High bar count metal encoder disks enable accurate optical measurement and control
Article Type: Industry news From: Soldering & Surface Mount Technology, Volume 21, Issue 4
Metal encoder disks for a wide array of high-accuracy motion control,positioning and measurement applications are available from custom-part manufacturer, Tecan. All standard slot counts as well as completely bespoke requirements can be produced by using Photo Electro Forming (PEF) or Photo-Chemical Machining (PCM) – processes which assure benefits such as superior accuracy and high bar counts.
The PEF process – where the parts are grown electro-chemically into a photolithographically-defined resist mould – enables the manufacture of the most accurate and fine-featured metal disks. These can be single or multi-level, with high bar counts and smooth optically-sharp edges. The multi-level PEF process produces optical slots of the finest possible resolution whilst selectively increasing the metal thickness of the disk, but not the slots. The result is a single rigid part, with localised thickness variations across its surface designed to suit both optical and mechanical requirements.
PEF disks are typically thinner, lighter and more robust than disks manufactured by other means. They feature slots with extremely smooth, yet optically sharp edges that facilitate a well-defined light pulse. Typical PEF tolerances are ±4 μm, and in some cases, ultra-high tolerances of ±2 μm or less can be achieved.
Photo Chemically Machined encoder disks – produced by selectively removing metal by chemical etching through a photo-lithographically defined resist layer – can be supplied in a variety of metals up to 1.5 mm thick. Using low-cost tooling, stress and burr free encoder disks can be manufactured in a wide range of magnetic or non-magnetic alloys as demanded by specific encoder applications. This method is ideal for the cost-effective manufacturer of bespoke or prototype encoders.
