Multi purpose Lunac application for screen changers
Regularly, conditions are very demanding and divergent in screen changers. Often, flow channels have to deal with corrosion, sticking problems as well as abrasive wear simultaneously. Additionally, the major bore has to deal with high mechanical forces, regularly leading to scratch or galling problems. For this reason, major bores at risk are separately plated with Lunac 2+. Lunac 1 applied to flow channels proved to be very effective in dealing with these is issues and can eliminate the formation and deposition of plastic degradation products. The spectrum of (sticking or corrosive) plastics that can be processed in these treated screen changers is suprisingly wide. Many feed back experiences are derived from screen changer applications and remarkebly long lasting! Some Lunac 1 coated screen changers operate for over 20 years already.
Generally, the Lunac 1 melt flow channel treatment is performed as follows:
- Flow channels are (pre) finished to Ra 0.2 - 0.3 µm
- 45-60 µm / 1.8 - 2.4 mil Lunac 1 will be deposited
- The coated flow channels will be polished to Ra <0.03 µm
- If any significant wear is expected to coating will be hardened to HRc 65
(very important: Lunac will not develop micro crack (last picture) after being
exposed to (hardening) temperatures over 290°C / 554 F !!)
Only bores wider than 5 mm can coated with Lunac 1
and
the preparation effort is rather high. However, the
melt
flow improvement is often worth the effort. Again,
the
frontal side has to be Lunac 2+ coated, to withstand
the adhesive and abrasive wear at this part.
