Types of Metals for Manufacturing: Properties, Machinability, Cost and Selection

What is metal in a manufacturing context? It is a metallic material selected not only by family name, but by alloy or grade, condition, product form, process route, service environment and verification requirement. The main types of metals used in manufacturing include ferrous metals such as carbon steel, alloy steel, stainless steel and cast iron, plus non ferrous metals such as aluminum, copper alloys, titanium, magnesium, zinc and nickel alloys. These metal types differ in strength, stiffness, density, hardness, ductility, conductivity, corrosion response and temperature capability. This guide compares different types of metals and turns those differences into a practical selection path for metal manufacturing, metal machining, sheet metal, welding, casting, additive manufacturing and finished-part procurement.

1. What Is Metal?

A metal is a material whose atomic bonding and electron structure give it characteristic electrical, thermal and mechanical behavior. What are metals in practical manufacturing terms? They are materials purchased as a defined alloy or grade in a defined condition and product form. What is a metal specification? It is the grade-level requirement that lets a supplier buy, process and verify the intended material.

Searches for metal, metals, metal material, metal materials and metallic materials often mix chemistry with manufacturing. For engineering material selection, the useful question is narrower: which material identity can meet the part’s function and still fit the chosen process, finish, inspection plan and supply chain?

What are metals made of? Pure metals are elemental materials. Metal alloys use controlled additions to change properties or processing behavior. Questions about metal and alloys, metal vs alloy, or alloy vs metal therefore describe different levels of material identity. Types of metal alloys and common metal alloys still need a grade-level designation before a supplier can treat the callout as a purchasing requirement.

2. Types of Metals Used in Manufacturing

The classification of metals can use several systems. Searches for base metals, light metals, transition metals, magnetic metals and non magnetic metals describe different scientific or commercial groupings. For manufacturing selection, the most useful first split is ferrous metals and nonferrous metals, followed by the exact alloy, condition and product form. This keeps broad metal categories connected to engineering and procurement.

2.1 Ferrous vs Non-Ferrous Metals

Ferrous metals are iron based. Common types of ferrous metals include carbon steel, alloy steel, stainless steel and cast iron. Non ferrous metals use another metallic base; common types of non ferrous metals include aluminum, copper and copper alloys, titanium, magnesium, zinc and nickel alloys.

Ferrous vs non ferrous metals is a useful first split, but iron content alone does not predict magnetism, corrosion resistance, strength or machinability. The spelling variant ferrous vs nonferrous describes the same distinction. Stainless steel is still ferrous. Some stainless grades are weakly magnetic or non magnetic in a given condition. Cast iron and wrought steel also machine differently because their microstructures and production routes differ. EPOC CRAFTER’s cast iron vs steel CNC machining guide examines that process-level difference by grade and microstructure.

2.2 Pure Metals, Base Metals and Light Metals

Pure metals matter when conductivity, corrosion behavior or another property is tied closely to chemistry. Most structural and machining applications use metal alloys because alloying can change strength, hardenability, wear, corrosion response or workability.

Base metals and light metals are useful search categories, but neither term is a complete material specification. Aluminum and magnesium are light metals by density, while copper, nickel and zinc are commonly treated as base metals in commercial usage. A drawing still needs the grade, condition and stock form that the supplier will purchase.

2.3 Common Metals, Metal Alloys and Grades

Common metals used in engineering include steels, aluminum alloys, copper alloys, titanium alloys, nickel alloys, magnesium alloys, zinc alloys and cast irons. The metal grade is the level that connects the material to a specification, certificate and acceptance requirement.

A drawing that says “aluminum” leaves open 5052 sheet, 6061 plate or bar, 7075 stock and many casting alloys. “Stainless steel” leaves 304, 316L, 303, 17-4 PH and other grades open. The same issue appears with copper, brass, bronze and alloy steel. EPOC CRAFTER’s metal grades and material properties resource carries the grade-level data that a broad metal article should not duplicate.

3. Properties of Metals That Matter in Manufacturing

The properties of metals matter only when they answer a design, process or service question. Mechanical properties of metals include yield strength, tensile strength, elastic modulus, hardness, ductility and toughness. Chemical properties of metals and environmental behavior include corrosion response and compatibility with service media. Density, melting behavior, conductivity and magnetism may control weight, thermal, electrical or process decisions.

ASTM E8/E8M-25 covers room-temperature tensile testing of metallic materials and determination of yield strength, tensile strength, elongation and reduction of area. ISO 6892-1:2019 is current after confirmation in 2025 and specifies tensile testing of metallic materials at room temperature. Test values need their material condition, specimen basis and applicable product specification; a generic property table is not a purchase requirement.

3.1 Strength, Hardness, Toughness and Ductility

Metal strength is not one number. Yield strength addresses permanent deformation, tensile strength addresses maximum tensile loading before fracture in the test, and elastic modulus addresses elastic stiffness. Searches for the strongest metal or strongest metals therefore need a defined metric and service condition. High strength metals can still be poor choices when stiffness, fatigue, corrosion, weight or manufacturing behavior controls the part.

The hardness of metals helps with indentation and wear questions, but metal hardness can also increase cutting forces or change tool selection. Metal ductility and the ductility of metals matter when a feature must bend or redistribute local strain. Metal toughness matters where crack initiation and propagation under impact or cyclic loading are relevant.

ASTM E111-17(2025)e1 covers Young’s modulus, tangent modulus and chord modulus. The method ties modulus to the stress mode and test conditions. EPOC CRAFTER’s metal strength chart for CNC materials keeps grade, condition, hardness and density together for detailed comparison.

3.2 Density and Lightweight Metals

The density of metals controls mass at a fixed volume. Metal density alone does not identify the lightest successful design because section geometry may change when strength or stiffness changes. Lightweight metals such as aluminum, magnesium and titanium can reduce mass, but a strong lightweight metal still has to meet stiffness, joining, corrosion and process requirements.

A density comparison therefore belongs beside strength and geometry, not in a separate ranking. The final design may use more volume of a lower-density material or less volume of a denser one.

3.3 Electrical and Thermal Conductivity

The conductivity of metals can dominate bus bars, electrical contacts, heat spreaders and thermal interfaces. Electrical conductivity of metals is not the same decision as thermal conductivity of metals, even though both are influenced by alloy chemistry and condition. Conductive metals and high conductivity metals can sacrifice strength or machinability compared with more heavily alloyed grades, so metal conductivity must be tied to the function being designed.

Copper is a common example: C10100, C10200 and C11000 are distinct copper designations. A requirement for electrical conductivity should name the grade and verification basis instead of relying on the word “copper.”

3.4 Corrosion, Heat, Magnetism and Wear

Corrosion resistant metals include suitable stainless steels, titanium alloys, nickel alloys, aluminum alloys and copper alloys, but resistance depends on the actual medium, temperature, galvanic couple and finish. Heat resistant metals need acceptable properties at service temperature, not only a high melting point. The melting point of metals and a metal melting point value can inform process limits, yet neither replaces elevated-temperature strength or oxidation data.

Magnetic metals and non magnetic metals need grade and condition context. Austenitic stainless steels can respond differently from ferritic or martensitic grades. Wear resistant metals, hard metals and ductile metals can each solve a different service problem while changing machining, forming or joining behavior. These property conflicts are why metal properties comparison should be tied to the part’s controlling requirement.

Property	Engineering question	Why it changes selection	What to verify
Yield strength	Will the part permanently deform under design load?	Sets a strength boundary for load-bearing features	Grade, condition, product specification, test basis
Tensile strength	Is tensile fracture part of the governing failure mode?	Supports tensile strength and fracture comparisons	Grade, condition, specimen and test standard
Elastic modulus	Will the part deflect too far while still elastic?	Controls elastic stiffness with geometry	Stress mode, temperature, material condition and test basis
Density	What mass results from the required geometry?	Affects weight and stock mass	Material identity and property source
Hardness	Does the surface need wear or indentation resistance?	Can change wear response and machining route	Hardness scale, condition and test method
Ductility / malleability	Must the part bend or tolerate local strain?	Influences forming and crack risk	Temper or condition, product form and test basis
Corrosion resistance	Will the material survive the service environment?	Can override strength or cost advantages	Medium, temperature, galvanic couple, exposure and finish
Thermal / electrical conductivity	Must the part transfer heat or current?	Can dominate heat-spreader, bus-bar and contact design	Alloy, condition, temperature and requirement

4. Metal Alloys and Grades: Condition and Product Form

Metal alloys and metal grades are the bridge between broad material selection and procurement. Grade alone can still be incomplete because temper, heat treatment and product form can change specified properties and manufacturing behavior.

ASTM B209/B209M-21a covers aluminum sheet and plate. ASTM B211/B211M-23 covers rolled or cold finished aluminum bar, rod and wire. ASTM B221-21 / B221M-21 covers extruded bars, rods, wire, profiles and tubes. The same alloy designation can appear in more than one product form, but the governing product specification changes.

Stainless bar shows the same split. ASTM A276/A276M-25 covers stainless steel bars and shapes and recognizes supplied conditions. ASTM A582/A582M-22 separately covers free machining stainless steel bars. Copper bar and rod are covered by product-specific standards such as ASTM B187/B187M-26 for defined copper products and UNS designations.

A supplier substitution that changes plate to extrusion, bar to forging, or one heat-treatment condition to another should be treated as an engineering change until the controlling properties, process route and acceptance evidence have been checked. EPOC CRAFTER’s heat treatment before or after CNC machining article explains why thermal sequence can change hardness, machining strategy and dimensional control.

Product form	Current ASTM example used here	Scope distinction
Sheet and plate	ASTM B209/B209M-21a	Flat sheet, coiled sheet and plate in listed alloys and tempers
Rolled or cold finished bar, rod and wire	ASTM B211/B211M-23	Rolled or cold finished wrought products in listed alloys and tempers
Extruded bar, rod, wire, profiles and tubes	ASTM B221-21 / B221M-21	Extruded wrought products; product form and temper remain part of the specification

5. Metal Manufacturing Process Fit

Metal manufacturing is not a single process. The same material family can behave very differently in metal CNC machining, sheet forming, welding, casting, additive manufacturing or surface finishing. Process fit should be screened before the grade is frozen.

Manufacturing route	Material behavior to check	Manufacturing consequence
CNC machining	Chip formation, hardness, work hardening, thermal behavior	Tool wear, chip control, burrs, heat and dimensional movement
Sheet metal fabrication	Ductility, malleability, bend response, springback, surface condition	Cracking, bend variation and cosmetic damage
Welding	Alloy chemistry, heat-affected-zone response, thermal expansion	Cracking, distortion and local property change
Casting	Castability, shrinkage, feeding and section sensitivity	Porosity, shrinkage and local variation
Metal additive manufacturing	Feedstock, qualified process, build orientation and post processing	Support removal, distortion, anisotropy and secondary machining
Surface finishing	Substrate chemistry, hardness and surface condition	Finish compatibility, appearance and dimensional change

5.1 CNC Machining and Metal Cutting

Metal machining exposes chip formation, hardness, work hardening, thermal behavior, burr formation and tool wear. Metal cutting therefore depends on the exact alloy and condition. ASTM A582/A582M-22 is a useful example because free machining stainless steel bar is specified separately from broader stainless bar products.

Metals for CNC machining are chosen by a combination of function and machinability. A CNC metal that cuts quickly but fails corrosion, strength or conductivity requirements is not a viable substitute. EPOC CRAFTER’s CNC machining material cost guide compares machining-related cost drivers, while its CNC machining services page defines the process capability route.

5.2 Sheet Metal, Welding, Casting, Additive Manufacturing and Finishing

Sheet metal fabrication puts more weight on ductility, malleability of metals, bend response, springback and surface condition. EPOC CRAFTER’s sheet metal material selection guide separates material choice from the broader sheet metal fabrication services process route.

Welding adds a thermal cycle that can alter local properties and geometry. Casting brings solidification and section sensitivity into the decision. Metal additive manufacturing links performance to feedstock, build process, orientation and post processing. Surface finishing can change dimensions and corrosion behavior; EPOC CRAFTER’s surface finishing services resource connects substrate choice with the finishing route. ASTM A967/A967M-25 provides one standards example for chemical passivation treatments on stainless steel parts.

Table 3 is a process-screening table, not a property database. It states mechanisms and decision consequences without unsupported universal rankings.

6. Machinability and CNC Machining of Metals

Machinability of metals is not one universal scale. Metal machinability can be evaluated through tool life, cutting force, cutting power, chip control, surface condition or production rate under a defined test. A rating from one system should not be treated as a universal score for every milling, turning, drilling or threading operation.

Machinable metals tend to support stable cutting with manageable chips and tool wear under the selected conditions. Long continuous chips can obstruct evacuation. Work hardening can leave a harder local surface after rubbing or unstable cutting. Low thermal conductivity can keep more heat near the tool. Soft, adhesive alloys can build up on the cutting edge. These mechanisms explain why machining metals must be evaluated by grade, condition, geometry, tool engagement and coolant strategy.

Thin walls add another variable. A material can have high strength and still move after heavy stock removal because stock condition, residual stress, clamping, heat and cutting sequence affect dimensional stability.

7. Metal Cost, Availability and Sourcing

Metal cost should be evaluated as finished-part cost, not only stock price. The cost of metals enters the quote together with stock utilization, machining time, tooling, setup, heat treatment, surface finishing, inspection, scrap risk and material availability.

Metal sourcing also works at the grade and product-form level. A technically suitable alloy may be hard to obtain in the required temper, diameter, plate thickness or extrusion size. Metal availability can change lead time or make another verified grade more practical. Metal procurement should therefore lock the required function first, then allow supplier proposals only inside defined substitution rules.

A metal cost comparison remains durable when it explains cost drivers instead of live market prices. Metal price comparison changes with region and date, while machining time, tool wear, finishing steps and inspection requirements remain part-specific cost drivers.

8. How to Choose a Metal for Manufacturing

A practical metal selection guide should move from function to evidence. Start with the service load, environment, temperature, weight, conductivity or wear requirement. Then screen manufacturing materials by process fit. Resolve the alloy or grade, condition and product form, then define finish, CTQs, documentation and substitution rules.

This sequence works for materials for manufacturing across CNC, sheet metal and mixed-process assemblies. It also prevents metal material selection from collapsing into a simple “aluminum vs steel” choice when geometry, heat treatment, corrosion or inspection is driving the part.

8.1 Drawing and RFQ Requirements

A manufacturing-ready material callout should identify the alloy or grade, condition or temper, product form and applicable material specification. Finished-part CTQs such as dimensions, GD&T, surface texture, threads, hardness and finish should remain separate so raw material conformity is not confused with final part acceptance. EPOC CRAFTER’s tolerances and standards resource covers the dimensional and inspection side, while its DFM design guidelines connect geometry with manufacturing constraints.

Depending on the program, the RFQ may also state MTR or CoC requirements, heat or lot traceability, chemistry or mechanical-property evidence, hardness checks and process certifications. A broad “or equivalent” note creates risk when it does not define who approves the substitute and which properties must remain equivalent.

8.2 Material Substitution Review

A proposed substitute should be checked against the reason the original material was selected. Compare specification scope, grade, condition, product form, design-controlling properties, corrosion environment, process route, finish and inspection evidence.

A substitute can match yield strength and still differ in conductivity, corrosion behavior, work hardening, weldability or stock form. Supplier availability is useful commercial information, but it does not replace engineering approval when the change affects a CTQ or service requirement. EPOC CRAFTER’s end-to-end manufacturing services page shows where material procurement, processing, finishing and inspection meet in one project path.

RFQ or drawing field	What to state	Decision value
Alloy or grade	Recognized grade, alloy or UNS designation	Defines material identity
Condition or temper	Applicable temper or heat-treated condition	Controls property and process state
Product form	Plate, sheet, bar, extrusion, casting or forging	Connects material to the correct product specification
Material specification	Applicable ASTM, ISO, SAE, AMS or contract requirement	Defines acceptance requirements
Critical properties	Only the properties required by the design	Prevents generic property assumptions
Heat treatment and finish	Required final condition and finish	Controls process sequence and final function
Dimensional CTQs	Dimensions, GD&T and surface texture	Separates finished-part acceptance from raw-material acceptance
Documentation	MTR, CoC or other required records	Defines traceability evidence
Substitution policy	Allowed, prohibited or approval required	Prevents uncontrolled material changes
Inspection requirement	Defined material, dimensional or finish checks	Connects verification to functional risk

9. Common Metal Applications in Manufacturing

The uses of metals follow the property and process requirements of the part. Aluminum alloys appear in lightweight housings, fixtures, heat-management parts and formed enclosures. Steels and cast irons appear in shafts, tooling, machine structures and loaded components. Copper alloys appear in electrical, thermal, bearing and wear applications. Titanium and nickel alloys serve environments where corrosion, temperature or specific strength justify their higher processing cost.

Industrial uses of metals are broad, so this section stays at application level. Dedicated material pages should carry grade-specific property data. Metals used in manufacturing and metals used in engineering become actionable only after the grade, condition, product form and process route are defined.

10. Practical Metal Selection Matrix

A metal properties comparison should narrow candidates without implying that one family is universally better. The matrix below uses representative grades and groups as navigation points. Final procurement still needs the exact grade, condition, product form and governing specification.

Metal family	Representative grades / groups	Selection driver	Manufacturing issue to check	Main selection risk
Aluminum	5052, 6061, 7075 families	Low density; broad machining or forming use depending on grade	Temper, residual stress, forming and anodizing response	Leaving grade, temper or form undefined
Stainless steel	304, 316L, 303, 17-4 PH families	Corrosion resistance, strength or service environment	Work hardening, machinability, heat treatment and passivation	Treating all stainless grades as interchangeable
Carbon / alloy steel	1018, 1045, 4140 families	Strength, stiffness, wear and heat-treatment options	Condition, hardness and corrosion protection	Comparing grades without delivery condition
Copper	C10100, C10200, C11000 families	Electrical or thermal conductivity	Chip control, burrs and required conductivity	Assuming all copper grades behave alike
Brass	C36000 and application-specific brasses	Machinability, threads, fittings or wear	Exact alloy, forming, joining and regulatory limits	Extending free-cutting behavior to every brass
Bronze	Bearing bronze and aluminum bronze families	Wear, bearing service or corrosion	Casting or wrought form, machining and joining	Treating bronze as one material
Titanium	Grade 2, Grade 5 and other specified grades	Specific strength or corrosion resistance	Cutting heat, tool wear, stock form and finishing	Using family data without resolving grade
Nickel alloys	Alloy-specific nickel systems	Heat or corrosion service	Work hardening, cutting heat and certification	Using a family or trade name as a complete specification
Cast iron	Gray, ductile and other specified cast irons	Damping, cast geometry, wear or structure	Graphite form, casting condition and machined CTQs	Applying wrought-steel assumptions

Source basis: representative grades and groups are cross-checked against EPOC CRAFTER’s published materials and properties data and the product-specific standards cited in Sections 3 and 4. No universal property ranking is implied.

11. Questions Engineers Ask Before Choosing a Metal

11.1 How do you choose a metal for manufacturing?

Choose a metal by screening the function first, then the manufacturing route, grade, condition, product form, finish, CTQs and verification requirement. Cost and availability enter after the part’s controlling requirements are known.

11.2 Which metals are easiest to machine?

There is no universal easiest metal across all operations. Free cutting brass and free machining steels or stainless grades can machine very well, but chip control, hardness, geometry, tooling and finish requirements still change the result.

11.3 What metals are used in CNC machining?

Common CNC metals include aluminum alloys, carbon and alloy steels, stainless steels, brass, bronze, copper, titanium and nickel alloys. The useful choice is the specific grade and condition that satisfies function while remaining practical to cut and inspect.

11.4 Can one metal grade be substituted for another?

A substitution can be accepted after the controlling requirements are checked and the responsible engineering authority approves the change. Matching one strength value does not prove equivalence in corrosion, conductivity, formability, machinability or product form.

11.5 How should metal be specified on an engineering drawing?

State the alloy or grade, condition or temper, product form and applicable material specification. Add heat treatment, finish, CTQs, inspection and documentation requirements where the design needs them.