A consistent feed to the calender will substantially reduce gauge variations. Consistent, uniform, dwell times on the break down and feed mills, as well as consistent bank size, will result in consistent
stock temperatures, work history, and reduced variations in roll separating forces.
The stock temperatures, bank sizes, and work history all directly influence roll-separating forces. Minimizing variations in these 3 important process parameters will minimize variations in roll separating forces, and this in turn will minimize gauge variations. Good mill and bank control practice also results in improved uniformity for other final calendered gum and/or fabric properties.
The feed to the calender must also assure that the rubber bank does not have areas that stagnate. If rubber remains in the bank on the calender for an excessive amount of time it will partially cure and
become much harder. Edge trim that returns to the bank and stagnates is a common source of this problem. These areas will introduce gauge variations as well as negatively influence other properties of the calendered material. In extreme cases, burned lumps will appear in the calendered gum.
Regarding CORD PLACEMENT for corderd rubber(tires):
Bands of hard stock also make it hard to properly penetrate the cord and may cause cord disturbance and improper cord distribution in these areas. In such cases the cushion force causes lateral movement in the nip and this results in cord displacement that is visible. Paired cords are often the first indicator. The thickness will be heavy and there will be cord displacement and irregularities but the weight of test samples will not be significantly affected.
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