Kiss-off and shut-off are two fundamental concepts in plastic molding and are often encountered in mold design parting surfaces to determine how to use kiss-off or shut-off.
Kiss-up is a hole in the product surface (the shape of the hole is not limited, it can be round, square or irregular, depending on the structure of the products), when the front and back molds are closed, the holes are exactly touching each other. At the point of contact, the surface where the front and rear molds come into contact is the contact surface, which can be either flat or beveled.
Shut-off is when the front and back molds touch laterally at an angle, usually when there is a hole or gap in the side of product. If there is a hole in the side of product, it depends on the structure of product to decide whether shut-off or not, if not shut-off then make a lifter or slide.
The above picture shows that there are holes on the right side of the product, as shown in picture (a), along the direction of the arrow in a mold to do shut-off, shut-off hole position due to friction, easy to make the plastic parts produce burr. The smaller angle of shut-off, the more likely to produce burr. The use of shut-off can effectively reduce mold costs. Picture (b) shows that the slider is made at front mold to avoid shut-off. The slider can effectively improve product quality, which is usually used in places with high product requirements. The disadvantage is that the mold cost is higher than shut-off.
In simple terms, kiss-off and shut-off are separated by a 45° angle. kiss-off is when molds only touch in the opening direction without friction; kiss-off is when front and back molds are in frontal contact; shut-off is when front and back molds are in the opening direction with friction. The two parts that are shut-off take different heat treatment hardnesses where possible.
