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Sems
Compare your fastener to our visual size guide to confirm size, pitch and length.
Match your spanner / socket AF (across-flats) to the size it fits - our reference chart covers every metric and imperial size we stock.
"Sems" stands for "Self-Energising Mechanical Screws" — bolts that ship pre-assembled with a captive washer (or pair of washers) permanently held under the head. The washer can spin freely but cannot fall off, so the right washer is always present at install time.
On a production line, sems save time and eliminate one of the most common assembly errors — forgetting to fit a washer. Each sems bolt is supplied with a flat washer and a spring (lock) washer combination under the head, so you get a load-spreading washer AND vibration resistance in a single fastener.
MATERIAL AND FINISH
Zinc Yellow Plated — The only finish stocked. Mild steel with yellow chromate electroplate.
GRADES STOCKED
Class 8.8 High Tensile — The workhorse grade for sems used in automotive, appliance and machinery assembly.
Class 4.6 Low Tensile — Economical grade for lower-load assembly work.
Sizes: M5, M6 and M8 metric coarse — M8 is the busiest.
Thread system: Metric Coarse.
Drive types: Hex (the majority) plus Hex/Phillips combination heads where the option of a Phillips screwdriver is helpful.
Refer to our Technical PDF's Library for clamping load data and torque specifications.
WHY AUSTRALIA TRUSTS BOLT & NUT
With 15+ years selling fasteners online from Brisbane, we hold over 25,000 stock lines and 200 million pieces — 98.75% of online orders placed before 1pm leave same day. Save more as you buy more — we offer up to 13 price breaks plus 3 spend-tier discounts. Read our customer reviews or get in touch if you need help picking the right bolt.
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Bolts that ship preassembled with captive flat and spring washers under the head - the washers spin freely but cannot fall off, saving time on production assembly work. Zinc yellow finish.
TECHNICAL RESOURCES
Key charts and specification sheets: Imperial vs Metric Strength Chart · Specs - SEM Hex Bolt Metric Coarse High Tensile 8.8 Zinc Yellow · Specs - SEM Hex Bolt Metric Coarse Zinc Yellow
For the full library, see our Technical PDF's Library.
