Mold-Vac Q&A

What is the Mold-Vac?

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.

What molding problems does the Mold-Vac solve?

The unit eliminates 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.

How would I know if the Mold-Vac is suited for my application?

First determine the cause of the problem. Are you trapping air or gas in the mold? Are you sacrificing cycle time to let the air and gas escape? Are your part burns caused by air and gas entrapment? If the answer is yes, then the Mold-Vac is well suited for your application.

What types of materials have been used with the Mold-Vac?

Both thermoplastic and thermoset. From ABS, Acetyl, Nylon, Ultem, PPO, PP to Phenolics. The operation of the unit is not dependent on material type. If part quality problems are the result of gas or air entrapment, the Mold-Vac is an ideal solution.

You offer 3 various sizes, which unit should I purchase?

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.

What are the vacuum ratings for each unit?

What is required for installation?

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) and lastly, connect vacuum type tubing from the Mold-Vac to the mold.

How does the Mold-Vac operate?

After connecting the necessary utilities, follow these steps for proper operation.

• 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.

How much vacuum can be drawn?

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

Is the vacuum level adjustable?

Yes, by adjusting the inlet air pressure the vacuum level can be adjusted from 0” to 26” of vacuum. Simply turn the pressure regulator control valve to the desired setting as indicated by the vacuum gauge.

The Mold-Vac has two phases of blowback, describe the first phase. Why is this feature important?

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.

How does the second phase of blowback operate?

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.

Are mold modifications required?

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.

Can C.A.E. Services provide the necessary tooling recommendations?

Yes, available as an option when purchasing a system, we will review the necessary modifications required. A concept drwaing is provided. Please submit core/cavity plan and section views as well as rejected parts.

How does the “O” ring stay in place, what is the maximum temperature the “O” ring can withstand?

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

Vacuum systems are nothing new, consequently what advantages does the Mold-Vac have as compared to a conventional vacuum pump?

There are 8 major reasons:

• 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.
• Lack of Maintenance:
  Since the Mold-Vac is basically free of moving parts, it eliminates the expense and maintenance associated with conventional motor driven designs.
• Motor Failure:
  The Mold-Vac does not require a motor to operate, consequently the “life” of the Mold-Vac is infinite.
• Unit Size:
  The Mold-Vac is compact and portable by design, which saves floor space and allows for installation on the press.
• 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 injection molders.

Are customer references available?

Yes, here are just a few!

“Before the Mold-Vac was installed, our molds needed to be cleaned about every four hours, the machines had to be shut down and tools disassembled every 48 to 72 hours. Now the tools only require disassembling every three weeks. For maintenance downtime alone, a 700% improvement is reported. The frequency of short shots caused by poor venting and tar buildup blocking vents was also reduced.”
-ROBINSON NUGENT

“The vacuum reduces the amount of oxygen available to support charring and burning, so the parts no longer burn. By using this system, we’ve also reduced tooling maintenance from daily cleaning of the vent holes and vacuum ports to intervals ranging from three to five production days. The Mold-Vac system helped reduce reject rates from 10% to 0%.”
-HAUSER PLASTECH

“We were able to save thousands of dollars by purchasing the Mold-Vac instead of re-gating. The Mold-Vac payback period was about three months.”
-W.M. PLASTICS

“Previous to the purchase of the Mold-Vac 4000, we were experiencing fill difficulties on one of our thin wall musicality molds resulting in shorts and sinks at the furthermost point from the gate. Upon modifying the mold as specified and incorporating your unit, we have eliminated the above problems while decreasing the fill time from 3 to 1 ½ seconds (13 oz. shot). Also, pressure to fill has been decreases minimizing the tendency to flash and burn. The overall result has been a 5% - 7% faster cycle with wider processing parameters.”
-BINNEY & SMITH