What are you doing to make your production process more efficient? Would a specialized purging compound make that big of a difference?
Thermoplastic molding companies and other manufacturers suffering from carbonization turn to glass-filed purging compounds to attach carbon deposits and, above all, defect rates.
Have you considered what glass-filled purging compounds could do for your manufacturing process?
How To Reduce Carbonization With Hard Cleaning
In many cases, an unfilled grade of purging compound is effective for cleaning injection molding machines and extruders.
Once resin degradation has progressed in the barrel and degraded resins layer over the screw and barrel, however, regular unfilled grades of purging compound may not be able to clean it completely.
Carbon is extremely hard to clean due to its affinity for metal. A stronger scrubber is needed to reduce carbonization.
Glass-Filled Purging Compounds: Excellent Scrubbing Power
These stronger scrubbers are formulated to provide efficient cleaning and maximum benefits while minimizing purging residue.
Benefits of using glass-filled purging compounds include:
- Maximum deposit removal, especially for hard-to-purge resins.
- Highly effective when used to facilitate screw pulls – it may even eliminate the need for screw pulls.
- Generally formulated to minimize purging residue. (Unfilled grades generally have better residue properties, of course.)
How Glass-Filled Purging Compounds Differ From General Grades
A glass-filled purging compound is perfect for thermoplastic injection molding and extrusion machines. These compounds – like EX Grade and NF Grade – are designed to provide superior scrubbing of carbon and color deposits while leaving behind less residue.
The following precautions should be taken when using glass-filled purging compounds:
- Not recommended for sealing.
- Should not be left idle in the barrel.
- Not recommended for hot runner cleaning.
- Screen packs should be removed when purging.
- Operators should wear appropriate protective glasses and gloves due to the glass fiber content.
Follow these general steps for purging with glass-filled compounds (with the above precautions in mind):
- Make sure all zones are in the proper temperature range for the glass-filled purging compound being used.
- Retract the injection unit. Empty screw and barrel. Clean hopper and feed throat.
- Feed 1-2 barrel capacities of purging compound into the feed throat.
- With the screw completely forward, increase the back-pressure to the maximum safe level (at least high enough to keep the screw in the forward position during purging).
- After the compound begins coming from the nozzle, increase the screw speed to maximum safe level.
- Drop the back-pressure after the compound coming from the nozzle appears clean.
- Retract the screw and perform short, high-velocity injection shots to clean the check ring and nozzle.
- Repeat the steps above if carbon or other contaminants are still visible.
- Displace the remaining glass-filled compound with the next resin at the maximum safe back pressure and screw speed with the screw completely forward.
- When resin is free of purge, begin production
The Importance Of The Right Purging Compound Provider
Not every purging compound will be right for your manufacturing process or machines. Each compound behaves differently under different situations. One of the worst mistakes any manufacturer can make is to purchase a purging compound based on the wrong criteria.
This makes partnering with the right provider extremely important. You need someone to take a holistic view of your processes and recommend the best purging compound grade along with tips for maximizing performance.
Learn more about how purging compounds impact your production efficiency.