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Pickout cam allows for lengthy side-action pulls

Proto Labs : 10 November, 2013  (Technical Article)
Protomold has increased its capabilities to support longer side-action pulls, or pickout cams. Where at one time, the maximum length for side actions was limited to 74mm, extensions are now offered up to 200mm dependent on the geometry of the mould. The original cam is still used to facilitate the extraction of the cam, which would be physically difficult to pull out by hand without the mechanical assistance. The operator then places the cam back in the mould and the process starts again.
When discussing side-action mechanics in a mould, it can be simplified to: cam slides into mould with core, core makes through hole in part, cam slides off removing core from mould. And within that process at Protomold, cams have traditionally been limited to shorter pulls. 
Now, for those with part designs in need of longer through holes and undercuts, the increase allows deeper geometry within parts like tubes or sleeves.
Pickout cam geometry is typically round or square and preferably open on both ends so that the core is supported between both halves of the mould. When a part has one closed end, the inner core can deflect creating an undesired thin wall. Different geometry is possible however, upon review.
In Fig 1 (above) the amber part used pickout cam capabilities to achieve a longer, open-ended through hole. Parts using this added capability are normally larger on one end than the other, meaning a degree of draft was designed for the cam (see Fig 2, right, which shows a cross section of the amber part with draft applied to it). Specifically for pickout cams, the minimum amount of draft required is 1 degree per side on low-shrink materials and 2 degrees per side on high-shrink materials. Plumbing tubes, for example, have zero draft since they have a uniform diameter from end to end, thus making them poor candidates for pickout cams.
Proper resin selection also plays a role in maximising pickout cam function. Stiffer resins like ABS, polycarbonate and glass-filled material work better since they shrink less and are ultimately less likely to stick to the core. Polypropylenes, polyethylenes and thermoplastic elastomers (TPEs), on the other hand, will be more problematic because of greater shrink.
Pickout cams can also be used to create cores in some parts, reducing the amount of material required and eliminating the problematic thin or thick areas. As with standard hand inserts there are always limitations.
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