Product News - Quick Mold Changes Without Wet Feet

Quick Mold Changes

Without Wet Feet

The Purge-Master system from Injection Molding Industries is designed to vent and purge valves for quick mold changes without water leakage and from the front of the injection molding machine. The system is built around multi-valved manifold assemblies in two standard sizes (PM300 and PM400) and one optional size (PM500).

All sizes use a series of servo-actuated, bi-directional diaphragm valves, which allows valve operation using water pressure (5 to 180 psi) or air pressure (3 to 180 psi), irrespective of which is greater or if fluctuations occur. The valves can be pipe mounted or used with flexible hose.

PM300 has a 1-in. tapped supply ('to mold,' 'from mold' and 'return' ports) that will accept 1-in. unions or that can accommodate 3/4-in., 1-in. or 1-1/4-in. hose tails.

PM400 has 1-1/2-in. tapped ports that will accept 1-1/2-in. unions or 1-1/4-in., 1-1/2-in. or 1-3/4-in. hose tails.

PM500 has 2-in. tapped ports that will accept 2-in. unions or 1-3/4-in., 2-in. or 2-1/4-in. hose tails.

These valve assemblies are normally open and allow free flow of coolant to and from the mold with minimum pressure loss, typically 3 psi, dependent on flow. When the first valve is actuated, the supply line is closed off and then the return line is closed off. This reduces the water pressure in the mold and connecting pipework to that of the drain pressure.

The vent valve is then opened, which reduces the pressure in the mold and connecting pipework to zero pressure. This is said to be particularly useful where there is a leaking pipe, a faulty fitting that needs to be replaced or a temporary cycle interruption.

Finally, the last valve is actuated to supply compressed air into the 'to' mold line displacing most of the coolant through the mold and returning it via the 'from' mold line to the vent and purge outlet.

This valve is then closed, allowing the mold and connecting pipework to return to zero pressure. The mold can then be removed from the press with very little coolant spillage.

The valve assembly has four control options and prices start at $1500.

The first, and lowest cost option uses the 24 v supply from the molding machine together with the Purge-Master remote switch, which has a selection switch for 'water on' or 'water off plus vent,' and a push-button to control compressed 'air on' or 'air off' (purge) and the desired Purge-Master valve (PM300, 400 or 500).

The second option uses the 24v supply from the molding machine together with the Purge-Master controller. This control has a selection switch for 'water on' or 'water off + vent,' and a purge push button that starts the purge sequence automatically.

It can also control two normally open valves, to all the fixed and moving halves of the mold to be controlled separately, which is said to improve the coolant removal from the mold. Each half can be purged multiple times automatically with the push of a button. A 24 v power supply is optional, if users do not wish to connect to their machines.

The third option is a completely integrated mold temperature and mold venting/purging system. This technology allows users to control multiple temperature zones with any mold, any material and any machine at mold temperatures from 60 to 300 F, but also, at the touch of a button it will vent and purge every zone separately and automatically.

The fourth option is for new machines and it allows any of the Purge-Master valves to be controlled directly from the machine control system.

Manufactured in the U.K. by REPS (RE Promotional Services Ltd., Canonic, England), Purge-Master is available in the U.S. through:

Injection Molding Industries

Orion, MI