Abrasives

Abrasives for Cutting, Grinding, Sanding and Surface Conditioning

Abrasives are the consumable side of metalwork, fabrication and finishing. Cutting discs slice through steel and stainless; grinding discs remove weld spatter and dress edges; flap discs and flap wheels blend the surface between cuts; sanding discs and Roloc surface-conditioning discs finish the job. Choosing the right grit and grain for the substrate is the single biggest decision - wrong abrasive on the wrong substrate wears out fast, produces poor finish, or risks the disc bursting under load.

Bolt & Nut Australia stocks the Klingspor and Alpha abrasive ranges from Brisbane: cutting discs (Klingspor TZ Special for metal and stainless), grinding discs (Klingspor Extra A24), flap discs (Alpha Silver Series and Klingspor), flap wheels (Alpha mounted), sanding discs (Klingspor PS22K hook-and-loop orbital), quick-change Roloc discs (Klingspor QRC411), hand pads (Klingspor NPA400) and flexible abrasive blocks. 180+ SKUs covering 100mm, 115mm, 125mm and smaller specialty sizes.

We've been supplying these online from Brisbane for over 15 years. With 25,000 stock lines and over 200 million pieces in stock, we carry one of the most comprehensive ranges of abrasives available in Australia — from Klingspor and Alpha cutting discs, grinding discs, flap discs, flap wheels, sanding discs, quick-change Roloc discs, hand pads and abrasive blocks in 100mm, 115mm and 125mm common sizes. Save more as you buy more — we offer up to 13 price breaks plus 3 spend-tier discounts.

CHOOSING THE RIGHT ABRASIVE FOR THE JOB

Cutting (slicing through steel / stainless / pipe): cutting disc - thin (1mm to 3.2mm) reinforced abrasive wheel sized for the angle grinder. The thinner the disc, the faster the cut and the less heat-affected zone, but thin discs are more fragile. 1mm cutting discs are standard for stainless sheet; 2.5mm for general steel section.

Grinding (weld dress, edge bevel, heavy stock removal): grinding disc - thicker (6mm) abrasive wheel with the grain bonded for removal not slicing. Used at 25-30 degrees off the workpiece face to remove metal at the edge of the wheel.

Blending (between cutting/grinding and finishing): flap disc - overlapping cloth flaps of bonded abrasive, used flat to the workpiece to blend a grinding mark down to a sanded finish in one tool change. Cooler than grinding discs, kinder to thin material.

Sanding (preparing a finish): sanding disc - hook-and-loop or PSA-backed abrasive disc on a flat orbital sander. 40 grit for coarse stock removal through to 240 grit for finish prep. Klingspor PS22K is the workhorse stocked here.

Surface conditioning (rust removal, weld cleanup, paint prep): quick-change Roloc disc on a roll-on / roll-off air or cordless tool, OR a hand pad for tighter access. Both use non-woven abrasive that scrubs the surface without removing base metal at significant rate.

Detail finishing on tubes and curves: mounted flap wheel on a die grinder for inside-radius and tube work where flat discs can't reach.

GRIT AND GRAIN - WHAT THE NUMBERS MEAN

Grit is the size of the abrasive particle - lower number = coarser grit, larger particle, faster stock removal, rougher finish. Higher number = finer grit, smaller particle, slower removal, smoother finish. Common range in the stocked abrasives:

24 grit - extra coarse. Heavy stock removal, weld dressing, mill-scale removal. Stocked on grinding discs.

36 / 40 grit - very coarse. Coarse blending, paint stripping, weld blending. Stocked on flap discs and Roloc.

60 grit - coarse. General blending and weld smoothing. The workshop default flap disc grit.

80 / 120 grit - medium. Finer blending, pre-finish preparation. Used at the back end of a flap-disc cycle or for sanding before paint.

180 / 240+ grit - fine. Finish prep, polish preparation, brushed-finish maintenance. Stocked on sanding discs.

Grain type - the abrasive mineral. Aluminium oxide (A24, A60 etc.) is the general-purpose workhorse - cheap, durable, suits steel and stainless. Zirconia alumina and ceramic grains (premium Alpha and Klingspor abrasives) self-sharpen as they wear, lasting 3-5x longer on tough stainless and alloy steel. Silicon carbide grain is sharper still, used on stone, masonry, glass, plastic and aluminium.

SAFE USE AND RPM LIMITS

Every abrasive disc carries a MAXIMUM rated RPM printed on the label. Exceeding this RPM is the most common cause of disc burst - the centrifugal force at over-speed exceeds the bond strength and the disc explodes. ALWAYS confirm the disc's maximum RPM is equal to or higher than your tool's no-load RPM.

100mm angle grinder: 11,000 to 14,000 RPM no-load. Use discs rated 80m/sec (typical of 100mm discs).

115mm and 125mm angle grinder: 9,000 to 12,000 RPM no-load. Use discs rated 80m/sec.

Mounted flap wheels (die grinder): typically rated 20,000 to 25,000 RPM.

Roloc on cordless / air tool: typically rated 18,000 to 20,000 RPM for the 50mm and 75mm sizes.

Use-by date: bonded abrasive discs have a manufacturer expiry date printed on the label - typically 3 years from manufacture. Discs past expiry are no longer safe to use at rated RPM; the bond can degrade over time. Check the date on every disc before use, especially from less-frequently used stock.

PPE: safety glasses are mandatory; a full face shield is the workshop standard for cutting and grinding. Hearing protection for sustained use. Dust mask or extraction for stainless and lead-painted substrate. NEVER use abrasive discs without the angle grinder's guard fitted and oriented correctly.

ABRASIVE BRANDS AT BNA

The abrasive range is stocked across three trade-grade brands. The brand you see on the disc, pad or block sets the grain technology, the published RPM rating and the consumable life under load. All three are stocked side by side because trade users tend to settle on a brand they trust.

Klingspor is a family-owned German manufacturer of coated and bonded abrasives, established in 1893 in Haiger and now in its fourth generation of family ownership. The Klingspor stocked range at BNA covers cutting discs (TZ Special for metal and stainless), grinding discs, flap discs, fibre discs, flexible abrasive blocks (SK500 series) and Quick-Change roll-on sanding discs across the standard 100mm, 115mm, 125mm and 180mm angle-grinder formats. Engineering-grade industrial abrasives with German manufacturing heritage.

Alpha is the Sheffield Group's premium drilling and abrasives brand, designed and specified in Australia to suit Australian metalwork, fabrication and construction conditions. The stocked Alpha abrasive range covers Silver Series and XTRA flap discs (zirconia / ceramic grain for stainless and alloy steel), mounted flap wheels and the XTRA combination cut / grind / notch disc. The Sheffield Group also carries Bordo, Tooline and the AlphaMag magnetic drill range so they are deep in metalworking consumables for Australian trade and industry.

Bristol is the value-tier abrasive brand stocked alongside Klingspor and Alpha for the cut and grind operations where the workshop wants a lower-cost consumable for high-frequency tasks. Limited range at BNA, supplementary to the primary Klingspor and Alpha lines.

Each SKU page surfaces the brand name in the specification table and renders an 'About the Brand' section describing the parent company, the country of manufacture and the brand's positioning in the abrasives market.

OUR RANGE

Cutting Disc — Klingspor TZ Special cutting discs for metal and stainless steel. 1mm thin discs for sheet stainless; 2.5mm and 3.2mm for general steel section. 100mm, 115mm and 125mm common sizes.

Grinding Disc — Klingspor Extra A24 grinding discs for metal and stainless. 6mm thick for weld dressing, edge bevels and heavy stock removal. 100mm and 115mm sizes.

Flap Disc — Alpha Silver Series and Klingspor flap discs in 40, 60, 80 and 120 grit for blending welds and surface prep. 100mm and 125mm. The trade-standard workhorse for fabrication finishing.

Sanding Disc — Klingspor PS22K hook-and-loop orbital sanding discs in 40, 60, 80, 120, 180 and 240 grit. 125mm 8-hole pattern for dust extraction compatibility.

Quick Change Roloc Disc — Klingspor QRC411 quick-change Roloc discs in 36, 60 and 80 grit. 50mm and 75mm sizes for the standard Roloc roll-on holder.

Hand Pads — Klingspor NPA400 non-woven hand pads in coarse (brown) and very fine (maroon) grades. 152mm x 229mm sheet size for hand surface conditioning and final cleanup.

Abrasive Block — Klingspor SK500 flexible abrasive blocks - 100mm x 75mm rectangular blocks in 80 and 120 grit. For hand finishing of curves and contours where a flat sanding disc won't follow the surface.

Need help choosing the right grade or size? Our Technical PDF's Library has specification guides and technical charts. Prices include GST and free standard delivery anywhere in Australia.

Working through a fabrication or construction job that also needs drill bits? Browse the matched Drill Bits range for jobber drills, cobalt drills for stainless, step-tip drills, holesaws and matched cutting compound.

FREQUENTLY ASKED QUESTIONS

How do I choose between a cutting disc and a grinding disc?

Cutting discs are thin (1-3mm) for slicing through metal at the disc edge - hold the grinder perpendicular to the workpiece and let the thin disc do the work. Grinding discs are thick (6mm) for removing metal with the disc face held at 25-30 degrees to the surface. Don't use cutting discs to grind (the thin disc fractures under side load) and don't use grinding discs to cut (the thick disc removes too much material and cuts wide).

Why does my flap disc wear out so fast on stainless?

Two reasons: wrong grain type and excessive pressure. Standard aluminium oxide flap discs glaze over on stainless's work-hardened surface. Switch to zirconia or ceramic grain (Alpha Silver Series, Klingspor premium) which self-sharpen as the grain fractures. Also reduce hand pressure - more pressure heats the disc and welds the grain to the surface, accelerating wear. Let the disc do the work.

What does 'TZ Special' mean on a cutting disc?

Klingspor's TZ Special designation marks their thin, high-performance metal-cutting disc series with bonded aluminium oxide grain. Reinforced with two layers of fibreglass for safety, rated 80m/sec, and made specifically for cordless and 110V angle grinders cutting steel and stainless. The general workshop default for sheet metal and section cutting.

Can I use a metal cutting disc on stainless steel?

Yes - the Klingspor TZ Special is rated for both. The 'A60' grain designation (60-grit aluminium oxide) is the standard for metal and stainless. Avoid using discs rated for ferrous metal only on stainless - sulphur or chlorine contamination in the bond contaminates the stainless surface and accelerates corrosion.

How fine should I sand metal before painting?

120 to 180 grit for general industrial paint; 240 grit for automotive primer; 320 grit for finish coats. Coarser sanding leaves scratch marks that show through paint; finer sanding doesn't give the paint enough mechanical key to adhere properly. The flap-disc-then-sanding-disc sequence (60 -> 120 -> 240) is the standard prep for a painted finish.

What's the difference between a flap disc and a sanding disc?

Flap discs are overlapping cloth flaps of bonded abrasive grain on a fibreglass backing - aggressive material removal, runs at angle grinder speeds (9-14,000 RPM). Sanding discs are flat single-layer abrasive on hook-and-loop or PSA backing, used on an orbital sander at much lower speed (4-10,000 OPM). Flap discs for fab work; sanding discs for surface finish prep.

Do abrasive discs have an expiry date?

Yes - bonded abrasive discs carry a manufacturer expiry date 3 years from manufacture. After that date the resin bond can degrade and the disc is no longer rated for its labelled RPM. Check the date code on every disc before use, especially low-turnover stock. Past-date discs are safe to dispose of in general waste.

What grit should I start with for weld dressing?

60 grit flap disc for the bulk weld removal, then 80 or 120 to blend the flap-disc marks into the surrounding base metal. For a heavy weld bead, start with a 6mm grinding disc, switch to a 60 grit flap disc once the bead is mostly removed, then finish with 80 / 120 / 180 depending on the required surface finish.

Can I use a 125mm disc on a 100mm angle grinder?

NO. The 100mm grinder's guard is sized for 100mm discs; a 125mm disc won't fit under the guard or will hit the guard during work. Worse, the 100mm grinder's higher RPM will exceed the 125mm disc's rated max speed - risking disc burst. Always match the disc size to the grinder, and confirm the disc max RPM is greater than or equal to the grinder no-load RPM.

Why does my Roloc disc keep falling off the holder?

Three causes: the roll-on holder's stud is worn, the disc was over-tightened (deforming the disc back), or the holder spec doesn't match the disc spec (3M-pattern vs Klingspor QRC411 are similar but not identical). Replace the holder if the stud shows wear; use only firm hand-tight on the disc; and confirm holder + disc are matched-pattern.

What's the difference between Alpha Silver Series and Klingspor?

Both are premium-tier abrasive ranges. Alpha is Australian-owned (Sheffield Group) and the Silver Series flap discs are zirconia/ceramic grain rated for stainless and alloy steel. Klingspor is German-engineered (a long-established European abrasive house) with the TZ Special cutting, Extra A24 grinding, and PS22K sanding lines. Both are stocked side by side because trade users tend to have a personal preference - pick by familiar brand or by published specifications.

Where do I find the technical data sheet for each abrasive?

Per-SKU technical data is on each product page. For the full abrasive selection chart by application, grit and substrate, see Technical PDF's Library.

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 abrasive disc or pad.