Raw Materials

Bronze Bar Stock

Tool Steels

About Raw Materials

Raw materials at AIMS Industrial means engineering bar stock for toolroom, maintenance and prototype work — high-speed steel (HSS), silver steel and bronze bar. This is a focused range built around what fitters, toolmakers and maintenance teams actually pull off the shelf to grind a custom punch, turn a replacement bush, or make a one-off pin to keep a machine running. We don't pretend to be a mill supplier — for structural mild steel, 4140 shaft stock, stainless rod or aluminium plate, you're better off with a steel merchant who carries those in length. What we do carry is the precision-grade tool-and-die material that's hard to find locally on short notice.

Quick Reference — Material Selection by Application

Application	Recommended material	Form factor	Why
Custom lathe tools, form tools, parting blades	M2 HSS	Square or rectangular bar	Hardens to ~63-65 HRC, good red-hardness for general cutting
Heavy-duty cutting in tough alloys, stainless	M42 cobalt HSS	Square bar	~67-69 HRC, holds edge at higher temperatures than M2
Custom drill bits, reamers, milling cutters	M2 HSS	Round bar	Standard toolmaking grade, easy to grind
Punches, pins, small shafts, gauge pins	Silver steel (W1)	Round bar, pre-ground	Water-hardening, ground to h9 tolerance — minimal turning needed
Plain bearings, bushes, wear strips, glands	Bronze (solid bar)	Solid round bar	Low-friction bearing surface, good machinability
Bushings where ID is close to bar OD	Bronze (hollow bar)	Hollow round bar	Saves machining time and material vs boring out solid stock
Replacement keys cut from stock	See key steel	Bright square bar	Pre-ground to BS 4235 key dimensions
Stocked key shapes (parallel, gib-head, Woodruff)	See key stocks	Cut to length	Buy the key, not the bar

The honest scope: AIMS' raw materials range is tooling and bearing stock. Mild steel structural bar, 4140 alloy shaft, stainless round and aluminium plate aren't part of this range. If you need those, a steel merchant will be cheaper and faster.

High-Speed Steel (HSS) — Tool & Cutter Material

HSS is the workshop's go-to grade for making your own cutting tools. It hardens to a hard, wear-resistant edge that holds up under cutting heat — the "high-speed" name comes from the fact early HSS grades could cut at speeds that destroyed carbon steel tools. AIMS stocks Maxigear HSS in two grades:

M2 HSS (Standard)

M2 is the workhorse general-purpose toolmaking grade. Hardens to roughly 63-65 HRC with proper heat treatment. Used for:

Lathe tool bits — turning, facing, parting, threading, form tools
Custom shapers and slotting tools
Small drills, reamers, taps when the standard size doesn't exist
Punches and dies for soft materials
Replacement cutters in older milling machines

Available in:

Round bar — metric and imperial sizes
Square bar — metric and imperial sizes
Rectangular flat bar — common toolbit cross-sections (e.g. 10mm × 100mm, 1/4" × 4", 3/8" × 4")

M42 Cobalt HSS

M42 contains around 8% cobalt and runs harder (~67-69 HRC) and hotter than M2. The cobalt content keeps the edge harder at elevated cutting temperatures, so M42 is the choice when you're cutting:

Stainless steel (304, 316, 17-4 PH)
Tough alloy steels (4140 heat-treated, 8620)
Inconel, titanium and other heat-resistant alloys (light work — for heavy work use carbide)
Hardened materials up to ~35 HRC

M42 is more brittle than M2 and harder to grind — but in the right application it lasts 2-3x longer between regrinds. Available in square bar sections.

Heat treatment of HSS

HSS arrives soft (annealed) for machining. After you've shaped the tool, it needs heat treatment to develop full hardness — typically austenitising at 1180-1220°C in a controlled atmosphere, quenching in oil or air, then triple-tempering at 540-560°C. This is shop work for a heat-treater, not a DIY job — quoting on heat treatment is something AIMS can help with if you don't have a local provider.

Silver Steel — Precision Punch and Pin Material

Silver steel is a water-hardening tool steel (broadly equivalent to BS 1407 / AISI W1, around 1.0-1.1% carbon) supplied as pre-ground bar. The bar arrives at close diametric tolerance (typically h9) with a polished finish — meaning a 6mm silver steel rod is actually 6.000mm to about 5.964mm, not 5.8mm like a hot-rolled round.

That precision is what makes silver steel useful: you can use it as supplied, or skim it lightly, instead of having to turn a chunk of bar down to size.

AIMS stocks Erasteel silver steel in both metric and imperial sizes, in round bar. Typical applications:

Custom punches — pin punches, ejector punches, marking punches
Drill bushings and locating pins — when a stock dowel pin doesn't fit the spec
Replacement shafts in small mechanisms — clock mechanisms, model engineering, gauge fixtures
Reamers and taps in unusual sizes — turn the body from silver steel, heat-treat, finish-grind the cutting geometry
Gauge pins for inspection work — heat-treat after machining, lap to size

Heat treatment of silver steel

Water-hardening, as the name suggests. Heat to ~780-810°C (cherry red), quench in clean water (no oil, no contamination), then temper for the hardness required:

180-220°C → ~63-64 HRC (punches, cutting tools)
250-300°C → ~60 HRC (springs, hard-wearing components)
400°C → ~55 HRC (tougher, less brittle)

Quench cracking is a real risk on water-hardening steel — keep the section uniform, avoid sharp internal corners, and chamfer holes before heat treatment.

Bronze Bar — Bearing & Bushing Material

Bronze is the standard plain bearing material for any application where you don't want a needle or ball bearing — slow-speed, oscillating, heavy-load, dusty, wet, or maintenance-light environments. Properly designed bronze bushings outlast rolling-element bearings in agriculture, mining, marine and heavy machinery applications because they tolerate misalignment, shock loading, and contaminated environments.

AIMS stocks bronze bar in two forms:

Bronze solid bar (imperial)

Solid round bronze bar for machining bushes, thrust washers, wear strips, glands, valve stems and gland-packing followers. Imperial sizes — standard fits and tolerances established under imperial conventions for replacement bushing work on older machinery (which is most of the bushing work tradies see).

Bronze hollow bar (imperial)

Pre-bored bronze tube saves time when the finished ID is close to the bar OD. Buying hollow bar instead of solid means less material to remove (faster machining, fewer chips, longer tool life) and a more concentric finished bore than boring a long deep hole in solid stock. Used heavily for:

Long bushings — pump shafts, conveyor pulley bushings
Replacement gland bushes on industrial valves
Custom-bored bushings where the finished ID is >50% of the OD

Bronze alloy notes

Bronze is a family of copper alloys, and the specific grade matters. Bearing bronze (often a phosphor-bronze or leaded bronze) is formulated for low friction and self-lubricating behaviour. Aluminium bronze is harder and tougher — used for marine fittings and heavy-load wear plates. Manganese bronze offers higher tensile strength. The stock AIMS carries is selected for general bushing/bearing service; if you have a specific alloy requirement (e.g. PB1, LG2, AB2, C95400), ring us with the application and we'll confirm what we can supply or source.

Form Factors — Round, Square, Rectangular

Form factor	Best for	Notes
Round bar	Shafts, pins, drills, reamers, bushings	Default for anything turned on a lathe
Square bar	Single-point lathe tools, shaper tools, slotting tools	Square section sits in a standard tool post without rotating
Rectangular (flat) bar	Form tools, parting blades, broaches	Wider face provides extra rigidity for cantilevered cuts
Hollow round bar (bronze)	Bushings where finished ID is >50% of OD	Saves machining time vs boring solid

Metric vs Imperial — What's Stocked

AIMS' raw materials range covers both metric and imperial. Maxigear HSS bar is stocked in metric (3mm, 4mm, 5mm, 6mm, 8mm, 10mm, 12mm rounds and similar square sections) and imperial (1/8", 3/16", 1/4", 5/16", 3/8", 1/2" — popular toolbit sections like 1/4" × 1/4", 3/8" × 3/8"). Erasteel silver steel comes in metric and imperial rounds. Bronze bar is supplied in imperial sizes — that's how the industry orders bronze for bushing work, and imperial sizes match the legacy fits on the machinery this material services.

If you're sizing a replacement bush from an imperial-spec original, work in imperial. If you're building something new from scratch, metric is normally easier to specify.

Standards Reference

Material	Standard	Notes
HSS — M2 grade	AISI M2 / DIN 1.3343 / BS BM2 / JIS SKH51	Tungsten-molybdenum HSS, ~6% W, 5% Mo, 4% Cr, 2% V
HSS — M42 cobalt grade	AISI M42 / DIN 1.3247 / BS BM42	~8% Co, 9.5% Mo, 1.5% W, 4% Cr — high-speed cobalt grade [VERIFY: AS 1239 currency for tool-steel grade classification]
Silver steel	BS 1407 / equivalent to AISI W1	Water-hardening, ~1.0-1.1% carbon, ground to h9 tolerance
Bronze bearing bar	AS 1565 (continuous-cast bronze rod) [VERIFY: current edition]	Australian standard for cast bronze rod stock — covers PB1, LG2, AB2 type alloys
Tolerance — ground bar	ISO 286 h9	Standard tolerance grade for ground silver steel

[VERIFY:] Standards edition years above are indicative. For certification-critical applications (defence, aerospace, food contact, nuclear) confirm the specific edition and material certification you need when you order, and we'll provide the corresponding mill test certificate where available.

Selection Criteria

Hardness and wear resistance

HSS (M2/M42) hardens to 63-69 HRC and holds an edge at cutting temperatures. Silver steel hardens to 63-64 HRC but loses temper above ~200°C — fine for punches and pins, not for cutting tools running hot. Bronze isn't heat-treated; its bearing properties come from the alloy composition, not from hardness.

Machinability before heat treatment

All three materials machine well in the supplied condition. HSS in annealed state is similar to mild steel in machinability. Silver steel cuts cleanly and chips well. Bronze cuts beautifully — sharp tools, light cuts, generous coolant, and it leaves a polished finish.

Toughness after heat treatment

M42 cobalt is harder but more brittle than M2 — don't use it for interrupted cuts where chipping is a concern. Silver steel quenched in water can crack on sharp section changes — design with generous radii. Bronze doesn't need heat treatment.

Cost

M42 cobalt is roughly 2-3x the price of M2. Worth it for high-volume work in tough materials; overkill for general lathe tools. Silver steel is similarly priced to mild ground bar in small diameters and well worth the premium for the pre-ground tolerance. Bronze hollow bar is more expensive per kilo than solid bar but saves so much machining time on long bushings that it usually wins on installed cost.

Common Applications by Trade

Toolmaking & jobbing

HSS square bar for lathe tools, HSS round for drills and reamers, silver steel rod for punches. Specialised tool steel grades (D2, A2, O1, H13) for production dies and moulds — AIMS doesn't currently stock these as bar; if you need them, talk to a tool steel specialist.

Maintenance & repair

Bronze bar for replacement bushings on conveyors, pumps, valve actuators, mining gearboxes, agricultural machinery. Silver steel for replacement pins, dowel pins, locating pins, ejector pins. HSS for grinding up custom lathe tools when the standard insert doesn't suit.

Marine & corrosion environments

Bronze handles seawater and chemical environments well. For specific marine bronze alloys (manganese bronze for propeller-shaft bushings, aluminium bronze for high-load marine fittings), contact us — we can advise on what's available and what we'd source.

Prototype & one-off engineering

The whole raw materials range exists for jobs where standard parts don't fit. A one-off replacement shaft for a forty-year-old machine. A custom punch profile that's not in any catalogue. A bushing where the original part number was lost decades ago. That's the role this range plays.

Cross-Material Comparison — When to Step Up or Across

From M2 HSS to M42 cobalt: when cutting stainless steel, hardened steel, or tough alloy steels, and tool life on M2 is too short. Don't jump to M42 for general carbon-steel work — M2 is cheaper to buy and easier to grind.

From HSS to solid carbide: at higher production volumes, faster cutting speeds, or in CNC environments, carbide outperforms even M42. AIMS' end mill range and reamer range are solid-carbide where appropriate. See our Carbide vs HSS guide for the threshold logic.

From silver steel to oil-hardening tool steel (O1): when the section is too large or too complex for water quenching without distortion or cracking. AIMS doesn't stock O1 in bar — talk to a tool steel merchant for sizes above 25mm or for parts with sharp section changes.

From bronze to needle/roller bearings: when speeds get higher and continuous-running duty is required. Bronze handles slow oscillating loads and shock; needle bearings handle high-RPM continuous duty. See our bearing reference guide for the crossover logic.

Companion Components

Raw materials sit alongside several adjacent ranges:

Key steel — bright pre-ground square bar for cutting your own keys. Stocked in metric and imperial sizes to BS 4235 dimensions. If you're cutting a key from stock, buy key steel rather than M2 HSS — it's cheaper and already at the right hardness.
Key stocks — pre-cut parallel keys, gib-head keys and Woodruff keys. If you can buy the key off the shelf, don't cut one from bar.
Shaft collars — for retaining components on shafts you've turned from bar stock.
Fasteners — bolts, screws, dowels and pins. Don't make a pin from silver steel when a standard dowel pin will do.
Cutting lubricants — Tap Magic and similar fluids for machining the bar stock you buy here.
Tool steels (parent collection) — the broader tool steel range, including HSS and silver steel.
Bronze bars (parent collection) — direct entry to bronze solid and hollow stock.

How to Order — What Info We Need

For raw materials orders, the more spec you can give us up front, the faster the quote comes back. Useful information:

Material and grade — e.g. "M2 HSS square bar" or "phosphor-bronze solid rod"
Section size — diameter (round), face size (square), face × depth (rectangular)
Length — cut-to-length, full bar, or specific number of cut pieces
Quantity — single piece, workshop pack, or production lot
Certification — mill test certificate required, or stock-grade material acceptable
Tolerance — for ground bar, the supplied tolerance band (h9 is standard for silver steel)

If you're working off a drawing or replacing an original part, send through the drawing or the old part details and we'll work out what suits. Some grades and sizes we hold stocked; others are mill-order with lead time. Ringing us up front saves a lot of back-and-forth.

AIMS' Note on Raw Material Sourcing

We're upfront about scope. AIMS' raw materials range is precision tooling and bearing stock — HSS, silver steel and bronze. For structural mild steel, 4140 alloy bar, stainless rod, aluminium plate, sheet steel, RHS/SHS sections, plate or coil, a steel merchant is the right supplier. We carry what fits the toolroom-and-maintenance use case AIMS has supported for decades, and we'd rather point you to the right place than sell you something that's not our strength.

For specialty tool steel grades (D2, A2, O1, H13, S7 — cold work, hot work, shock-resisting tool steels), we'd source on quote — talk to us about the application and we'll come back with options.

Companion Resources

Material Density Chart — Steel, aluminium, brass and bronze density values for weight calculations on bar stock.
Carbide vs HSS End Mill — When to upgrade from HSS to solid carbide for milling work.
Cobalt Drill Bit Guide — M35 vs M42 cobalt drill grades, stainless drilling, selection logic.
End Mill Guide — Geometry, flute count and material selection for milling cutters.
Bearing Cross Reference Guide — When bronze bushings are the right call vs needle/roller bearings.

Need to talk through a specific application, or want to confirm grade availability before ordering? Contact our team — we've been supplying Australian industry since 1988, and bar stock for one-off engineering work is bread and butter for us.