What Causes Plate-Out and How to Effectively Control It

Plate-out is an undesired deposit on the processing equipment that can lead to scraps and deficiencies in the final product, and therefore nonconformity. In severe cases, deposits may appear within just three hours of production. Depending on where in the process this happens, the shape of the plate-out may change, and it may either be temporary or permanent. More interestingly, the composition of deposits also varies based on where it occurs. Plate out can happen in three parts of process including:

• the degassing section
• in the adaptor and the die
• at the exit of the die
• calibration.

A photo of plate-out occurred in calibration stage

The mechanism and outcome of plate-out differ based on the location of its occurrence in the production unit. The complexity of resolving plate-out arises from the multitude of influencing factors.  Let’s delve into some main factors with examples:

Formula: The overall compatibility of PVC formulation components plays a crucial role. 65 to 98 percent  of plate out samples from tooling and adaptors are formed by inorganic components such as titanium dioxide and filler. Plate-out in the adaptor and die occurs mainly in the case of lead stabilizer but in rare cases also with organic stabilizers. For window profiles it is important  to maintain the balance with sufficient weatherability on one hand and plate-out on the other hand.   

M. Schiller; “PVC Additives”, first edition, C. Hanser Publisher, Munich, Germany (2015), p. 255

• Process Conditions: This can change the rheology of compound in the extruder. Variables like mass temperature, screw speed, torque, pressure can significantly impact plate-out levels. After maintenance, it is essential to monitor process conditions, as maintenance procedures may lead to changes in the rheology of the compound.

M. Schiller; “PVC Additives”, first edition, C. Hanser Publisher, Munich, Germany (2015), p. 236

• Moisture: Higher moisture levels in the dry blend lead to increased plate-out. Keep in mind that most formula components comprise 0.3-3.0% moisture. So, regularly monitoring the mixing process is recommended to ensure proper moisture content removal. Additionally, compounds can absorb moisture in silos.

M. Schiller; “PVC Additives”, first edition, C. Hanser Publisher, Munich, Germany (2015), p. 242

• Suppliers: One-pack stabilizers comprise a precise mix of ingredients, and every single component within them can increase or decrease the level of plate-out. The replacement of a stabilizer supplier, and therefore reaching a more balanced formulation, may prevent early plate-out formation. A well-balanced one-pack of stabilizers can effectively mitigate the formation of unwanted deposits.
  

At Baumann, we stand as your trusted partner in controlling plate-out. Despite its dependence on various parameters, our precise formula is designed to overcome plate-out challenges. Our experts are ready to collaborate with you, identify plate-out sources in your system, and provide tailored solutions.

Let’s start a conversation to address your specific needs!