Mechanical properties, corrosion behaviour and the full dimensional range for this grade.
Property Class 8.8 Steel EPDM Rubber Well Nuts 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.
Hidden Deck Fasteners Sourcing: Manufacturing, Types & Material Compatibility
Material specification page for epdm rubber well nuts in Property Class 8.8 Steel. Covers the grade designation (ISO 898-1 property class 8.8), corrosion and magnetic behavior, comparable grades and their trade-offs, and the sizes available to Trade series (rubber blind nuts).
Why Choose Property Class 8.8 Steel for EPDM Rubber Well Nuts
The workhorse medium-carbon alloy class for structural joints. For epdm rubber well nuts, 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 epdm rubber well nuts 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.
Comparable Grades
For EPDM Rubber Well Nuts, class 10.9 or 12.9 is the comparable strength step. Move up when the joint preload approaches the proof load of the current class; move down when the joint is over-specified. For corrosion-critical service, switch to stainless A2 or A4.
Sizes of EPDM Rubber Well Nuts Available in Property Class 8.8 Steel
Thread size
Representative hole diameter (mm)
Representative grip range (mm)
Temperature range (u00b0C)
Representative tightening torque (Nu00b7m)
Body / insert
M3
8.0
0.4~4.0
-30~+80
0.5
EPDM rubber / stainless threaded insert
M4
8.0
0.4~4.0
-30~+80
0.4
EPDM rubber / stainless threaded insert
M5
9.7
0.4~4.9
-30~+80
0.6
EPDM rubber / stainless threaded insert
M6
12.8
0.4~4.0 or 0.8~4.7
-30~+80
1.0
EPDM rubber / stainless threaded insert
M8
16.0
0.4~4.0
-30~+80
1.5
EPDM rubber / stainless threaded insert
Technical Drawing
Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.
Sends the selected values to the quote form below.
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The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.
Dimensions & Specifications (Trade series (rubber blind nuts))
Thread size
Representative hole diameter (mm)
Representative grip range (mm)
Temperature range (u00b0C)
Representative tightening torque (Nu00b7m)
Body / insert
M3
8.0
0.4~4.0
-30~+80
0.5
EPDM rubber / stainless threaded insert
M4
8.0
0.4~4.0
-30~+80
0.4
EPDM rubber / stainless threaded insert
M5
9.7
0.4~4.9
-30~+80
0.6
EPDM rubber / stainless threaded insert
M6
12.8
0.4~4.0 or 0.8~4.7
-30~+80
1.0
EPDM rubber / stainless threaded insert
M8
16.0
0.4~4.0
-30~+80
1.5
EPDM rubber / stainless threaded insert
Applications & Industries
Where EPDM Rubber Well Nuts are used, and what decides the specification in each case. Stocked from M3 to M8.
Industries that specify EPDM Rubber Well Nuts
Vehicle body panelsRubber well nuts isolate and seal trim fasteners through thin skins.
Motorcycle serviceBlind rubber inserts provide a thread where the rear face is inaccessible.
Outdoor enclosuresEPDM accommodates panel movement and keeps a small hole sealed.
Equipment coversStainless inserts resist corrosion while the rubber body clamps the panel.
Maintenance & MROReplacements matched to the existing bolt class, thread and finish.
Building servicesThreaded rod, channel and suspension assemblies.
Typical applications
adding a blind threaded point to a thin panel
matching hole diameter and grip range to the EPDM body
tightening only to the representative torque for the size
using the rubber body for isolation and sealing
completing a bolted joint on a stud, rod or bolt
locking an adjustment so it cannot drift
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.
Sealed joints
Used where the fixing has to keep water or air out as well as hold — the elastomer, not the fastener, decides service life.
Match the class
A nut below the bolt property class strips before the bolt reaches its own limit — pair class 8 nuts with 8.8 bolts, class 10 with 10.9.
Where to use something else
Do not over-tighten a well nut; excess compression can pull the insert through the panel or damage the seal.
This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.
01
Cold heading
Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.
Head dimensions and under-head radius checked at set-up and per shift.
02
Thread rolling
Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.
Go / no-go ring gauges to ISO 965 tolerance class 6g.
03
Heat treatment
Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.
Core hardness and tensile tested per lot to ISO 898-1.
04
Surface treatment
Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.
Coating thickness and neutral salt spray hours to ISO 9227.
Frequently Asked Questions
Which finish is best for outdoor EPDM Rubber Well Nuts?
For outdoor service in steel, hot-dip galvanizing gives the longest life; zinc-flake (Geomet/Delta-Tone family) gives a thinner film with excellent salt-spray performance; standard zinc plating is the lowest-cost option for general indoor / shielded outdoor use.
What's the service temperature limit for Property Class 8.8 Steel?
The practical service range is commonly limited to approx. +300 °C; confirm against the coating and the load.
Can Property Class 8.8 Steel replace stainless steel structurally?
No — stainless A2/A4 cannot match class 10.9 / 12.9 strength. Stainless is selected for corrosion, not raw strength.
Are Property Class 8.8 Steel EPDM Rubber Well Nuts magnetic?
Property Class 8.8 Steel EPDM Rubber Well Nuts are magnetic.
How do I request a quotation?
Use the technical drawing on this page to pick the exact configuration, then submit it with the quote form. We respond within one business day.
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