![]() You can estimate the density of your compound by multiplying the quantity of each ingredient with its individual density ( you can get this figure in any compounding handbook or ingredient supplier literature). 4) Estimate the Specific Gravity (SG) of your Compound Hence, we initially guesstimate the FF before stabilizing on the figure later on through actual trials. Generally, the lower the compound viscosity, the fill factor is higher. Each polymer also has its ideal fill factor and that varies again with Mooney viscosity and filler system.įill factor of a mixer depends on the age of the machine, wear and tear of the rotors and chamber, the rotor type, rotor speed, rotor friction ratio, nature of elastomer, ratio of elastomers/ fillers, mixing sequence, kind of polymers, fillers and individual SG of the ingredients in your recipe, viscosity of ingredients, etc. This compound will have an increased FF of about 0.78 for a tangential mixer with four-wing rotors. This creates a mess under the mixer when the batch is dumped.įor example, NR-rich compounds in an intermeshing mixer has a fill factor of around 0.65 while for the same compound in a two-wing tangential mixer, it is about 0.75. An over-filled chamber leads to unmixed ingredients staying in the mixer throat. This reduces the pressure on the rubber stock and increases the mixing time. Knowledge of the fill factor is necessary because an under-filled mixing chamber results in the ram bottoming out too soon. And for a Intermeshing Mixer (aka Intermix), your FF can range between 0.62 and 0.70. If you have a Tangential Mixer (aka Banbury) , then your FF can range between 0.70 and 0.85. Annual measurements of chamber are recommended to update your batch weight correctly.Įxcessively worn out mixers will have to be rebuilt or reconditioned (Read our posts on mixer rebuilding – Top 25 Things You Should Know to Discuss with Mixer Rebuilder and 17 Essential Questions to Select the Right Rebuilder for your Internal Mixer) 3) Guesstimate the Fill Factor (FF) If not compensated for this inside wear, your batch volume will be effectively too small leading to insufficient ram pressure on the compound, poor dispersion and longer mixing times. When the mixer is used regularly ( or if you have procured a used-mixer) the effective volume increases due to wear on the rotors and mixing chamber. This can be obtained from the manufacturer directly or in some cases from their literature for their various models. Since Internal mixer has a fixed volume mixing chamber, knowledge of the net volume (in liters) is required. This is only a starting or reference point and you need to arrive at your own mixing batch weight for your compound recipes, following some of the other tips stated below. But remember, what they give you is only a theoretical number. Generally, most mixer manufacturers share this calculation with you. ![]() Where W – Batch Wt NV – Net Mixer Volume SG – Specific Gravity (density) of the mixed batch and FF= Fill Factor. The thumb rule is the theoretical equation (Updated on 23rd Dec 2015: Flip through this post in our digital edition and download here) 1) Theoretical Equation Here’s 7 quick tips for you to fix the batch weight for your rubber mixing.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |