Thus, if a part is sealed to eliminate vacuum leaks, a holding force of approximately 10 pounds per square inch is developed. A one foot by one foot part is held in place by 1,440 pounds of force. If the vacuum seal is lost, however, because of the low flow the holding force quickly disappears. The advantage of conventional vacuum is that, properly applied, with a relatively small investment parts can be held securely. The 4 HP pump offered by Thermwood is a conventional vacuum pump.
Universal vacuum relies on a high flow vacuum pump.
A porous spoilboard is placed over a vacuum plenum built into the machine table. The high flow pump pulls air through the spoilboard. Even with the continuous leak, a panel placed on the table is held in place with 2 to 4 pounds per square inch. A one foot by one foot panel is held with 300 to 500 pounds which is adequate for most materials. The new high flow pump offered by Thermwood combines the features of the conventional and high flow universal pumps in a single unit.