two-stage process of an internal mixer. During the first stage of mixing, the temperature is increased to allow the moisture and volatiles in the raw materials to fully volatilize. The rubber compound is parked and then mixed in two stages. Within the temperature range, avoid short scorch time or scorch.
3. Control the place time of semi-finished product in every procedure strictly. Make additives disperse completely and improve the homogeneity of materials
4. Adopt the operation method of hot-melting glue supply and molding separately to improve the smoothness of the surface of the molding compound.
5. Extrude the rubber material and there will not be air.
Methods for operation
1. Control the temperature of roller and avoid the bubble by overheat.
2. After calendering, arrange multiple groups of cotton threads along the warp to increase the exhaust effect between the rubber cord fabric layers.
3. Strictly control the construction dimensions and tolerances of the semi-finished rubber compound to prevent the product from harbouring air
4. If multiple material have to pile up, use exhaust valve to exhaust air
5. The steel cord change to extrusion coating, which reduces the air content in the steel wire in the glue and reduces the phenomenon of trapping air when sticking the film.
6. Reasonably set the cavity pressure to ensure the pressure that vulcanization should reach, so that the rubber material can flow and fill the cavity
7. Operate with strict vulcanize temperature and time.
Methods for equipment and mould
1. Improve the temperature measurement point and temperature control sensing system of the flat vulcanizing agent, so that the temperature in the mold cavity is consistent with the temperature displayed by the instrument
2. Repair the damage part in time and take some protection measures
3. Regularly clean the mould
4. Improve the layout of the mold exhaust line and the exhaust hole, run vertically and horizontally, and the distribution tends to be reasonable. Appropriately thicken the exhaust line, increase the diameter of the exhaust hole, and enhance the exhaust effect
These are the methods to solve the bubble problem. EverFlex in an expert in hoses and other plastic and rubber products. If you have any inquiry about hose and relevant products or have questions about the production technology, we will offer you the best products and the best solution. Contact us now.