Presumably the drive is at the outlet end and the connection from the screw to the drive shaft is building up with a cohesive powder. 30 degrees inclination is about the limit for an inclined screw conveyor as the angle of the flight to the horizontal becomes very shallow and lifts the product, rather than is sliding on the face of the flight. Assuming that the material is conveying up the inclination OK the best approach would be to enlarge the width of the outlet wider than the casing and take the casing through, to project slightly into the larger outlet. This way, the material will fall clear of the walls.

It is then practical to converge the outlet to the size required, lining the walls with a low friction material if necessary to prevent build up due to surface cohesion. A small radius in the corners of the outlet also helps to prevent product sticking. If in doubt, conduct some wall friction tests to establish correct design parameters and optimum surface contact material. ■