Stud Grades 6.8, 8.8 and 10.9 Explained: Choosing the Right Studs Manufacturer in Pune

Studs hold cylinder heads, manifolds, turbochargers, gearboxes and hydraulic cylinders together. Picking the wrong grade – or a supplier who cannot hold the thread and length tolerances – shows up later as loosening, thread stripping or failure in service. This guide explains the common property classes and what to look for in a studs manufacturer.

What do 6.8, 8.8 and 10.9 mean?

The property class on a metric stud tells you its strength. The first number is one-hundredth of the nominal tensile strength in MPa; the second is ten times the ratio of yield to tensile strength.

• Class 6.8 – about 600 MPa tensile, 480 MPa yield. General-purpose studs where loads are moderate.
• Class 8.8 – about 800 MPa tensile, 640 MPa yield. The workhorse for automotive and machinery joints; usually quenched and tempered.
• Class 10.9 – about 1,000 MPa tensile, 900 MPa yield. High-tensile studs for highly loaded joints such as engine heads and connecting parts.

When should you use stainless-steel studs?

Where corrosion matters more than ultimate strength – exhaust areas, food and pharma equipment, outdoor and marine use – stainless steel (SS) studs are the better choice. Grades such as A2/A4 trade some strength for long-term corrosion resistance.

What to check in a studs manufacturer

• Complete in-house manufacturing – cutting, CNC turning, thread rolling or cutting, chamfering and inspection under one roof gives consistent quality.
• Thread and length control – thread gauges, stud-end lengths and runout checked in process, not only at final inspection.
• Material and heat-treatment traceability – mill certificates and hardness results for every batch.
• Delivery reliability – a supplier close to your plant (Chakan, Talegaon, Pimpri-Chinchwad) reduces lead times.

Studs and special fasteners from Santosh Engineering Works

Since 1980 we have manufactured Class 6.8, 8.8 and 10.9 studs, SS studs, special threaded studs, hex bolts and lifting eye bolts at Dehu, Pune – to customer drawings, under ISO 9001:2015, with ZEISS CMM inspection. See our studs & special fasteners range or send your drawing for a quote.