Reducing cycle times is an important aspect when separating good parts from sprues by means of a reject chute - installed beneath the the tool of an injection moulding machine.
Moreover, in case of small parts it is necessary to prevent parts from getting stuck in any gaps.
In addition, in case of clean room conditions, it is important to prevent abrasion and allow for easy cleaning.
For these requirements, MTF Technik has developed a new selection switch (pending patent application). The chute is not equipped with changever flaps but with a rotating center shaft which is tiltable in three directions.
The rotating shaft is designed without any gaps, as the runoff plate and the lateral guidings are fixed together.
This effectively prevents deadlocks and abrasions and allows simple cleaning, as the rotating shaft is positioned within the gear drive and the ball bearing outside the chute body.
The powerful servo drive allows for switching speed of 3 tenths-of a second at exact positioning. The control is effected via two potential-free contacts, which steer the frequency converter of the servo drive.
As an option, the product contacted parts of the selection switch can be equipped with a teflon coating (FDA-approved), in order to have a smooth slide of parts into the lateral shafts.
In this example, medical plastic parts are produced in cleanroom conditions. A 3-way-chute serves to conduct the parts in 3 directions:
- Good parts are conveyed via an angled conveyor to a buffer station.
- Sprues and rejects are dicscharged centrally downwards into a box.
- Quality shots are directed to the operating side.