Quality Control Inspection

A comprehensive quality control inspection for professional scissors evaluates the following parameters: **Visual inspection:** - Surface finish uniformity — no grinding marks, scratches, or polishing defects visible to naked eye - Plating or coating quality (if applicable) — no bubbles, flaking, or discolouration - Laser marking or engraving — legible, correctly positioned - Overall symmetry — the two blades should appear balanced when viewed from the front **Dimensional checks:** - Overall length: ±0.5mm of specification - Blade length: ±0.3mm - Handle symmetry: finger ring alignment within ±0.2mm - Pivot hole position: ±0.1mm (critical for proper blade engagement) - Blade thickness at key points: within ±0.05mm of specification **Blade alignment:** - With scissors closed, blade tips should meet precisely — gap or overlap indicates misalignment - Maximum acceptable tip gap: 0.05mm for premium scissors, 0.1mm for standard - Blade tips should not cross (overriding) by more than 0.1mm - Viewed from the side, blades should be in the same plane — no twist or bow **Ride line contact test:** The inspector slowly closes the scissors and observes the contact point between blades: - Contact should start near the pivot and progress smoothly to the tips - No gaps should appear between the blades during closing - No binding or catching at any point in the stroke - Contact should be a single point, not a wide band (which indicates excessive tension or flat ride line) **Tension assessment:** - Opening force should be consistent throughout the range of motion - For screw-type tension systems: the scissors should close under their own weight from a 45° opening when held vertically by one handle (gravity test) - For click-type tension systems: each click position should produce a defined, consistent change in resistance - No looseness or play at the pivot point **Cutting performance test (tameshigiri / Schneidprüfung):** - **Tissue paper test:** Single layer of tissue paper cut from pivot to tip in one smooth stroke — should cut cleanly with no tearing or pushing - **Cotton gauze test:** folded cotton gauze cut to verify the scissors handle thicker material without blade separation - **Synthetic hair test:** (some manufacturers) bundle of synthetic fibres cut to simulate salon conditions - **Wet paper test:** damp tissue paper — more demanding than dry, reveals minor blade alignment issues - Test cuts should produce a clean, audible "shk" sound without squeaking (which indicates insufficient lubrication or excessive tension) or clicking (which indicates loose tension or pivot play) **Specific defects checked:** | Defect | Test Method | Reject Threshold | |--------|------------|------------------| | Blade gap at tips | Visual, feeler gauge | >0.05mm (premium), >0.1mm (standard) | | Uneven tension | Manual feel, gravity test | Inconsistent resistance during closing | | Edge damage | 10x loupe inspection | Any visible chip or roll >0.02mm | | Ride line discontinuity | Slow-close visual test | Any gap or catch during closing | | Surface defect | Visual under directed light | Any scratch visible at 30cm distance | | Hardness variation | Portable hardness tester (sampling) | >1 HRC difference between blades | **Seki City's kenpin system:** In the Seki City division-of-labour structure, quality control workshops (検品所, kenpinjo) function as independent businesses, separate from the blade-making and handle-making workshops. This independence is important — the inspector has no incentive to pass marginal work. A kenpin workshop may serve 5-10 different blade-making workshops, providing consistent standards across the supply chain. The kenpin step also includes final assembly adjustments: - Tension screw torque setting - Finger rest installation and alignment - Silencer (bumper) installation - Lubrication of the pivot area - Packaging preparation **Documentation:** Premium manufacturers maintain inspection records per pair, identified by serial number. This traceability allows investigation if a customer reports a defect — the manufacturer can identify which workshops produced each component and review the production batch for systemic issues.