Factory exit inspection (outgoing quality control, or OQC) is the final quality gate that ensures strong magnetic table signs—desk and conference signage held together by embedded neodymium magnets—meet dimensional, magnetic, cosmetic and durability requirements before shipment. This guide explains the sampling logic, testing items, and inspection methods commonly applied to strong magnetic table signs, with reference to international standards such as ISO 2859-1, IEC 60068, ISO 2409, ASTM D3359, ISO 4892-3 and ASTM B117. It is intended for quality engineers, sourcing teams and factory QC personnel who need a practical, standards-based inspection framework.
Technical Overview
A strong magnetic table sign is a reusable desk or tabletop signage product typically composed of a clear acrylic or tempered glass panel, an anodized aluminum or acrylic base, and embedded sintered neodymium-iron-boron (NdFeB) magnets that allow tool-free insertion and removal of printed name cards or inserts. Because the product combines optical-grade plastics, precision-machined metal parts, adhesive assemblies and high-energy permanent magnets, several failure modes can only be detected through a structured outgoing inspection: weak or mismatched magnet pairs, bubbles or inclusions in the transparent panel, print defects, dimensional misalignment between the card slot and the base, and corrosion of metal components during storage or transport.
Factory exit inspection (also called pre-shipment inspection or OQC) is performed on fully finished, packaged lots using statistical sampling rather than 100% screening. The generally accepted framework is attribute sampling under ISO 2859-1 (equivalently GB/T 2828.1 or ANSI/ASQ Z1.4), in which sample size is determined by lot size and inspection level, and accept/reject decisions are based on Acceptable Quality Limits (AQL) assigned to critical, major and minor defects. Magnetic performance, coating adhesion and environmental durability are typically verified through periodic type tests in addition to routine lot-by-lot checks, and can be subcontracted to accredited third-party laboratories when independent verification is required.
- Product scope: magnetic desk nameplates, conference room signs, hotel counter signs, restaurant table-number signs and swivel magnetic sign holders.
- Typical magnet grades: N35 to N42 NdFeB, with operating temperature limits verified during type testing.
- Core standards framework: ISO 2859-1 for sampling, IEC 60068 series for environmental testing, ISO 2409 and ASTM D3359 for adhesion, ISO 4892-3 for light aging, ASTM B117 and ISO 9227 for corrosion resistance of metal parts.
- Objective: prevent shipment of lots with weak magnets, cosmetic rejects, incorrect print content or inadequate packaging protection.
Testing Samples
Finished Product Samples (Lot Sampling)
Finished, fully assembled signs are drawn at random from fully packed cartons, not from the production line, so that packaging errors are also captured. Sample size follows the inspection level agreed with the buyer—Level II (general inspection level) under ISO 2859-1 is the default; Level I may be used for stable, high-volume production and Level III or tightened inspection for new products or lots with a poor history. Sealed cartons are sampled across the lot, including cartons from different pallets and production time slots, to avoid non-representative sampling.
Component and Material Samples
Although component-level verification is primarily part of incoming quality control, the exit inspection retains reference samples of the key components for comparison purposes: the NdFeB magnet discs or blocks, the acrylic or glass panel, the aluminum base, the double-sided industrial adhesive tape, and the printed insert. Discrepancies between shipped product and approved golden samples—such as a magnet supplier change or a substitution of acrylic grade—are treated as critical defects even if the finished sign still functions.
Packaging and Labeling Samples
A designated number of packed units per lot is checked for correct carton markings, quantity per carton, protective films on acrylic surfaces, insertion of instruction or warning cards (strong-magnet handling warnings), and barcode scannability. For the first shipment of a new product, full shipping cartons are also subjected to transport simulation such as drop testing under ISO 2248 or GB/T 4857.
Testing Items
The defect classification and testing items below represent a typical inspection checklist for strong magnetic table signs. Exact AQL values should be agreed between buyer and factory; common assignments are 0 for critical defects, 1.0 to 1.5 for major defects and 2.5 to 4.0 for minor defects under ISO 2859-1 general inspection Level II.
- Appearance of transparent panel: bubbles, inclusions, scratches, flow marks, sink marks, orange peel, edge chipping and polishing quality.
- Appearance of base and metal parts: anodizing color consistency, machining marks, burrs, dents, fingerprints or oil film, protective-film integrity.
- Dimensions and tolerances: overall length, width and thickness, card slot width and depth, magnet pocket positions, flatness and perpendicularity of the assembled sign against the approved drawing.
- Magnetic performance: pull-off (normal) holding force between panel and base, shear resistance along the mating plane, and surface magnetic flux density of each magnet.
- Print and insert quality: text correctness, font and color match against artwork, sharpness, registration, no missing or smeared characters, correct double-sided orientation.
- Assembly and function: card insertion and removal force, swivel or rotation action (where applicable), stable standing without rocking, no rattling of loose magnets.
- Adhesion and coating integrity: cross-cut adhesion of coatings and printed layers, tape test on adhesive-bonded magnet pockets.
- Environmental and mechanical durability (periodic type tests): temperature and humidity endurance, light aging of acrylic, salt spray resistance of metal parts, drop resistance.
- Packaging and marking: carton strength, quantity accuracy, label content, warning cards, barcode scannability.
Defect classification examples: a missing magnet, a crack, or wrong printed content is critical; a holding force below the specified minimum or a visible scratch on the display face is major; minor polishing haze or a slightly uneven protective film edge is minor.
Testing Methods
Visual and Appearance Inspection
Appearance is inspected under diffuse lighting of at least 800 to 1000 lux with a daylight-simulating (D65) light source, at a viewing distance of 30 to 40 cm and a viewing time of roughly 5 to 10 seconds per face. The inspector checks each visible surface of the assembled sign against the approved limit-sample (golden sample) board, and protective films are peeled on sampled units to verify the condition of the protected surfaces.
Dimensional Measurement
Linear dimensions are measured with calibrated digital calipers (resolution 0.02 mm) or a micrometer for panel thickness; slot widths are verified with plug or feeler gauges; hole and pocket positions are checked with a height gauge on a surface plate. Flatness of the panel is assessed by placing it on a calibrated marble or granite plate and inserting feeler gauges at the corners. Unless otherwise specified on the drawing, machined dimensions are held to approximately ±0.2 mm and molded acrylic dimensions to ±0.3 to ±0.5 mm.
Magnetic Force Testing
Normal (pull-off) holding force is measured with a calibrated digital push-pull force gauge: the sign is fixed on a rigid fixture, the gauge is attached to the panel by a non-magnetic clamp, and the panel is pulled perpendicular to the mating plane at a slow, steady rate; the peak force in newtons (or kilogram-force) is recorded for at least three attachment cycles and the average is compared with the specification, typically with a rejection threshold of 10% below nominal. Shear resistance is measured by applying force parallel to the mating plane until the panel slides off the base. Surface magnetic flux density of individual magnets is verified with a Hall-effect teslameter (gaussmeter), probing the defined measurement point of each magnet pocket; readings outside the specified millitesla band indicate wrong magnet grade, wrong magnetization direction or a substituted magnet lot.
Print, Insert and Adhesion Testing
Printed layers and coatings are evaluated by the cross-cut test per ISO 2409 or ASTM D3359 (classification 0 or 1 is generally required), followed by adhesive tape removal. Print abrasion resistance is checked by a rub test—for example, 30 to 50 rubbing cycles with an alcohol-soaked cloth under a defined deadweight—with no visible ink loss allowed. For inserts produced by the factory, color difference against the approved proof is measured with a colorimeter, and acceptance is typically defined by a maximum color difference value (for example, a total color difference of no more than 2).
Environmental and Mechanical Durability Testing
Periodic type tests follow the IEC 60068 environmental testing series: cold exposure (for example, IEC 60068-2-1 at -20 °C for 4 h), dry heat (IEC 60068-2-2 at 60 to 80 °C for 4 h, respecting the operating temperature limit of standard NdFeB grades) and damp heat, steady state (IEC 60068-2-78 at 40 °C and 93% relative humidity for 48 h), after which samples must show no cracking, delamination, magnet corrosion or loss of holding force greater than the specified allowance. Light aging of acrylic components is assessed per ISO 4892-3 (fluorescent UV lamps), verifying that yellowing and transmittance change remain within limits. Functional drop resistance is verified by letting an assembled sign fall from typical table height (0.8 to 1.0 m) onto a hardwood surface in several orientations; shipping cartons are drop tested per ISO 2248 or GB/T 4857. Corrosion resistance of aluminum and any steel components is verified by neutral salt spray exposure per ASTM B117 or ISO 9227, commonly 24 to 48 hours with no white or red rust.
Rejection and Re-inspection Rules
If the number of defects found in the sample exceeds the acceptance number for its AQL class, the lot is rejected. The factory must then screen 100% of the lot for the failed characteristic (for example, re-testing holding force of every unit), remove and rework defective units, and present the lot for re-inspection under tightened inspection. Repeated failure of the same characteristic across consecutive lots triggers a corrective action request addressing root cause, such as magnet supplier control, adhesive curing parameters or molding process conditions.
Applications
Strong magnetic table signs are used wherever frequently changing names, titles or table assignments must be displayed with a clean, frameless look and without adhesive residue or mechanical fasteners. Rigorous factory exit inspection is particularly important in the following scenarios, because defects such as weak magnets or misprinted inserts directly affect the end user's brand presentation.
- Corporate offices and open-plan workstations: desk nameplates with swappable name inserts for staff rotation and hot-desking programs.
- Conference and meeting rooms: magnetic panel signs for room names, meeting topics and agenda displays.
- Hotels and hospitality: front-desk signage, function-room indicators and banquet table-direction signs.
- Restaurants and cafés: reusable magnetic table-number signs that survive frequent handling and cleaning.
- Hospitals, banks and government service halls: counter and queue signage requiring durable, easy-to-sanitize surfaces.
- Exhibitions and events: quick-assembly table signage with interchangeable printed panels.
In these environments, the inspection program guarantees consistent magnetic clamping so that panels do not fall off when bumped, correct printed content for each order, and corrosion-free components that maintain appearance over years of indoor service.
FAQ
What AQL and inspection level are typically used for strong magnetic table signs?
For routine lot-by-lot exit inspection, general inspection Level II under ISO 2859-1 with AQL 0 (critical), 1.0 to 1.5 (major) and 2.5 to 4.0 (minor) is the most common arrangement. Tightened inspection is applied after a lot rejection or at the start of a new production run.
How is magnetic holding force specified and verified?
Holding force is specified as a minimum normal pull-off force in newtons (or kilogram-force) between the panel and base, measured with a calibrated digital force gauge at a controlled slow pull rate. Individual magnet quality is additionally verified with a Hall-effect teslameter measuring surface flux density in millitesla against a defined acceptance band.
Which tests are performed on every lot versus periodically?
Appearance, dimensions, magnetic pull-off force, print content, assembly function and packaging are checked on sampled units of every lot. Environmental tests (cold, dry heat, damp heat, UV aging), salt spray testing and packaging drop tests are type tests performed at defined intervals, after design or material changes, or for first shipments.
What happens if a lot fails the exit inspection?
The lot is rejected, 100% screened or reworked for the failed characteristic, and re-submitted for inspection under tightened sampling. Persistent failures require documented corrective action addressing root cause before further shipments are released.
Should accredited third-party laboratories be involved?
Routine exit inspection is normally performed by the factory's own QC department. Accredited third-party laboratories are recommended for independent verification of type tests—such as IEC 60068 environmental tests, ISO 4892-3 light aging or ASTM B117 salt spray—especially for large contracts, new suppliers or products entering regulated markets.
Are there special handling requirements during inspection?
Yes. Strong NdFeB magnets can pinch skin, attract tools and damage magnetically sensitive devices such as watches, pacemakers and measurement equipment. Inspection stations should be kept free of loose steel items, magnet pairs should be separated with dedicated tools, and packaged products must include appropriate strong-magnet warning labels per the shipping requirements.
What documentation should accompany each shipped lot?
Each lot should be released with an exit inspection report recording lot size, sampling plan, defect counts against each AQL class, measured holding force and dimensional results, calibration status of the instruments used, and a certificate of conformity referencing the applicable product specification and test standards.