Transportation tracks for plastic components

Transportation using air as the convection media means that the component should be very light with non complicate geometry and large dimensions. The transportation track is usually a long length orthogonal bar having its upper side milled along with a slot relative to transported components transverse shape. The track enclosures the components inside the slot with the aid of one or two sheet metal cover. The covers are bolted on the track and hold the component in position whilst leaving an adequate opening (see figure below). Through this opening the pressurized air is driven by air nozzles directly to the component queue inside the transportation track. The pressurized air forces the plastic components to move inside the track from the input to the output side.

The milled slot on the transportation track must have enough clearance in order the components to move freely (no friction forces). Another reason for adequate clearance is the high speed which the plastics can achieve inside an empty track. In this case the plastic maybe damaged (skinning). Due to this damages the slot must be polished, nickel or other smooth surface coatings don't last for long time because of the number of transferred plastic components (thousands in one day creating small friction each one). The size and weight is the limit for the plastic component which can be transferred through the track. If the track length is large and the plastic has considerable weight we can use many air nozzles along the track. Large number of air nozzles means high pressurized air consumption and high noise levels (decibel). Experiment with speed (how fast the plastic components will move from the feeding bowl to the assembly machine), air consumption and noise levels in order to decide how many air nozzles will be needed for the particular track.

The transportation track is ideal for other applications concerning the plastic component. Applications such as counting, marking and inject printing can be performed. The track will be used as a buffer with the appropriate level control of the plastic components (optic sensors) due to high speed transportation. Another useful feature is plane shifting of the track in order to have the best usage of space around of the assembly machine.

The rotational track is also a track with the ability to axis symmetrical rotation of the plastic component along its length. When the part is inserting the track is boosting by an initial air stream and forced to follow the rotational path of the track (see figure below). This track can be used only with plastics which have transversal features (one sided protrusions) and in small lengths.

Very useful for the designer are the product tolerances. Usually plastic molding follows the DIN16901 standard which describes product tolerances from normal to precision classes. At the below tables there is part of the tolerance table (only up to 90mm). For further explanations refer to DIN16901 full text (DIN STANDARDS).