Stern Rubber Company is adding to its extrusion capabilities by adding a 3 1/2″ NRM vacuum extruder.
After being a custom rubber molder for over 40 years, Stern Rubber Company added extrusion capabilities in 2010, when they partnered with a customer to add a 3 1/2″ extrusion line with microwave/hot air cure to the Plant 2 location in Staples, MN. At the end of 2010, a 3 1/2″ extrusion line with salt bath cure was added to complement the microwave/hot air line.
The microwave/hot air line includes a 3 tier microwave oven, 3 pullers, a cooling bath, and a guillotine cutter, which requires the line to stop to make the cut. The salt bath rubber extruder includes a 40′ salt bath, a two dimensional laser that monitors the size of the part, and modifies the speeds of the puller to keep the part in specified size, a hot water rinse tank, a rotary cutter, and an automatic winder.
Stern Rubber Company has found that the current extruder on the salt line has some limitations in regards to what material it runs well. Some of the current projects include EPDM, neoprene, NBR, butyl, SBR and CPE, including sponge rubber. Some of the materials that have proven to be difficult include natural rubber, and any material that is softer than 50 durometer. Because of these limitations, the extruder will be replaced with one that has a larger L/D ratio (Length/Diameter), and has vacuum capabilities. The vacuum capabilities require the extruder to have a special vacuum screw, and has a chamber located near the center of the extruder that allows the vacuum to pull trapped air out of the material.
Being added at the same time as the new extruder to the salt bath line is an additional cooling and rinse tank. The additional cooling capacity will allow the rotary cutter to hold tighter tolerances on cut length, by allowing the parts to be cooled further, so there is not further shrink, after they are cut.
Give Stern Rubber Company a chance to quote your extrusion projects!