Options to Aid Extruder Screw Removal and Cleaning John L Options to Aid Extruder Screw Removal and Cleaning John L. Presa Fabrication Leader-Dow Chemical jlpresa@dow.com 979.238.1723

What Do These Tasks Have In Common? Going to dentist for a root canal… Christmas shopping for last minute gifts day before Christmas… Preparing your own tax returns… Changing a flat tire on the side of the road…

Outcome Ability to make an informed decision of best method for extruder screw removal using different materials. These being considered: Time savings Cost of materials Personnel Safety

Why Remove Screw? Measure wear Change screw Clean screw and barrel

Methods Used Today to Pull Extruder Screws Mechanical screw puller/pusher Forklifts – pushing or pulling Chain hoists/come-alongs Hydraulic press

Material Types Used “Pulling/cleaning” Aid LDPE 350°F 2 MI .920 d HDPE 350°F .85 MI .962 d Acrylic Purge blend 350°F (proprietary info) PVC (plasticized) 300°F CAUTION Temp must be kept below 350°F Purge Compound #1 400°F Purge Compound #2 350°F Purge Compound #3 400°F

Equipment Description Egan Davis-Standard Pilot Cast Film Line 5 Extruders: (2) 2” (3) 2.5” All data collected from core 2.5” extruders Single flight screws with Egan mixer Rear screw removal

Procedure Protocol The following steps were taken for all materials: Used the 2.5” extruders (after being disconnected from die assembly) Started with LDPE in extruder Slow rolled extruders until LDPE stopped exiting then added “pulling/cleaning” aid Added approximately 2.5 gallons of “pulling /cleaning” aid Continued slow rolling until nothing was being conveyed out of extruder Pulled screw out using chain come-along until we could easily pull screw out manually Cleaning begins

Rear Screw Removal

LDPE

HDPE

Acrylic Purge Blend

Acrylic Purge Blend

Acrylic Purge Blend

PVC (plasticized)

PVC (plasticized)

PVC (plasticized)

PVC (plasticized)

Purge Compound #1

Purge Compound #1

Purge Compound #1

Purge Compound #2

Purge Compound #2

Purge Compound #2

Purge Compound #3

Ranking System Numerical Ranking System (values assigned by team) 1- very easy 2- easy 3- moderate 4- difficult 5- very difficult

Results LDPE HDPE Acrylic Purge Blend PVC (plasticized) Purge Compound #1 Purge Compound #2 Purge Compound #3 Ease of Pulling Screw Ease of Cleaning Screw Price/lb Time to Clean (man min.) Order of Preference (ease to remove and clean)

Results 5 .70 - .85 45 7 LDPE HDPE Acrylic Purge Blend PVC (plasticized) Purge Compound #1 Purge Compound #2 Purge Compound #3 Ease of Pulling Screw 5 Ease of Cleaning Screw Price/lb .70 - .85 Time to Clean (man min.) 45 Order of Preference (ease to remove and clean) 7

Results 5 3 .70 - .85 .65 - .80 45 15 7 LDPE HDPE Acrylic Purge Blend PVC (plasticized) Purge Compound #1 Purge Compound #2 Purge Compound #3 Ease of Pulling Screw 5 3 Ease of Cleaning Screw Price/lb .70 - .85 .65 - .80 Time to Clean (man min.) 45 15 Order of Preference (ease to remove and clean) 7

Results LDPE HDPE Acrylic Purge Blend PVC (plasticized) Purge Compound #1 Purge Compound #2 Purge Compound #3 Ease of Pulling Screw 5 3 4 Ease of Cleaning Screw 2 Price/lb .70 - .85 .65 - .80 2.50 Time to Clean (man min.) 45 15 12 Order of Preference (ease to remove and clean) 7

Results LDPE HDPE Acrylic Purge Blend PVC (plasticized) Purge Compound #1 Purge Compound #2 Purge Compound #3 Ease of Pulling Screw 5 3 4 1 Ease of Cleaning Screw 2 Price/lb .70 - .85 .65 - .80 2.50 2.00 -7.00 Time to Clean (man min.) 45 15 12 9 Order of Preference (ease to remove and clean) 7

Results LDPE HDPE Acrylic Purge Blend PVC (plasticized) Purge Compound #1 Purge Compound #2 Purge Compound #3 Ease of Pulling Screw 5 3 4 1 Ease of Cleaning Screw 2 Price/lb .70 - .85 .65 - .80 2.50 2.00 -7.00 1.95 – 2.80 Time to Clean (man min.) 45 15 12 9 Order of Preference (ease to remove and clean) 7

Results LDPE HDPE Acrylic Purge Blend PVC (plasticized) Purge Compound #1 Purge Compound #2 Purge Compound #3 Ease of Pulling Screw 5 3 4 1 Ease of Cleaning Screw 2 Price/lb .70 - .85 .65 - .80 2.50 2.00 -7.00 1.95 – 2.80 2.10 – 4.00 Time to Clean (man min.) 45 15 12 9 Order of Preference (ease to remove and clean) 7 6

Results LDPE HDPE Acrylic Purge Blend PVC (plasticized) Purge Compound #1 Purge Compound #2 Purge Compound #3 Ease of Pulling Screw 5 3 4 1 Ease of Cleaning Screw 2 Price/lb .70 - .85 .65 - .80 2.50 2.00 -7.00 1.95 – 2.80 2.10 – 4.00 6.25 – 8.50 Time to Clean (man min.) 45 15 12 9 Order of Preference (ease to remove and clean) 7 6

Conclusions As far as time savings and effort, purge compound #1 is the preferred material. PVC (plasticized) was near the top. However, much tighter processing window needed for the PVC. Purge Compound #3 was next due to being a little more difficult to remove screw. The Acrylic purge blend and HDPE were somewhat comparable in performance as far as removal of screw and cleaning, however, the Acrylic purge blend took slightly less time to clean. Purge compound #2 was a little more difficult to remove and clean than the previous materials. LDPE was the most difficult to extract from extruder and remove from screw surface, thus requiring the most labor time.

Thank You! Questions?