Utilizing Granite for Air Chuck Applications
Improved processing and material technologies have led to an increasing number of applications where it is necessary to move very thin or flexible substrates into place and secure (or chuck) them. Other parts are too small to effectively move without damaging, or they need to be moved into a precision location and then chucked with repeatable accuracy.
Tru-Vac from Starrett Tru-Stone Utilizes Granite for an Advanced Air Chuck Solution
The Tru-Stone solution, Tru-Vac, involves imbedding a porous medium (such as porous ceramic or porous aluminum) into a stable base material (such as granite, solid ceramic or carbon fiber). The porous zones and base materials are then processed to meet very tight geometric tolerance specifications and are then pneumatically (air) plumbed to provide either vacuum or positive pressure airflow. The porous and base materials are usually, but not always, processed to be co-planar with each other. Porous zones can be plumbed to offer vacuum holding force as well as positive air pressure flow for controlled part movement.
The Tru-Vac proprietary air plenum design and pneumatic plumbing options offer extremely uniform airflow over the entire porous surface. Several air chuck designs and size options are available to suit customer-specific needs such as; optimal flatness, proper levels of airflow, minimal weight, and additional geometric tolerance requirements related to a porous air zone. Additionally, an air zone can be incorporated as part of a larger precision granite assembly.
Hot Zones, Dead Zones and Deformed Parts
A problem inherent with other vacuum chucks can be inconsistent airflow, also known as “hot” or “dead” zones, over some areas of the porous surface.Previous ways to chuck or move materials may not allow the processing or inspection methods now required since previous chuck methods can deform a part or may be in the way of further processing. In addition, alternative methods to move small parts may require very expensive automated equipment.
Smaller than a Hockey Puck – Larger than a Conference Table
Tru-Vac applications range from smaller than a hockey puck to larger than a conference room table. Tru-Stone has conducted extensive R&D to offer several air chuck designs and size options to suit customer-specific needs. These include optimal flatness, proper levels of airflow, minimal weight, and additional geometric tolerance requirements related to a porous air zone. Additionally, an air zone can be incorporated as part of a larger precision granite assembly.
Tru-Vac is ideal for processes or inspection methods. Capabilities include, but are not limited to:
• Inspect for geometric tolerances, material imperfections, light transmission or reflectivity
• Laminate liquids or other substrates to the material
• Assemble products to the material (i.e. pick and place)
• Conduct further processing such as machining or scoring
Design Qualities and Possibilities
• With sophisticated CNC equipment, Tru-Stone is able to produce a wide variety of porous zone shapes and configurations to meet customer design requirements
• Geometric tolerances (i.e. flatness, parallelism, coplanar, perpendicularity) of porous zones and surrounding granite surfaces can be created to within just a few microns
• Porous zones can be plumbed to offer vacuum holding force as well as positive air pressure flow for controlled part movement
• The same porous zone can be plumbed to offer both vacuum and positive air flow within the same zone
• Several different porous zones can be incorporated into one assembly for processing and inspection flexibility, or to meet additional end-user design requirements
• Multiple porous tiles can also be placed side-by-side to create large overall vacuum zones to meet end-user large component processing requirements
• Multiple porous zones can be pneumatically plumbed together with each other, or can be plumbed to be isolated from one another for separate airflow control
• Concentric zones can be created to accommodate multiple substrate sizes within one chuck assembly
Resurfacing & Calibration
Tru-Vac chuck assemblies can be resurfaced, as needed. One reason for resurfacing could be to meet periodic re-calibration needs. Another reason is damage caused by chips during heavy use of the chuck. These chips can sometimes be removed by resurfacing the chuck, depending on the size of the chip. New market technology continually offers processing and inspection challenges not yet known that could likely be solved with an air chuck.