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Phosphate Coated Cylinder Head Flange Bolts

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Introduction

Phosphate coated cylinder head flange bolts are hex head bolts with an integral washer face, made for engine and housing joints that need an even clamp load. A phosphate conversion coating with oil gives a stable friction level during tightening and a good base for retaining oil. Typical products are alloy steel class 8.8 or 10.9, such as the M8x100 size used on cylinder head and gearbox covers.

Shanghai Soverchannel Industrial Co., Ltd. manufactures flange bolts in M6 to M14 at its Nantong Jinzhai Hardware plant, drawing on years of automotive fastener experience, with phosphate and zinc flake finishes and torque-friction testing on request.

Specification

Specification

TypeHex head flange bolt, cylinder head style
StandardDIN 6921, ISO 4162 or drawing
MaterialAlloy steel or medium carbon steel
Property class8.8 or 10.9
Size rangeM6 to M14
Length20 mm to 150 mm
Surface finishPhosphate with oil, Dacromet on request
Friction controlFriction coefficient test available
HeadIntegral flange, optional serration
PackingCartons, anti-rust paper available

Advantages

Applications

Machinery Assembly

Frames, gearbox housings, motor mounts and guards where a full thread gives maximum engagement.

Equipment Maintenance

Replacement bolts for pumps, conveyors and crushers, ordered by standard number and class.

Steel Framing

Brackets, base plates and light structural connections.

Automotive Chassis

Cross-members, subframe brackets and suspension mounts where class 8.8 is specified.

Agricultural Machinery

Implement frames and hitch assemblies exposed to dirt and vibration.

Core Features

  1. Hex head: standard wrench sizes allow fast tightening with common tools.
  2. Quenched and tempered core: delivers the 800 MPa tensile level required for class 8.8.
  3. Rolled thread: improves fatigue performance compared with cut threads.
  4. Gauge-checked threads: go and no-go gauges confirm fit before packing.

Frequently Asked Questions

What is the difference between DIN 933 and DIN 931?
DIN 933 is fully threaded, while DIN 931 has a plain shank section. Use DIN 933 for short grips or tapped holes, and DIN 931 when the unthreaded shank should carry shear load.
Is DIN 933 the same as ISO 4017?
Dimensions are very close and the two are used interchangeably in most orders. State both numbers on the purchase order and the drawing to avoid confusion at inspection.
Can I get class 8.8 bolts with a hot-dip galvanized finish?
Yes. Class 8.8 is generally accepted for hot-dip galvanizing. Nuts must then be tapped oversize so the thread still assembles.
What documents can be supplied with an order?
Material certificates, mechanical test reports and coating thickness records can be provided for each batch when requested at the quotation stage.
Why Global B2B Buyers Choose Our Fasteners

EN 10204 3.1 MTC

Every batch comes with full traceability, including material certificates, tensile strength, and hardness test reports to ensure smooth project acceptance.

500+ Tons/Month Capacity

Direct supply from our Nantong Jinzhai Hardware plant. Standard sizes (M8-M24) are kept in stock for 3-7 days rapid dispatch.

100% Thread Gauge Check

Strict go/no-go gauge inspection after thread rolling guarantees perfect 6g tolerance fit, eliminating the risk of stripped threads.

OEM/ODM Flexibility

Support custom lengths, special head shapes, fine threads, and head marking (Logo/Grade) with fast CAD drawing confirmation.

Export Standard Packaging Pallet

Export-Standard Packaging & Logistics

We understand the harsh conditions of international shipping. Our packaging is designed to prevent rust, damage, and customs delays.

  • ISPM 15 Fumigation-Free Wooden Pallets: Meets global customs quarantine requirements for hassle-free clearance.
  • Heavy-Duty Cartons + Inner PE Liner: Double protection against high humidity and salt spray during ocean freight.
  • Customized Shipping Marks: Clear, durable labels with your company info, item number, and quantity for easy warehouse counting.
  • Transparent Packing Data: We provide exact CBM, GW, and carton dimensions in the quotation to help you calculate shipping costs accurately.
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About Us
Shanghai Soverchannel Industrial Co., Ltd.
Shanghai Soverchannel Industrial Co., Ltd. is a manufacturer integrating R&D, production, and sales, focusing on providing high-precision non-standard and standard fastening solutions for customers. China Phosphate Coated Cylinder Head Flange Bolts ManufacturersOEM/ODM Phosphate Coated Cylinder Head Flange Bolts Manufacturers and China Phosphate Coated Cylinder Head Flange Bolts Manufacturers. The company has been deeply engaged in the automotive fastener industry for many years. It owns its own manufacturing plant, Nantong Jinzhai Hardware Co., Ltd., and has accumulated solid technical strength and rigorous quality control experience.

Our main products cover various high-quality bolts, nuts, steel processing parts, welding components, and customized special-shaped parts. China Phosphate Coated Cylinder Head Flange Bolts Manufacturers. Relying on advanced production equipment and a full-process inspection system, we are not only capable of mass-producing high-standard parts but also excel in customizing non-standard bolts and complex special-shaped components according to specific customer requirements. Over the years, we have always adhered to technology-driven development and earned trust through quality, becoming a reliable partner for numerous customers in the automotive and industrial fields.
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