Tips for Eliminating Carbon Contamination
Carbon contamination can be a big headache for many thermoplastic processing companies as lingering black specks can result in a huge loss of production and create quality control issues. Along with using an effective commercial purging compound, here are few basic tips a company may follow in order to limit carbon contamination.
- Develop a preventative maintenance program to avoid layers of carbon from forming on the screw. In many situations carbon contamination can be easily managed by periodically purging the plastic processing machine. However, if the carbon issue is neglected and many layers of carbon form on the screw it may become impossible to remove all the contamination. Thus, in these situations it is best to pull and clean the screw manually and then establish a preventative maintenance program to keep the screw clean.
- Shut down machines with a commercial purging compound to neutralize carbon from forming on the screw. Machines that are improperly shut down can take hours to clean up before good parts (black speck free) are produced. Ultra Purge procedures recommend using a half barrel capacity on the shut down and then another half barrel capacity on the start up.
- Refurbish worn out screws. Screws that are in bad condition are more prone to develop carbon contamination issues.
- Do not let thermo sensitive resins that easily degrade sit in the barrel for an extended period of time. However, if a machine must sit idle for a long time it is best to first purge with a commercial purging compound.
- Make sure the virgin resin is clean and free of debris. Foreign material that is accidently introduced into the virgin resin will many times degrade in the machine and create a black speck issues.