Timing screws are helical-screw devices used within automated equipment to advance product at a specific rate and interval of movement. They facilitate the smooth flow of containers into or between packaging machinery, and can halt or position products for various packaging operations. Timing screws are also used to speed, slow, divide or combine the flow of containers. By pairing two timing screws of the same configuration, multiple machines can supply a single packaging line. Conversely, a pair of timing screws can distribute a single line of product into multiple lanes. This feature is useful with multiple-case packing operations that need to divide a single lane into multiple lanes at relatively high speeds.
Timing screws use several basic straight-root designs. To create a smooth infeed, thread height usually increases relative to the outside diameter (OD). Timing screws with an inverse-taper infeed are designed to separate square or box-like containers. With these timing screws, the initial pocket is formed at the maximum OD, but gradually tapers to the root diameter. On high-speed packaging lines, straight-root timing screws may have a constant pitch in order to prevent products from colliding. These devices accept containers at the discharge end of one packager and then direct the product to the infeed of the next machine. Straight-root timing screws use dual-flight or double-lead, multiple-dwell, and grouping designs. By discharging products with every 180 degrees of rotation instead of the usual 360 degrees, dual-flight products can double the output of a packaging line.
Multiple-dwell or stop-position timing screws are also commonly available. These products have a vertical section in the screw pitch and are used for operations such as banding, filling, labeling, closing, and sleeving. The number of dwells and the degree of dwell time varies widely. Grouping timing screws are suitable for combining operations, when multiple products must be collated. To enable banding and overwrapping, containers are discharged close together.
There are many different types of custom timing screws. Examples include turnaround, orienting, twisting, turning, body and neck stabilizing, shingling, and form-fitting screws. Turnaround screws can be cut to discharge product at various angle. Twisting screws enable non-standard containers to travel with either a point or a flat surface. They are designed for air cleaning, bottle washing, marking and labeling operations. Turning timing screws allow containers to take up less space, while body and neck stabilizing timing screws are often used with bottles. Shingling screws offset a square or rectangular container. Form-fitting timing screws are used to control oval, elliptical and tear-shaped containers at relatively high operating speeds.