Tabs
What are tabs?
In most cases, your part will be etched from a sheet of metal. Parts are held in sheets by several small tabs which may leave a burr when detached. It is important to note that this burr is unlike a progressive die burr. Therefore Fotofab will refer to these "burrs" as tabs. There are two types of tabs used in the Fotofab Process: External and Recessed.
External Tabs
External tabs will produce a break-off point that will leave a small part of the metal sheet on the part. If you have one of Fotofab's business cards, you may be able to feel the external burr used on our cards.
Recessed Tabs
Recessed tabs are similar to external tabs except that the break-off point will be recessed into the part. > Use this option if your part cannot have any areas extend beyond its perimeter. Typical applications that use the recessed tab are parts such as encoder discs and other circular parts, washers, and shields. RF/EMI shields will use recess tabs so that the tab does not affect the fence's attachment to the PCB.
What are my options if my part cannot have tabs?
We can produce your part without placing any tabs to hold the part to the sheet. This is referred to a having drop-out parts. The benefit of going with drop-outs is clearly losing tab, but since the parts are less stable (they are no longer tabbed into the sheet) we generally have looser tolerances on drop-outs. Additionally, the etching and stripping processes create a higher yield loss. Parts that make good candidates for drop outs depend on metal thickness (the thicker the better), part design and most importantly tolerances.