This project is a long-term supply program for an Australian customer, including custom safety chain pins in several regular sizes. The pins are manufactured from 4140 alloy steel, heat treated to 38–44 HRC, and finished with Geomet 720-720H coating for improved surface protection.
The order includes multiple pin specifications, such as BK10, BK13, BK16 and BK20 series. Each size is produced according to the customer’s drawings and repeated purchasing requirements. The proforma invoice for this project lists BK10-02, BK10-03, BK13-02, BK13-03, BK16-02, BK16-03, BK20-02 and BK20-03 safety chain pins, all made from 4140 material with 38–44 HRC hardness and NOF Metal Coating Shanghai-Geomet 720-720H surface coating.
Project Overview
These safety chain pins are used as durable connection components for transport and automotive-related applications. Since the customer orders these parts regularly, stable dimensions, surface quality, batch identification and packing protection are all important.
The pins have different body diameters and end structures depending on the size. Some versions include cross holes for assembly, and the flat section is marked with the product code for easy identification.
For this project, the customer also requires batch code marking. The batch code changes according to the production year and month. For example, the year code for 2026 is Z, and the month code for March is C, so the batch code for a March 2026 batch is marked as ZC.
Manufacturing Process
The safety chain pins are manufactured through machining, drilling, heat treatment and surface treatment.
The main production steps include:
- Cutting raw 4140 alloy steel material
- CNC machining of the pin body and stepped sections
- Drilling cross holes according to the drawing
- Machining flat surfaces for product code marking
- Heat treatment to reach 38–44 HRC
- Surface preparation before coating
- Geomet 720-720H coating
- Batch code and part number marking
- Final inspection and protective packing
For similar drawing-based parts, Yutung Industrial also manufactures custom washers, bolts, pins and chain components according to customer requirements.
Geomet Coating and Surface Protection
The surface treatment used for this project is Geomet 720-720H, which is a zinc flake coating system commonly used for corrosion protection on metal components. It is suitable for fasteners, pins and other mechanical parts that need a protective coating without traditional electroplating.
For this type of surface treatment and coated parts, handling and packing are very important. The coated surface can be scratched if the parts rub against each other during transportation.
To reduce surface damage, each pin is protected with an individual blue mesh sleeve before packing. This small packing detail helps protect the coated finish and keeps the parts in better condition when they arrive at the customer’s warehouse.
Quality Control
Because this is a long-term project, repeatable quality is more important than one-time production. We check the key dimensions, hardness, coating appearance, marking and packaging condition before shipment.
Key inspection points include:
- Pin diameter and length
- Hole position and hole diameter
- Machined flat section
- Product code marking
- Batch code marking
- Heat treatment hardness
- Geomet coating appearance
- Surface scratches or handling damage
- Individual mesh sleeve protection
- Carton packing condition
The customer uses different pin sizes in repeated batches, so clear marking is helpful for warehouse management, assembly identification and after-sales traceability.
Long-Term Supply for Australian Customer
This project has been supplied to the Australian customer as a regular long-term item. The customer orders several sizes together, including small, medium and large safety chain pins, and each batch follows the required material, hardness, coating and marking rules.
For automotive and transport-related parts, stable quality and traceability are especially important. These pins are suitable for automotive component applications where durable machined metal parts and reliable surface treatment are required.
By managing machining, heat treatment, coating, marking and packing together, we help the customer maintain consistent quality across repeated orders.
Need Custom Pins or Coated Mechanical Parts?
If you need custom safety chain pins, bolts, washers, shafts, sleeves or other coated mechanical components, Yutung Industrial can manufacture them according to your drawings, samples and application requirements.
