Comprehensive understanding of screen printing II

Stretching Stretching <br> <br> with a pin at the time of selection for a 0.5 inch (1.2 cm) long flat head pin carpet. The warp direction of the screen cloth should be consistent with the long side of the frame, because most of the screen cloths have better pulling force in this direction and can withstand the drag and draw of the squeegee back and forth. In addition, the pattern must be aligned with the direction of dragging the squeegee to reduce the distortion of the image during printing. When the screen cloth is nailed to the net frame, the nails must first be started at the center of one side of the net frame. Each nail is about 0.75 to 1 inch and the nail is 3/8 inch (0.95 cm) from the edge of the frame. Tighten the screen cloth and nail a row of nails on one side of the frame. The first row of nails is on the outside, and it must be tightened so that the tack nails are in close contact with the wooden frame. After nailing it, nail the opposite side of the nail and notice that it must be tightened when nailing. Also, nail the other two sides of the frame. Finally, nail a nail in the position where the inner side of the frame is staggered with the outer nail to ensure that the screen cloth tightly stretches on the frame.

After the screen cloth is nailed to the frame, it should be carefully cleaned with cold or warm water or soapy water. It not only removes any glue that may be present, but also helps to tension the screen. When the screen cloth dries, check if the tensioned screen is smooth. If there isn't enough tension in one place, you can use a screwdriver to carefully remove the nail from there, re-tighten the wire mesh, and then re-nail the nail. The screen cloth must be very tight, otherwise it is difficult to attach a screen printing film or a coating emulsion. Some screen printers gently grind the fibers of nylon, polyester, and other silk fabrics with fine pumice or clay to facilitate firm bonding before applying the screen cloth. But be careful not to weaken the elasticity of the screen. In addition, there are many other screen cleaning and degreasing methods in actual production.

Some screen printers apply shellac at the bottom of the frame, that is, nails, to prevent ink from leaking between the screen and the frame.

The gutter frame has a slot on the bottom edge of the frame that can be cut using a circular saw, or it can be dug using a special dedicated trenching tool or wood chisel. The depth of the groove should be slightly deeper than the thickness of the splint. If the splint is made of harder wood such as maple or birch, its service life is longer and it can be reused. About 3/8 inch (0.93 cm) is a good size for splints. Its shape can be a square wood strip or a round tip rod, which is suitable for being pressed into the groove.
When the net is stretched, the screen is forced into the groove by the clamp. The edges of the grooves and splints should be smoothed with emery cloth to avoid scratching the screen during extrusion. Fix with about 3/4 inch (1.9 cm) of No. 4 or No. 5 flat-head wire nails. The screw holes in the clamp plate should be countersunk holes to ensure that the screw head can be tightly coupled with the clamp plate when nailing. The hole clearance is about two to four inches.

When stretching the net, first press the wire into the groove and add the screw, but not too tight. Fix the splint on the opposite side of the frame to the same degree, and tighten the screen as much as possible during the fixing. However, it does not matter if it is loose at one end of the splint. Finally, it can be adjusted again. In the same way, fix the other two sides. After all the splints are fixed, tighten the screws step by step, one at a time, to achieve consistent tension at all points of the screen.

Using automatic mechanical stretching is a very quick and easy method. The stapler is the same as the staple and is located approximately in the same position. If the stapler pulls in the direction parallel to the screen cloth, it will tear the screen cloth. In the actual operation, a piece of paperboard can be used to pad the screen cloth, and the stapler can hold the screen cloth and the paperboard together without pulling the screen cloth directly. This not only avoids pulling the screen, but also easily removes the stapler by pulling out the paper.

The following provides a simple commercial stretching method, whether beginners or advanced screen printers can quickly get started. This method is suitable for screens of various sizes, but the frame needs to have the same grooves as the pressure grooved net frame. When the net is stretched, the screen cloth is placed on the groove, and a wire having a diameter of about 1/8 to 3/16 inch (0.31 to 0.47 centimeters) together with the screen is pressed into the groove with a tool. The rope can be reused for multiple tensions. At any time, when the screen cloth must be re-tightened, the groove can be deepened and then pressed back into the groove with the same rope.

A netting system is included in the actual screen making process. The system features a separate aluminum frame with four sides that are automatically taut. The frame can stretch the screen to the desired degree of tension. And after printing, the screen can be removed, rolled up and re-installed.

Regardless of the kind of stretch method used, there are various types of mesh frames that have been made available for use. However, for special product printing such as circuit printing or chemical mechanical or special screen printing machines, it is best to use patented stretch netting equipment, which helps to ensure the quality of printed products.