YM series if machines are adopted for rubber plate engraving. Generally, the 50mm focusing lens and PLT and BMP format are chosen. PLT is mainly used for edge engraving. Each format has its own advantages and it should be analyzed according to the actual case. If the height of the character to be engraved is over 10mm or the width of the line is over 1.5mm, the edge engraving method can be chosen. Take the first 7mm single layer common rubber plate for example, when edge engraving, wet newspaper should be laid on its surface and leaking air ejector should be used. Strong air blow that can uplift the newspaper should be avoided. In this way, the line engraved will be more exquisite. The speed for such circumstance is usually 0.5-0.8 meters per minute and the higher the speed, the bigger the saw tooth is. The optical density should be between 20%-50%. It should be adjusted according to the depth. If it’s deeper, the optical density can be adjusted to 60%-70%. And for double layer rubber plates: the optical density depth should reach 1.5mm for 4mm double layer rubber plate and the speed should be adjusted to 0.5 meters per minute with optical density of 45%. It should be determined by actual conditions. If the height of character to be engraved is lower than 10mm, the method of engraving can be adopted and the speed is generally 10-15 meters per minute, the optical density is generally adjusted to 18%-28% of the total depth and the optical density depth is generally 55%-75%, the gradient is between 0.8-1.5, and the resolution is 500-600dpi. The denser or the smaller the characters, the smaller the optical density and the gradient will be set.