Harp screens

Assembly instructions

The screen is produced with fixing welts and is tensioned lengthwise or crosswise so that it lays firmly on the supporting longitudinal beam of the sorter; under-tensioning or over-tensioning of the screen decreases its lifetime; transverse wires (enlacements) must always lay (at least some transverse enlacement) on the supporting longitudinal beam of the sorter and may be reinforced with polyurethane; sorter longitudinal beams must be equipped with a protective rubber profile (except for hot sorting); arched fixing of the screen must be made with a camber of approx. 18 - 20 mm per 1 m of the screen width or length.

Material

Abrasion resistant spring steel, stainless spring steel.

Delivered dimensions.

According to a sorter construction.

Harp screen with horizontally crimped wires

Use

Used for sorting of dry and wet, difficult to separate materials with spherical or cubic grain shapes as well as flat and spiky ones

Characteristics

Lengthwise horizontally crimped wires create approx. square holes which allow relatively precise sorting even for grains of flat or spiky shape. The oscillation of the lengthwise wires causes self cleaning effect therefore the screen is almost choke free.

The mesh size

Usual width of rectangular mesh is 1,1 - 22 mm, length according to the distance of crosswise enlacements; recommended size of meshes is about 10-20 % smaller than for square meshes, correct size has to be tested.

Wire diameter

1 - 4,5 mm.

Harp screen with vertically crimped wires

Use

Used for sorting of dry and wet, difficult to separate materials with spherical or cubic grain shapes, the screen is not suitable for lengthwise grain shapes.

Characteristics

Lengthwise vertically crimped wires and enlacements form rectangular meshes; the oscillation of the lengthwise wires causes self-cleaning effect therefore the screen is almost choke free.

The mesh size

Usual 2 - 18 mm, recommended size of meshes is about 10 % smaller than for square meshes, correct size has to be tested.

Wire diameter

1 - 4 mm.

Harp screen with horizontally crimped and straight lengthwise wires

Use

For sorting of large volumes of dry and wet, difficult to separate materials with spherical or cubic grain shapes, possibly also flat or spiky grain shapes.

Characteristics

Triangular holes are made by using lengthwise horizontally crimped and straight wires. The oscillation of the lengthwise wires causes self cleaning effect therefore the screen is almost choke free. The screen construction does not allow over-tensioning during the assembly; the screen can hold higher layer of material.

The mesh size

Usual 1,8 - 16 mm, recommended size of meshes is about 10 - 20 % smaller than for square meshes, correct size has to be tested.

Wire diameter

1 - 4 mm.

Harp screen with straight wires and polyurethane reinforcement

Use

For sorting of dry and especially wet, highly clayey and other hard to sort materials with spherical or cubic grain shape.

Characteristics

Lengthwise straight wires and enlacements form long rectangular meshes; the oscillation of the lengthwise wires causes self-cleaning effect therefore the screen is almost choke free; with regard to the large free open area, the screen has a high sorting performance, but shorter lifetime.

The mesh size

Normally 1.8 to 16 mm. Size is recommended approximately 10-20% less than the square mesh. Correct size is to be tested.

Wire diameter

1 - 3 mm.

Zick-zack

Characteristics

They are used when sorting a particularly sticky materials. It is a
screen made of  horizontally waved wires which are placed parallelly and 
do not touch each other. Bent and crimped wire creates a circular shape of the eye as it is in the picture. This prevents the elongated elements to fall through. Screen is made from wires of smaller diameters, sorting on the border of 1.5 to 5 mm. Screens are attached on the sorter longitudinally.

References