Property Class 8.8 Steel Ball-Ended Thrust Screws are supplied to ISO 898-1 property class 8.8. Corrosion behaviour is requires plating (zinc) for corrosion protection, the material is magnetic, and the usable service range is commonly limited to approx. +300 °C; confirm against the coating and the load. In practice this grade is the workhorse medium-carbon alloy class for structural joints.
- Grade
- ISO 898-1 property class 8.8
- Corrosion resistance
- Requires plating (zinc) for corrosion protection
- Magnetic response
- Magnetic
- Service temperature
- commonly limited to approx. +300 °C; confirm against the coating and the load
Property values are typical for the grade. Certified mechanical test data is available on request for production orders.
Property Class 8.8 Steel (ISO 898-1 property class 8.8) is the workhorse medium-carbon alloy class for structural joints. Specified on ball-ended thrust screws it determines the corrosion behaviour (requires plating (zinc) for corrosion protection) and the service temperature range (commonly limited to approx. +300 °C; confirm against the coating and the load); the dimensions are ours rather than a standard's, and are listed in full below.
Why Choose Property Class 8.8 Steel for Ball-Ended Thrust Screws
The workhorse medium-carbon alloy class for structural joints. For ball-ended thrust screws, this matters when requires plating (zinc) for corrosion protection is the primary requirement.
Mechanical & Physical Properties
| Grade designation | ISO 898-1 property class 8.8 |
|---|
| Magnetic response | Magnetic |
|---|
| Service temperature | commonly limited to approx. +300 °C; confirm against the coating and the load |
|---|
| Corrosion characteristic | Requires plating (zinc) for corrosion protection |
|---|
Corrosion Behavior in Service
Carbon and alloy steel ball-ended thrust screws require a coating for corrosion protection. Zinc plating (with or without passivation) is the most common; hot-dip galvanizing is used for outdoor structural service; black-oxide is mainly a tarnish-prevention finish for tool-room use.
Galvanic & Galling Considerations
For ball-ended thrust screws in steel, the dominant compatibility issue is hydrogen embrittlement at high property classes (10.9 and above) when electroplated. Plating must be followed by an appropriate baking treatment, or a non-electroplated finish (mechanical zinc, zinc flake) should be substituted.
Sizes of Ball-Ended Thrust Screws Available in Property Class 8.8 Steel
| Thread size | Length options | Tip diameter | Drive size | Tip action | Hardness |
|---|
| 1/4-20 | 1/2 or 3/4 in | 0.157 in | 1/8 in | 360-degree swiveling ball | Rockwell C32 |
| M3×0.5 | 5 / 7.5 / 10 mm | 1.5 mm | 1.5 mm | 360-degree swiveling ball | Rockwell C39 |
| M4×0.7 | 6 / 8 / 10 / 12 / 16 mm | 2.5 mm | 2 mm | 360-degree swiveling ball | Rockwell C39 |
| M5×0.8 | 8 / 10 mm | 3 mm | 2.5 mm | 360-degree swiveling ball | Rockwell C39 |
Dimensions are independent of the material: every size above is available in Property Class 8.8 Steel.
Custom manufacturing · Made to drawing
Need this screw in a grade that is not listed?
Grade 8 8 Steel is one of the grades the catalog describes. Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
Custom screw manufacturingSend a drawing
Applications & Industries
The sectors that buy Ball-Ended Thrust Screws, and the duty each one buys them for. Stocked from 1/4-20 to M5×0.8 (screw size).
Industries that specify Ball-Ended Thrust Screws
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Clamping mechanisms
Ball-ended screws distribute point contact during adjustment.
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Alignment tooling
Metric and inch lengths suit small stops and supports.
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Optical equipment
Black-oxide alloy steel provides a compact adjustment point.
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Machine fixtures
A swiveling ball tip contacts an angled workpiece without gouging it.
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Energy & infrastructure
Tower, pipework, switchgear and plant fixings specified for long service life and inspectable joints.
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Maintenance & MRO
Stocked replacements matched to an existing property class, thread and finish.
Typical applications
- choosing tip diameter and drive size
- matching length to the adjustment travel
- using the listed hardness and material for the contact duty
- clamping an angled surface with a swiveling ball tip
- bolting brackets, motors and gearboxes to a frame
- assemblies that are dismantled for service and re-torqued
Service conditions to specify against
- Marine and coastal
- Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
- High load
- Supplied in ISO 898-1 property classes, so the joint can be designed to a stated proof load and tightened to a calculated torque rather than by feel.
- Torque and preload
- The joint is designed around bolt tension, so lubrication, coating and the friction coefficient all change the torque figure — state them together.
Where to use something else
- Do not use a ball-ended thrust screw as a high-load hinge or shear pin; the ball tip is an adjusting contact.
- Do not use a machine thread into unthreaded sheet or timber; use a tapping screw, rivet nut or insert made for that parent material.
Full application guide: where Ball-Ended Thrust Screws are used, how to specify them, and the cases they are wrong for
