( 1) Metal stamping parts grounding piece mould blade abrasion: feather size is too large or larger; Smaller; Flatness is not good. Need to grind or replace the die. ( 2) No guide: guide pin or other positioning device is not working, feeder did not relax or guide pin size is differ, not correct guidance. Positioning block wear, long distance. ( 3) Die too short: camber, chamfering, forming an incomplete. ( 4) Article out enough: material, the material on poor bending, stripping and mould puller, lengthen out. ( 5) Improper out: top pin configuration is undeserved, inappropriate or head had long spring force. Adjust the elastic or a change in position or pin number: short pin mill to cooperate. ( 6) Feed the poor, guide plate length is differ, or guide material clearance is too large, or die and feeding machine deflection or die with feeder distance is too long. ( 7) Blanking deformation: part of the metal stamping ground lug bending parts can't allow material overlap, each fall, overcome by pressure pad. ( 8) Bending deformation: WanWanChu on crowded; Close holes by tensile deformation. ( 9) Punching and shearing deformation: material distortion, size or eccentric asymmetry. ( 10) The impact deformation: products blow out air pressure is too strong or gravity drop impact deformation. ( Metal stamping parts improper grounding piece of material: material width or thickness, material or material hardness is not appropriate, also can produce adverse. ( 12) Poorly designed: engineering arrangement is bad, bad gap setting, unless the change design, otherwise difficult to overcome metal stamping ground lug size variation.