𝐒𝐮𝐧𝐝𝐚𝐲'𝐬 𝐓𝐇𝐎𝐔𝐆𝐇𝐓𝐅𝐔𝐋 Post : 𝐑𝐞𝐦𝐨𝐯𝐢𝐧𝐠 𝐭𝐡𝐞 𝐬𝐜𝐫𝐞𝐰 𝐟𝐫𝐨𝐦 𝐭𝐡𝐞 𝐛𝐚𝐫𝐫𝐞𝐥 𝐢𝐬 𝐜𝐡𝐚𝐥𝐥𝐞𝐧𝐠𝐢𝐧𝐠, 𝐚𝐧𝐝 𝐢𝐦𝐩𝐫𝐨𝐩𝐞𝐫 𝐫𝐞𝐦𝐨𝐯𝐚𝐥 𝐜𝐚𝐧 𝐝𝐚𝐦𝐚𝐠𝐞 𝐛𝐨𝐭𝐡 𝐜𝐨𝐦𝐩𝐨𝐧𝐞𝐧𝐭𝐬.

𝐒𝐮𝐧𝐝𝐚𝐲'𝐬 𝐓𝐇𝐎𝐔𝐆𝐇𝐓𝐅𝐔𝐋 Post

𝐑𝐞𝐦𝐨𝐯𝐢𝐧𝐠 𝐭𝐡𝐞 𝐬𝐜𝐫𝐞𝐰 𝐟𝐫𝐨𝐦 𝐭𝐡𝐞 𝐛𝐚𝐫𝐫𝐞𝐥 𝐢𝐬 𝐜𝐡𝐚𝐥𝐥𝐞𝐧𝐠𝐢𝐧𝐠, 𝐚𝐧𝐝 𝐢𝐦𝐩𝐫𝐨𝐩𝐞𝐫 𝐫𝐞𝐦𝐨𝐯𝐚𝐥 𝐜𝐚𝐧 𝐝𝐚𝐦𝐚𝐠𝐞 𝐛𝐨𝐭𝐡 𝐜𝐨𝐦𝐩𝐨𝐧𝐞𝐧𝐭𝐬.

Good preventative maintenance on single-screw extruders requires the periodic removal of the screw and the measurement of the outside diameter and overall inspection of the screw. Typically, the screw should be removed and inspected at least once a year or when the processing performance changes.

When installing a new or rebuilt screw, inspect for blemishes and measure channel depths, lengths, and outside diameters. A cold screw should always be installed into a cold and clean barrel. Excessive force should never be used to install a screw.

For removal, operate the extruder at slow screw speeds with the hopper empty until resin stops coming out of the die. While hot, remove the transfer line and die, then push the screw out using a hydraulic pushing jack or threaded push rod.

- Push the screw out three to four diameters and inspect residual resin for degradation.

- Clean using only brass tools, copper gauze, stearic acid, and cotton cloth.

- Repeat until the screw is fully out.

- Clean the hot barrel with a brass brush wrapped in copper gauze, rotated by an electric drill.

Steel tools should never be used to clean a screw, as they may damage the base metal and chrome plating. Resin should never be removed using a torch, as localized heating can change the grain structure and decrease screw strength.

source : Plastics Technology