Frequently Asked Questions

Mold-Vac’s are mold evacuation systems designed to eliminate entrapped air and gas within the mold cavities prior to and during the injection cycle. Additionally, the patented blowback feature provides the capability to clean and purge vented ejector and core pins after each cycle.

The Mold-Vac was developed to eliminate part burns, voids, and associated molding problems caused by gas and air entrapment. The unit cleans and purges vent pins thus eliminating residue build up, while reducing mold maintenance.

First determine the root cause of the problem. Is the problem caused by air or gas entrapment? Are you sacrificing cycle time to let the air and gas escape? Is the gas trap opposite the gate? If the answer is yes to either, then consider the Mold-Vac.

Both thermoplastic and thermoset. From ABS, Acetyl, Nylon, Ultem, PPO, PVC, PP, Phenolics, TPE, TPO - you name it! The unit will eliminate gas entrapment regardless of the material.

Proper selection is based upon a number of variables, part volume (cubic inches), fill time, and mold design. To select the unit for your application, please provide the information requested per our “Mold-Vac Application Criteria” worksheet.

Vacuum and evacuation time. Please review the following vacuum ratings:

The Mold-Vac is self-contained, i.e., all controls, gauges, etc. are mounted in a common panel for immediate installation and operation. Simply mount the unit beside the press, position the limit switches (2 supplied) or connect directly to open/closed contacts of molding machine and lastly, connect vacuum type tubing from the Mold-Vac to the mold.

Yes, the Mold-Vac can be interfaced to the mold open/mold closed signals from the molding machine.

• Connect utilities, electrical & compressed air.

• Connect tubing from the mold to the Mold-Vac.

• Position vacuum and blowback limit switches.

Note: Activation of the vacuum limit switch starts both vacuum and blowback timers.

• Set vacuum timer, same as first stage fill time.

• Set blowback timer, same as total cycle time or total mold closed time.

• Turn unit on.

• Turn blowback on (if required).

• Adjust vacuum and blowback regulators.

Note: For MV-4,000 & 10,000 models compressed air is required to generate vacuum. Verify proper CFM.

All units pull up to 20-24” of vacuum.

• Vent-Vac 14cfm @ 110psi

• MV-4000 17cfm @ 65psi

• MV-10,000 33cfm @ 65psi

• MV-20,000 Blowback only

• MV-40,000 Blowback only

Note: compressed air is required to generate vacuum for the 4,000 & 10,000 series.

A servo driven motor generates vacuum for the MV-20,000 & 40,000 series.

Yes, by adjusting the inlet air pressure (MV 4,000 & 10,000 models only) the vacuum level can be adjusted from 0” to 24” of vacuum. Simply turn the pressure regulator control valve to the desired setting as indicated by the vacuum gauge. For the 20,000 & 40,000 series vacuum adjustments are made via the control panel.

To assist in part ejection, the Mold-Vac provides a burst of compressed air just prior to mold open. Simply set the blowback timer to the desired setting (same as total cycle time). Opening the mold under vacuum can cause part distortion, the Mold-Vac’s blowback feature eliminates this possibility.

The second phase is controlled by the blowback limit switch. To eliminate residue buildup in vented pins, or tool steel erosion, position the blowback limit switch to activate upon mold open. Upon activation, compressed air will purge vented pins (with proper mold modifications) which will reduce mold maintenance.

Yes, minor tool modifications are necessary. The literature illustrates parting line and ejector pin modifications. A parting line installation consists of installing an “O” ring and a chimney around the cavities. The “O” ring is required to seal the mold and prevent ambient air from entering the cavities which, in turn, assists in creating the vacuum.

It depends on the location of the gas trap and how much vacuum is required.

Yes, we can provide the necessary drawings illustrating the modifications required.

Please submit core/cavity plan and section views of the mold, a sample part and an explanation of the problem.

The “O” ring can be glued in by using RTV (room temperature vulcanizing) silicone. A neoprene “O” ring can withstand temperature up to 160°F, vyton up to 400°F. “O” rings are available through various suppliers as outlined in the Thomas Register.

Your material supplier will recommend the vent depth.

All contaminates are captured in an in-line filter, simply change the filter when necessary.

Absolutely, the unit works with all porous metals exceptionally well!

Very little, if any. Please refer to the operations manual for maintenance schedule.

All units pull up to 20-24” of vacuum.

• Vacuum & Blowback

The only commercially available unit designed specifically for the injection molder.

• Precise Control

The Mold-Vac provides precise control for both vacuum level and vacuum time.

This eliminates potential flashing concerns.

• Unit Assembly

The Mold-Vac is self-contained, i.e, all controls, gauges, etc. are assembled in one housing, tested prior to shipment and delivered ready for installation.

• Blowback Feature

The Mold-Vac is the only commercially available system which offers this feature.

Cleaning and purging vented pins after every cycle reduces mold maintenance and increases productivity.

• Unit Size

The Mold-Vac is compact by design, which provides portability and allows installation on or beside the press and, in turn, saves floor space.

• Application Know How

After years of molding experience, we understand the complexity of molding and mold design.

Consequently, we are able to provide the necessary information to properly modify your mold thus insuring a successful installation.

• Guarantee

The Mold-Vac offers a one year parts guarantee and is backed by a corporation dedicated to the needs of the injection molder.