Hex Bolts & Screws

JIAXING SINI FASTENER CO., LTD. manufactures hex bolts and hex-head screws in carbon steel for machinery assembly, equipment maintenance, automotive components and structural connections. Established in 2004, we supply standard and custom-engineered fasteners from production facilities in Haiyan, Zhejiang and Lianyungang, Jiangsu, serving construction hardware, machinery, machine tool, electrical appliance and furniture customers across North America, South America and Europe. The hex bolts on the category are produced to ASME B18.2.1 and DIN 933 / DIN 931, with a hexagonal head sized for standard wrenches and sockets.

Hex Bolts & Screws We Manufacture

This is our general-purpose industrial hex bolt: a hexagonal-head, externally threaded fastener used where a joint must be clamped, inspected and later released. The shank is available fully threaded or partially threaded so the unthreaded portion can carry shear across a fitted joint. Bolts are normally paired with hex nuts to develop clamping force, and the black oxide finish reduces glare and improves visibility in complex working environments.

• Standards: ASME B18.2.1, DIN 933 (full thread), DIN 931 (partial thread)
• Material: carbon steel; stainless steel available across our bolt and screw range
• Grades: A307A, GR2 / GR5 / GR8, 4.8, 8.8
• Thread size: 3/16"–2" (M5–M52)
• Length: 1/2"–6" (12 mm–600 mm)
• Coatings: plain, black oxide, zinc, hot-dip galvanized
• Sizing systems: inch and metric, produced side by side

Specification Range and What Each Parameter Controls

Each line in a hex bolt specification changes how the fastener behaves in service. The table below shows the range we build to and the practical effect of each choice.

Where Hex Bolts Fit

Carbon Steel Plain Hex Bolts are the workhorse fastener in assemblies that are built, serviced and rebuilt. Our customers use them in engine parts, drivetrain systems, metal frames, agricultural machinery and general industrial equipment where durability and strength matter more than appearance.

• Machinery and equipment assembly — frames, guards, brackets and bolted joints that must be re-torqued during maintenance
• Automotive and drivetrain components — engine and transmission assemblies where grade and thread fit are specified
• Structural connections — metal frames and supports where a defined grade and coating are required
• Agricultural machinery — field equipment exposed to moisture, mud and vibration
• Construction hardware and general maintenance — stock fasteners held in mixed inch and metric sizes

Where the joint demands a larger bearing face or a heavier head, we supply Heavy Hex Bolts from the same production base. Where the application calls for a square neck that locks into timber or a domed head that resists rotation, Carriage Bolts are the appropriate family.

Configuration Options We Build To

Hex bolts are configured around the joint, not around a catalogue default. We confirm the following points before releasing a production order.

• Thread length: full thread for thin stacks and clamp-up through the whole shank; partial thread where shear passes through the unthreaded section
• Grade pairing: bolt grade matched to the nut grade so the joint fails in the intended mode rather than stripping the nut
• Coating selection: plain for painted or dry indoor assemblies, black oxide for general industrial use, zinc for outdoor exposure, hot-dip galvanized for heavy corrosion duty
• Head marking: grade and manufacturer identification applied as required by the governing standard or the customer drawing
• Thread fit: inch coarse or fine and metric coarse or fine, produced to the tolerance class named on the drawing
• Point and end finish: chamfered ends for free starting, with burr control on the thread run-out

Materials, Coatings and Corrosion Strategy

Carbon steel is the base material for this ASME B18.2.1 Hex Bolts range, and most items across our bolt and screw production are also available in stainless steel. The coating decision follows the service environment: an indoor machine frame and a field-mounted agricultural assembly do not need the same finish, and over-specifying the coating adds cost without adding life.

Black oxide gives moderate corrosion resistance for general industrial use and keeps the surface non-reflective. Zinc plating suits outdoor and intermittently wet conditions. Hot-dip galvanizing is the choice for long-term atmospheric exposure and heavier section sizes. Where stainless steel is specified, we produce to the grade named on the drawing rather than substituting a generic corrosion-resistant material.

Quality Control and Acceptance Testing

SINI FASTENER is ISO 9001 certified. We inspect after each process step, and finished products receive a comprehensive inspection against customer requirements and the applicable international standard before packing. That sequence catches dimensional drift at the forming stage rather than at final inspection.

• Optical Emission Spectrometer (OES) for chemical composition verification
• Universal Testing Machine and tensile testing machine for mechanical properties
• Hardness tester for grade confirmation
• Video Measuring System and metallographic microscope for dimensional and structural checks
• Salt spray test chamber for coating performance

Acceptance criteria are agreed at order stage: the standard or drawing revision, the inspection items, the sampling basis and the records that travel with the shipment.

Information We Use to Configure Your Solution

Our proposal is built from the working point, the material and the production target. The following inputs let us confirm a hex bolt configuration and quote without a second round of questions.

• Governing standard or a dimensioned drawing, including revision
• Thread size, pitch and thread form (inch or metric)
• Length, thread length and whether the shank is full or partial thread
• Property grade and the nut grade it will be paired with
• Material and coating, with the service environment described
• Head marking, packaging format and labelling requirements
• Order quantity, delivery schedule and any inspection or documentation requirement

Packaging, Documentation and Project Handoff

DIN933 Hex Bolts, DIN931 Hex Bolts are packed to the format agreed at order stage — bulk cartons, small boxes, or labelled cartons prepared for a specific line or distributor shelf. Carton marking, quantity per carton and pallet configuration are confirmed before production so the goods can be received and put away without rework.

Documentation follows the shipment and typically includes the inspection records agreed for the order. For custom-engineered items, we develop and produce from customer drawings or samples, and we keep the approved drawing as the reference for repeat orders. Inquiries receive a response within 12 hours on weekdays, and more than 60,000 tonnes of fasteners and hardware-related products leave our facilities each year.

Frequently Asked Questions

What hex bolt sizes and grades can SINI FASTENER produce?

Our hex bolts run from 3/16" to 2" (M5 to M52) in thread size and 1/2" to 6" (12 mm to 600 mm) in length, in grades A307A, GR2, GR5, GR8, 4.8 and 8.8. Carbon steel is standard, with stainless steel available across our bolt and screw range, and coatings including plain, black oxide, zinc and hot-dip galvanized.

Can you produce hex bolts to our own drawing instead of a published standard?

Yes. We manufacture to DIN and IFI standards and also develop and produce from customer-specific designs and drawings. Send the dimensioned drawing or a physical sample, and we will confirm the head dimensions, thread tolerance, grade and coating before quoting.

How is quality controlled on a hex bolt order?

We inspect after each process step and carry out a comprehensive finished-goods inspection based on customer requirements and international standards. In-house equipment includes an optical emission spectrometer, universal and tensile testing machines, a hardness tester, a video measuring system, a metallographic microscope and a salt spray chamber. SINI FASTENER is ISO 9001 certified.

Which industries use your hex bolts?

Machinery assembly, equipment maintenance, automotive components and structural connections are the main uses, including engine parts, drivetrain systems, metal frames and agricultural machinery. Our wider customer base covers construction hardware, machine tools, electrical appliances and furniture.

Do you supply matching nuts and washers with hex bolts?

We do. Nuts and washers are produced alongside our bolt and screw lines, so a joint can be supplied as a matched set with the bolt grade and nut grade confirmed together. Threaded rods and studs are also available where a fully threaded connection is required.

What information do you need to quote a hex bolt order?

Standard or drawing, thread size and form, length and thread length, property grade, material and coating, head marking, packaging format, quantity and delivery schedule. With those details we can confirm the configuration and prepare a quotation without further clarification.

JIAXING SINI FASTENER CO., LTD. is a Hex Bolts & Screws manufacturer supplying standard and custom-engineered fasteners from Haiyan, Zhejiang and Lianyungang, Jiangsu to customers in North America, South America and Europe.