WITTE VACUUM WORKHOLDING SLOT CHUCKS
This type of vacuum holding tables is used for machining workpieces with complicated geometries or parts with many perforations or pockets. A rubber adaptor mat, which is prepared especially for a particular job, is placed over the slot vacuum chuck. The perforations on the rubber mat have to be aligned with the slots on the chuck, as the air is pumped out through these slots.
When the component has a small area available to apply vacuum then the slot vacuum chuck is the system then can solve your clamping problems. It is suited for jobs where small machining forces occur, as for instance in engraving.
Using an adjustable vacuum stopper, which is placed in a right angle to the slots, the area of the plate where vacuum is pulled, can be adjusted to the requirements of the task.
The slot vacuum plates are also available in a thin version (28 mm plate thickness), which have been developed primarily for the use on engraving machines. Together with a rubber adaptor mat with or without perforations (according to the work piece contour approx diameter 2 to 6 mm) they are ideal for engraving or working on small plastic signs and labels. This is achieved by the high friction coefficient between the rubber mat and the usually smooth work piece.
Holes, perforations and pockets can be drilled/milled without loss of vacuum when using the rubber adaptor mat, which is 3 mm thick so that the cutter can penetrate the mat to a maximum depth of 2,5 mm.
Due to the elasticity of the rubber adaptor mats, a thickness tolerance of approximately +/-0,15mm can be achieved. A machine with a self-adjusting spindle is the optimal solution in such cases. There are also machineable rubber adaptor mats, which offer the possibility to skim the surface of the mat to obtain a perfect parallelism between the machining plane (XY) and the top surface of the chuck.
Slot vacuum chucks are used successfully in the manufacturing process of printed circuit boards (PCB’s). Substantial savings in process time have been achieved. The advantages are as follows:
- Short clamping and release times.
- Using the machineable adaptor mats, depth and thickness tolerances of <0.015 mm are achieved.
- Profiling the component out from the sheet is possible.
- The vacuum flattens warped sheets, achieving therefore higher accuracies.
- Instead of having a fixture for each board design, only a rubber mat with the specific hole patters is required, reducing the fixturing costs substantially.
WITTE SLOT VACUUM CHUCKS ARE SUCCESSFULLY USED IN THE MANUFACTURING PROCESS OF PRINTED CIRCUIT BOARDS (PCB’s):
- Drilling and tapping of the PCB can be performed whilst clamped with the vacuum chuck
- Depth accuracies of ± 15 µ can be achieved
- Large areas can be milled from the board
- Warped boards are flattened by the action of the vacuum
- Components can be easily machined on both sides
- Small components can be held with vacuum during profiling from the main board
- Basically, any size or shape of PCB can be clamped with vacuum
PREPARATION OF THE RUBBER ADAPTOR MATS:
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1. Locate the rubber adaptor mat on the slot type chuck |
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2. mark the shape of the work piece on the rubber adaptor mat. |
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3. mark the position of the suction holes on the mat |
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4. punch the suction holes on the rubber mat. |
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5. place the mat back on the chuck, position the component and apply vacuum |
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