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Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ

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PVC sticks in 420 Steel sea-wall extrusion die

I Work for a company that makes sea walls. The company is about eight years old and we have a problem. We have several different types of dies. Our biggest die consist of 17 plates. The problem is after running the die for 36 hrs or less it starts to burn. This is what we call a carbon build up. In order to clear the die of the carbon it has to be taken apart and cleaned by hand or a sandblaster. This process can take about eight hours then another 4 hrs to heat up. We have twin extruders, one is for the substrate an the other is for co-ex. Substrate is what makes the center of the wall and the co-ex is the skin or color of the wall. The substrate is made of recycled PVC Siding, and sometimes injection molding. The skin is made of virgin material.

If any suggestions are available the question at hand is what can be done to clean the carbon out of the die without taking it apart. Also these dies are in a range of 300 to 400 degrees. What causes the burn is for some reason the PVC gets trapped in a small spot and other PVC travels around that spot until it is finnaly fried.

Anthony Capel
Extrusion - Powder Springs, Georgia
2005

I would expect this to get worse over time as the sandblasting gradually takes its toll by imparting a texture to the mold. In general, problems like this are addressed thru mold coatings that reduce the tendency of the PVC to stick to the mold. Electroless nickel plating, hard chrome plating, maybe even Teflon coating might be coating candidates. Can you send one of your smaller but troublesome molds out for coating?

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2005

We are leading manufacturere of PVC plates, but pvc being very velnarable causes chrome plating to vanish & erosion of die steel. if you have any solution to get rid of this burning of pvc plese email.
Sanjay Patil.

Sanjay Patil
- Pune, Maharastra, India
October 15, 2008

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