D24 Recommendation for pairing selection: Cutting clearance Sliding guide Ball bearing guide Description Recommendation small small large Piece parts with small tolerances, closely specified cut edge properties and contours – also parts from thin material Pairing 1 medium medium medium Piece parts from sheet thicker than 1 mm – also preferably for progression dies Pairing 2 large large small Where demands on edges and burrs are not stringent; note that large die clearances require smaller shearing forces Pairing 3 Selection of punch-matrix clearance is largely determined by piece part characteristics: percentage of sheared land versus breakaway, but also by demands on burr formation. Further criteria are the part piece material, as well as the type and condition of the tooling and the press. PAIRING CLASSIFICATION SLIDING GUIDE (SINTERED FERRITE) ROLLER BEARING Note for 4-pillar die sets: Please be aware that tight bushing clearances or high preloads are generally unsuitable for 4-pillar die sets. Deviation from the bore geometry and from the perpendicularity requires a pairing classification of pairing 2 or even better pairing 3. The pairing classification does not signify any difference in quality, rather a selection of the optimum bushing clearance in the case of guide pillars or the optimum preloading in the case of ball bearings (see also chart next page). Ordering Code (example): Guide pillar in tolerance code yellow = 202.19.040.260.10 Sintered ferrite bushing with tolerance code green = 2081.31.040.20 Combination possibilities guide pillars, cages and bushings: Sliding guide Ball bearing guide Guide pillar Guide bushing Guide pillar Guide bushing Colour Order No. Colour Order No. Colour Order No. Colour Order No. yellow .10 yellow .10 yellow .10 red .30 Pairing 1 green .20 yellow .10 yellow .10 green .20 green .20 red .30 green .20 green .20 yellow .10 yellow .10 Pairing 2 red .30 yellow .10 green .20 green .20 yellow .10 green .20 red .30 red .30 red .30 red .30 green .20 yellow .10 Pairing 3 green .20 red .30 red .30 green .20 yellow .10 red .30 red .30 yellow .10 Identification for tolerances with colour dots on the outside of the guide pillars and bushings. Selection Criteria: die clearance – stock thickness – material
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