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Q Can I have my box design and put my logo on the products?
A Yes, sure. we can customize the box and put your logo according to your design for your order.
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Q Do you have quality system?
A Yes, we have. We have set up our quality system and well controlled our production quality as per the instructions and requirements in it and well-control each procedure throughout the mass-production.
①To ensure the material component follows the ASTM standard, D&D use spectrometer to check the stainless steel raw material before production.
②D&D use measuring tools to check the product in each procedure throughout the mass-production to ensure the dimension of product meet customer’s requirement.
③ D&D arrange Quality control department in each step of the mass-production to ensure each production fulfill their duty to produce well-product.
④D&D use salt spray testing machine to test the product, to ensure it meet specific corrosion-resistance requirement.
⑤ D&D test products on testing machine very often to ensure products meeting CE / UL / ANSI standard.
⑥ D&D use 2D and 3D drawing to communicate with customer, which is clearly and accurately.
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Q What's your main market?
A We has established long business relations with customers from Europe, Middle East , America and Asia, benefit from quality assurance, expertise knowledge ,competitive pricing, customization ability and great service.
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Q What certificate you have?
A We have CE，UL and ANSI/BHMA cerfificate, all our product design follow up the international standard（European Standards& American Standards）, such as the EN/CE, UL, ANSI standard. Suitable for education, healthcare, hospitality, residential and commercial applications.
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Q How do I get a quotation?
A Email sales@danddhardware.com or message +86 139 2903 7292 on WhatsApp with your door types, target certification (UL or EN), load requirements and estimated quantities. Our sales engineers respond with a tailored quotation, datasheets and certification documents within 24 hours on business days.
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Q Do you support OEM/ODM? What are the MOQ, sample and lead times?
A Yes — OEM/ODM is core to our business. Choose from finishes including satin nickel, matt black, PVD, antique brass and antique copper, or specify custom load ratings, branding and packaging. Typical MOQ is 200–500 pieces, samples ship in 5–7 working days, production takes 30–35 days, and monthly capacity is 200,000 units.
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Q What is a hydraulic concealed hinge and where should I use it?
A A hydraulic concealed hinge integrates a damped self-closing mechanism inside the hinge body, replacing a visible overhead door closer. Our DDCHSL613 supports doors up to 60kg and 900mm wide, opens to 180° and offers adjustable closing speed. It is ideal for hotel rooms, hospitals, offices and residential invisible doors where silent, automatic closing matters.
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Q What load capacities are available for the certified models?
A The DDCH008 is available in 40kg, 80kg and 120kg load ratings; the DDCH011 comes in 60kg and 100kg versions. Final capacity depends on door dimensions, weight distribution and the number of hinges per leaf — send us your door schedule and our engineers will recommend the correct configuration.
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Q Are D&D concealed hinges certified for fire-rated doors?
A Yes. Our DDCH008 and DDCH011 models are UL 10C fire rated under File No. R38013 for the North American market, and certified to BS EN1935 (200,000 cycles), EN1634 fire rated 132 minutes, and EN1670 corrosion resistance 48 hours for European markets. The fire-resistant construction includes an expanding graphite seal, ceramic fire-retardant coated fasteners, and a 304 stainless steel cover plate rated to 1000°C — suitable for fire-rated metal doors, wooden fire doors and smoke doors.
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Q What is a concealed door hinge and how is it different from a butt hinge?
A A concealed door hinge — also called an invisible hinge or hidden hinge — is mortised into the door leaf and frame so it is completely invisible when the door is closed. Unlike a butt hinge, it has no exposed knuckle or removable pin. That means a seamless flush appearance, better tamper resistance, and precise 2D or 3D alignment adjustment after installation, which a traditional butt hinge cannot offer.
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Q Do you offer OEM or custom branding options?
A Yes. D&D Hardware offers comprehensive OEM/ODM services including custom logo stamping or laser marking on hinge leaves, custom packaging with your branding, and tailored finishes or sizes to meet specific project requirements. Our experienced engineering team works closely with clients to develop custom solutions. Minimum quantities for OEM orders typically start at 500 pairs per SKU.
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Q Can I get samples before placing a bulk order?
A Yes. We provide free product samples so you can evaluate hinge quality, finish, and fit before placing a bulk order. Sample requests are typically processed within 3–5 business days. Simply reach out through our inquiry form or contact us directly, and our team will arrange sample shipment to your specified address.
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Q What is the MOQ for D&D ANSI/BHMA certified hinges?
A We offer flexible minimum order quantities to accommodate projects of all sizes. For first-time trial orders, there is no minimum order requirement — allowing you to evaluate our product quality before committing to larger volumes. Standard bulk orders typically start at 500 pairs per size/finish combination. Contact our sales team for specific MOQ details based on your project requirements.
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Q Does D&D support OEM programs, custom finishes and bulk distributor pricing?
A Yes. As the factory, D&D supports private labeling, custom packaging, PVD and matte black finishes, stainless steel 201/304/316 material options and volume pricing structures for distributors, importers and door manufacturers. Custom sizes are available on request alongside the 11 certified standard sizes.
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Q What documentation does D&D provide for project submittals and procurement?
A Every quotation can include independent laboratory test reports, ANSI/BHMA certificates for A156.1 and A156.18, UL listing documentation, material certificates and finish specifications — formatted for architect review, building control submission and distributor compliance files.
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Q Are these hinges compatible with fire-rated door assemblies?
A Yes. D&D ANSI/BHMA hinges carry UL/cUL UL 10C certification with a 3-hour fire rating under File No. R38013, satisfying NFPA 80 and IBC requirements for fire door assemblies. See our dedicated UL fire door hinge guide for listing details and certified sizes.
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Q When should NRP (non-removable pin) hinges be specified?
A Specify NRP on any out-swinging exterior or security-sensitive door where the hinge barrel is exposed to the unsecured side. The set screw locks the pin in place while the door is closed, eliminating pin extraction as a forced-entry route. NRP is available across D&D's Grade 1 and Grade 2 configurations.
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Q What is the practical difference between A156.1 and A156.18 certification?
A A156.1 certifies the mechanical performance of the hinge itself — cycles, wear, friction and strength. A156.18 certifies the finish: corrosion resistance via 240-hour ASTM B117 salt spray, adhesion and color consistency. A complete commercial submittal should reference both, which is why D&D certifies its range to the two standards together.
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Q Why should a commercial project never specify Grade 3 hinges?
A Grade 3 is tested to only 350,000 cycles — designed for light residential service. Under commercial traffic it produces door sag, latch misalignment and cascading damage to closers and locks, forcing early replacement. The labor cost of one replacement typically erases any purchase saving several times over.
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Q How do I translate hinge cycle tests into expected service life?
A Divide the certified cycle count by realistic daily usage. A Grade 1 hinge (2,500,000 cycles) on a high-traffic entrance operating 200 times daily gives a theoretical mechanical life of over 34 years; at 100 cycles per day it exceeds 68 years. This calculation is the backbone of any total-cost-of-ownership comparison a facility manager will accept.
